HP 5920 & 5900 Switch Series
Layer 3 - IP Routing
Configuration Guide
Part number: 5998-2895
Software version: Release2207
Document version: 6W100-20121130
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Contents
IP routing basics ··························································································································································· 1 Routing table ······································································································································································ 1 Dynamic routing protocols ··············································································································································· 2 Route preference ······························································································································································· 2 Load sharing ······································································································································································ 3 Route backup ····································································································································································· 3 Route recursion ·································································································································································· 3 Route redistribution ··························································································································································· 3 Configuring the maximum number of ECMP routes ······································································································ 4 Displaying and maintaining a routing table ·················································································································· 4 Configuring static routing ············································································································································ 6 Configuring a static route················································································································································· 6 Configuring BFD for static routes····································································································································· 7 Bidirectional control mode ······································································································································ 7 Single-hop echo mode ············································································································································· 8 Configuring static route FRR ············································································································································· 9 Configuration guidelines ········································································································································· 9 Configuration procedure ········································································································································· 9 Displaying and maintaining static routes ···················································································································· 10 Static route configuration examples ····························································································································· 10 Basic static route configuration example ············································································································ 10 BFD for static routes configuration example (direct next hop) ·········································································· 12 BFD for static routes configuration example (indirect next hop) ······································································· 14 Static route FRR configuration example ·············································································································· 17 Configuring a default route ······································································································································· 19 Configuring RIP ·························································································································································· 20 Overview········································································································································································· 20 RIP route entries ····················································································································································· 20 Routing loop prevention ········································································································································ 20 RIP operation ·························································································································································· 20 RIP versions ···························································································································································· 21 Protocols and standards ······································································································································· 21 RIP configuration task list ··············································································································································· 21 Configuring basic RIP ···················································································································································· 22 Enabling RIP ··························································································································································· 22 Controlling RIP reception and advertisement on interfaces ·············································································· 23 Configuring a RIP version ····································································································································· 23 Configuring RIP route control ········································································································································ 24 Configuring an additional routing metric ··········································································································· 24 Configuring RIPv2 route summarization·············································································································· 25 Disabling host route reception ····························································································································· 26 Advertising a default route ··································································································································· 26 Configuring inbound/outbound route filtering ··································································································· 26 Configuring a preference for RIP ························································································································· 27 Configuring RIP route redistribution····················································································································· 27 Tuning and optimizing RIP networks ···························································································································· 28 Configuration prerequisites ·································································································································· 28 i
Configuring RIP timers··········································································································································· 28 Configuring split horizon and poison reverse ···································································································· 29 Configuring the maximum number of ECMP routes ·························································································· 29 Enabling zero field check on incoming RIPv1 messages ·················································································· 30 Enabling source IP address check on incoming RIP updates ············································································ 30 Configuring RIPv2 message authentication ········································································································ 31 Configuring the RIP packet sending rate ············································································································ 31 Configuring RIP Graceful Restart ·································································································································· 31 Configuring BFD for RIP················································································································································· 32 Configuring RIP FRR ······················································································································································· 32 Displaying and maintaining RIP ··································································································································· 33 RIP configuration examples ··········································································································································· 34 Configuring basic RIP ··········································································································································· 34 Configuring RIP route redistribution····················································································································· 36 Configuring an additional metric for a RIP interface ························································································· 38 Configuring RIP to advertise a summary route ··································································································· 40 Configuring BFD for RIP (single-hop echo detection) ························································································· 42 Configuring RIP FRR ·············································································································································· 45 Configuring OSPF ······················································································································································ 48 Overview········································································································································································· 48 OSPF packets ························································································································································· 48 LSA types ································································································································································ 48 OSPF areas ···························································································································································· 49 Router types···························································································································································· 51 Route types ····························································································································································· 52 Route calculation ··················································································································································· 53 OSPF network types ·············································································································································· 53 DR and BDR ··························································································································································· 53 Protocols and standards ······································································································································· 54 OSPF configuration task list ·········································································································································· 55 Enabling OSPF ······························································································································································· 56 Configuration prerequisites ·································································································································· 56 Configuration guidelines ······································································································································ 56 Configuration procedure ······································································································································ 57 Configuring OSPF areas ··············································································································································· 57 Configuring a stub area ······································································································································· 58 Configuring an NSSA area·································································································································· 58 Configuring a virtual link ······································································································································ 59 Configuring OSPF network types ································································································································· 59 Configuration prerequisites ·································································································································· 60 Configuring the broadcast network type for an interface ················································································· 60 Configuring the NBMA network type for an interface ······················································································ 60 Configuring the P2MP network type for an interface ························································································ 61 Configuring the P2P network type for an interface ··························································································· 62 Configuring OSPF route control ··································································································································· 62 Configuration prerequisites ·································································································································· 62 Configuring OSPF route summarization ············································································································· 62 Configuring inbound OSPF route filtering ·········································································································· 63 Configuring Type-3 LSA filtering ·························································································································· 64 Configuring an OSPF cost for an interface ········································································································ 64 Configuring the maximum number of ECMP routes ·························································································· 65 Configuring OSPF preference ······························································································································ 65 Configuring OSPF route redistribution ················································································································ 65 Advertising a host route ········································································································································ 67 ii
Tuning and optimizing OSPF networks························································································································ 67 Configuration prerequisites ·································································································································· 67 Configuring OSPF timers ······································································································································ 68 Specifying LSA transmission delay ······················································································································ 68 Specifying SPF calculation interval ······················································································································ 69 Specifying the LSA arrival interval······················································································································· 69 Specifying the LSA generation interval ··············································································································· 70 Disabling interfaces from receiving and sending OSPF packets······································································ 70 Configuring stub routers ······································································································································· 71 Configuring OSPF authentication ························································································································ 71 Adding the interface MTU into DD packets ········································································································ 72 Configuring the maximum number of external LSAs in LSDB ··········································································· 72 Configuring OSPF exit overflow interval············································································································· 72 Enabling compatibility with RFC 1583 ··············································································································· 73 Logging neighbor state changes·························································································································· 73 Configuring OSPF network management ··········································································································· 73 Configuring the LSU transmit rate ························································································································ 74 Enabling OSPF ISPF ·············································································································································· 74 Configuring OSPF Graceful Restart······························································································································ 75 Configuring the OSPF GR Restarter····················································································································· 75 Configuring OSPF GR Helper ······························································································································ 76 Triggering OSPF Graceful Restart························································································································ 77 Configuring BFD for OSPF ············································································································································ 77 Configuring bidirectional control detection ········································································································ 77 Configuring single-hop echo detection ··············································································································· 77 Configuring OSPF FRR ··················································································································································· 78 Configuration prerequisites ·································································································································· 78 Configuration guidelines ······································································································································ 78 Configuring OSPF FRR to calculate a backup next hop using the LFA algorithm ·········································· 78 Configuring OSPF FRR to specify a backup next hop using a routing policy················································· 79 Displaying and maintaining OSPF ······························································································································· 79 OSPF configuration examples ······································································································································ 80 Configuring basic OSPF ······································································································································· 80 Configuring OSPF route redistribution ················································································································ 83 Configuring OSPF to advertise a summary route······························································································· 85 Configuring an OSPF stub area··························································································································· 88 Configuring an OSPF NSSA area ······················································································································· 90 Configuring OSPF DR election ····························································································································· 92 Configuring OSPF virtual links ····························································································································· 96 Configuring OSPF Graceful Restart ····················································································································· 98 Configuring BFD for OSPF ································································································································· 101 Configuring OSPF FRR ········································································································································ 104 Troubleshooting OSPF configuration ························································································································· 106 No OSPF neighbor relationship established ···································································································· 106 Incorrect routing information ······························································································································ 106 Configuring IS-IS ····················································································································································· 108 Overview······································································································································································· 108 Terminology ························································································································································· 108 IS-IS address format············································································································································· 108 NET ······································································································································································· 109 IS-IS area ······························································································································································ 110 IS-IS network types ·············································································································································· 112 IS-IS PDUs ····························································································································································· 113 Protocols and standards ····································································································································· 114 iii
IS-IS configuration task list ··········································································································································· 115 Configuring basic IS-IS ················································································································································ 116 Configuration prerequisites ································································································································ 116 Enabling IS-IS ······················································································································································· 116 Configuring the IS level and circuit level ·········································································································· 117 Configuring P2P network type for an interface ································································································ 117 Configuring IS-IS route control ···································································································································· 118 Configuration prerequisites ································································································································ 118 Configuring IS-IS link cost ··································································································································· 118 Specifying a preference for IS-IS ······················································································································· 119 Configuring the maximum number of ECMP routes ························································································ 120 Configuring IS-IS route summarization ·············································································································· 120 Advertising a default route ································································································································· 121 Configuring IS-IS route redistribution ················································································································ 121 Configuring IS-IS route filtering ·························································································································· 121 Configuring IS-IS route leaking ·························································································································· 122 Tuning and optimizing IS-IS networks ························································································································ 123 Configuration prerequisites ································································································································ 123 Specifying intervals for sending IS-IS hello and CSNP packets ····································································· 123 Specifying the IS-IS hello multiplier ···················································································································· 123 Configuring a DIS priority for an interface ······································································································· 124 Disabling an interface from sending/receiving IS-IS packets ········································································· 124 Enabling an interface to send small hello packets ··························································································· 124 Configuring LSP parameters ······························································································································· 125 Controlling SPF calculation interval ··················································································································· 127 Configuring convergence priorities for specific routes ···················································································· 128 Setting the LSDB overload bit ····························································································································· 128 Configuring system ID to host name mappings································································································ 129 Enabling the logging of neighbor state changes ····························································································· 130 Enabling IS-IS ISPF ··············································································································································· 130 Enhancing IS-IS network security ································································································································ 130 Configuration prerequisites ································································································································ 130 Configuring neighbor relationship authentication ··························································································· 131 Configuring area authentication ························································································································ 131 Configuring routing domain authentication······································································································ 131 Configuring IS-IS GR ···················································································································································· 132 Configuring BFD for IS-IS············································································································································· 133 Configuring IS-IS FRR ··················································································································································· 133 Configuration prerequisites ································································································································ 133 Configuration guidelines ···································································································································· 134 Configuring IS-IS FRR to automatically calculate a backup next hop ···························································· 134 Configuring IS-IS FRR using a routing policy ···································································································· 134 Displaying and maintaining IS-IS ······························································································································· 134 IS-IS configuration examples ······································································································································· 135 Basic IS-IS configuration example ····················································································································· 135 DIS election configuration example··················································································································· 140 IS-IS route redistribution configuration example ······························································································ 144 IS-IS authentication configuration example······································································································· 147 IS-IS Graceful Restart configuration example ··································································································· 150 BFD for IS-IS configuration example ·················································································································· 151 IS-IS FRR configuration example ························································································································ 154 Configuring BGP ····················································································································································· 157 Overview······································································································································································· 157 BGP speaker and BGP peer ······························································································································· 157 iv
BGP message types ············································································································································· 157 BGP path attributes ············································································································································· 158 BGP route selection ············································································································································· 162 BGP route advertisement rules ··························································································································· 162 BGP load balancing ············································································································································ 162 Settlements for problems in large-scale BGP networks ···················································································· 163 MP-BGP································································································································································· 166 BGP configuration views ···································································································································· 167 Protocols and standards ····································································································································· 168 BGP configuration task list ·········································································································································· 168 Configuring basic BGP ················································································································································ 171 Enabling BGP······················································································································································· 171 Configuring a BGP peer ····································································································································· 171 Configuring a BGP peer group·························································································································· 173 Specifying the source interface for TCP connections ······················································································· 178 Generating BGP routes ················································································································································ 179 Injecting a local network ···································································································································· 180 Redistributing IGP routes····································································································································· 180 Controlling route distribution and reception ············································································································· 181 Configuring BGP route summarization ············································································································· 182 Advertising optimal routes in the IP routing table ···························································································· 183 Advertising a default route to a peer or peer group ······················································································· 183 Limiting routes received from a peer or peer group ························································································ 184 Configuring BGP route filtering policies ··········································································································· 185 Configuring BGP route dampening ··················································································································· 190 Controlling BGP path selection ··································································································································· 191 Specifying a preferred value for routes received ····························································································· 191 Configuring preferences for BGP routes ··········································································································· 192 Configuring the default local preference ·········································································································· 193 Configuring the MED attribute ··························································································································· 194 Configuring the NEXT_HOP attribute ················································································································ 198 Configuring the AS_PATH attribute ··················································································································· 200 Tuning and optimizing BGP networks························································································································ 205 Configuring the keepalive interval and hold time···························································································· 205 Configuring the interval for sending updates for the same route ··································································· 206 Enabling BGP to establish an EBGP session over multiple hops ···································································· 207 Enabling immediate reestablishment of direct EBGP connections upon link failure····································· 208 Enabling 4-byte AS number suppression ·········································································································· 208 Configuring MD5 authentication for BGP ········································································································ 209 Configuring BGP load balancing ······················································································································ 210 Disabling BGP to establish a session to a peer or peer group ······································································ 211 Configuring BGP soft-reset·································································································································· 211 Protecting an EBGP peer when memory usage reaches level 2 threshold···················································· 215 Configuring a large-scale BGP network ···················································································································· 216 Configuring BGP community ······························································································································ 216 Configuring a BGP route reflector ····················································································································· 218 Configuring a BGP confederation ····················································································································· 218 Configuring BGP GR ··················································································································································· 219 Enabling trap ································································································································································ 220 Enabling logging of session state changes ··············································································································· 221 Configuring BFD for BGP ············································································································································ 221 Displaying and maintaining BGP ······························································································································· 222 IPv4 BGP configuration examples ······························································································································ 225 Basic BGP configuration example ····················································································································· 225 v
BGP and IGP route redistribution configuration example ··············································································· 229 BGP route summarization configuration example ··························································································· 232 BGP load balancing configuration example ···································································································· 235 BGP community configuration example ············································································································ 238 BGP route reflector configuration example······································································································· 241 BGP confederation configuration example······································································································· 243 BGP path selection configuration example······································································································· 247 BGP GR configuration example ························································································································· 250 BFD for BGP configuration example ················································································································· 252 IPv6 BGP configuration examples ······························································································································ 256 IPv6 BGP basic configuration example ············································································································· 256 IPv6 BGP route reflector configuration example ······························································································ 259 BFD for IPv6 BGP configuration example ········································································································· 261 Troubleshooting BGP ··················································································································································· 265 Symptom ······························································································································································· 265 Analysis ································································································································································ 265 Solution ································································································································································· 265 Configuring PBR ······················································································································································ 267 Introduction to PBR ······················································································································································· 267 Policy ···································································································································································· 267 PBR and track······················································································································································· 268 PBR configuration task list ··········································································································································· 268 Configuring a policy ···················································································································································· 268 Creating a node ·················································································································································· 268 Configuring match criteria for a node ·············································································································· 268 Configuring actions for a node·························································································································· 269 Configuring PBR ··························································································································································· 269 Displaying and maintaining PBR ································································································································ 269 Packet type-based interface PBR configuration example ························································································· 270 Configuring IPv6 static routing ······························································································································· 272 Configuring an IPv6 static route ································································································································· 272 Configuring BFD for IPv6 static routes ······················································································································· 272 Bidirectional control mode ································································································································· 273 Single-hop echo mode ········································································································································ 274 Displaying and maintaining IPv6 static routes ·········································································································· 274 IPv6 static routing configuration examples ················································································································ 275 Basic IPv6 static route configuration example ·································································································· 275 BFD for IPv6 static routes configuration example (direct next hop) ······························································· 276 BFD for IPv6 static routes configuration example (indirect next hop) ···························································· 279 Configuring an IPv6 default route ·························································································································· 282 Configuring RIPng ··················································································································································· 283 Overview······································································································································································· 283 RIPng route entries ··············································································································································· 283 RIPng packets ······················································································································································· 283 Protocols and standards ····································································································································· 284 RIPng configuration task list ········································································································································ 284 Configuring basic RIPng ·············································································································································· 284 Configuring RIPng route control ································································································································· 285 Configuring an additional routing metric ········································································································· 285 Configuring RIPng route summarization ··········································································································· 285 Advertising a default route ································································································································· 286 Configuring inbound/outbound route filtering ································································································· 286 vi
Configuring a preference for RIPng··················································································································· 286 Configuring RIPng route redistribution ·············································································································· 287 Tuning and optimizing the RIPng network ················································································································· 287 Configuring RIPng timers ···································································································································· 287 Configuring split horizon and poison reverse ·································································································· 288 Configuring zero field check on RIPng packets ······························································································· 288 Configuring the maximum number of ECMP routes ························································································ 289 Configuring RIPng Graceful Restart···························································································································· 289 Displaying and maintaining RIPng ····························································································································· 290 RIPng configuration examples····································································································································· 290 Basic RIPng configuration example ··················································································································· 290 Configuring RIPng route redistribution ·············································································································· 292 Configuring OSPFv3 ··············································································································································· 296 OSPFv3 overview ························································································································································· 296 OSPFv3 packets··················································································································································· 296 OSPFv3 LSA types ··············································································································································· 296 Protocols and standards ····································································································································· 297 OSPFv3 configuration task list ···································································································································· 297 Enabling OSPFv3 ························································································································································· 298 Configuring OSPFv3 area parameters ······················································································································ 299 Configuration prerequisites ································································································································ 299 Configuring a stub area ····································································································································· 299 Configuring an OSPFv3 virtual link ··················································································································· 299 Configuring OSPFv3 network types ··························································································································· 300 Configuration prerequisites ································································································································ 300 Configuring the OSPFv3 network type for an interface ·················································································· 300 Configuring an NBMA or P2MP neighbor ······································································································· 301 Configuring OSPFv3 route control ····························································································································· 301 Configuration prerequisites ································································································································ 301 Configuring OSPFv3 route summarization ······································································································· 301 Configuring OSPFv3 inbound route filtering ···································································································· 301 Configuring Inter-Area-Prefix-LSA filtering ········································································································· 302 Configuring an OSPFv3 cost for an interface ·································································································· 302 Configuring the maximum number of OSPFv3 ECMP routes ········································································· 303 Configuring a preference for OSPFv3 ·············································································································· 303 Configuring OSPFv3 route redistribution ·········································································································· 303 Tuning and optimizing OSPFv3 networks ················································································································· 304 Configuration prerequisites ································································································································ 304 Configuring OSPFv3 timers ································································································································ 304 Specifying LSA transmission delay ···················································································································· 305 Specifying SPF calculation interval ···················································································································· 305 Specifying the LSA generation interval ············································································································· 306 Configuring a DR priority for an interface ········································································································ 306 Ignoring MTU check for DD packets ················································································································· 306 Disabling interfaces from receiving and sending OSPFv3 packets ······························································· 307 Enabling the logging of neighbor state changes ····························································································· 307 Configuring OSPFv3 GR ············································································································································· 307 Configuring GR Restarter···································································································································· 308 Configuring GR Helper ······································································································································· 308 Configuring BFD for OSPFv3 ······································································································································ 308 Displaying and maintaining OSPFv3 ························································································································· 309 OSPFv3 configuration examples ································································································································ 310 Configuring OSPFv3 areas ································································································································ 310 Configuring OSPFv3 DR election······················································································································· 314 vii
Configuring OSPFv3 route redistribution ·········································································································· 317 Configuring OSPFv3 GR ···································································································································· 320 Configuring BFD for OSPFv3 ····························································································································· 321 Configuring IPv6 IS-IS ············································································································································· 324 Overview······································································································································································· 324 Configuring basic IPv6 IS-IS ········································································································································ 324 Configuring IPv6 IS-IS route control ··························································································································· 325 Configuring BFD for IPv6 IS-IS ···································································································································· 326 Displaying and maintaining IPv6 IS-IS ······················································································································· 326 IPv6 IS-IS configuration examples ······························································································································ 327 IPv6 IS-IS basic configuration example ············································································································· 327 BFD for IPv6 IS-IS configuration example ········································································································· 331 Configuring IPv6 PBR ·············································································································································· 334 Introduction to IPv6 PBR ··············································································································································· 334 Policy ···································································································································································· 334 PBR and track······················································································································································· 335 IPv6 PBR configuration task list ··································································································································· 335 Configuring an IPv6 policy ········································································································································· 335 Creating an IPv6 node ········································································································································ 335 Configuring match criteria for an IPv6 node ···································································································· 335 Configuring actions for an IPv6 node ··············································································································· 336 Configuring IPv6 PBR ··················································································································································· 336 Displaying and maintaining IPv6 PBR························································································································ 336 Packet type-based IPv6 interface PBR configuration example ················································································· 337 Configuring routing policies ··································································································································· 339 Overview······································································································································································· 339 Filters ····································································································································································· 339 Routing policy ······················································································································································ 340 Configuring filters ························································································································································· 340 Configuration prerequisites ································································································································ 340 Configuring an IP prefix list ································································································································ 340 Configuring an AS path list ································································································································ 341 Configuring a community list ····························································································································· 341 Configuring an extended community list ·········································································································· 342 Configuring a routing policy······································································································································· 342 Configuration prerequisites ································································································································ 342 Creating a routing policy ··································································································································· 342 Configuring if-match clauses ······························································································································ 343 Configuring apply clauses·································································································································· 344 Configuring a continue clause ··························································································································· 345 Displaying and maintaining the routing policy ········································································································· 346 Routing policy configuration examples ······················································································································ 346 Applying a routing policy to IPv4 route redistribution····················································································· 346 Applying a routing policy to IPv6 route redistribution····················································································· 349 Support and other resources ·································································································································· 352 Contacting HP ······························································································································································ 352 Subscription service ············································································································································ 352 Related information ······················································································································································ 352 Documents ···························································································································································· 352 Websites······························································································································································· 352 Conventions ·································································································································································· 353 Index ········································································································································································ 355 viii
IP routing basics
IP routing directs IP packet forwarding on routers based on a routing table. This chapter focuses on
unicast routing protocols. For more information about multicast routing protocols, see IP Multicast
Configuration Guide.
Routing table
A router maintains at least two routing tables: a global routing table and a FIB. The FIB table contains
only the optimal routes, and the global routing table contains all routes. The router uses the FIB table to
forward packets. For more information about the FIB table, see Layer 3—IP Services Configuration
Guide.
Table 1 categorizes routes by different criteria.
Table 1 Route categories
Criterion
Categories
Destination
• Network route—The destination is a network. The subnet mask is less than 32 bits.
• Host route—The destination is a host. The subnet mask is 32 bits.
Whether the
destination is directly
connected
• Direct route—The destination is directly connected.
• Indirect route—The destination is indirectly connected.
• Direct route—A direct route is discovered by the data link protocol on an interface,
and is also called an "interface route."
Origin
• Static route—A static route is manually configured by an administrator.
• Dynamic route—A dynamic route is dynamically discovered by a routing protocol.
To view brief information about a routing table, use the display ip routing-table command:
<Sysname> display ip routing-table
Destinations : 19
Routes : 19
Destination/Mask
Proto
Cost
NextHop
Interface
0.0.0.0/32
Direct 0
Pre
0
127.0.0.1
InLoop0
1.1.1.0/24
Direct 0
0
1.1.1.1
Vlan1
1.1.1.0/32
Direct 0
0
1.1.1.1
Vlan1
1.1.1.1/32
Direct 0
0
127.0.0.1
InLoop0
1.1.1.255/32
Direct 0
0
1.1.1.1
Vlan1
2.2.2.0/24
Static 60
0
12.2.2.2
Vlan2
80.1.1.0/24
OSPF
2
80.1.1.1
Vlan3
10
...
A route entry includes the following key items:
•
Destination—IP address of the destination host or network.
•
Mask—Mask length of the IP address.
1
•
Pre—Preference of the route. Among routes to the same destination, the route with the highest
preference is optimal.
•
Cost—If multiple routes to a destination have the same preference, the one with the smallest cost is
the optimal route.
•
NextHop—Next hop.
•
Interface—Output interface.
Dynamic routing protocols
Static routes work well in small, stable networks. They are easy to configure and require fewer system
resources. However, in networks where topology changes occur frequently, a typical practice is to
configure a dynamic routing protocol. Compared with static routing, a dynamic routing protocol is
complicated to configure, requires more routers resources, and consumes more network resources.
Dynamic routing protocols dynamically collect and report reachability information to adapt to topology
changes. They are suitable for large networks.
Dynamic routing protocols can be classified by different criteria, as shown in Table 2.
Table 2 Categories of dynamic routing protocols
Criterion
Categories
Operation scope
• IGPs—Work within an AS. Examples include RIP, OSPF, and IS-IS.
• EGPs—Work between ASs. The most popular EGP is BGP.
• Distance-vector protocols—Examples include RIP and BGP. BGP is also considered
Routing algorithm
a path-vector protocol.
• Link-state protocols—Examples include OSPF and IS-IS.
Destination address
type
• Unicast routing protocols—Examples include RIP, OSPF, BGP, and IS-IS.
• Multicast routing protocols—Examples include PIM-SM and PIM-DM.
IP version
• IPv4 routing protocols—Examples include RIP, OSPF, BGP, and IS-IS.
• IPv6 routing protocols—Examples include RIPng, OSPFv3, IPv6 BGP, and IPv6 IS-IS.
An AS refers to a group of routers that use the same routing policy and work under the same
administration.
Route preference
Routing protocols, including static and direct routing, each by default have a preference. If they find
multiple routes to the same destination, the router selects the route with the highest preference as the
optimal route.
The preference of a direct route is always 0 and cannot be changed. You can configure a preference for
each static route and each dynamic routing protocol. The following table lists the route types and default
preferences. The smaller the value, the higher the preference.
Table 3 Route types and default route preferences
Route type
Preference
Direct route
0
2
Route type
Preference
Multicast static route
1
OSPF
10
IS-IS
15
Unicast static route
60
RIP
100
OSPF ASE
150
OSPF NSSA
150
IBGP
255
EBGP
255
Unknown (route from an untrusted source)
256
Load sharing
A routing protocol may find multiple optimal equal-cost routes to the same destination. You can use these
routes to implement equal-cost multi-path (ECMP) load sharing.
Static routing, IPv6 static routing, RIP, RIPng, OSPF, OSPFv3, BGP, IPv6 BGP, IS-IS, and IPv6 IS-IS support
ECMP load sharing.
Route backup
Route backup can improve network availability. Among multiple routes to the same destination, the route
with the highest priority is the primary route and others are secondary routes.
The router forwards matching packets through the primary route. When the primary route fails, the route
with the highest preference among the secondary routes is selected to forward packets. When the
primary route recovers, the router uses it to forward packets.
Route recursion
To use a BGP or static route, a router must perform route recursion to find the outgoing interface to reach
the next hop.
Link-state routing protocols, such as OSPF and IS-IS, do not need route recursion, because they obtain
directly connected next hops through route calculation.
Route redistribution
Route redistribution enables routing protocols to learn route information from each other. A dynamic
routing protocol can redistribute routes from other routing protocols, including direct and static routing.
For more information, see the respective chapters on those routing protocols in this configuration guide.
3
Configuring the maximum number of ECMP routes
This configuration takes effect at next reboot. Make sure the reboot does not impact your network.
To configure the maximum number of ECMP routes:
Step
Command
Remarks
1.
Enter system view.
system-view
N/A
2.
Configure the maximum
number of ECMP routes.
max-ecmp-num number
By default, the maximum
number of ECMP routes is 8.
3.
(Optional.) Display the
maximum number of ECMP
routes.
display max-ecmp-num
You can execute the display
command in any view.
Displaying and maintaining a routing table
Execute display commands in any view and reset commands in user view.
Task
Command
Display routing table information.
display ip routing-table [ vpn-instance vpn-instance-name ]
[ verbose ]
Display information about routes
permitted by an IPv4 basic ACL.
display ip routing-table [ vpn-instance vpn-instance-name ] acl
acl-number [ verbose ]
Display information about routes to a
specific destination address.
display ip routing-table [ vpn-instance vpn-instance-name ]
ip-address [ mask | mask-length ] [ longer-match ] [ verbose ]
Display information about routes to a
range of destination addresses.
display ip routing-table [ vpn-instance vpn-instance-name ]
ip-address1 to ip-address2 [ verbose ]
Display information about routes
permitted by an IP prefix list.
display ip routing-table [ vpn-instance vpn-instance-name ] prefix-list
prefix-list-name [ verbose ]
Display information about routes
installed by a protocol.
display ip routing-table [ vpn-instance vpn-instance-name ] protocol
protocol [ inactive | verbose ]
Display IPv4 route statistics.
display ip routing-table [ vpn-instance vpn-instance-name ] statistics
Clear IPv4 route statistics.
reset ip routing-table statistics protocol [ vpn-instance
vpn-instance-name ] { protocol | all }
Display IPv6 routing table information.
display ipv6 routing-table [ vpn-instance vpn-instance-name ]
[ verbose ]
Display information about routes to an
IPv6 destination address.
display ipv6 routing-table [ vpn-instance vpn-instance-name ]
ipv6-address [ prefix-length ] [ longer-match ] [ verbose ]
Display information about routes
permitted by an IPv6 basic ACL.
display ipv6 routing-table [ vpn-instance vpn-instance-name ] acl
acl6-number [ verbose ]
Display information about routes to a
range of IPv6 destination addresses.
display ipv6 routing-table [ vpn-instance vpn-instance-name ]
ipv6-address1 to ipv6-address2 [ verbose ]
Display information about routes
permitted by an IPv6 prefix list.
display ipv6 routing-table [ vpn-instance vpn-instance-name ]
prefix-list prefix-list-name [ verbose ]
4
Task
Command
Display information about routes
installed by an IPv6 protocol.
display ipv6 routing-table [ vpn-instance vpn-instance-name ]
protocol protocol [ inactive | verbose ]
Display IPv6 route statistics.
display ipv6 routing-table [ vpn-instance vpn-instance-name ]
statistics
Clear IPv6 route statistics.
reset ipv6 routing-table statistics protocol [ vpn-instance
vpn-instance-name ] { protocol | all }
5
Configuring static routing
Static routes are manually configured. If a network's topology is simple, you only need to configure static
routes for the network to work properly.
Static routes cannot adapt to network topology changes. If a fault or a topological change occurs in the
network, the network administrator must modify the static routes manually.
Configuring a static route
Before you configure a static route, complete the following tasks:
•
Configure the physical parameters for related interfaces.
•
Configure the link-layer attributes for related interfaces.
•
Configure the IP addresses for related interfaces.
You can associate track with a static route to monitor the reachability of the next hops. For more
information about track, see High Availability Configuration Guide.
To configure a static route:
Step
1.
Enter system view.
Command
Remarks
system-view
N/A
• Approach 1:
2.
3.
4.
ip route-static dest-address { mask |
mask-length } { next-hop-address [ track
track-entry-number ] | interface-type
interface-number [ next-hop-address ] |
vpn-instance d-vpn-instance-name
next-hop-address [ track track-entry-number ] }
[ permanent ] [ preference preference-value ]
[ tag tag-value ] [ description description-text ]
Use either approach.
Configure a static
route.
• Approach 2:
By default, no static route is
configured.
(Optional.)
Configure the default
preference for static
routes.
ip route-static default-preference
default-preference-value
The default setting is 60.
(Optional.) Delete all
static routes,
including the default
route.
delete [ vpn-instance vpn-instance-name ]
static-routes all
To delete one static route,
use the undo ip route-static
command.
ip route-static vpn-instance
s-vpn-instance-name dest-address { mask |
mask-length } { next-hop-address [ public ]
[ track track-entry-number ] | interface-type
interface-number [ next-hop-address ] |
vpn-instance d-vpn-instance-name
next-hop-address [ track track-entry-number ] }
[ permanent ] [ preference preference-value ]
[ tag tag-value ] [ description description-text ]
6
Configuring BFD for static routes
IMPORTANT:
Enabling BFD for a flapping route could worsen the situation.
BFD provides a general-purpose, standard, medium-, and protocol-independent fast failure detection
mechanism. It can uniformly and quickly detect the failures of the bidirectional forwarding paths between
two routers for protocols, such as routing protocols and MPLS.
For more information about BFD, see High Availability Configuration Guide.
Bidirectional control mode
To use BFD bidirectional control detection between two devices, enable BFD control mode for each
device's static route destined to the peer.
To configure a static route and enable BFD control mode for it, specify an output interface and a direct
next hop, or specify an indirect next hop and a specific BFD packet source address for the static route.
To configure BFD control mode for a static route (direct next hop):
Step
1.
Enter system view.
Command
Remarks
system-view
N/A
• Approach 1:
2.
Configure BFD
control mode for a
static route.
ip route-static dest-address { mask | mask-length }
interface-type interface-number next-hop-address
bfd control-packet [ preference preference-value ]
[ tag tag-value ] [ description description-text ]
• Approach 2:
ip route-static vpn-instance s-vpn-instance-name
dest-address { mask | mask-length } interface-type
interface-number next-hop-address bfd
control-packet [ preference preference-value ] [ tag
tag-value ] [ description description-text ]
Use either approach.
By default, BFD control
mode for a static route is
not configured.
To configure BFD control mode for a static route (indirect next hop):
Step
1.
Enter system view.
Command
Remarks
system-view
N/A
7
Step
Command
Remarks
• Approach 1:
2.
Configure BFD
control mode for a
static route.
ip route-static dest-address { mask | mask-length }
{ next-hop-address bfd control-packet bfd-source
ip-address | vpn-instance d-vpn-instance-name
next-hop-address bfd control-packet bfd-source
ip-address } [ preference preference-value ] [ tag
tag-value ] [ description description-text ]
• Approach 2:
ip route-static vpn-instance s-vpn-instance-name
dest-address { mask | mask-length }
{ next-hop-address bfd control-packet bfd-source
ip-address | vpn-instance d-vpn-instance-name
next-hop-address bfd control-packet bfd-source
ip-address } [ preference preference-value ] [ tag
tag-value ] [ description description-text ]
Use either approach.
By default, BFD control
mode for a static route is
not configured.
Single-hop echo mode
With BFD echo mode enabled for a static route, the output interface sends BFD echo packets to the
destination device, which loops the packets back to test the link reachability.
IMPORTANT:
Do not use BFD for a static route with the output interface in spoofing state.
To configure BFD echo mode for a static route:
Step
1.
2.
Enter system view.
Configure the source
address of echo
packets.
Command
Remarks
system-view
N/A
By default, the source
address of echo packets is
not configured.
bfd echo-source-ip ip-address
For more information about
this command, see High
Availability Command
Reference.
• Approach 1:
3.
Configure BFD echo
mode for a static
route.
ip route-static dest-address { mask |
mask-length } interface-type interface-number
next-hop-address bfd echo-packet [ preference
preference-value ] [ tag tag-value ] [ description
description-text ]
• Approach 2:
ip route-static vpn-instance
s-vpn-instance-name dest-address { mask |
mask-length } interface-type interface-number
next-hop-address bfd echo-packet [ preference
preference-value ] [ tag tag-value ] [ description
description-text ]
8
Use either approach.
By default, BFD echo mode
for a static route is not
configured.
Configuring static route FRR
A link or router failure on a path can cause packet loss and even routing loop. Static route fast reroute
(FRR) enables fast rerouting to minimize the impact of link or node failures.
Figure 1 Network diagram
As shown in Figure 1, upon a link failure, FRR specifies a backup next hop by using a routing policy for
routes matching the specified criteria. Packets are directed to the backup next hop to avoid traffic
interruption.
Configuration guidelines
•
Do not use static route FRR and BFD (for a static route) at the same time.
•
Static route does not take effect when the backup output interface is unavailable.
•
Equal-cost routes do not support FRR.
•
The backup output interface and next hop cannot be modified directly or the same as the primary
output interface and next hop.
Configuration procedure
To configure static route FRR:
Step
1.
2.
Enter system view.
Configure the source
address of BFD echo
packets.
Command
Remarks
system-view
N/A
By default, the source address
of BFD echo packets is not
configured.
bfd echo-source-ip ip-address
9
For more information about
this command, see High
Availability Command
Reference.
Step
Command
Remarks
• Approach 1:
3.
Configure static route
FRR.
ip route-static dest-address { mask |
mask-length } interface-type
interface-number [ next-hop-address
[ backup-interface interface-type
interface-number [ backup-nexthop
backup-nexthop-address ] ] ] [ permanent ]
• Approach 2:
ip route-static vpn-instance
s-vpn-instance-name dest-address { mask |
mask-length } interface-type
interface-number [ next-hop-address
[ backup-interface interface-type
interface-number [ backup-nexthop
backup-nexthop-address ] ] ] [ permanent ]
Use either approach.
By default, static route FRR is
not configured.
Displaying and maintaining static routes
Execute the display command in any view.
Task
Command
Display static route information.
display ip routing-table protocol static [ inactive | verbose ]
Static route configuration examples
Basic static route configuration example
Network requirements
Configure static routes on the switches in Figure 2 for interconnections between any two hosts.
Figure 2 Network diagram
10
Configuration procedure
1.
Configure IP addresses for interfaces. (Details not shown.)
2.
Configure static routes:
# Configure a default route on Switch A.
<SwitchA> system-view
[SwitchA] ip route-static 0.0.0.0 0.0.0.0 1.1.4.2
# Configure two static routes on Switch B.
<SwitchB> system-view
[SwitchB] ip route-static 1.1.2.0 255.255.255.0 1.1.4.1
[SwitchB] ip route-static 1.1.3.0 255.255.255.0 1.1.5.6
# Configure a default route on Switch C.
<SwitchC> system-view
[SwitchC] ip route-static 0.0.0.0 0.0.0.0 1.1.5.5
3.
Configure the default gateways of Host A, Host B, and Host C as 1.1.2.3, 1.1.6.1, and 1.1.3.1.
(Details not shown.)
Verifying the configuration
# Display static routes on Switch A.
[SwitchA] display ip routing-table protocol static
Summary Count : 1
Static Routing table Status : <Active>
Summary Count : 1
Destination/Mask
Proto
Pre
0.0.0.0/0
Static 60
Cost
NextHop
Interface
0
1.1.4.2
Vlan500
Static Routing table Status : <Inactive>
Summary Count : 0
# Display static routes on Switch B.
[SwitchB] display ip routing-table protocol static
Summary Count : 2
Static Routing table Status : <Active>
Summary Count : 2
Destination/Mask
Proto
1.1.2.0/24
Static 60
Pre
Cost
NextHop
Interface
0
1.1.4.1
Vlan500
Static Routing table Status : <Inactive>
Summary Count : 0
# Use the ping command on Host B to test the reachability of Host A (Windows XP runs on the two hosts).
C:\Documents and Settings\Administrator>ping 1.1.2.2
11
Pinging 1.1.2.2 with 32 bytes of data:
Reply from 1.1.2.2: bytes=32 time=1ms TTL=126
Reply from 1.1.2.2: bytes=32 time=1ms TTL=126
Reply from 1.1.2.2: bytes=32 time=1ms TTL=126
Reply from 1.1.2.2: bytes=32 time=1ms TTL=126
Ping statistics for 1.1.2.2:
Packets: Sent = 4, Received = 4, Lost = 0 (0% loss),
Approximate round trip times in milli-seconds:
Minimum = 1ms, Maximum = 1ms, Average = 1ms
# Use the tracert command on Host B to test the reachability of Host A.
C:\Documents and Settings\Administrator>tracert 1.1.2.2
Tracing route to 1.1.2.2 over a maximum of 30 hops
1
<1 ms
<1 ms
<1 ms
1.1.6.1
2
<1 ms
<1 ms
<1 ms
1.1.4.1
3
1 ms
<1 ms
<1 ms
1.1.2.2
Trace complete.
BFD for static routes configuration example (direct next hop)
Network requirements
In Figure 3, configure a static route to subnet 120.1.1.0/24 on Switch A, and configure a static route to
subnet 121.1.1.0/24 on Switch B. Enable BFD for both routes. Configure a static route to subnet
120.1.1.0/24 and a static route to subnet 121.1.1.0/24 on Switch C. When the link between Switch A and
Switch B through the Layer 2 switch fails, BFD can detect the failure immediately and inform Switch A and
Switch B to communicate through Switch C.
Figure 3 Network diagram
Device
Interface
IP address
Device
Interface
IP address
Switch A
Vlan-int10
12.1.1.1/24
Switch B
Vlan-int10
12.1.1.2/24
Vlan-int11
10.1.1.102/24
Vlan-int13
13.1.1.1/24
Switch C
Vlan-int11
10.1.1.100/24
Vlan-int13
13.1.1.2/24
12
Configuration procedure
1.
Configure IP addresses for the interfaces. (Details not shown.)
2.
Configure static routes and BFD:
# Configure static routes on Switch A and enable BFD control mode for the static route that
traverses the Layer 2 switch.
<SwitchA> system-view
[SwitchA] interface vlan-interface 10
[SwitchA-vlan-interface10] bfd min-transmit-interval 500
[SwitchA-vlan-interface10] bfd min-receive-interval 500
[SwitchA-vlan-interface10] bfd detect-multiplier 9
[SwitchA-vlan-interface10] quit
[SwitchA] ip route-static 120.1.1.0 24 vlan-interface 10 12.1.1.2 bfd control-packet
[SwitchA] ip route-static 120.1.1.0 24 vlan-interface 11 10.1.1.100 preference 65
[SwitchA] quit
# Configure static routes on Switch B and enable BFD control mode for the static route that
traverses the Layer 2 switch.
<SwitchB> system-view
[SwitchB] interface vlan-interface 10
[SwitchB-vlan-interface10] bfd min-transmit-interval 500
[SwitchB-vlan-interface10] bfd min-receive-interval 500
[SwitchB-vlan-interface10] bfd detect-multiplier 9
[SwitchB-vlan-interface10] quit
[SwitchB] ip route-static 121.1.1.0 24 vlan-interface 10 12.1.1.1 bfd control-packet
[SwitchB] ip route-static 121.1.1.0 24 vlan-interface 13 13.1.1.2 preference 65
[SwitchB] quit
# Configure static routes on Switch C.
<SwitchC> system-view
[SwitchC] ip route-static 120.1.1.0 24 13.1.1.1
[SwitchC] ip route-static 121.1.1.0 24 10.1.1.102
Verifying the configuration
# Display BFD sessions on Switch A.
<SwitchA> display bfd session
Total Session Num: 1
Up Session Num: 1
Init Mode: Active
IPv4 Session Working Under Ctrl Mode:
LD/RD
SourceAddr
DestAddr
State
Holdtime
Interface
4/7
12.1.1.1
12.1.1.2
Up
2000ms
Vlan10
The output shows that the BFD session has been created.
# Display the static routes on Switch A.
<SwitchA> display ip routing-table protocol static
Summary Count : 1
Static Routing table Status : <Active>
13
Summary Count : 1
Destination/Mask
Proto
120.1.1.0/24
Static 60
Pre
Cost
NextHop
Interface
0
12.1.1.2
Vlan10
Static Routing table Status : <Inactive>
Summary Count : 0
The output shows that Switch A communicates with Switch B through VLAN-interface 10. Then the link
over VLAN-interface 10 fails.
# Display static routes on Switch A.
<SwitchA> display ip routing-table protocol static
Summary Count : 1
Static Routing table Status : <Active>
Summary Count : 1
Destination/Mask
Proto
Pre
120.1.1.0/24
Static 65
Cost
NextHop
Interface
0
10.1.1.100
Vlan11
Static Routing table Status : <Inactive>
Summary Count : 0
The output shows that Switch A communicates with Switch B through VLAN-interface 11.
BFD for static routes configuration example (indirect next hop)
Network requirements
In Figure 4, Switch A has a route to interface Loopback1 (2.2.2.9/32) on Switch B, with the output
interface VLAN-interface 10. Switch B has a route to interface Loopback1 (1.1.1.9/32) on Switch A, with
the output interface VLAN-interface 12. Switch D has a route to 1.1.1.9/32, with the output interface
VLAN-interface 10, and a route to 2.2.2.9/32, with the output interface VLAN-interface 12.
Configure a static route to subnet 120.1.1.0/24 on Switch A, and configure a static route to subnet
121.1.1.0/24 on Switch B. Enable BFD for both routes. Configure a static route to subnet 120.1.1.0/24 and
a static route to subnet 121.1.1.0/24 on both Switch C and Switch D. When the link between Switch A and
Switch B through Switch D fails, BFD can detect the failure immediately and inform Switch A and Switch
B to communicate through Switch C.
14
Figure 4 Network diagram
Configuration procedure
1.
Configure IP addresses for interfaces. (Details not shown.)
2.
Configure static routes and BFD:
# Configure static routes on Switch A and enable BFD control mode for the static route that
traverses Switch D.
<SwitchA> system-view
[SwitchA] bfd multi-hop min-transmit-interval 500
[SwitchA] bfd multi-hop min-receive-interval 500
[SwitchA] bfd multi-hop detect-multiplier 9
[SwitchA] ip route-static 120.1.1.0 24 2.2.2.9 bfd control-packet bfd-source 1.1.1.9
[SwitchA] ip route-static 120.1.1.0 24 vlan-interface 11 10.1.1.100 preference 65
[SwitchA] quit
# Configure static routes on Switch B and enable BFD control mode for the static route that
traverses Switch D.
<SwitchB> system-view
[SwitchB] bfd multi-hop min-transmit-interval 500
[SwitchB] bfd multi-hop min-receive-interval 500
[SwitchB] bfd multi-hop detect-multiplier 9
[SwitchB] ip route-static 121.1.1.0 24 1.1.1.9 bfd control-packet bfd-source 2.2.2.9
[SwitchB] ip route-static 121.1.1.0 24 vlan-interface 13 13.1.1.2 preference 65
[SwitchB] quit
# Configure static routes on Switch C.
<SwitchC> system-view
[SwitchC] ip route-static 120.1.1.0 24 13.1.1.1
[SwitchC] ip route-static 121.1.1.0 24 10.1.1.102
# Configure static routes on Switch D.
<SwitchD> system-view
[SwitchD] ip route-static 120.1.1.0 24 11.1.1.1
[SwitchD] ip route-static 121.1.1.0 24 12.1.1.1
Verifying the configuration
# Display BFD sessions on Switch A.
<SwitchA> display bfd session
15
Total Session Num: 1
Up Session Num: 1
Init Mode: Active
IPv4 Session Working Under Ctrl Mode:
LD/RD
SourceAddr
DestAddr
State
Holdtime
Interface
4/7
1.1.1.9
2.2.2.9
Up
2000ms
Loop1
The output shows that the BFD session has been created.
# Display the static routes on Switch A.
<SwitchA> display ip routing-table protocol static
Summary Count : 1
Static Routing table Status : <Active>
Summary Count : 1
Destination/Mask
Proto
120.1.1.0/24
Static 60
Pre
Cost
NextHop
Interface
0
12.1.1.2
Vlan10
Static Routing table Status : <Inactive>
Summary Count : 0
The output shows that Switch A communicates with Switch B through VLAN-interface 10. Then the link
over VLAN-interface 10 fails.
# Display static routes on Switch A.
<SwitchA> display ip routing-table protocol static
Summary Count : 1
Static Routing table Status : <Active>
Summary Count : 1
Destination/Mask
Proto
Pre
120.1.1.0/24
Static 65
Cost
NextHop
Interface
0
10.1.1.100
Vlan11
Static Routing table Status : <Inactive>
Summary Count : 0
The output shows that Switch A communicates with Switch B through VLAN-interface 11.
16
Static route FRR configuration example
Network requirements
As shown in Figure 5, configure static routes on Switch S, Switch A, and Switch D, and configure static
route FRR so when Link A fails, traffic can be switched to Link B immediately.
Figure 5 Network diagram
Configuration procedure
1.
Configure IP addresses for interfaces. (Details not shown.)
2.
Configure static routes FRR on link A:
# Configure a static route on Switch S, and specify VLAN-inteface 100 as the backup output
interface and 12.12.12.2 as the backup next hop.
<SwitchS> system-view
[SwitchS] bfd echo-source-ip 4.4.4.4
[SwitchS] ip route-static 4.4.4.4 32 vlan-interface 200 13.13.13.2 backup-interface
vlan-interface 100 backup-nexthop 12.12.12.2
# Configure a static route on Switch D, and specify VLAN-interface 101 as the backup output
interface and 24.24.24.2 as the backup next hop.
<SwitchD> system-view
[SwitchD] bfd echo-source-ip 1.1.1.1
[SwitchD] ip route-static 1.1.1.1 32 vlan-interface 200 13.13.13.1 backup-interface
vlan-interface 101 backup-nexthop 24.24.24.2
3.
Configure static routes on Switch A.
<SwitchA> system-view
[SwitchA] ip route-static 4.4.4.4 32 vlan-interface 101 24.24.24.4
[SwitchA] ip route-static 1.1.1.1 32 vlan-interface 100 12.12.12.1
Verifying the configuration
# Display route 4.4.4.4/32 on Switch S to view the backup next hop information.
[SwitchS] display ip routing-table 4.4.4.4 verbose
Summary Count : 1
Destination: 4.4.4.4/32
Protocol: Static
SubProtID: 0x0
Cost: 0
Tag: 0
Process ID: 0
Age: 04h20m37s
Preference: 60
State: Active Adv
17
OrigTblID: 0x0
TableID: 0x2
NBRID: 0x26000002
AttrID: 0xffffffff
OrigVrf: default-vrf
OrigAs: 0
LastAs: 0
Neighbor: 0.0.0.0
Flags: 0x1008c
OrigNextHop: 13.13.13.2
Label: NULL
RealNextHop: 13.13.13.2
BkLabel: NULL
BkNextHop: 12.12.12.2
Tunnel ID: Invalid
Interface: Vlan-interface200
BkTunnel ID: Invalid
BkInterface: Vlan-interface100
# Display route 1.1.1.1/32 on Switch D to view the backup next hop information.
[SwitchD] display ip routing-table 1.1.1.1 verbose
Summary Count : 1
Destination: 1.1.1.1/32
Protocol: Static
SubProtID: 0x0
Cost: 0
Tag: 0
OrigTblID: 0x0
TableID: 0x2
NBRID: 0x26000002
AttrID: 0xffffffff
Process ID: 0
Age: 04h20m37s
Preference: 60
State: Active Adv
OrigVrf: default-vrf
OrigAs: 0
LastAs: 0
Neighbor: 0.0.0.0
Flags: 0x1008c
OrigNextHop: 13.13.13.1
Label: NULL
RealNextHop: 13.13.13.1
BkLabel: NULL
BkNextHop: 24.24.24.2
Tunnel ID: Invalid
Interface: Vlan-interface200
BkTunnel ID: Invalid
BkInterface: Vlan-interface101
18
Configuring a default route
A default route is used to forward packets that do not match any specific routing entry in the routing table.
Without a default route, packets that do not match any routing entries are discarded.
A default route can be configured in either of the following ways:
•
The network administrator can configure a default route with both destination and mask being
0.0.0.0. For more information, see "Configuring a static route."
•
Some dynamic routing protocols, such as OSPF, RIP, and IS-IS, can generate a default route. For
example, an upstream router running OSPF can generate a default route and advertise it to other
routers, which install the default route with the next hop being the upstream router. For more
information, see the respective chapters on these routing protocols in this configuration guide.
19
Configuring RIP
Routing Information Protocol (RIP) is a distance-vector IGP suited to small-sized networks. It employs UDP
to exchange route information through port 520.
Overview
RIP uses a hop count to measure the distance to a destination. The hop count from a router to a directly
connected network is 0. The hop count from a router to a directly connected router is 1. To limit
convergence time, RIP restricts the metric range from 0 to 15. A destination with a metric value of 16 (or
greater) is considered unreachable. For this reason, RIP is not suitable for large-sized networks.
RIP route entries
RIP stores routing entries in a database. Each routing entry contains the following elements:
•
Destination address—IP address of a destination host or a network.
•
Next hop—IP address of the next hop.
•
Egress interface—Egress interface of the route.
•
Metric—Cost from the local router to the destination.
•
Route time—Time elapsed since the last update. The time is reset to 0 when the routing entry is
updated.
•
Route tag—Used for route control. For more information, see "Configuring routing policies."
Routing loop prevention
RIP uses the following mechanisms to prevent routing loops:
•
Counting to infinity—A destination with a metric value of 16 is considered unreachable. When a
routing loop occurs, the metric value of a route will increment to 16 to avoid endless looping.
•
Triggered updates—RIP immediately advertises triggered updates for topology changes to reduce
the possibility of routing loops and to speed up convergence.
•
Split horizon—Disables RIP from sending routing information on the interface from which the
information was learned to prevent routing loops and save bandwidth.
•
Poison reverse—Enables RIP to set the metric of routes received from a neighbor to 16 and sends
these routes back to the neighbor so the neighbor can delete such information from its routing table
to prevent routing loops.
RIP operation
RIP works as follows:
1.
RIP sends request messages to neighboring routers. Neighboring routers return response
messages that contain their routing tables.
20
2.
RIP uses the received responses to update the local routing table and sends triggered update
messages to its neighbors. All RIP routers on the network do this to learn latest routing information.
3.
RIP periodically sends the local routing table to its neighbors. After a RIP neighbor receives the
message, it updates its routing table, selects optimal routes, and sends an update to other
neighbors. RIP ages routes to keep only valid routes.
RIP versions
There are two RIP versions, RIPv1 and RIPv2.
RIPv1 is a classful routing protocol. It advertises messages through broadcast only. RIPv1 messages do
not carry mask information, so RIPv1 can only recognize natural networks such as Class A, B, and C. For
this reason, RIPv1 does not support discontiguous subnets.
RIPv2 is a classless routing protocol. It has the following advantages over RIPv1:
•
Supports route tags to implement flexible route control through routing policies.
•
Supports masks, route summarization, and CIDR.
•
Supports designated next hops to select the best ones on broadcast networks.
•
Supports multicasting route updates so only RIPv2 routers can receive these updates to reduce
resource consumption.
•
Supports plain text authentication and MD5 authentication to enhance security.
RIPv2 supports two transmission modes: broadcast and multicast. Multicast is the default mode using
224.0.0.9 as the multicast address. An interface operating in RIPv2 broadcast mode can also receive
RIPv1 messages.
Protocols and standards
•
RFC 1058, Routing Information Protocol
•
RFC 1723, RIP Version 2 - Carrying Additional Information
•
RFC 1721, RIP Version 2 Protocol Analysis
•
RFC 1722, RIP Version 2 Protocol Applicability Statement
•
RFC 1724, RIP Version 2 MIB Extension
•
RFC 2082, RIPv2 MD5 Authentication
•
RFC 2091, Triggered Extensions to RIP to Support Demand Circuits
•
RFC 2453, RIP Version 2
RIP configuration task list
Tasks at a glance
Configuring basic RIP
• (Required.) Enabling RIP
• (Optional.) Controlling RIP reception and advertisement on interfaces
• (Optional.) Configuring a RIP version
21
Tasks at a glance
(Optional.) Configuring RIP route control
•
•
•
•
•
•
•
Configuring an additional routing metric
Configuring RIPv2 route summarization
Disabling host route reception
Advertising a default route
Configuring inbound/outbound route filtering
Configuring a preference for RIP
Configuring RIP route redistribution
(Optional.) Tuning and optimizing RIP networks
•
•
•
•
•
•
•
Configuring RIP timers
Configuring split horizon and poison reverse
Configuring the maximum number of ECMP routes
Enabling zero field check on incoming RIPv1 messages
Enabling source IP address check on incoming RIP updates
Configuring RIPv2 message authentication
Configuring the RIP packet sending rate
(Optional.) Configuring RIP Graceful Restart
(Optional.) Configuring BFD for RIP
(Optional.) Configuring RIP FRR
Configuring basic RIP
Before you configure basic RIP settings, complete the following tasks:
•
Configure the link layer protocol.
•
Configure IP addresses for interfaces to ensure IP connectivity between neighboring routers.
Enabling RIP
Perform this task to create a RIP process and enable the RIP process on the interface attached to the
specified network. An interface that is not on the specified network does not run RIP.
To enable multiple RIP processes on a router, you must specify an ID for each process. A RIP process ID
has only local significance. Two RIP routers having different process IDs can also exchange RIP packets.
If you configure RIP settings in interface view before enabling RIP, the settings do not take effect until RIP
is enabled. If a physical interface is attached to multiple networks, you cannot advertise these networks
in different RIP processes.
To enable RIP:
Step
Command
Remarks
1.
Enter system view.
system-view
N/A
2.
Create a RIP process and
enter RIP view.
rip [ process-id ] [ vpn-instance
vpn-instance-name ]
By default, no RIP process is
enabled.
22
Step
3.
Command
Enable the RIP process on the
interface attached to the
specified network.
Remarks
By default, RIP is disabled on an
interface.
network network-address
The network 0.0.0.0 command
can enable RIP on all interfaces in
a single process, but does not
apply to multiple RIP processes.
Controlling RIP reception and advertisement on interfaces
Step
Command
Remarks
1.
Enter system view.
system-view
N/A
2.
Enter RIP view.
rip [ process-id ] [ vpn-instance
vpn-instance-name ]
N/A
By default, all RIP-enabled
interfaces can send RIP messages.
3.
Disable a specified interface
from sending RIP messages.
silent-interface { interface-type
interface-number | all }
The disabled interface can still
receive RIP messages and respond
to unicast requests containing
unknown ports.
4.
Return to system view.
quit
N/A
5.
Enter interface view.
interface interface-type
interface-number
N/A
6.
Enable an interface to receive
RIP messages.
rip input
By default, a RIP-enabled interface
can receive RIP messages.
7.
Enable an interface to send
RIP messages.
rip output
By default, a RIP-enabled interface
can send RIP messages.
Configuring a RIP version
You can configure a global RIP version in RIP view or an interface-specific RIP version in interface view.
An interface preferentially uses the interface-specific RIP version. If no interface-specific version is
specified, the interface uses the global RIP version. If neither global nor interface-specific RIP version is
configured, the interface sends RIPv1 broadcasts, and can receive RIPv1 broadcasts and unicasts, and
RIPv2 broadcasts, multicasts, and unicasts.
To configure a RIP version:
Step
Command
Remarks
1.
Enter system view.
system-view
N/A
2.
Enter RIP view.
rip [ process-id ] [ vpn-instance
vpn-instance-name ]
N/A
23
Step
Command
Remarks
3.
Specify a global RIP version.
version { 1 | 2 }
By default, no global version is
specified, and an interface sends
RIPv1 broadcasts, and can receive
RIPv1 broadcasts and unicasts,
and RIPv2 broadcasts, multicasts,
and unicasts.
4.
Return to system view.
quit
N/A
5.
Enter interface view.
interface interface-type
interface-number
N/A
rip version { 1 | 2 [ broadcast |
multicast ] }
By default, no interface-specific RIP
version is specified, and the
interface sends RIPv1 broadcasts,
and can receive RIPv1 broadcasts
and unicasts, and RIPv2
broadcasts, multicasts, and
unicasts.
Specify a RIP version for the
interface.
6.
Configuring RIP route control
Before you configure RIP route control, complete the following tasks:
•
Configure IP addresses for interfaces to ensure IP connectivity between neighboring routers.
•
Configure basic RIP.
Configuring an additional routing metric
An additional routing metric (hop count) can be added to the metric of an inbound or outbound RIP
route.
An outbound additional metric is added to the metric of a sent route, and it does not change the route's
metric in the routing table.
An inbound additional metric is added to the metric of a received route before the route is added into the
routing table, and the route's metric is changed. If the sum of the additional metric and the original metric
is greater than 16, the metric of the route is 16.
To configure additional routing metrics:
Step
Command
Remarks
1.
Enter system view.
system-view
N/A
2.
Enter interface view.
interface interface-type
interface-number
N/A
3.
Specify an inbound
additional routing metric.
rip metricin [ route-policy
route-policy-name ] value
The default setting is 0.
4.
Specify an outbound
additional routing metric.
rip metricout [ route-policy
route-policy-name ] value
The default setting is 1.
24
Configuring RIPv2 route summarization
Perform this task to summarize contiguous subnets into a summary network and sends the network to
neighbors. The smallest metric among all summarized routes is used as the metric of the summary route.
Enabling RIPv2 automatic route summarization
Automatic summarization enables RIPv2 to generate a natural network for contiguous subnets. For
example, suppose there are three subnet routes 10.1.1.0/24, 10.1.2.0/24, and 10.1.3.0/24. Automatic
summarization automatically creates and advertises a summary route 10.0.0.0/8 instead of the more
specific routes.
To enable RIPv2 automatic route summarization:
Step
Command
Remarks
1.
Enter system view.
system-view
N/A
2.
Enter RIP view.
rip [ process-id ] [ vpn-instance
vpn-instance-name ]
N/A
3.
(Optional.) Enable RIPv2
automatic route
summarization.
By default, RIPv2 automatic route
summarization is enabled.
If subnets in the routing table are
not contiguous, disable automatic
route summarization to advertise
more specific routes.
summary
Advertising a summary route
Perform this task to manually configure a summary route.
For example, suppose contiguous subnets routes 10.1.1.0/24, 10.1.2.0/24, and 10.1.3.0/24 exist in the
routing table. You can create a summary route 10.1.0.0/16 on Ethernet 1/1 to advertise the summary
route instead of the more specific routes.
To configure a summary route:
Step
Command
Remarks
1.
Enter system view.
system-view
N/A
2.
Enter RIP view.
rip [ process-id ] [ vpn-instance
vpn-instance-name ]
N/A
3.
Disable RIPv2 automatic route
summarization.
undo summary
By default, RIPv2 automatic route
summarization is enabled.
4.
Return to system view.
quit
N/A
5.
Enter interface view.
interface interface-type
interface-number
N/A
6.
Configure a summary route.
rip summary-address ip-address
{ mask | mask-length }
By default, no summary route is
configured.
25
Disabling host route reception
Perform this task to disable RIPv2 from receiving host routes from the same network to save network
resources. This feature does not apply to RIPv1.
To disable RIP from receiving host routes:
Step
Command
Remarks
1.
Enter system view.
system-view
N/A
2.
Enter RIP view.
rip [ process-id ] [ vpn-instance
vpn-instance-name ]
N/A
3.
Disable RIP from receiving
host routes.
undo host-route
By default, RIP receives host routes.
Advertising a default route
You can advertise a default route on all RIP interfaces in RIP view or on a specific RIP interface in interface
view. The interface view setting takes precedence over the RIP view settings.
To disable an interface from advertising a default route, use the rip default-route no-originate command
on the interface.
To configure RIP to advertise a default route:
Step
Command
Remarks
1.
Enter system view.
system-view
N/A
2.
Enter RIP view.
rip [ process-id ] [ vpn-instance
vpn-instance-name ]
N/A
3.
Enable RIP to advertise a
default route.
default-route { only | originate }
[ cost cost ]
By default, RIP does not advertise a
default route.
4.
Return to system view.
quit
N/A
5.
Enter interface view.
interface interface-type
interface-number
N/A
6.
Configure the RIP interface to
advertise a default route.
rip default-route { { only |
originate } [ cost cost ] |
no-originate }
By default, a RIP interface can
advertise a default route if the RIP
process is enabled to advertise a
default route.
NOTE:
The router enabled to advertise a default route does not accept default routes from RIP neighbors.
Configuring inbound/outbound route filtering
Perform this task to filter inbound and outbound routes by using an IP prefix list. You can also configure
RIP to receive routes only from a specified neighbor.
26
To configure route filtering:
Step
Command
Remarks
1.
Enter system view.
system-view
N/A
2.
Enter RIP view.
rip [ process-id ] [ vpn-instance
vpn-instance-name ]
N/A
Configure the filtering of
inbound routes.
filter-policy { acl-number | gateway
prefix-list-name | prefix-list
prefix-list-name [ gateway
prefix-list-name ] } import
[ interface-type interface-number ]
3.
4.
Configure the filtering of
outbound routes.
filter-policy { acl-number | prefix-list
prefix-list-name } export [ protocol
[ process-id ] | interface-type
interface-number ]
By default, the filtering of inbound
routes is not configured.
This command filters inbound
routes. Filtered routes are not
installed into the routing table or
advertised to neighbors.
By default, the filtering of
outbound routes is not
configured.
This command filters outbound
routes, including routes
redistributed with the
import-route command.
Configuring a preference for RIP
If multiple IGPs find routes to the same destination, the route found by the IGP that has the highest priority
is selected as the optimal route. Perform this task to assign a preference to RIP. The smaller the preference
value, the higher the priority.
To configure a preference for RIP:
Step
Command
Remarks
1.
Enter system view.
system-view
N/A
2.
Enter RIP view.
rip [ process-id ] [ vpn-instance
vpn-instance-name ]
N/A
3.
Configure a preference for
RIP.
preference [ route-policy
route-policy-name ] value
The default setting is 100.
Configuring RIP route redistribution
Perform this task to configure RIP to redistribute routes from other routing protocols, including OSPF, IS-IS,
BGP, static, and direct.
To configure RIP route redistribution:
Step
Command
Remarks
1.
Enter system view.
system-view
N/A
2.
Enter RIP view.
rip [ process-id ] [ vpn-instance
vpn-instance-name ]
N/A
27
Step
Command
Remarks
3.
Redistribute routes from
another routing protocol.
import-route protocol [ process-id
| all-processes | allow-ibgp ] [ cost
cost | route-policy
route-policy-name | tag tag ] *
4.
(Optional.) Configure a
default cost for redistributed
routes.
default cost value
By default, RIP route redistribution
is disabled.
This command can redistribute
only active routes. To view active
routes, use the display ip
routing-table protocol command.
The default setting is 0.
Tuning and optimizing RIP networks
Configuration prerequisites
Before you tune and optimize RIP networks, complete the following tasks:
•
Configure IP addresses for interfaces to ensure IP connectivity between neighboring nodes.
•
Configure basic RIP.
Configuring RIP timers
You can change the RIP network convergence speed by adjusting the following RIP timers:
•
Update timer—Specifies the interval between route updates.
•
Timeout timer—Specifies the route aging time. If no update for a route is received within the aging
time, the metric of the route is set to 16.
•
Suppress timer—Specifies how long a RIP route stays in suppressed state. When the metric of a
route is 16, the route enters the suppressed state. A suppressed route can be replaced by an
updated route that is received from the same neighbor before the suppress timer expires and has a
metric less than 16.
•
Garbage-collect timer—Specifies the interval from when the metric of a route becomes 16 to when
it is deleted from the routing table. RIP advertises the route with a metric of 16. If no update is
announced for that route before the garbage-collect timer expires, the route is deleted from the
routing table.
IMPORTANT:
To avoid unnecessary traffic or route flapping, configure identical RIP timer settings on RIP routers.
To configure RIP timers:
Step
Command
Remarks
1.
Enter system view.
system-view
N/A
2.
Enter RIP view.
rip [ process-id ] [ vpn-instance
vpn-instance-name ]
N/A
28
Step
Command
3.
timers { garbage-collect
garbage-collect-value | suppress
suppress-value | timeout
timeout-value | update
update-value } *
Configure RIP timers.
Remarks
By default:
• The garbage-collect timer is 120
seconds.
• The suppress timer is 120 seconds.
• The timeout timer is 180 seconds.
• The update timer is 30 seconds.
Configuring split horizon and poison reverse
The split horizon and poison reverse functions can prevent routing loops.
If both split horizon and poison reverse are configured, only the poison reverse function takes effect.
Enabling split horizon
Split horizon disables RIP from sending routes through the interface where the routes were learned to
prevent routing loops between adjacent routers.
To enable split horizon:
Step
Command
Remarks
1.
Enter system view.
system-view
N/A
2.
Enter interface view.
interface interface-type
interface-number
N/A
3.
Enable split horizon.
rip split-horizon
By default, split horizon is enabled.
Enabling poison reverse
Poison reverse allows RIP to send routes through the interface where the routes were learned, but the
metric of these routes is always set to 16 (unreachable) to avoid routing loops between neighbors.
To enable poison reverse:
Step
Command
Remarks
1.
Enter system view.
system-view
N/A
2.
Enter interface view.
interface interface-type
interface-number
N/A
3.
Enable poison reverse.
rip poison-reverse
By default, poison reverse is
disabled.
Configuring the maximum number of ECMP routes
Perform this task to implement load sharing over ECMP routes.
To configure the maximum number of ECMP routes:
29
Step
Command
Remarks
1.
Enter system view.
system-view
N/A
2.
Enter RIP view.
rip [ process-id ] [ vpn-instance
vpn-instance-name ]
N/A
maximum load-balancing number
By default, the maximum number of
ECMP routes is the same as that
configured in the max-ecmp-num
command. For more information
about the max-ecmp-num
command, see IP Routing
Command Reference.
3.
Configure the maximum
number of ECMP routes.
Enabling zero field check on incoming RIPv1 messages
Some fields in the RIPv1 message must be set to zero. These fields are called "zero fields." You can
enable zero field check on incoming RIPv1 messages. If a zero field of a message contains a non-zero
value, RIP does not process the message. If you are certain that all messages are trustworthy, disable zero
field check to save CPU resources.
This feature does not apply to RIPv2 packets, because they have no zero fields.
To enable zero field check on incoming RIPv1 messages:
Step
Command
Remarks
1.
Enter system view.
system-view
N/A
2.
Enter RIP view.
rip [ process-id ] [ vpn-instance
vpn-instance-name ]
N/A
3.
Enable zero field check on
incoming RIPv1 messages.
checkzero
The default setting is enabled.
Enabling source IP address check on incoming RIP updates
Perform this task to enable source IP address check on incoming RIP updates.
Upon receiving a message on an Ethernet interface, RIP compares the source IP address of the message
with the IP address of the interface. If they are not in the same network segment, RIP discards the
message.
Upon receiving a message on a serial interface, RIP checks whether the source address of the message
is the IP address of the peer interface. If not, RIP discards the message.
To enable source IP address check on incoming RIP updates:
Step
Command
Remarks
1.
Enter system view.
system-view
N/A
2.
Enter RIP view.
rip [ process-id ] [ vpn-instance
vpn-instance-name ]
N/A
30
Step
Enable source IP address
check on incoming RIP
messages.
3.
Command
Remarks
validate-source-address
By default, this function is enabled.
Configuring RIPv2 message authentication
Perform this task to enable authentication on RIPv2 messages. This feature does not apply to RIPv1
because RIPv1 does not support authentication. Although you can specify an authentication mode for
RIPv1 in interface view, the configuration does not take effect.
RIPv2 supports two authentication modes: simple authentication and MD5 authentication.
To configure RIPv2 message authentication:
Step
Command
Remarks
1.
Enter system view.
system-view
N/A
2.
Enter interface view.
interface interface-type interface-number
N/A
Configure RIPv2
authentication.
rip authentication-mode { md5 { rfc2082
{ cipher cipher-string | plain plain-string } key-id
| rfc2453 { cipher cipher-string | plain
plain-string } } | simple { cipher cipher-string |
plain plain-string } }
By default, RIPv2
authentication is not
configured.
3.
Configuring the RIP packet sending rate
Perform this task to specify the interval for sending RIP packets and the maximum number of RIP packets
that can be sent at each interval. This feature can avoid excessive RIP packets from affecting system
performance and consuming too much bandwidth.
To configure the RIP packet sending rate:
Step
Command…
Remarks
1.
Enter system view.
system-view
N/A
2.
Enter RIP view.
rip [ process-id ] [ vpn-instance
vpn-instance-name ]
N/A
3.
Specify the interval for
sending RIP packets and the
maximum number of RIP
packets that can be sent at
each interval.
output-delay time count count
By default, an interface sends up to
three RIP packets every 20
milliseconds.
Configuring RIP Graceful Restart
GR ensures the continuity of packet forwarding when a routing protocol restarts or an active/standby
switchover occurs.
•
GR Restarter—Graceful restarting router. It must have GR capability.
31
GR Helper—A neighbor of the GR Restarter. It helps the GR Restarter to complete the GR process.
•
After RIP restarts on a router, the router must learn RIP routes again and updates its FIB table, which
causes network disconnections and route reconvergence.
With the GR feature, the restarting router (known as the "GR Restarter") can notify the event to its GR
capable neighbors. GR capable neighbors (known as "GR Helpers") keep their adjacencies with the
router within a GR interval. During this process, the FIB table of the router does not change. After the
restart, the router contacts its neighbors to retrieve its FIB.
By default, a RIP-enabled device acts as the GR Helper. Perform this task on the GR Restarter.
To configure GR on the GR Restarter:
Step
Command
Remarks
1.
Enter system view.
system-view
N/A
2.
Enable RIP and enter RIP
view.
rip [ process-id ] [ vpn-instance
vpn-instance-name ]
N/A
3.
Enable GR for RIP.
graceful-restart
By default, RIP GR is disabled.
Configuring BFD for RIP
RIP detects route failures by periodically sending requests. If it receives no response for a route within a
certain time, RIP considers the route unreachable. This detection mechanism is not fast enough. To speed
up convergence, perform this task to enable BFD for RIP. For more information about BFD, see High
Availability Configuration Guide.
BFD provides only single-hop echo detection mode for directly connected RIP neighbors. In this mode, a
BFD session is established only when the neighbor has route information to send.
To enable BFD for RIP (single-hop echo detection):
Step
Command
Remarks
1.
Enter system view.
system-view
N/A
2.
Configure the source IP
address of BFD echo packets.
bfd echo-source-ip ip-address
By default, the source IP address of
BFD echo packets is not
configured.
3.
Enter interface view.
interface interface-type
interface-number
N/A
4.
Enable BFD for RIP.
rip bfd enable
By default, BFD for RIP is disabled.
Configuring RIP FRR
A link or router failure on a path can cause packet loss and even routing loop until RIP completes routing
convergence based on the new network topology. FRR enables fast rerouting to minimize the impact of
link or node failures.
32
Figure 6 Network diagram for RIP FRR
In Figure 6, configure FRR on Router B by using a routing policy to specify a backup next hop. When the
primary link fails, RIP directs packets to the backup next hop. At the same time, RIP calculates the shortest
path based on the new network topology, and forwards packets over that path after network
convergence.
Configuration restrictions and guidelines
•
RIP FRR takes effect only for RIP routes learned from directly connected neighbors.
•
Do not use RIP FRR and BFD for RIP at the same time. Otherwise, FRR might fail to work.
•
RIP FRR is available only when the state of primary link (with Layer 3 interfaces staying up) changes
from bidirectional to unidirectional or when the primary link fails. This function is not available
when the Layer 3 interfaces are down. A unidirectional link refers to the link through which packets
are forwarded only from one end to the other.
Configuration prerequisites
You must specify a next hop by using the apply fast-reroute backup-interface command in a routing
policy and reference the routing policy for FRR. For more information about routing policy configuration,
see "Configuring routing policies."
Configuration procedure
To configure RIP FRR:
Step
Command
Remarks
1.
Enter system view.
system-view
N/A
2.
Configure the source address
of echo packets.
bfd echo-source-ip ip-address
By default, the source address of
echo packets is not configured.
3.
Enter RIP view.
rip [ process-id ] [ vpn-instance
vpn-instance-name ]
N/A
4.
Configure RIP FRR.
fast-reroute route-policy
route-policy-name
By default, RIP FRR is disabled.
Displaying and maintaining RIP
Execute display commands in any view and execute reset commands in user view.
Task
Command
Display RIP current status and configuration
information.
display rip [ process-id ]
33
Task
Command
Display all active routes in RIP database.
display rip process-id database
Display RIP interface information.
display rip process-id interface [ interface-type
interface-number ]
Display routing information about a specified RIP
process.
display rip process-id route [ ip-address { mask |
mask-length } | peer ip-address | statistics ]
Reset a RIP process.
reset rip process-id process
Clear the statistics of a RIP process.
reset rip process-id statistics
RIP configuration examples
Configuring basic RIP
Network requirements
As shown in Figure 7, enable RIPv2 on all interfaces on Router A and Router B. Configure Switch B to not
advertise route 10.2.1.0/24 to Switch A, and to accept only route 2.1.1.0/24 from Switch A.
Figure 7 Network diagram
Configuration procedure
1.
Configure IP addresses for interfaces. (Details not shown.)
2.
Configure basic RIP:
# Configure Switch A.
<SwitchA> system-view
[SwitchA] rip
[SwitchA-rip-1] network 192.168.1.0
[SwitchA-rip-1] network 172.16.0.0
[SwitchA-rip-1] network 172.17.0.0
[SwitchA-rip-1] quit
# Configure Switch B.
<SwitchB> system-view
[SwitchB] rip
[SwitchB-rip-1] network 192.168.1.0
[SwitchB-rip-1] network 10.0.0.0
[SwitchB-rip-1] quit
# Display the RIP routing table of Switch A.
[SwitchA] display rip 1 route
Route Flags: R - RIP
34
A - Aging, S - Suppressed, G - Garbage-collect
---------------------------------------------------------------------------Peer 192.168.1.2
on Vlan-interface100
Destination/Mask
Nexthop
Cost
Tag
Flags
Sec
10.0.0.0/8
192.168.1.2
1
0
RA
11
The output shows that RIPv1 uses a natural mask.
3.
Configure a RIP version:
# Configure RIPv2 on Switch A.
[SwitchA] rip
[SwitchA-rip-1] version 2
[SwitchA-rip-1] undo summary
[SwitchA-rip-1] quit
# Configure RIPv2 on Switch B.
[SwitchB] rip
[SwitchB-rip-1] version 2
[SwitchB-rip-1] undo summary
[SwitchB-rip-1] quit
# Display the RIP routing table on Switch A.
[SwitchA] display rip 1 route
Route Flags: R - RIP
A - Aging, S - Suppressed, G - Garbage-collect
---------------------------------------------------------------------------Peer 192.168.1.2 on Vlan-interface100
Destination/Mask
Nexthop
Cost
Tag
Flags
Sec
10.0.0.0/8
192.168.1.2
1
0
RA
50
10.2.1.0/24
192.168.1.2
1
0
RA
16
10.1.1.0/24
192.168.1.2
1
0
RA
16
The output shows that RIPv2 uses classless subnet masks.
NOTE:
After RIPv2 is configured, RIPv1 routes might still exist in the routing table until they are aged out.
# Display the RIP routing table on Switch B.
[SwitchB] display rip 1 route
Route Flags: R - RIP
A - Aging, S - Suppressed, G - Garbage-collect
---------------------------------------------------------------------------Peer 192.168.1.3 on Vlan-interface100
4.
Destination/Mask
Nexthop
Cost
Tag
Flags
Sec
172.16.1.0/24
192.168.1.3
1
0
RA
19
172.17.1.0/24
192.168.1.3
1
0
RA
19
Configure route filtering:
# Reference IP prefix lists on Switch B to filter inbound and outbound routes.
[SwitchB] ip prefix-list aaa index 10 permit 172.16.1.0 24
[SwitchB] ip prefix-list bbb index 10 permit 10.1.1.0 24
35
[SwitchB] rip 1
[SwitchB-rip-1] filter-policy prefix-list aaa import
[SwitchB-rip-1] filter-policy prefix-list bbb export
[SwitchB-rip-1] quit
# Display the RIP routing table on Switch A.
[SwitchA] display rip 100 route
Route Flags: R - RIP
A - Aging, S - Suppressed, G - Garbage-collect
---------------------------------------------------------------------------Peer 192.168.1.2 on Vlan-interface100
Destination/Mask
Nexthop
Cost
Tag
Flags
Sec
10.1.1.0/24
192.168.1.2
1
0
RA
19
# Displays the RIP routing table on Switch B.
[SwitchB] display rip 1 route
Route Flags: R - RIP
A - Aging, S - Suppressed, G - Garbage-collect
---------------------------------------------------------------------------Peer 192.168.1.3 on Vlan-interface100
Destination/Mask
Nexthop
Cost
Tag
Flags
Sec
172.16.1.0/24
192.168.1.3
1
0
RA
19
Configuring RIP route redistribution
Network requirements
As shown in Figure 8, Switch B communicates with Switch A through RIP 100 and with Switch C through
RIP 200.
Configure RIP 200 to redistribute direct routes and routes from RIP 100 on Switch B so Switch C can learn
routes destined for 10.2.1.0/24 and 11.1.1.0/24. Switch A cannot learn routes destined for 12.3.1.0/24
and 16.4.1.0/24.
Figure 8 Network diagram
Configuration procedure
1.
Configure IP addresses for interfaces. (Details not shown.)
2.
Configure basic RIP:
# Enable RIP 100, and configure RIPv2 on Switch A.
<SwitchA> system-view
[SwitchA] rip 100
[SwitchA-rip-100] network 10.0.0.0
[SwitchA-rip-100] network 11.0.0.0
36
[SwitchA-rip-100] version 2
[SwitchA-rip-100] undo summary
[SwitchA-rip-100] quit
# Enable RIP 100 and RIP 200, and configure RIPv2 on Switch B.
<SwitchB> system-view
[SwitchB] rip 100
[SwitchB-rip-100] network 11.0.0.0
[SwitchB-rip-100] version 2
[SwitchB-rip-100] undo summary
[SwitchB-rip-100] quit
[SwitchB] rip 200
[SwitchB-rip-200] network 12.0.0.0
[SwitchB-rip-200] version 2
[SwitchB-rip-200] undo summary
[SwitchB-rip-200] quit
# Enable RIP 200, and configure RIPv2 on Switch C.
<SwitchC> system-view
[SwitchC] rip 200
[SwitchC-rip-200] network 12.0.0.0
[SwitchC-rip-200] network 16.0.0.0
[SwitchC-rip-200] version 2
[SwitchC-rip-200] undo summary
[SwitchC-rip-200] quit
# Display the IP routing table on Switch C.
[SwitchC] display ip routing-table
Destinations : 13
3.
Routes : 13
Destination/Mask
Proto
Cost
NextHop
Interface
0.0.0.0/32
Direct 0
Pre
0
127.0.0.1
InLoop0
12.3.1.0/24
Direct 0
0
12.3.1.2
Vlan200
12.3.1.0/32
Direct 0
0
12.3.1.2
Vlan200
12.3.1.2/32
Direct 0
0
127.0.0.1
InLoop0
12.3.1.255/32
Direct 0
0
12.3.1.2
Vlan200
16.4.1.0/24
Direct 0
0
16.4.1.1
Vlan400
16.4.1.0/32
Direct 0
0
16.4.1.1
Vlan400
16.4.1.1/32
Direct 0
0
127.0.0.1
InLoop0
16.4.1.255/32
Direct 0
0
16.4.1.1
Vlan400
127.0.0.0/8
Direct 0
0
127.0.0.1
InLoop0
127.0.0.0/32
Direct 0
0
127.0.0.1
InLoop0
127.0.0.1/32
Direct 0
0
127.0.0.1
InLoop0
127.255.255.255/32
Direct 0
0
127.0.0.1
InLoop0
Configure route redistribution:
# Configure RIP 200 to redistribute routes from RIP 100 and direct routes on Switch B.
[SwitchB] rip 200
[SwitchB-rip-200] import-route rip 100
[SwitchB-rip-200] import-route direct
37
[SwitchB-rip-200] quit
# Display the IP routing table on Switch C.
[SwitchC] display ip routing-table
Destinations : 15
Routes : 15
Destination/Mask
Proto
0.0.0.0/32
10.2.1.0/24
Pre
Cost
NextHop
Interface
Direct 0
0
127.0.0.1
InLoop0
RIP
100
1
12.3.1.1
Vlan200
11.1.1.0/24
RIP
100
1
12.3.1.1
Vlan200
12.3.1.0/24
Direct 0
0
12.3.1.2
Vlan200
12.3.1.0/32
Direct 0
0
12.3.1.2
Vlan200
12.3.1.2/32
Direct 0
0
127.0.0.1
InLoop0
12.3.1.255/32
Direct 0
0
12.3.1.2
Vlan200
16.4.1.0/24
Direct 0
0
16.4.1.1
Vlan400
16.4.1.0/32
Direct 0
0
16.4.1.1
Vlan400
16.4.1.1/32
Direct 0
0
127.0.0.1
InLoop0
16.4.1.255/32
Direct 0
0
16.4.1.1
Vlan400
127.0.0.0/8
Direct 0
0
127.0.0.1
InLoop0
127.0.0.0/32
Direct 0
0
127.0.0.1
InLoop0
127.0.0.1/32
Direct 0
0
127.0.0.1
InLoop0
127.255.255.255/32
Direct 0
0
127.0.0.1
InLoop0
Configuring an additional metric for a RIP interface
Network requirements
As shown in Figure 9, run RIPv2 on all the interfaces of Switch A, Switch B, Switch C, Switch D, and
Switch E.
Switch A has two links to Switch D. The link from Switch B to Switch D is more stable than that from Switch
C to Switch D. Configure an additional metric for RIP routes received from VLAN-interface 200 on Switch
A so Switch A prefers route 1.1.5.0/24 learned from Switch B.
Figure 9 Network diagram
Vlan-int100
1.1.1.2/24
Vlan-int100
1.1.1.1/24
Vlan-int400
1.1.3.1/24
Vlan-int400
1.1.3.2/24
Switch B
Vlan-int300
1.1.4.2/24
Switch A
Switch D
Vlan-int200
1.1.2.1/24
Vlan-int200
1.1.2.2/24
Vlan-int500
1.1.5.2/24
Vlan-int500
1.1.5.1/24
Vlan-int300
1.1.4.1/24
Switch C
Configuration procedure
1.
Configure IP addresses for interfaces. (Details not shown.)
2.
Configure basic RIP:
# Configure Switch A.
38
Switch E
<SwitchA> system-view
[SwitchA] rip 1
[SwitchA-rip-1] network 1.0.0.0
[SwitchA-rip-1] version 2
[SwitchA-rip-1] undo summary
[SwitchA-rip-1] quit
# Configure Switch B.
<SwitchB> system-view
[SwitchB] rip 1
[SwitchB-rip-1] network 1.0.0.0
[SwitchB-rip-1] version 2
[SwitchB-rip-1] undo summary
# Configure Switch C.
<SwitchC> system-view
[SwitchB] rip 1
[SwitchC-rip-1] network 1.0.0.0
[SwitchC-rip-1] version 2
[SwitchC-rip-1] undo summary
# Configure Switch D.
<SwitchD> system-view
[SwitchD] rip 1
[SwitchD-rip-1] network 1.0.0.0
[SwitchD-rip-1] version 2
[SwitchD-rip-1] undo summary
# Configure Switch E.
<SwitchE> system-view
[SwitchE] rip 1
[SwitchE-rip-1] network 1.0.0.0
[SwitchE-rip-1] version 2
[SwitchE-rip-1] undo summary
# Display the IP routing table on Switch A.
[SwitchA] display rip 1 database
1.0.0.0/8, cost 0, ClassfulSumm
1.1.1.0/24, cost 0, nexthop 1.1.1.1, Rip-interface
1.1.2.0/24, cost 0, nexthop 1.1.2.1, Rip-interface
1.1.3.0/24, cost 1, nexthop 1.1.1.2
1.1.4.0/24, cost 1, nexthop 1.1.2.2
1.1.5.0/24, cost 2, nexthop 1.1.1.2
1.1.5.0/24, cost 2, nexthop 1.1.2.2
The output shows two RIP routes destined for network 1.1.5.0/24, with the next hops as Switch B
(1.1.1.2) and Switch C (1.1.2.2), and with the same cost of 2. Switch C is the next hop router to
reach network 1.1.4.0/24, with a cost of 1.
3.
Configure an additional metric of 3 for RIP-enabled VLAN-interface 200 on Switch A.
[SwitchA] interface vlan-interface 200
[SwitchA-Vlan-interface200] rip metricin 3
[SwitchA-Vlan-interface200] display rip 1 database
39
1.0.0.0/8, cost 0, auto-summary
1.1.1.0/24, cost 0, nexthop 1.1.1.1, RIP-interface
1.1.2.0/24, cost 0, nexthop 1.1.2.1, RIP-interface
1.1.3.0/24, cost 1, nexthop 1.1.1.2
1.1.4.0/24, cost 2, nexthop 1.1.1.2
1.1.5.0/24, cost 2, nexthop 1.1.1.2
The output shows that only one RIP route reaches network 1.1.5.0/24, with the next hop as Switch
B (1.1.1.2) and a cost of 2.
Configuring RIP to advertise a summary route
Network requirements
As shown in Figure 10, Switch A and Switch B run OSPF, Switch D runs RIP, and Switch C runs OSPF and
RIP. Configure RIP to redistribute OSPF routes on Switch C so Switch D can learn routes destined for
networks 10.1.1.0/24, 10.2.1.0/24, 10.5.1.0/24, and 10.6.1.0/24.
To reduce the routing table size of Switch D, configure route summarization on Switch C to advertise only
the summary route 10.0.0.0/8 to Switch D.
Figure 10 Network diagram
Vlan-int200
10.1.1.1/24
Vlan-int500
10.6.1.2/24
Switch B
Vlan-int200
10.1.1.2/24
Vlan-int600 OSPF
Vlan-int100
Vlan-int300
10.5.1.2/24
10.2.1.2/24
11.3.1.1/24
Vlan-int100
10.2.1.1/24
Switch C
RIP
Vlan-int400
11.4.1.2/24
Switch A
Vlan-int300
11.3.1.2/24
Switch D
Configuration procedure
1.
Configure IP addresses for interfaces. (Details not shown.)
2.
Configure basic OSPF:
# Configure Switch A.
<SwitchA> system-view
[SwitchA] ospf
[SwitchA-ospf-1] area 0
[SwitchA-ospf-1-area-0.0.0.0] network 10.5.1.0 0.0.0.255
[SwitchA-ospf-1-area-0.0.0.0] network 10.2.1.0 0.0.0.255
[SwitchA-ospf-1-area-0.0.0.0] quit
# Configure Switch B.
<SwitchB> system-view
[SwitchB] ospf
[SwitchB-ospf-1] area 0
[SwitchB-ospf-1-area-0.0.0.0] network 10.1.1.0 0.0.0.255
40
[SwitchB-ospf-1-area-0.0.0.0] network 10.6.1.0 0.0.0.255
[SwitchB-ospf-1-area-0.0.0.0] quit
# Configure Switch C.
<SwitchC> system-view
[SwitchC] ospf
[SwitchC-ospf-1] area 0
[SwitchC-ospf-1-area-0.0.0.0] network 10.1.1.0 0.0.0.255
[SwitchC-ospf-1-area-0.0.0.0] network 10.2.1.0 0.0.0.255
[SwitchC-ospf-1-area-0.0.0.0] quit
[SwitchC-ospf-1] quit
3.
Configure basic RIP:
# Configure Switch C.
[SwitchC] rip 1
[SwitchC-rip-1] network 11.3.1.0
[SwitchC-rip-1] version 2
[SwitchC-rip-1] undo summary
# Configure Switch D.
<SwitchD> system-view
[SwitchD] rip 1
[SwitchD-rip-1] network 11.0.0.0
[SwitchD-rip-1] version 2
[SwitchD-rip-1] undo summary
[SwitchD-rip-1] quit
# Configure RIP to redistribute routes from OSPF process 1 and direct routes on Switch C.
[SwitchC-rip-1] import-route direct
[SwitchC-rip-1] import-route ospf 1
[SwitchC-rip-1] quit
# Display the IP routing table on Switch D.
[SwitchD] display ip routing-table
Destinations : 15
Routes : 15
Destination/Mask
Proto
0.0.0.0/32
10.1.1.0/24
Pre
Cost
NextHop
Interface
Direct 0
0
127.0.0.1
InLoop0
RIP
100
1
11.3.1.1
Vlan300
10.2.1.0/24
RIP
100
1
11.3.1.1
Vlan300
10.5.1.0/24
RIP
100
1
11.3.1.1
Vlan300
10.6.1.0/24
RIP
100
1
11.3.1.1
Vlan300
11.3.1.0/24
Direct 0
0
11.3.1.2
Vlan300
11.3.1.0/32
Direct 0
0
11.3.1.2
Vlan300
11.3.1.2/32
Direct 0
0
127.0.0.1
InLoop0
11.4.1.0/24
Direct 0
0
11.4.1.2
Vlan400
11.4.1.0/32
Direct 0
0
11.4.1.2
Vlan400
11.4.1.2/32
Direct 0
0
127.0.0.1
InLoop0
127.0.0.0/8
Direct 0
0
127.0.0.1
InLoop0
127.0.0.0/32
Direct 0
0
127.0.0.1
InLoop0
41
4.
127.0.0.1/32
Direct 0
0
127.0.0.1
InLoop0
127.255.255.255/32
Direct 0
0
127.0.0.1
InLoop0
Configure route summarization:
# Configure route summarization on Switch C and advertise only the summary route 10.0.0.0/8.
[SwitchC] interface vlan-interface 300
[SwitchC-Vlan-interface300] rip summary-address 10.0.0.0 8
# Display the IP routing table on Switch D.
[SwitchD] display ip routing-table
Destinations : 12
Routes : 12
Destination/Mask
Proto
0.0.0.0/32
10.0.0.0/8
11.3.1.0/24
11.3.1.0/32
Pre
Cost
NextHop
Interface
Direct 0
0
127.0.0.1
InLoop0
RIP
1
11.3.1.1
Vlan300
Direct 0
0
11.3.1.2
Vlan300
Direct 0
0
11.3.1.2
Vlan300
11.3.1.2/32
Direct 0
0
127.0.0.1
InLoop0
11.4.1.0/24
Direct 0
0
11.4.1.2
Vlan400
11.4.1.0/32
Direct 0
0
11.4.1.2
Vlan400
11.4.1.2/32
Direct 0
0
127.0.0.1
InLoop0
127.0.0.0/8
Direct 0
0
127.0.0.1
InLoop0
127.0.0.0/32
Direct 0
0
127.0.0.1
InLoop0
127.0.0.1/32
Direct 0
0
127.0.0.1
InLoop0
127.255.255.255/32
Direct 0
0
127.0.0.1
InLoop0
100
Configuring BFD for RIP (single-hop echo detection)
Network requirements
As shown in Figure 11, VLAN-interface 100 of Switch A and Switch C runs RIP process 1. VLAN-interface
200 of Switch A runs RIP process 2. VLAN-interface 300 of Switch C and VLAN-interface 200 and
VLAN-interface 300 of Switch B run RIP process 1.
Configure a static route destined for 100.1.1.1/24 and enable static route redistribution into RIP on Switch
C so Switch A can learn two routes destined for 100.1.1.1/24 through VLAN-interface 100 and
VLAN-interface 200 respectively, and uses the one through VLAN-interface 100.
Enable BFD for RIP on VLAN-interface 100 of Switch A. When the link over VLAN-interface 100 fails,
BFD can quickly detect the failure and notify it to RIP so RIP deletes the neighbor relationship and route
information learned on VLAN-interface 100, and uses the route destined for 100.1.1.1 24 through
VLAN-interface 200.
42
Figure 11 Network diagram
Configuration procedure
1.
Configure IP addresses for interfaces. (Details not shown.)
2.
Configure basic RIP:
# Configure Switch A.
<SwitchA> system-view
[SwitchA] rip 1
[SwitchA-rip-1] version 2
[SwitchA-rip-1] undo summary
[SwitchA-rip-1] network 192.168.1.0
[SwitchA-rip-1] quit
[SwitchA] interface vlan-interface 100
[SwitchA-Vlan-interface100] rip bfd enable
[SwitchA-Vlan-interface100] quit
[SwitchA] rip 2
[SwitchA-rip-2] version 2
[SwitchA-rip-2] undo summary
[SwitchA-rip-2] network 192.168.2.0
[SwitchA-rip-2] quit
# Configure Switch B.
<SwitchB> system-view
[SwitchB] rip 1
[SwitchB-rip-1] version 2
[SwitchB-rip-1] undo summary
[SwitchB-rip-1] network 192.168.2.0
[SwitchB-rip-1] network 192.168.3.0
[SwitchB-rip-1] quit
# Configure Switch C.
<SwitchC> system-view
[SwitchC] rip 1
[SwitchC-rip-1] version 2
[SwitchC-rip-1] undo summary
43
[SwitchC-rip-1] network 192.168.1.0
[SwitchC-rip-1] network 192.168.3.0
[SwitchC-rip-1] import-route static
[SwitchC-rip-1] quit
Configure BFD parameters on VLAN-interface 100 of Switch A.
3.
[SwitchA] bfd session init-mode active
[SwitchA] bfd echo-source-ip 11.11.11.11
[SwitchA] interface vlan-interface 100
[SwitchA-Vlan-interface100] bfd min-transmit-interval 500
[SwitchA-Vlan-interface100] bfd min-receive-interval 500
[SwitchA-Vlan-interface100] bfd detect-multiplier 7
[SwitchA-Vlan-interface100] quit
[SwitchA] quit
Configure a static route on Switch C.
4.
[SwitchC] ip route-static 120.1.1.1 24 null 0
Verifying the configuration
# Display the BFD session information on Switch A.
<SwitchA> display bfd session
Total Session Num: 1
Up Session Num: 1
Init Mode: Active
IPv4 Session Working Under Echo Mode:
LD
4
SourceAddr
192.168.1.1
DestAddr
192.168.1.2
State
Holdtime
Interface
Up
2000ms
Vlan100
# Display RIP routes destined for 120.1.1.0/24 on Switch A.
<SwitchA> display ip routing-table 120.1.1.0 24 verbose
Summary Count : 1
Destination: 120.1.1.0/24
Protocol: RIP
SubProtID: 0x1
Cost: 1
Tag: 0
OrigTblID: 0x0
TableID: 0x2
NBRID: 0x26000002
AttrID: 0xffffffff
Process ID: 1
Age: 04h20m37s
Preference: 100
State: Active Adv
OrigVrf: default-vrf
OrigAs: 0
LastAs: 0
Neighbor: 192.168.1.2
Flags: 0x1008c
OrigNextHop: 192.168.1.2
Label: NULL
RealNextHop: 192.168.1.2
BkLabel: NULL
Tunnel ID: Invalid
BkTunnel ID: Invalid
BkNextHop: N/A
Interface: Vlan-interface100
BkInterface: N/A
The output shows that Switch A communicates with Switch C through VLAN-interface 100. Then the link
over VLAN-interface 100 fails.
44
# Display RIP routes destined for 120.1.1.0/24 on Switch A.
<SwitchA> display ip routing-table 120.1.1.0 24 verbose
Summary Count : 1
Destination: 120.1.1.0/24
Protocol: RIP
SubProtID: 0x1
Cost: 1
Tag: 0
OrigTblID: 0x0
TableID: 0x2
NBRID: 0x26000002
AttrID: 0xffffffff
Process ID: 2
Age: 04h20m37s
Preference: 100
State: Active Adv
OrigVrf: default-vrf
OrigAs: 0
LastAs: 0
Neighbor: 192.168.2.2
Flags: 0x1008c
OrigNextHop: 192.168.2.2
Label: NULL
RealNextHop: 192.168.2.2
BkLabel: NULL
Tunnel ID: Invalid
BkTunnel ID: Invalid
BkNextHop: N/A
Interface: Vlan-interface200
BkInterface: N/A
The output shows that Switch A communicates with Switch C through VLAN-interface 200.
Configuring RIP FRR
Network requirements
As shown in Figure 12, Switch S, Switch A, and Switch D run RIPv2. Configure RIP FRR so that when Link
A fails, services can be switched to Link B immediately.
Figure 12 Network diagram
Configuration procedure
1.
Configure IP addresses and subnet masks for interfaces on the switches. (Details not shown.)
2.
Configure RIPv2 on the switches to make sure Switch A, Switch D, and Switch S can communicate
with each other at Layer 3. (Details not shown.)
3.
Configure RIP FRR:
# Configure Switch S.
<SwitchS> system-view
[SwitchS] bfd echo-source-ip 1.1.1.1
[SwitchS] ip prefix-list abc index 10 permit 4.4.4.4 32
45
[SwitchS] route-policy frr permit node 10
[SwitchS-route-policy-frr-10] if-match ip address prefix-list abc
[SwitchS-route-policy-frr-10] apply fast-reroute backup-interface vlan-interface
100 backup-nexthop 12.12.12.2
[SwitchS-route-policy-frr-10] quit
[SwitchS] rip 1
[SwitchS-rip-1] fast-reroute route-policy frr
[SwitchS-rip-1] quit
# Configure Switch D.
<SwitchD> system-view
[SwitchD] bfd echo-source-ip 4.4.4.4
[SwitchD] ip prefix-list abc index 10 permit 1.1.1.1 32
[SwitchD] route-policy frr permit node 10
[SwitchD-route-policy-frr-10] if-match ip address prefix-list abc
[SwitchD-route-policy-frr-10] apply fast-reroute backup-interface vlan-interface
101 backup-nexthop 24.24.24.2
[SwitchD-route-policy-frr-10] quit
[SwitchD] rip 1
[SwitchD-rip-1] fast-reroute route-policy frr
[SwitchD-rip-1] quit
Verifying the configuration
# Display route 4.4.4.4/32 on Switch S to view the backup next hop information.
[SwitchS] display ip routing-table 4.4.4.4 verbose
Summary Count : 1
Destination: 4.4.4.4/32
Protocol: RIP
SubProtID: 0x1
Cost: 1
Tag: 0
OrigTblID: 0x0
TableID: 0x2
NBRID: 0x26000002
AttrID: 0xffffffff
Process ID: 1
Age: 04h20m37s
Preference: 100
State: Active Adv
OrigVrf: default-vrf
OrigAs: 0
LastAs: 0
Neighbor: 13.13.13.2
Flags: 0x1008c
OrigNextHop: 13.13.13.2
Label: NULL
RealNextHop: 13.13.13.2
BkLabel: NULL
BkNextHop: 12.12.12.2
Tunnel ID: Invalid
Interface: Vlan-interface200
BkTunnel ID: Invalid
BkInterface: Vlan-interface100
# Display route 1.1.1.1/32 on Switch D to view the backup next hop information.
[SwitchD] display ip routing-table 1.1.1.1 verbose
Summary Count : 1
Destination: 1.1.1.1/32
Protocol: RIP
Process ID: 1
46
SubProtID: 0x1
Cost: 1
Tag: 0
OrigTblID: 0x0
TableID: 0x2
NBRID: 0x26000002
AttrID: 0xffffffff
Age: 04h20m37s
Preference: 100
State: Active Adv
OrigVrf: default-vrf
OrigAs: 0
LastAs: 0
Neighbor: 13.13.13.1
Flags: 0x1008c
OrigNextHop: 13.13.13.1
Label: NULL
RealNextHop: 13.13.13.1
BkLabel: NULL
BkNextHop: 24.24.24.2
Tunnel ID: Invalid
Interface: Vlan-interface200
BkTunnel ID: Invalid
BkInterface: Vlan-interface101
47
Configuring OSPF
Open Shortest Path First (OSPF) is a link-state IGP developed by the OSPF working group of the IETF.
OSPF version 2 is used for IPv4. OSPF refers to OSPFv2 throughout this chapter.
Overview
OSPF offers the following features:
•
Wide scope—Supports various network sizes and up to several hundred routers in an OSPF routing
domain.
•
Fast convergence—Advertises routing updates instantly upon network topology changes.
•
Loop free—Computes routes with the SPF algorithm to avoid routing loops.
•
Area-based network partition—Splits an AS into multiple areas to facilitate management. This
feature reduces the LSDB size on routers to save memory and CPU resources, and reduces route
updates transmitted between areas to save bandwidth.
•
ECMP routing—Supports multiple equal-cost routes to a destination.
•
Routing hierarchy—Supports a 4-level routing hierarchy that prioritizes routes into intra-area,
inter-area, external Type-1, and external Type-2 routes.
•
Authentication—Supports area- and interface-based packet authentication to ensure secure packet
exchange.
•
Support for multicasting—Multicasts protocol packets on some types of links to avoid impacting
other devices.
OSPF packets
OSPF messages are carried directly over IP. The protocol number is 89.
OSPF uses the following packet types:
•
Hello—Periodically sent to find and maintain neighbors, containing timer values, information about
the DR, BDR, and known neighbors.
•
Database description (DD)—Describes the digest of each LSA in the LSDB, exchanged between two
routers for data synchronization.
•
Link state request (LSR)—Requests needed LSAs from a neighbor. After exchanging the DD packets,
the two routers know which LSAs of the neighbor are missing from their LSDBs. They then exchange
LSR packets requesting the missing LSAs. The LSA packet contains the digest of the missing LSAs.
•
Link state update (LSU)—Transmits the requested LSAs to the neighbor.
•
Link state acknowledgment (LSAck)—Acknowledges received LSU packets. It contains the headers
of received LSAs (an LSAck packet can acknowledge multiple LSAs).
LSA types
OSPF advertises routing information in Link State Advertisements (LSAs). The following LSAs are
commonly used:
48
•
Router LSA—Type-1 LSA, originated by all routers and flooded throughout a single area only. This
LSA describes the collected states of the router's interfaces to an area.
•
Network LSA—Type-2 LSA, originated for broadcast and NBMA networks by the designated router,
and flooded throughout a single area only. This LSA contains the list of routers connected to the
network.
•
Network Summary LSA—Type-3 LSA, originated by Area Border Routers (ABRs), and flooded
throughout the LSA's associated area. Each summary-LSA describes a route to a destination outside
the area, yet still inside the AS (an inter-area route).
•
ASBR Summary LSA—Type-4 LSA, originated by ABRs and flooded throughout the LSA's
associated area. Type 4 summary-LSAs describe routes to Autonomous System Boundary Router
(ASBR).
•
AS External LSA—Type-5 LSA, originated by ASBRs, and flooded throughout the AS (except stub
and NSSA areas). Each AS-external-LSA describes a route to another AS.
•
NSSA LSA—Type-7 LSA, as defined in RFC 1587, originated by ASBRs in NSSAs and flooded
throughout a single NSSA. NSSA LSAs describe routes to other ASs.
•
Opaque LSA—A proposed type of LSA. Its format consists of a standard LSA header and
application specific information. Opaque LSAs are used by the OSPF protocol or by some
applications to distribute information into the OSPF routing domain. The opaque LSA includes Type
9, Type 10, and Type 11. The Type 9 opaque LSA is flooded into the local subnet, the Type 10 is
flooded into the local area, and the Type 11 is flooded throughout the AS.
OSPF areas
In large OSPF routing domains, SPF route computations consume too many storage and CPU resources,
and enormous OSPF packets generated for route synchronization occupy excessive bandwidth.
To resolve these issues, OSPF splits an AS into multiple areas. Each area is identified by an area ID. The
boundaries between areas are routers rather than links. A network segment (or a link) can only reside in
one area as shown in Figure 13.
You can configure route summarization on ABRs to reduce the number of LSAs advertised to other areas
and minimize the effect of topology changes.
49
Figure 13 Area-based OSPF network partition
Area 4
Area 1
Area 0
Area 2
Area 3
Backbone area and virtual links
Each AS has a backbone area that distributes routing information between non-backbone areas. Routing
information between non-backbone areas must be forwarded by the backbone area. OSPF includes the
following requirements:
•
All non-backbone areas must maintain connectivity to the backbone area.
•
The backbone area must maintain connectivity within itself.
In practice, these requirements might not be satisfied due to lack of physical links. OSPF virtual links can
resolve this issue.
A virtual link is established between two ABRs through a non-backbone area. It must be configured on
both ABRs to take effect. The non-backbone area is called a transit area.
In Figure 14, Area 2 has no direct physical link to the backbone area 0. You can configure a virtual link
between the two ABRs to connect Area 2 to the backbone area.
Figure 14 Virtual link application 1
Virtual links can also be used to provide redundant links. If the backbone area cannot maintain internal
connectivity due to the failure of a physical link, you can configure a virtual link to replace the failed
physical link, as shown in Figure 15.
50
Figure 15 Virtual link application 2
Area 1
Virtual link
R2
R1
Area 0
The virtual link between the two ABRs acts as a point-to-point connection. You can configure interface
parameters, such as hello interval, on the virtual link as they are configured on a physical interface.
The two ABRs on the virtual link unicast OSPF packets to each other, and the OSPF routers in between
convey these OSPF packets as normal IP packets.
Stub area and totally stub area
A stub area does not distribute Type-5 LSAs to reduce the routing table size and LSAs advertised within
the area. The ABR of the stub area advertises a default route in a Type-3 LSA so that the routers in the area
can reach external networks through the default route.
To further reduce the routing table size and advertised LSAs, you can configure the stub area as a totally
stub area. The ABR of a totally stub area does no advertise inter-area routes or external routes. It
advertises a default route in a Type-3 LSA so that the routers in the area can reach external networks
through the default route.
NSSA area and totally NSSA area
An NSSA area does not import AS external LSAs (Type-5 LSAs) but can import Type-7 LSAs generated by
the NSSA ASBR. The NSSA ABR translates Type-7 LSAs into Type-5 LSAs and advertises the Type-5 LSAs
to other areas.
In Figure 16, the OSPF AS contains Area 1, Area 2, and Area 0. The other two ASs run RIP. Area 1 is an
NSSA area where the ASBR redistributes RIP routes in Type-7 LSAs into Area 1. Upon receiving the Type-7
LSAs, the NSSA ABR translates them to Type-5 LSAs, and advertises the Type-5 LSAs to Area 0.
The ASBR of Area 2 redistributes RIP routes in Type-5 LSAs into the OSPF routing domain. However, Area
1 does not receive Type-5 LSAs because it is an NSSA area.
Figure 16 NSSA area
Router types
OSPF routers are classified into the following types based on their positions in the AS:
51
•
Internal router—All interfaces on an internal router belong to one OSPF area.
•
ABR—Belongs to more than two areas, one of which must be the backbone area. ABR connects the
backbone area to a non-backbone area. An ABR and the backbone area can be connected
through a physical or logical link.
•
Backbone router—At least one interface of a backbone router must reside in the backbone area.
All ABRs and internal routers in area 0 are backbone routers.
•
ASBR—Exchanges routing information with another AS is an ASBR. An ASBR might not reside on
the border of the AS. It can be an internal router or an ABR.
Figure 17 OSPF router types
RIP
IS-IS
ASBR
Area 1
Area 4
Backbone router
Internal router
Area 0
ABR
Area 3
Area 2
Route types
OSPF prioritizes routes into the following route levels:
•
Intra-area route
•
Inter-area route
•
Type-1 external route
•
Type-2 external route
The intra-area and inter-area routes describe the network topology of the AS. The external routes describe
routes to external ASs.
A Type-1 external route has high credibility. The cost from a router to the destination of a Type-1 external
route = the cost from the router to the corresponding ASBR + the cost from the ASBR to the destination of
the external route.
A Type-2 external route has low credibility. OSPF considers the cost from the ASBR to the destination of
a Type-2 external route is much greater than the cost from the ASBR to an OSPF internal router. The cost
from the internal router to the destination of the Type-2 external route = the cost from the ASBR to the
52
destination of the Type-2 external route. If two Type-2 routes to the same destination have the same cost,
OSPF takes the cost from the router to the ASBR into consideration to determine the best route.
Route calculation
OSPF computes routes in an area as follows:
•
Each router generates LSAs based on the network topology around itself, and sends them to other
routers in update packets.
•
Each OSPF router collects LSAs from other routers to compose an LSDB. An LSA describes the
network topology around a router, and the LSDB describes the entire network topology of the area.
•
Each router transforms the LSDB to a weighted directed graph that shows the topology of the area.
All the routers within the area have the same graph.
•
Each router uses the SPF algorithm to compute a shortest path tree that shows the routes to the nodes
in the area. The router itself is the root of the tree.
OSPF network types
OSPF classifies networks into the following types, depending on different link layer protocols:
•
Broadcast—If the link layer protocol is Ethernet or FDDI, OSPF considers the network type as
broadcast by default. On a broadcast network, hello, LSU, and LSAck packets are multicast to
224.0.0.5 that identifies all OSPF routers or to 224.0.0.6 that identifies the DR; DD packets and LSR
packets are unicast.
•
NBMA—If the link layer protocol is Frame Relay, ATM, or X.25, OSPF considers the network type
as NBMA by default. OSPF packets are unicast on a NBMA network.
•
P2MP—No link is P2MP type by default. P2MP must be a conversion from other network types such
as NBMA. On a P2MP network, OSPF packets are multicast to 224.0.0.5.
•
P2P—If the link layer protocol is PPP or HDLC, OSPF considers the network type as P2P. On a P2P
network, OSPF packets are multicast to 224.0.0.5.
The following are the differences between NBMA and P2MP networks:
•
NBMA networks are fully meshed. P2MP networks are not required to be fully meshed.
•
NBMA networks require DR and BDR election. P2MP networks do not have DR or BDR.
•
On a NBMA network, OSPF packets are unicast, and neighbors are manually configured. On a
P2MP network, OSPF packets are multicast by default, and you can configure OSPF to unicast
protocol packets.
DR and BDR
On a broadcast or NBMA network, any two routers must establish an adjacency to exchange routing
information with each other. If n routers are present on the network, n(n-1)/2 adjacencies are established.
Any topology change on the network results in an increase in traffic for route synchronization, consuming
many system and bandwidth resources.
The DR and BDR mechanisms can solve this problem.
•
DR—Elected to advertise routing information among other routers. If the DR fails, routers on the
network must elect another DR and synchronize information with the new DR. Using this mechanism
alone is time-consuming and prone to route calculation errors.
53
•
BDR—Elected along with the DR to establish adjacencies with all other routers. If the DR fails, the
BDR immediately becomes the new DR, and other routers elect a new BDR.
Routers other than the DR and BDR are called "DROthers." They do not establish adjacencies with one
another, so the number of adjacencies is reduced.
The role of a router is subnet (or interface) specific. It might be a DR on one interface and a BDR or
DROther on another interface.
In Figure 18, solid lines are Ethernet physical links, and dashed lines represent OSPF adjacencies. With
the DR and BDR, only seven adjacencies are established.
Figure 18 DR and BDR in a network
DR
DR other
BDR
DR other
Physical links
DR other
Adjacencies
NOTE:
In OSPF, "neighbor" and "adjacency" are different concepts. After startup, OSPF sends a hello packet on
each OSPF interface. A receiving router checks parameters in the packet. If the parameters match its own,
the receiving router considers the sending router an OSPF neighbor. Two OSPF neighbors establish an
adjacency relationship after they synchronize their LSDBs through exchange of DD packets and LSAs.
DR and BDR election
DR election is performed on broadcast or NBMA networks but not on P2P and P2MP networks.
Routers in a broadcast or NBMA network elect the DR and BDR by router priority and ID. Routers with a
router priority value higher than 0 are candidates for DR and BDR election.
The election votes are hello packets. Each router sends the DR elected by itself in a hello packet to all the
other routers. If two routers on the network declare themselves as the DR, the router with the higher router
priority wins. If router priorities are the same, the router with the higher router ID wins.
If a router with a higher router priority is added to the network after DR and BDR election, the router
cannot become the DR or BDR immediately as no DR election is performed for it. Therefore, the DR of a
network might not be the router with the highest priority, and the BDR might not be the router with the
second highest priority.
Protocols and standards
•
RFC 1765, OSPF Database Overflow
•
RFC 2328, OSPF Version 2
•
RFC 3101, OSPF Not-So-Stubby Area (NSSA) Option
54
•
RFC 3137, OSPF Stub Router Advertisement
•
RFC 4811, OSPF Out-of-Band LSDB Resynchronization
•
RFC 4812, OSPF Restart Signaling
•
RFC 4813, OSPF Link-Local Signaling
OSPF configuration task list
To run OSPF, you must first enable OSPF on the router. Make a proper configuration plan to avoid
incorrect settings that can result in route blocking and routing loops.
To configure OSPF, perform the following tasks:
Tasks at a glance
(Required.) Enabling OSPF
(Optional.) Configuring OSPF areas:
• Configuring a stub area
• Configuring an NSSA area
• Configuring a virtual link
(Optional.) Configuring OSPF network types:
•
•
•
•
Configuring the broadcast network type for an interface
Configuring the NBMA network type for an interface
Configuring the P2MP network type for an interface
Configuring the P2P network type for an interface
(Optional.) Configuring OSPF route control:
• Configuring OSPF route summarization
•
•
•
•
•
•
{
Configuring route summarization on an ABR
{
Configuring route summarization when redistributing routes into OSPF on an ASBR
Configuring inbound OSPF route filtering
Configuring Type-3 LSA filtering
Configuring an OSPF cost for an interface
Configuring the maximum number of ECMP routes
Configuring OSPF preference
Configuring OSPF route redistribution
{
Configuring OSPF to redistribute routes from another routing protocol
{
Configuring OSPF to redistribute a default route
{
Configuring default parameters for redistributed routes
• Advertising a host route
55
Tasks at a glance
(Optional.) Tuning and optimizing OSPF networks:
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
Configuring OSPF timers
Specifying LSA transmission delay
Specifying SPF calculation interval
Specifying the LSA arrival interval
Specifying the LSA generation interval
Disabling interfaces from receiving and sending OSPF packets
Configuring stub routers
Configuring OSPF authentication
Adding the interface MTU into DD packets
Configuring the maximum number of external LSAs in LSDB
Configuring OSPF exit overflow interval
Enabling compatibility with RFC 1583
Logging neighbor state changes
Configuring OSPF network management
Configuring the LSU transmit rate
Enabling OSPF ISPF
(Optional.) Configuring OSPF Graceful Restart:
• Configuring the OSPF GR Restarter
• Configuring OSPF GR Helper
• Triggering OSPF Graceful Restart
(Optional.) Configuring BFD for OSPF
(Optional.) Configuring OSPF FRR
Enabling OSPF
Enable OSPF before you perform other OSPF configuration tasks.
Configuration prerequisites
Configure the link layer protocol and IP addresses for interfaces to ensure IP connectivity between
neighboring nodes.
Configuration guidelines
Complete the following tasks to enable an interface to run an OSPF process in an area:
•
Enable the OSPF process.
•
Create the area for the OSPF process.
•
Add the network segment where the interface resides to the area. The OSPF process advertises the
direct route of the interface.
•
Specify a router ID, the unique identifier of the router in the AS.
You can also specify a router ID when you create an OSPF process.
56
•
If you specify a router ID when you create an OSPF process, any two routers in an AS must have
different router IDs. A common practice is to specify the IP address of an interface as the router ID.
•
If you specify no router ID when you create the OSPF process, the global router ID is used. HP
recommends specifying a router ID when you create the OSPF process.
OSPF can run multiple processes and supports VPNs:
•
To run multiple OSPF processes, you must specify an ID for each process. The process IDs take effect
locally and has no influence on packet exchange between routers. Two routers with different
process IDs can exchange packets.
•
VPN support enables an OSPF process to run in a specified VPN. For more information about VPN,
see MCE Configuration Guide.
Configuration procedure
To enable OSPF:
Step
1.
Enter system view.
Command
Remarks
system-view
N/A
By default, no global router ID is configured.
2.
(Optional.) Configure a
global router ID.
router id router-id
3.
Enable an OSPF process
and enter OSPF view.
ospf [ process-id | router-id
router-id | vpn-instance
vpn-instance-name ] *
4.
(Optional.) Configure a
description for the OSPF
process.
description description
5.
Create an OSPF area and
enter OSPF area view.
area area-id
6.
(Optional.) Configure a
description for the area.
description description
Specify a network to enable
the interface attached to the
network to run the OSPF
process in the area.
network ip-address
wildcard-mask
7.
If no global router ID is configured, the
highest loopback interface IP address, if
any, is used as the router ID. If no loopback
interface IP address is available, the highest
physical interface IP address is used,
regardless of the interface status (up or
down).
By default, no OSPF process is enabled.
By default, no description is configured for
the OSPF process.
HP recommends configuring a description
for each OSPF process.
By default, no OSPF area is created.
By default, no description is configured for
the area.
HP recommends configuring a description
for each OSPF area.
By default, no network is specified.
A network can be added to only one area.
Configuring OSPF areas
Before you configure an OSPF area, complete the following tasks:
•
Configure IP addresses for interfaces to ensure IP connectivity between neighboring nodes.
57
Enable OSPF.
•
Configuring a stub area
You can configure a non-backbone area at an AS edge as a stub area. To do so, issue the stub command
on all routers attached to the area. The routing table size is reduced because Type-5 LSAs will not be
flooded within the stub area. The ABR generates a default route into the stub area so all packets destined
outside of the AS are sent through the default route.
To further reduce the routing table size and routing information exchanged in the stub area, configure a
totally stub area by using the stub [ no-summary ] command on the ABR. AS external routes and
inter-area routes will not be distributed into the area. All the packets destined outside of the AS or area
will be sent to the ABR for forwarding.
A stub or totally stub area cannot have an ASBR because external routes cannot be distributed into the
area.
Virtual links cannot transit a stub area or totally stub area.
To configure an OSPF stub area:
Step
Command
Remarks
1.
Enter system view.
system-view
N/A
2.
Enter OSPF view.
ospf [ process-id | router-id
router-id | vpn-instance
vpn-instance-name ] *
N/A
3.
Enter area view.
area area-id
N/A
4.
Configure the area as a stub
area.
stub [ default-route-advertise |
no-summary ] *
By default, no stub area is configured.
5.
(Optional.) Specify a cost
for the default route
advertised to the stub area.
The default setting is 1.
default-cost cost
The default-cost cost command takes
effect only on the ABR of a stub area or
totally stub area.
Configuring an NSSA area
A stub area cannot import external routes, but an NSSA area can import external routes into the OSPF
routing domain while retaining other stub area characteristics.
Do not configure the backbone area as an NSSA area or totally NSSA area.
To configure an NSSA area, configure the nssa command on all the routers attached to the area.
To configure a totally NSSA area, configure the nssa command on all the routers attached to the area
and configure the nssa no-summary command on the ABR. The ABR of a totally NSSA area does not
advertise inter-area routes into the area.
Virtual links cannot transit a stub area or totally stub area.
To configure an NSSA area:
Step
1.
Enter system view.
Command
Remarks
system-view
N/A
58
Step
Command
Remarks
2.
Enter OSPF view.
ospf [ process-id | router-id
router-id | vpn-instance
vpn-instance-name ] *
N/A
3.
Enter area view.
area area-id
N/A
4.
Configure the area as an
NSSA area.
nssa [ default-route-advertise |
no-import-route | no-summary |
translate-always |
translator-stability-interval value ]
*
By default, no area is configured as
an NSSA area.
5.
(Optional.) Specify a cost for
the default route advertised
to the NSSA area.
The default setting is 1.
default-cost cost
This command takes effect only on
the ABR/ASBR of an NSSA or totally
NSSA area.
Configuring a virtual link
Virtual links are configured for connecting backbone area routers that have no direct physical links.
Virtual links cannot transit a stub area, totally stub area, NSSA area, or totally NSSA area.
To configure a virtual link:
Step
Command
Remarks
1.
Enter system view.
system-view
N/A
2.
Enter OSPF view.
ospf [ process-id | router-id
router-id | vpn-instance
vpn-instance-name ] *
N/A
3.
Enter area view.
area area-id
N/A
By default, no virtual link is
configured.
4.
Configure a virtual link.
vlink-peer router-id [ dead seconds
| hello seconds | { hmac-md5 |
md5 } key-id { cipher cipher-string
| plain plain-string } | retransmit
seconds | simple { cipher
cipher-string | plain plain-string } |
trans-delay seconds ] *
Configure this command on both
ends of a virtual link, and the hello
and dead intervals must be identical
on both ends of the virtual link.
The authentication mode (MD5 or
simple) of the virtual link is
determined by the authentication
mode configured for the backbone
area.
Configuring OSPF network types
OSPF classifies networks into the following types based on the link layer protocol:
•
Broadcast—When the link layer protocol is Ethernet or FDDI, OSPF classifies the network type as
broadcast by default.
59
•
NBMA—When the link layer protocol is Frame Relay, ATM, or X.25, OSPF classifies the network
type as NBMA by default.
•
P2P—When the link layer protocol is PPP, LAPB, or HDLC, OSPF classifies the network type as P2P
by default.
When you change the network type of an interface, follow these guidelines:
•
When an NBMA network becomes fully meshed, change the network type to broadcast to avoid
manual configuration of neighbors.
•
If any routers in a broadcast network do not support multicasting, change the network type to
NBMA.
•
An NBMA network must be fully meshed. OSPF requires that an NBMA network be fully meshed.
If a network is partially meshed, change the network type to P2MP.
•
If a router on an NBMA network has only one neighbor, you can change the network type to P2P
to save costs.
Two broadcast-, NBMA-, and P2MP-interfaces can establish a neighbor relationship only when they are
on the same network segment.
Configuration prerequisites
Before you configure OSPF network types, complete the following tasks:
•
Configure IP addresses for interfaces to ensure IP connectivity between neighboring nodes.
•
Enable OSPF.
Configuring the broadcast network type for an interface
Step
Command
Remarks
1.
Enter system view.
system-view
N/A
2.
Enter interface view.
interface interface-type
interface-number
N/A
3.
Configure the OSPF network
type for the interface as
broadcast.
ospf network-type broadcast
By default, the network type of an
interface depends on the link layer
protocol.
(Optional.) Configure a router
priority for the interface.
ospf dr-priority priority
The default router priority is 1.
4.
Configuring the NBMA network type for an interface
After you configure the network type as NBMA, you must specify neighbors and their router priorities
because NBMA interfaces cannot find neighbors by broadcasting hello packets.
To configure the NBMA network type for an interface:
Step
1.
Enter system view.
Command
Remarks
system-view
N/A
60
Step
Command
Remarks
2.
Enter interface view.
interface interface-type
interface-number
N/A
3.
Configure the OSPF
network type for the
interface as NBMA.
ospf network-type nbma
By default, the network type of an
interface depends on the link layer
protocol.
The default setting is 1.
(Optional.) Configure a
router priority for the
interface.
ospf dr-priority priority
The router priority configured with this
command is for DR election.
5.
Return to system view.
quit
N/A
6.
Enter OSPF view.
ospf [ process-id | router-id
router-id | vpn-instance
vpn-instance-name ] *
N/A
4.
By default, no neighbor is specified.
7.
Specify a neighbor and its
router priority.
peer ip-address [ cost value |
dr-priority dr-priority ]
The priority configured with this
command indicates whether a
neighbor has the election right or not. If
you configure the router priority for a
neighbor as 0, the local router
determines the neighbor has no
election right, and does not send hello
packets to this neighbor. However, if
the local router is the DR or BDR, it still
sends hello packets to the neighbor for
neighbor relationship establishment.
Configuring the P2MP network type for an interface
Step
Command
Remarks
1.
Enter system view.
system-view
N/A
2.
Enter interface view.
interface interface-type
interface-number
N/A
By default, the network type of an
interface depends on the link layer
protocol.
After you configure the OSPF
network type for an interface as
P2MP unicast, all packets are unicast
over the interface. The interface
cannot broadcast hello packets to
discover neighbors, so you must
manually specify the neighbors.
Configure the OSPF network
type for the interface as
P2MP.
ospf network-type p2mp [ unicast ]
4.
Exit to system view.
quit
N/A
5.
Enter OSPF view.
ospf [ process-id | router-id
router-id | vpn-instance
vpn-instance-name ] *
N/A
3.
61
Step
Command
(Optional.) Specify a
neighbor and its router
priority.
6.
Remarks
By default, no neighbor is specified.
peer ip-address [ cost value |
dr-priority dr-priority ]
This step must be performed if the
network type is P2MP unicast, and is
optional if the network type is P2MP.
Configuring the P2P network type for an interface
Step
Command
Remarks
1.
Enter system view.
system-view
N/A
2.
Enter interface view.
interface interface-type
interface-number
N/A
3.
Configure the OSPF network
type for the interface as P2P.
ospf network-type p2p
By default, the network type of an
interface depends on the link layer
protocol.
Configuring OSPF route control
This section describes how to control the advertisement and reception of OSPF routing information, as
well as route redistribution from other protocols.
Configuration prerequisites
Before you configure OSPF route control, complete the following tasks:
•
Configure IP addresses for interfaces to ensure IP connectivity between neighboring nodes.
•
Enable OSPF.
•
Configure filters if routing information filtering is needed.
Configuring OSPF route summarization
Configure route summarization on an ABR or ASBR to summarize contiguous networks into a single
network and distribute it to other areas.
Route summarization reduces the routing information exchanged between areas and the size of routing
tables, and improves routing performance. For example, three internal networks 19.1.1.0/24,
19.1.2.0/24, and 19.1.3.0/24 are available within an area. You can summarize the three networks into
network 19.1.0.0/16, and advertise the summary network to other areas.
Configuring route summarization on an ABR
After you configure a summary route on an ABR, the ABR generates a summary LSA instead of more
specific LSAs so that the scale of LSDBs on routers in other areas and the influence of topology changes
are reduced.
To configure route summarization on an ABR:
62
Step
Command
Remarks
1.
Enter system view.
system-view
N/A
2.
Enter OSPF view.
ospf [ process-id | router-id router-id
| vpn-instance vpn-instance-name ] *
N/A
3.
Enter OSPF area view.
area area-id
N/A
4.
Configure ABR route
summarization.
abr-summary ip-address { mask |
mask-length } [ advertise |
not-advertise ] [ cost cost ]
By default, no route summarization
is configured.
The command takes effect only on
an ABR.
Configuring route summarization when redistributing routes into OSPF on an ASBR
Without route summarization, an ASBR advertises each redistributed route in a separate ASE LSA. After
you configure a summary route, the ASBR advertises only the summary route in an ASE LSA instead of
more specific routes, reducing the number of LSAs in the LSDB.
The ASBR summarizes redistributed Type-5 LSAs that fall into the specified address range. If the ASBR is
in an NSSA area, it also summarizes Type-7 LSAs that fall into the specified address range. If the ASBR
is also the ABR, it summarizes Type-5 LSAs translated from Type-7 LSAs.
To configure route summarization when redistributing routes into OSPF on an ASBR:
Step
Command
Remarks
1.
Enter system view.
system-view
N/A
2.
Enter OSPF view.
ospf [ process-id | router-id router-id
| vpn-instance vpn-instance-name ]*
N/A
Configure ASBR route
summarization.
asbr-summary ip-address { mask |
mask-length } [ tag tag | not-advertise
| cost cost ] *
3.
By default, no ASBR route
summarization is configured.
The command takes effect only on an
ASBR.
Configuring inbound OSPF route filtering
Perform this task to filter routes calculated using received LSAs.
The following filtering methods are available:
•
Use an ACL or IP prefix list to filter routing information by destination address.
•
Use the gateway keyword to filter routing information by next hop.
•
Use an ACL or IP prefix list to filter routing information by destination address and at the same time
use the gateway keyword to filter routing information by next hop.
•
Use a routing policy to filter routing information.
To configure OSPF to filter routes calculated using received LSAs:
Step
Command
Remarks
1.
Enter system view.
system-view
N/A
2.
Enter OSPF view.
ospf [ process-id | router-id router-id |
vpn-instance vpn-instance-name ] *
N/A
63
Step
Configure OSPF to
filter routes calculated
using received LSAs.
3.
Command
Remarks
filter-policy { acl-number [ gateway
ip-prefix-name ] | gateway ip-prefix-name |
ip-prefix ip-prefix-name [ gateway
ip-prefix-name ] | route-policy
route-policy-name } import
By default, OSPF accepts all
routes calculated using
received LSAs.
Configuring Type-3 LSA filtering
Perform this task to filter Type-3 LSAs advertised to an area on an ABR.
To configure Type-3 LSA filtering:
Step
Command
Remarks
1.
Enter system view.
system-view
N/A
2.
Enter OSPF view.
ospf [ process-id | router-id router-id |
vpn-instance vpn-instance-name ] *
N/A
3.
Enter area view.
area area-id
N/A
4.
Configure Type-3 LSA
filtering.
filter { acl-number | ip-prefix
ip-prefix-name } { import | export }
By default, the ABR does
not filter Type-3 LSAs.
Configuring an OSPF cost for an interface
Configure an OSPF cost for an interface by using either of the following methods:
•
Configure the cost value in interface view.
•
Configure a bandwidth reference value for the interface. OSPF computes the cost with this formula:
Interface OSPF cost = Bandwidth reference value (100 Mbps)/Interface bandwidth (Mbps). If the
calculated cost is greater than 65535, the value of 65535 is used. If the calculated cost is less than
1, the value of 1 is used. If no cost or bandwidth reference value is configured for an interface,
OSPF computes the interface cost based on the interface bandwidth and default bandwidth
reference value.
To configure an OSPF cost for an interface:
Step
Command
Remarks
1.
Enter system view.
system-view
N/A
2.
Enter interface view.
interface interface-type
interface-number
N/A
3.
Configure an OSPF cost
for the interface.
ospf cost value
By default, the OSPF cost is calculated
according to the interface bandwidth. For
a loopback interface, the OSPF cost is 0
by default.
To configure a bandwidth reference value:
Step
1.
Enter system view.
Command
Remarks
system-view
N/A
64
Step
Command
Remarks
2.
Enter OSPF view.
ospf [ process-id | router-id router-id |
vpn-instance vpn-instance-name ] *
N/A
3.
Configure a bandwidth
reference value.
bandwidth-reference value
The default setting is 100
Mbps.
Configuring the maximum number of ECMP routes
Perform this task to implement load sharing over ECMP routes.
To configure the maximum number of ECMP routes:
Step
Command
Remarks
1.
Enter system view.
system-view
N/A
2.
Enter OSPF view.
ospf [ process-id | router-id router-id |
vpn-instance vpn-instance-name ] *
N/A
maximum load-balancing maximum
By default, the
maximum number of
ECMP routes is the
same as that configured
in the max-ecmp-num
command. For more
information about the
max-ecmp-num
command, see IP
Routing Command
Reference.
3.
Configure the maximum
number of ECMP routes.
Configuring OSPF preference
A router can run multiple routing protocols, and each protocol is assigned a preference. If multiple routes
are available to the same destination, the one with the highest protocol preference is selected as the best
route.
To configure OSPF preference:
Step
Command
Remarks
1.
Enter system view.
system-view
N/A
2.
Enter OSPF view.
ospf [ process-id | router-id router-id
| vpn-instance vpn-instance-name ] *
N/A
3.
Configure a
preference for OSPF.
preference [ ase ] [ route-policy
route-policy-name ] value
By default, the preference of OSPF
internal routes is 10 and the preference
of OSPF external routes is 150.
Configuring OSPF route redistribution
On a router running OSPF and other routing protocols, you can configure OSPF to redistribute routes
from other protocols, such as RIP, IS-IS, BGP, static, and direct, and advertise them in Type-5 LSAs or
65
Type-7 LSAs. In addition, you can configure OSPF to filter redistributed routes so that OSPF advertises
only permitted routes.
IMPORTANT:
The import-route bgp command redistributes only EBGP routes. Because the import-route bgp
allow-ibgp command redistributes both EBGP and IBGP routes, and might cause routing loops, use it with
caution.
Configuring OSPF to redistribute routes from another routing protocol
Step
Command
Remarks
1.
Enter system view.
system-view
N/A
2.
Enter OSPF view.
ospf [ process-id | router-id router-id |
vpn-instance vpn-instance-name ] *
N/A
3.
Configure OSPF to
redistribute routes from
another routing protocol.
import-route protocol [ process-id |
all-processes | allow-ibgp ] [ cost cost |
route-policy route-policy-name | tag tag
| type type ] *
4.
(Optional.) Configure
OSPF to filter redistributed
routes.
filter-policy { acl-number | prefix-list
ip-prefix-name } export [ protocol
[ process-id ] ]
By default, no route redistribution
is configured.
This command redistributes only
active routes. To view information
about active routes, use the
display ip routing-table protocol
command.
By default, OSPF accepts all
redistributed routes.
Configuring OSPF to redistribute a default route
The import-route command cannot redistribute a default external route. Perform this task to redistribute a
default route.
To redistribute a default route:
Step
Command
Remarks
1.
Enter system view.
system-view
N/A
2.
Enter OSPF view.
ospf [ process-id | router-id router-id |
vpn-instance vpn-instance-name ] *
N/A
Redistribute a default
route.
default-route-advertise [ [ [ always |
permit-calculate-other ] | cost cost |
route-policy route-policy-name | type
type ] * | summary cost cost ]
3.
66
By default, no default route is
redistributed.
This command is applicable
only to VPNs. The PE router
advertises a default route in a
Type-3 LSA to a CE router.
Configuring default parameters for redistributed routes
Perform this task to configure default parameters for redistributed routes, including cost, tag, and type.
Tags indicate information about protocols. For example, when redistributing BGP routes, OSPF uses tags
to identify AS IDs.
To configure the default parameters for redistributed routes:
Step
Command
Remarks
1.
Enter system view.
system-view
N/A
2.
Enter OSPF view.
ospf [ process-id | router-id router-id |
vpn-instance vpn-instance-name ] *
N/A
3.
Configure the default
parameters for
redistributed routes (cost,
upper limit, tag, and
type).
default { cost cost | tag tag | type type } *
By default, the cost is 1, the
tag is 1, and the type is
Type-2.
Advertising a host route
Step
Command
Remarks
1.
Enter system view.
system-view
N/A
2.
Enter OSPF view.
ospf [ process-id | router-id
router-id | vpn-instance
vpn-instance-name ] *
N/A
3.
Enter area view.
area area-id
N/A
4.
Advertise a host route.
host-advertise ip-address cost
By default, no host route is
advertised.
Tuning and optimizing OSPF networks
You can use one of the following methods to optimize an OSPF network:
•
Change OSPF packet timers to adjust the convergence speed and network load. On low-speed
links, consider the delay time for sending LSAs.
•
Change the SPF calculation interval to reduce resource consumption caused by frequent network
changes.
•
Configure OSPF authentication to improve security.
Configuration prerequisites
Before you configure OSPF network optimization, complete the following tasks:
•
Configure IP addresses for interfaces to ensure IP connectivity between neighboring nodes.
•
Enable OSPF.
67
Configuring OSPF timers
An OSPF interface includes the following timers:
•
Hello timer—Interval for sending hello packets. It must be identical on OSPF neighbors.
•
Poll timer—Interval for sending hello packets to a neighbor that is down on the NBMA network.
•
Dead timer—Interval within which if the interface receives no hello packet from the neighbor, it
declares the neighbor is down.
•
LSA retransmission timer—Interval within which if the interface receives no acknowledgement
packets after sending a LSA to the neighbor, it retransmits the LSA.
To configure OSPF timers:
Step
Command
Remarks
1.
Enter system view.
system-view
N/A
2.
Enter interface
view.
interface interface-type
interface-number
N/A
By default:
• The hello interval on P2P and broadcast
3.
4.
Specify the hello
interval.
Specify the poll
interval.
interfaces is 10 seconds.
ospf timer hello seconds
• The hello interval on P2MP and NBMA
interfaces is 30 seconds.The default hello
interval is restored when the network type for an
interface is changed.
The default setting is 120 seconds.
ospf timer poll seconds
The poll interval is at least four times the hello
interval.
By default:
• The dead interval on P2P and broadcast
interfaces is 40 seconds.
5.
Specify the dead
interval.
• The dead interval on P2MP and NBMA
ospf timer dead seconds
interfaces is 120 seconds.
The dead interval must be at least four times the
hello interval on an interface.
The default dead interval is restored when the
network type for an interface is changed.
The default setting is 5 seconds.
6.
Specify the
retransmission
interval.
ospf timer retransmit interval
A retransmission interval setting that is too small
can cause unnecessary LSA retransmissions.
This interval is typically set bigger than the
round-trip time of a packet between two
neighbors.
Specifying LSA transmission delay
To avoid LSAs from aging out during transmission, set an LSA retransmission delay especially for low
speed links.
To specify the LSA transmission delay on an interface:
68
Step
Command
Remarks
1.
Enter system view.
system-view
N/A
2.
Enter interface view.
interface interface-type
interface-number
N/A
3.
Specify the LSA transmission
delay.
ospf trans-delay seconds
The default setting is 1 second.
Specifying SPF calculation interval
LSDB changes result in SPF calculations. When the topology changes frequently, a large amount of
network and router resources are occupied by SPF calculation. You can adjust the SPF calculation
interval to reduce the impact.
When network changes are not frequent, the minimum-interval is adopted. If network changes become
frequent, the SPF calculation interval is incremented by incremental-interval × 2n-2 (n is the number of
calculation times) each time a calculation occurs until the maximum-interval is reached.
To configure the SPF calculation interval:
Step
Command
Remarks
1.
Enter system view.
system-view
N/A
2.
Enter OSPF view.
ospf [ process-id | router-id router-id
| vpn-instance vpn-instance-name ] *
N/A
By default:
3.
Specify the SPF
calculation interval.
spf-schedule-interval
maximum-interval [ minimum-interval
[ incremental-interval ] ]
• The maximum interval is 5 seconds.
• The minimum interval is 50
milliseconds.
• The incremental interval is 200
milliseconds.
Specifying the LSA arrival interval
If OSPF receives an LSA that has the same LSA type, LS ID, and router ID as the previously received LSA
within the LSA arrival interval, OSPF discards the LSA to save bandwidth and route resources.
To configure the LSA arrival interval:
Step
Command
Remarks
1.
Enter system view.
system-view
N/A
2.
Enter OSPF view.
ospf [ process-id | router-id
router-id | vpn-instance
vpn-instance-name ] *
N/A
3.
Configure the LSA arrival
interval.
The default setting is 1000
milliseconds.
lsa-arrival-interval interval
69
Make sure this interval is smaller than
or equal to the interval set with the
lsa-generation-interval command.
Specifying the LSA generation interval
Adjust the LSA generation interval to protect network resources and routers from being overwhelmed by
LSAs at the time of frequent network changes.
When network changes are not frequent, LSAs are generated at the minimum-interval. If network
changes become frequent, the LSA generation interval is incremented by incremental-interval × 2n-2 (n is
the number of generation times) each time a LSA generation occurs until the maximum-interval is
reached.
To configure the LSA generation interval:
Step
Command
Remarks
1.
Enter system view.
system-view
N/A
2.
Enter OSPF view.
ospf [ process-id | router-id router-id |
vpn-instance vpn-instance-name ] *
N/A
By default:
• The maximum interval is 5
3.
Configure the LSA
generation interval.
lsa-generation-interval
maximum-interval [ minimum-interval
[ incremental-interval ] ]
seconds.
• The minimum interval is 0
milliseconds.
• The incremental interval is 0
milliseconds.
Disabling interfaces from receiving and sending OSPF packets
To enhance OSPF adaptability and reduce resource consumption, you can set an OSPF interface to
"silent." A silent OSPF interface blocks OSPF packets and cannot establish any OSPF neighbor
relationship. However, other interfaces on the router can still advertise direct routes of the interface in
Router LSAs.
To disable interfaces from receiving and sending routing information:
Step
Command
Remarks
1.
Enter system view.
system-view
N/A
2.
Enter OSPF view.
ospf [ process-id | router-id router-id
| vpn-instance vpn-instance-name ] *
N/A
By default, an OSPF interface can
receive and send OSPF packets.
3.
Disable interfaces from
receiving and sending
OSPF packets.
silent-interface { interface-type
interface-number | all }
70
The silent-interface command
disables only the interfaces
associated with the current process
rather than other processes.
Multiple OSPF processes can
disable the same interface from
receiving and sending OSPF
packets.
Configuring stub routers
A stub router is used for traffic control. It reports its status as a stub router to neighboring OSPF routers.
The neighboring routers do not use the stub router to forward data although they have a route to it.
Router LSAs from the stub router might contain different link type values. A value of 3 means a link to a
stub network, and the cost of the link will not be changed. A value of 1, 2 or 4 means a point-to-point link,
a link to a transit network, or a virtual link. On such links, a maximum cost value of 65535 is used.
Neighbors do not send packets to the stub router as long as they have a route with a smaller cost.
To configure a router as a stub router:
Step
Command
Remarks
1.
Enter system view.
system-view
N/A
2.
Enter OSPF view.
ospf [ process-id | router-id router-id |
vpn-instance vpn-instance-name ] *
N/A
3.
Configure the router as a
stub router.
By default, the router is not
configured as a stub router.
stub-router
A stub router has no associations
with a stub area.
Configuring OSPF authentication
Configure OSPF packet authentication to ensure the packet exchange security.
After authentication is configured, OSPF only receives packets that pass authentication. Failed packets
cannot establish neighboring relationships.
You must configure the same area authentication mode on all the routers in an area. In addition, the
authentication mode and password for all interfaces attached to the same area must be identical.
To configure OSPF authentication:
Step
Command
Remarks
1.
Enter system view.
system-view
N/A
2.
Enter OSPF view.
ospf [ process-id | router-id router-id |
vpn-instance vpn-instance-name ] *
N/A
3.
Enter area view.
area area-id
N/A
4.
Configure area authentication
mode.
authentication-mode { md5 | simple }
By default, no
authentication is
configured.
5.
Return to OSPF view.
quit
N/A
6.
Return to system view.
quit
N/A
7.
Enter interface view.
interface interface-type interface-number
N/A
71
Step
Command
Remarks
• Configure simple authentication:
8.
Configure interface
authentication mode.
ospf authentication-mode simple { cipher
cipher-string | plain plain-string }
• Configure MD5 authentication:
ospf authentication-mode { hmac-md5 |
md5 } key-id { cipher cipher-string | plain
plain-string }
Use either approach.
By default, no interface
authentication is
configured.
Adding the interface MTU into DD packets
By default, an OSPF interface adds a value of 0 into the interface MTU field of a DD packet rather than
the actual interface MTU. You can enable an interface to add its MTU into DD packets.
To add the interface MTU into DD packets:
Step
Command
Remarks
1.
Enter system view.
system-view
N/A
2.
Enter interface view.
interface interface-type
interface-number
N/A
3.
Enable the interface to add its
MTU into DD packets.
ospf mtu-enable
By default, the interface adds an
MTU value of 0 into DD packets.
Configuring the maximum number of external LSAs in LSDB
Step
Command
Remarks
1.
Enter system view.
system-view
N/A
2.
Enter OSPF view.
ospf [ process-id | router-id router-id |
vpn-instance vpn-instance-name ] *
N/A
3.
Specify the maximum number
of external LSAs in the LSDB.
lsdb-overflow-limit number
By default, the
maximum number of
external LSAs in the
LSDB is not limited.
Configuring OSPF exit overflow interval
When the number of LSAs in the LSDB exceeds the upper limit, the LSDB is in an overflow state. To save
resources, OSPF does not receive any external LSAs and deletes the external LSAs generated by itself
when in this state.
Perform this task to configure the interval that OSPF exits overflow state.
To configure the OSPF exit overflow interval:
72
Step
Command
Remarks
1.
Enter system view.
system-view
N/A
2.
Enter OSPF view.
ospf [ process-id | router-id router-id |
vpn-instance vpn-instance-name ] *
N/A
3.
Configure the OSPF exit
overflow interval.
The default setting is 300
seconds.
lsdb-overflow-interval interval
The value of 0 indicates that
OSPF does not exit overflow
state.
Enabling compatibility with RFC 1583
RFC 1583 specifies a different method than RFC 2328 for selecting an external route from multiple LSAs.
This task enables RFC 2328 to be compatible with RFC 1583 so that the intra-area route in the backbone
area is preferred. If they are not compatible, the intra-area route in a non-backbone area is preferred to
reduce the burden of the backbone area.
To avoid routing loops, HP recommends enabling or disabling RFC 1583-compatibility on all routers in
a routing domain.
To enable compatibility with RFC 1583:
Step
Command
Remarks
1.
Enter system view.
system-view
N/A
2.
Enter OSPF view.
ospf [ process-id | router-id router-id |
vpn-instance vpn-instance-name ] *
N/A
3.
Enable compatibility
with RFC 1583.
rfc1583 compatible
By default, this feature is enabled.
Logging neighbor state changes
Perform this task to enable output of log information to the terminal upon neighbor state changes.
To enable the logging of neighbor state changes:
Step
Command
Remarks
1.
Enter system view.
system-view
N/A
2.
Enter OSPF view.
ospf [ process-id | router-id router-id |
vpn-instance vpn-instance-name ] *
N/A
3.
Enable the logging of
neighbor state changes.
log-peer-change
By default, this feature is
enabled.
Configuring OSPF network management
OSPF network management allows you to save system resources by enabling trap generation to report
important events and configuring the maximum number of output traps for a specific time period.
To configure OSPF network management:
73
Step
Command
Remarks
1.
Enter system view.
system-view
N/A
2.
Bind OSPF MIB to an
OSPF process.
ospf mib-binding process-id
By defaut, OSPF MIB is bound to
the process with the smallest
process ID.
3.
Enable OSPF trap
generation.
snmp-agent trap enable ospf
[ authentication-failure | bad-packet |
config-error | grhelper-status-change |
grrestarter-status-change | if-state-change
| lsa-maxage | lsa-originate |
lsdb-approaching-overflow |
lsdb-overflow | neighbor-state-change |
nssatranslator-status-change | retransmit |
virt-authentication-failure | virt-bad-packet
| virt-config-error | virt-retransmit |
virtgrhelper-status-change |
virtif-state-change |
virtneighbor-state-change ] *
By default, OSPF trap sending is
enabled.
4.
Configure the
number of output
traps in a specific
time.
snmp trap rate-limit interval trap-interval
count trap-number
By default, OSPF outputs seven
traps in 10 seconds.
Configuring the LSU transmit rate
Sending large numbers of LSU packets affects router performance and consumes too much network
bandwidth. You can configure the router to send LSU packets at a proper interval and limit the maximum
number of LSU packets sent out of an OSPF interface each time.
To configure the LSU transmit rate:
Step
Command
Remarks
1.
Enter system view.
system-view
N/A
2.
Enter OSPF view.
ospf [ process-id | router-id router-id |
vpn-instance vpn-instance-name ] *
N/A
3.
Configure the LSU
transmit rate.
transmit-pacing interval interval count count
By default, an OSPF interface
sends up to three LSU packets
every 20 milliseconds.
Enabling OSPF ISPF
When the topology changes, Incremental Shortest Path First (ISPF) computes only the affected part of the
SPT, instead of the entire SPT.
To enable OSPF ISPF:
Step
1.
Enter system view.
Command
Remarks
system-view
N/A
74
Step
Command
Remarks
2.
Enter OSPF view.
ospf [ process-id | router-id router-id |
vpn-instance vpn-instance-name ] *
N/A
3.
Enable OSPF ISPF.
ispf enable
By default, OSPF ISPF is
enabled.
Configuring OSPF Graceful Restart
GR ensures the continuity of packet forwarding when a routing protocol restarts or an active/standby
switchover occurs.
•
GR Restarter—Graceful restarting router. It must have GR capability.
•
GR Helper—A neighbor of the GR Restarter. It helps the GR Restarter to complete the GR process.
OSPF GR has the following types:
•
IETF GR—Uses Opaque LSAs to implement GR.
•
Non-IETF GR—Uses link local signaling (LLS) to advertise GR capability and uses out of band
synchronization to synchronize the LSDB.
A device can act as a GR Restarter and GR Helper at the same time.
Configuring the OSPF GR Restarter
You can configure the IETF or non IETF OSPF GR Restarter.
Configuring the IETF OSPF GR Restarter
Step
Command
Remarks
1.
Enter system view.
system-view
N/A
2.
Enable OSPF and enter its
view.
ospf [ process-id | router-id
router-id | vpn-instance
vpn-instance-name ] *
N/A
3.
Enable opaque LSA reception
and advertisement capability.
opaque-capability enable
By default, opaque LSA reception
and advertisement capability is
enabled.
4.
Enable the IETF GR.
graceful-restart ietf [ global |
planned-only ] *
By default, the IETF GR capability is
disabled.
5.
(Optional.) Configure GR
interval.
graceful-restart interval
interval-value
The default setting is 120 seconds.
Configuring the non-IETF OSPF GR Restarter
Step
Command
Remarks
1.
Enter system view.
system-view
N/A
2.
Enable OSPF and enter its
view.
ospf [ process-id | router-id
router-id | vpn-instance
vpn-instance-name ] *
N/A
75
Step
Command
Remarks
3.
Enable the link-local signaling
capability.
enable link-local-signaling
By default, the link-local signaling
capability is disabled.
4.
Enable the out-of-band
re-synchronization capability.
enable
out-of-band-resynchronization
By default, the out-of-band
re-synchronization capability is
disabled.
5.
Enable non-IETF GR.
graceful-restart [ nonstandard ]
[ global | planned-only ] *
By default, non-IETF GR capability
is disabled.
6.
(Optional.) Configure GR
interval.
graceful-restart interval
interval-value
The default setting is120.
Configuring OSPF GR Helper
You can configure the IETF or non IETF OSPF GR Helper.
Configuring the IETF OSPF GR Helper
Step
Command
Remarks
1.
Enter system view.
system-view
N/A
2.
Enable OSPF and enter its
view.
ospf [ process-id | router-id
router-id | vpn-instance
vpn-instance-name ] *
N/A
3.
Enable opaque LSA reception
and advertisement capability.
opaque-capability enable
By default, opaque LSA reception
and advertisement capability is
enabled.
4.
(Optional.) Enable GR Helper
capability.
graceful-restart helper enable
[ planned-only ]
By default, GR Helper capability is
enabled.
5.
(Optional.) Enable strict LSA
checking for the GR Helper.
graceful-restart helper
strict-lsa-checking
By default, strict LSA checking for
the GR Helper is disabled.
Configuring the non-IETF OSPF GR Helper
Step
Command
Remarks
1.
Enter system view.
system-view
N/A
2.
Enable OSPF and enter its
view.
ospf [ process-id | router-id
router-id | vpn-instance
vpn-instance-name ] *
N/A
3.
Enable the link-local signaling
capability.
enable link-local-signaling
By default, the link-local signaling
capability is disabled.
4.
Enable the out-of-band
re-synchronization capability.
enable
out-of-band-resynchronization
By default, the out-of-band
re-synchronization capability is
disabled.
5.
(Optional.) Enable GR
Helper.
graceful-restart helper enable
By default, GR Helper is enabled.
76
Step
(Optional.) Enable strict LSA
checking for the GR Helper.
6.
Command
Remarks
graceful-restart helper
strict-lsa-checking
By default, strict LSA checking for
the GR Helper is disabled.
Triggering OSPF Graceful Restart
To trigger OSPF Graceful Restart, perform the following command in user view:
Task
Command
Trigger OSPF Graceful Restart.
reset ospf [ process-id ] process graceful-restart
Configuring BFD for OSPF
BFD provides a single mechanism to quickly detect and monitor the connectivity of links between OSPF
neighbors, which improves the network convergence speed. For more information about BFD, see High
Availability Configuration Guide.
OSPF supports the following BFD detection modes:
•
Bidirectional control detection—Requires BFD configuration to be made on both OSPF routers on
the link.
•
Single-hop echo detection—Requires BFD configuration to be made on one OSPF router on the link.
Configuring bidirectional control detection
Step
Command
Remarks
1.
Enter system view.
system-view
N/A
2.
Enter interface view.
interface interface-type
interface-number
N/A
3.
Enable BFD bidirectional control
detection.
By default, BFD bidirectional
control detection is disabled.
ospf bfd enable
Both ends of a BFD session must be
on the same network segment and
in the same area.
Configuring single-hop echo detection
Step
Command
Remarks
1.
Enter system view.
system-view
N/A
2.
Configure the source address of echo
packets.
bfd echo-source-ip ip-address
By default, the source
address of echo packets is
not configured.
3.
Enter interface view.
interface interface-type
interface-number
N/A
77
Step
Enable BFD single-hop echo
detection.
4.
Command
Remarks
ospf bfd enable echo
By default, BFD single-hop
echo detection is disabled.
Configuring OSPF FRR
A link or router failure on a path can cause packet loss and even routing loop until OSPF completes
routing convergence based on the new network topology. FRR enables fast rerouting to minimize the
impact of link or node failures.
Figure 19 Network diagram for OSPF FRR
In Figure 19, configure FRR on Router B by using a routing policy to specify a backup next hop. When the
primary link fails, OSPF directs packets to the backup next hop. At the same time, OSPF calculates the
shortest path based on the new network topology, and forwards packets over the path after network
convergence.
You can configure OSPF FRR to calculate a backup next hop by using the loop free alternate (LFA)
algorithm, or specify a backup next hop by using a routing policy.
Configuration prerequisites
Before you configure OSPF FRR, complete the following tasks:
•
Configure IP addresses for interfaces to ensure IP connectivity between neighboring nodes.
•
Enable OSPF.
Configuration guidelines
•
Do not use FRR and BFD at the same time. Otherwise, FRR might fail to take effect.
•
Do not use the fast-reroute lfa command together with the command vlink-peer.
Configuring OSPF FRR to calculate a backup next hop using the
LFA algorithm
Step
Command
Remarks
1.
Enter system view.
system-view
N/A
2.
Configure the source address
of echo packets.
bfd echo-source-ip ip-address
By default, the source address of echo
packets is not configured.
78
Step
Command
Remarks
3.
Enter interface view.
interface interface-type
interface-number
N/A
4.
Enable LFA calculation on an
interface.
ospf fast-reroute lfa-backup
By default, the interface on which LFA
calculation is enabled can be selected
as a backup interface.
5.
Return to system view.
quit
N/A
6.
Enter OSPF view.
ospf [ process-id | router-id
router-id | vpn-instance
vpn-instance-name ] *
N/A
7.
Enable OSPF FRR to calculate
a backup next hop by using
the LFA algorithm.
fast-reroute lfa [ abr-only ]
By default, OSPF FRR is not configured.
If abr-only is specified, the route to the
ABR is selected as the backup path.
Configuring OSPF FRR to specify a backup next hop using a
routing policy
Before you configure this task, use the apply fast-reroute backup-interface command to specify a backup
next hop in the routing policy to be referenced. For more information about the apply fast-reroute
backup-interface command and routing policy configuration, see "Configuring routing policies."
To configure OSPF FRR to specify a backup next hop using a routing policy:
Step
Command
Remarks
1.
Enter system view.
system-view
N/A
2.
Configure the source address
of echo packets.
bfd echo-source-ip ip-address
By default, the source address of
echo packets is not configured.
3.
Enter OSPF view.
ospf [ process-id | router-id
router-id | vpn-instance
vpn-instance-name ] *
N/A
4.
Enable OSPF FRR to specify a
backup next hop by using a
routing policy.
fast-reroute route-policy
route-policy-name
By default, OSPF FRR is not
configured.
Displaying and maintaining OSPF
Execute display commands in any view and reset commands in user view.
Task
Command
Display OSPF brief information.
display ospf [ process-id ] brief
Display OSPF statistics.
display ospf [ process-id ] cumulative
Display GR status of the specified
OSPF process.
display ospf [ process-id ] graceful-restart [ verbose ]
79
Task
Command
Display Link State Database
information.
display ospf [ process-id ] lsdb [ brief | [ { ase | router | network |
summary | asbr | nssa | opaque-link | opaque-area | opaque-as }
[ link-state-id ] ] [ originate-router advertising-router-id | self-originate ] ]
Display OSPF neighbor
information.
display ospf [ process-id ] peer [ verbose ] [ interface-type
interface-number ] [ neighbor-id ]
Display neighbor statistics of OSPF
areas.
display ospf [ process-id ] peer statistics
Display routing table information.
display ospf [ process-id ] routing [ interface interface-type
interface-number ] [ nexthop nexthop-address ] [ verbose ]
Display virtual link information.
display ospf [ process-id ] vlink
Display OSPF request queue
information.
display ospf [ process-id ] request-queue [ interface-type
interface-number ] [ neighbor-id ]
Display OSPF retransmission
queue information.
display ospf [ process-id ] retrans-queue [ interface-type
interface-number ] [ neighbor-id ]
Display OSPF ABR and ASBR
information.
display ospf [ process-id ] abr-asbr
Display OSPF interface
information.
display ospf [ process-id ] interface [ all | interface-type
interface-number ]
Display OSPF error information.
display ospf [ process-id ] error
Display OSPF ASBR route
summarization information.
display ospf [ process-id ] asbr-summary [ ip-address { mask |
mask-length } ]
Display the global route ID.
display router id
Clear OSPF statistics.
reset ospf [ process-id ] counters
Reset an OSPF process.
reset ospf [ process-id ] process [ graceful-restart ]
Re-enable OSPF route
redistribution.
reset ospf [ process-id ] redistribution
OSPF configuration examples
These configuration examples only cover commands for OSPF configuration.
Configuring basic OSPF
Network requirements
•
Enable OSPF on all switches, and split the AS into three areas.
•
Configure Switch A and Switch B as ABRs.
80
Figure 20 Network diagram
Switch A
Area 0
Vlan-int100
10.1.1.2/24
Vlan-int200
10.2.1.1/24
Area 1
Switch B
Vlan-int100
10.1.1.1/24
Vlan-int200
10.2.1.2/24
Switch C
Vlan-int300
10.4.1.1/24
Vlan-int200
10.3.1.1/24
Vlan-int200
10.3.1.2/24
Area 2
Vlan-int300
10.5.1.1/24 Switch D
Configuration procedure
1.
Configure IP addresses for interfaces. (Details not shown.)
2.
Enable OSPF:
# Configure Switch A.
<SwitchA> system-view
[SwitchA] router id 10.2.1.1
[SwitchA] ospf
[SwitchA-ospf-1] area 0
[SwitchA-ospf-1-area-0.0.0.0] network 10.1.1.0 0.0.0.255
[SwitchA-ospf-1-area-0.0.0.0] quit
[SwitchA-ospf-1] area 1
[SwitchA-ospf-1-area-0.0.0.1] network 10.2.1.0 0.0.0.255
[SwitchA-ospf-1-area-0.0.0.1] quit
[SwitchA-ospf-1] quit
# Configure Switch B.
<SwitchB> system-view
[SwitchB] router id 10.3.1.1
[SwitchB] ospf
[SwitchB-ospf-1] area 0
[SwitchB-ospf-1-area-0.0.0.0] network 10.1.1.0 0.0.0.255
[SwitchB-ospf-1-area-0.0.0.0] quit
[SwitchB-ospf-1] area 2
[SwitchB-ospf-1-area-0.0.0.2] network 10.3.1.0 0.0.0.255
[SwitchB-ospf-1-area-0.0.0.2] quit
[SwitchB-ospf-1] quit
# Configure Switch C.
<SwitchC> system-view
[SwitchC] router id 10.4.1.1
[SwitchC] ospf
[SwitchC-ospf-1] area 1
[SwitchC-ospf-1-area-0.0.0.1] network 10.2.1.0 0.0.0.255
[SwitchC-ospf-1-area-0.0.0.1] network 10.4.1.0 0.0.0.255
[SwitchC-ospf-1-area-0.0.0.1] quit
[SwitchC-ospf-1] quit
81
# Configure Switch D.
<SwitchD> system-view
[SwitchD] router id 10.5.1.1
[SwitchD] ospf
[SwitchD-ospf-1] area 2
[SwitchD-ospf-1-area-0.0.0.2] network 10.3.1.0 0.0.0.255
[SwitchD-ospf-1-area-0.0.0.2] network 10.5.1.0 0.0.0.255
[SwitchD-ospf-1-area-0.0.0.2] quit
[SwitchD-ospf-1] quit
Verifying the configuration
# Display information about neighbors on Switch A.
[SwitchA] display ospf peer verbose
OSPF Process 1 with Router ID 10.2.1.1
Neighbors
Area 0.0.0.0 interface 10.1.1.1(Vlan-interface100)'s neighbors
Router ID: 10.3.1.1
State: Full
DR: 10.1.1.1
Address: 10.1.1.2
Mode: Nbr is Master
BDR: 10.1.1.2
GR State: Normal
Priority: 1
MTU: 0
Options is 0x02 (-|-|-|-|-|-|E|-)
Dead timer due in 37
sec
Neighbor is up for 06:03:59
Authentication Sequence: [ 0 ]
Neighbor state change count: 5
Neighbors
Area 0.0.0.1 interface 10.2.1.1(Vlan-interface200)'s neighbors
Router ID: 10.4.1.1
State: Full
DR: 10.2.1.1
Address: 10.2.1.2
Mode: Nbr is Master
BDR: 10.2.1.2
GR State: Normal
Priority: 1
MTU: 0
Options is 0x02 (-|-|-|-|-|-|E|-)
Dead timer due in 32
sec
Neighbor is up for 06:03:12
Authentication Sequence: [ 0 ]
Neighbor state change count: 5
# Display OSPF routing information on Switch A.
[SwitchA] display ospf routing
OSPF Process 1 with Router ID 10.2.1.1
Routing Tables
Routing for Network
Destination
Cost
10.2.1.0/24
1
10.3.1.0/24
2
Type
NextHop
Transit 10.2.1.1
Inter
10.1.1.2
82
AdvRouter
10.2.1.1
10.3.1.1
Area
0.0.0.1
0.0.0.0
10.4.1.0/24
2
Stub
10.2.1.2
10.4.1.1
0.0.0.1
10.5.1.0/24
3
Inter
10.1.1.2
10.3.1.1
0.0.0.0
10.1.1.0/24
1
Transit 10.1.1.1
10.2.1.1
0.0.0.0
AdvRouter
Area
Total Nets: 5
Intra Area: 3
Inter Area: 2
ASE: 0
NSSA: 0
# Display OSPF routing information on Switch D.
[SwitchD] display ospf routing
OSPF Process 1 with Router ID 10.5.1.1
Routing Tables
Routing for Network
Destination
Cost
Type
NextHop
10.2.1.0/24
10.3.1.0/24
3
Inter
10.3.1.1
10.3.1.1
0.0.0.2
1
Transit 10.3.1.2
10.3.1.1
0.0.0.2
10.4.1.0/24
4
Inter
10.3.1.1
10.3.1.1
0.0.0.2
10.5.1.0/24
1
Stub
10.5.1.1
10.5.1.1
0.0.0.2
10.1.1.0/24
2
Inter
10.3.1.1
10.3.1.1
0.0.0.2
Total Nets: 5
Intra Area: 2
Inter Area: 3
ASE: 0
NSSA: 0
# On Switch D, ping the IP address 10.4.1.1 to test reachability.
[SwitchD] ping 10.4.1.1
PING 10.4.1.1: 56
data bytes, press CTRL_C to break
Reply from 10.4.1.1: bytes=56 Sequence=2 ttl=253 time=2 ms
Reply from 10.4.1.1: bytes=56 Sequence=2 ttl=253 time=1 ms
Reply from 10.4.1.1: bytes=56 Sequence=3 ttl=253 time=1 ms
Reply from 10.4.1.1: bytes=56 Sequence=4 ttl=253 time=1 ms
Reply from 10.4.1.1: bytes=56 Sequence=5 ttl=253 time=1 ms
--- 10.4.1.1 ping statistics --5 packet(s) transmitted
5 packet(s) received
0.00% packet loss
round-trip min/avg/max = 1/1/2 ms
Configuring OSPF route redistribution
Network requirements
•
Enable OSPF on all the switches
•
Split the AS into three areas
•
Configure Switch A and Router B as ABRs
•
Configure Switch C as an ASBR to redistribute external routes (static routes).
83
Figure 21 Network diagram
Configuration procedure
1.
Configure IP addresses for interfaces. (Details not shown.)
2.
Enable OSPF (see "Configuring basic OSPF").
3.
Configure OSPF to redistribute routes:
# On Switch C, configure a static route destined for network 3.1.2.0/24.
<SwitchC> system-view
[SwitchC] ip route-static 3.1.2.1 24 10.4.1.2
# On Switch C, configure OSPF to redistribute static routes.
[SwitchC] ospf 1
[SwitchC-ospf-1] import-route static
Verifying the configuration
# Display the ABR/ASBR information of Switch D.
<SwitchD> display ospf abr-asbr
OSPF Process 1 with Router ID 10.5.1.1
Routing Table to ABR and ASBR
Type
Destination
Area
Cost
Nexthop
RtType
Intra
10.3.1.1
0.0.0.2
10
10.3.1.1
ABR
Inter
10.4.1.1
0.0.0.2
22
10.3.1.1
ASBR
# Display the OSPF routing table on Switch D.
<SwitchD> display ospf routing
OSPF Process 1 with Router ID 10.5.1.1
Routing Tables
Routing for Network
Destination
Cost
Type
NextHop
AdvRouter
Area
10.2.1.0/24
22
Inter
10.3.1.1
10.3.1.1
0.0.0.2
10.3.1.0/24
10
Transit 10.3.1.2
10.3.1.1
0.0.0.2
10.4.1.0/24
25
Inter
10.3.1.1
10.3.1.1
0.0.0.2
10.5.1.0/24
10
Stub
10.5.1.1
10.5.1.1
0.0.0.2
10.1.1.0/24
12
Inter
10.3.1.1
10.3.1.1
0.0.0.2
84
Routing for ASEs
Destination
Cost
Type
Tag
NextHop
AdvRouter
3.1.2.0/24
1
Type2
1
10.3.1.1
10.4.1.1
Total Nets: 6
Intra Area: 2
Inter Area: 3
ASE: 1
NSSA: 0
Configuring OSPF to advertise a summary route
Network requirements
•
Configure OSPF on Switch A and Switch B in AS 200.
•
Configure OSPF on Switch C, Switch D, and Switch E in AS 100.
•
Configure an eBGP connection between Switch B and Switch C. Configure Switch B and Switch C
to redistribute OSPF routes and direct routes into BGP and BGP routes into OSPF.
•
Configure Switch B to advertise only summary route 10.0.0.0/8 to Switch A.
Figure 22 Network diagram
Vlan-int600
10.4.1.1/24
Vlan-int500
10.3.1.1/24
Vlan-int400
10.1.1.1/24
Vlan-int300
10.2.1.2/24
Switch E
Switch D
Vlan-int300
10.2.1.1/24
Vlan-int400
10.1.1.2/24
AS 100
Switch C
Vlan-int200
11.1.1.2/24
EBGP
Vlan-int200
11.1.1.1/24
Switch B
Vlan-int100
11.2.1.1/24
Vlan-int100
11.2.1.2/24
AS 200
Switch A
Configuration procedure
1.
Configure IP addresses for interfaces. (Details not shown.)
2.
Enable OSPF:
# Configure Switch A.
<SwitchA> system-view
[SwitchA] router id 11.2.1.2
[SwitchA] ospf
[SwitchA-ospf-1] area 0
[SwitchA-ospf-1-area-0.0.0.0] network 11.2.1.0 0.0.0.255
[SwitchA-ospf-1-area-0.0.0.0] quit
[SwitchA-ospf-1] quit
85
# Configure Switch B.
<SwitchB> system-view
[SwitchB] router id 11.2.1.1
[SwitchB] ospf
[SwitchB-ospf-1] area 0
[SwitchB-ospf-1-area-0.0.0.0] network 11.2.1.0 0.0.0.255
[SwitchB-ospf-1-area-0.0.0.0] quit
[SwitchB-ospf-1] quit
# Configure Switch C.
<SwitchC> system-view
[SwitchC] router id 11.1.1.2
[SwitchC] ospf
[SwitchC-ospf-1] area 0
[SwitchC-ospf-1-area-0.0.0.0] network 10.1.1.0 0.0.0.255
[SwitchC-ospf-1-area-0.0.0.0] network 10.2.1.0 0.0.0.255
[SwitchC-ospf-1-area-0.0.0.0] quit
[SwitchC-ospf-1] quit
# Configure Switch D.
<SwitchD> system-view
[SwitchD] router id 10.3.1.1
[SwitchD] ospf
[SwitchD-ospf-1] area 0
[SwitchD-ospf-1-area-0.0.0.0] network 10.1.1.0 0.0.0.255
[SwitchD-ospf-1-area-0.0.0.0] network 10.3.1.0 0.0.0.255
[SwitchD-ospf-1-area-0.0.0.0] quit
# Configure Switch E.
<SwitchE> system-view
[SwitchE] router id 10.4.1.1
[SwitchE] ospf
[SwitchE-ospf-1] area 0
[SwitchE-ospf-1-area-0.0.0.0] network 10.2.1.0 0.0.0.255
[SwitchE-ospf-1-area-0.0.0.0] network 10.4.1.0 0.0.0.255
[SwitchE-ospf-1-area-0.0.0.0] quit
[SwitchE-ospf-1] quit
3.
Configure BGP to redistribute OSPF routes and direct routes:
# Configure Switch B.
[SwitchB] bgp 200
[SwitchB-bgp] peer 11.1.1.2 as 100
[SwitchB-bgp] ipv4-family unicast
[SwitchB-bgp-ipv4] import-route ospf
[SwitchB-bgp-ipv4] import-route direct
[SwitchB-bgp ipv4] quit
[SwitchB-bgp] quit
# Configure Switch C.
[SwitchC] bgp 100
[SwitchC-bgp] peer 11.1.1.1 as 200
[SwitchC-bgp] ipv4-family unicast
86
[SwitchC-bgp-ipv4] import-route ospf
[SwitchC-bgp-ipv4]import-route direct
[SwitchC-bgp-ipv4] quit
[SwitchC-bgp] quit
4.
Configure Switch B and Switch C to redistribute BGP routes into OSPF:
# Configure OSPF to redistribute routes from BGP on Switch B.
[SwitchB] ospf
[SwitchB-ospf-1] import-route bgp
# Configure OSPF to redistribute routes from BGP on Switch C.
[SwitchC] ospf
[SwitchC-ospf-1] import-route bgp
# Display the OSPF routing table on Switch A.
[SwitchA] display ip routing-table
Destinations : 16
5.
Destination/Mask
Proto
0.0.0.0/32
10.1.1.0/24
Routes : 16
Pre
Cost
NextHop
Interface
Direct 0
0
127.0.0.1
InLoop0
OSPF
150
1
11.2.1.1
Vlan100
10.2.1.0/24
OSPF
150
1
11.2.1.1
Vlan100
10.3.1.0/24
OSPF
150
1
11.2.1.1
Vlan100
10.4.1.0/24
OSPF
150
1
11.2.1.1
Vlan100
11.2.1.0/24
Direct 0
0
11.2.1.2
Vlan100
11.2.1.0/32
Direct 0
0
11.2.1.2
Vlan100
11.2.1.2/32
Direct 0
0
127.0.0.1
InLoop0
11.2.1.255/32
Direct 0
0
11.2.1.2
Vlan100
127.0.0.0/8
Direct 0
0
127.0.0.1
InLoop0
127.0.0.0/32
Direct 0
0
127.0.0.1
InLoop0
127.0.0.1/32
Direct 0
0
127.0.0.1
InLoop0
127.255.255.255/32
Direct 0
0
127.0.0.1
InLoop0
224.0.0.0/4
Direct 0
0
0.0.0.0
NULL0
224.0.0.0/24
Direct 0
0
0.0.0.0
NULL0
255.255.255.255/32
Direct 0
0
127.0.0.1
InLoop0
Configure route summarization:
# Configure route summarization on Switch B to advertise a summary route 10.0.0.0/8.
[SwitchB-ospf-1] asbr-summary 10.0.0.0 8
# Display the IP routing table on Switch A.
[SwitchA] display ip routing-table
Destinations : 13
Destination/Mask
Proto
0.0.0.0/32
10.0.0.0/8
11.2.1.0/24
11.2.1.0/32
Routes : 13
Pre
Cost
NextHop
Interface
Direct 0
0
127.0.0.1
InLoop0
OSPF
2
11.2.1.1
Vlan100
Direct 0
0
11.2.1.2
Vlan100
Direct 0
0
11.2.1.2
Vlan100
150
87
11.2.1.2/32
Direct 0
0
127.0.0.1
InLoop0
11.2.1.255/32
Direct 0
0
11.2.1.2
Vlan100
127.0.0.0/8
Direct 0
0
127.0.0.1
InLoop0
127.0.0.0/32
Direct 0
0
127.0.0.1
InLoop0
127.0.0.1/32
Direct 0
0
127.0.0.1
InLoop0
127.255.255.255/32
Direct 0
0
127.0.0.1
InLoop0
224.0.0.0/4
Direct 0
0
0.0.0.0
NULL0
224.0.0.0/24
Direct 0
0
0.0.0.0
NULL0
255.255.255.255/32
Direct 0
0
127.0.0.1
InLoop0
The output shows that routes 10.1.1.0/24, 10.2.1.0/24, 10.3.1.0/24 and 10.4.1.0/24 are
summarized into a single route 10.0.0.0/8.
Configuring an OSPF stub area
Network requirements
•
Enable OSPF on all switches, and split the AS into three areas.
•
Configure Switch A and Switch B as ABRs to forward routing information between areas.
•
Configure Switch D as the ASBR to redistribute static routes.
•
Configure Area 1 as a stub area to reduce advertised LSAs without influencing reachability.
Figure 23 Network diagram
Switch A
Area 0
Switch B
Vlan-int100
10.1.1.1/24
Vlan-int100
10.1.1.2/24
Vlan-int200
10.2.1.1/24
Area 1
Stub
Vlan-int200
10.2.1.2/24
Area 2
Vlan-int200
10.3.1.1/24
Vlan-int200
10.3.1.2/24
ASBR
Switch C
Vlan-int300
10.4.1.1/24
Vlan-int300
10.5.1.1/24 Switch D
Configuration procedure
1.
Configure IP addresses for interfaces. (Details not shown.)
2.
Enable OSPF (see "Configuring basic OSPF").
3.
Configure route redistribution:
# Configure Switch D to redistribute static routes.
<SwitchD> system-view
[SwitchD] ip route-static 3.1.2.1 24 10.5.1.2
[SwitchD] ospf
[SwitchD-ospf-1] import-route static
[SwitchD-ospf-1] quit
# Display ABR/ASBR information on Switch C.
<SwitchC> display ospf abr-asbr
OSPF Process 1 with Router ID 10.4.1.1
88
Routing Table to ABR and ASBR
Type
Destination
Area
Cost
Nexthop
RtType
Intra
10.2.1.1
0.0.0.1
3
10.2.1.1
ABR
Inter
10.5.1.1
0.0.0.1
7
10.2.1.1
ASBR
# Display OSPF routing table on Switch C.
<SwitchC> display ospf routing
OSPF Process 1 with Router ID 10.4.1.1
Routing Tables
Routing for Network
Destination
Cost
Type
10.2.1.0/24
3
10.3.1.0/24
7
10.4.1.0/24
10.5.1.0/24
10.1.1.0/24
NextHop
AdvRouter
Area
Transit 10.2.1.2
10.2.1.1
0.0.0.1
Inter
10.2.1.1
10.2.1.1
0.0.0.1
3
Stub
10.4.1.1
10.4.1.1
0.0.0.1
17
Inter
10.2.1.1
10.2.1.1
0.0.0.1
5
Inter
10.2.1.1
10.2.1.1
0.0.0.1
Destination
Cost
Type
Tag
NextHop
AdvRouter
3.1.2.0/24
1
Type2
1
10.2.1.1
10.5.1.1
Routing for ASEs
Total Nets: 6
Intra Area: 2
Inter Area: 3
ASE: 1
NSSA: 0
Because Switch C resides in a normal OSPF area, its routing table contains an AS external route.
4.
Configure Area 1 as a stub area:
# Configure Switch A.
<SwitchA> system-view
[SwitchA] ospf
[SwitchA-ospf-1] area 1
[SwitchA-ospf-1-area-0.0.0.1] stub
[SwitchA-ospf-1-area-0.0.0.1] quit
[SwitchA-ospf-1] quit
# Configure Switch C.
<SwitchC> system-view
[SwitchC] ospf
[SwitchC-ospf-1] area 1
[SwitchC-ospf-1-area-0.0.0.1] stub
[SwitchC-ospf-1-area-0.0.0.1] quit
[SwitchC-ospf-1] quit
# Display OSPF routing information on Switch C
[SwitchC] display ospf routing
OSPF Process 1 with Router ID 10.4.1.1
Routing Tables
89
Routing for Network
Destination
Cost
Type
NextHop
AdvRouter
Area
0.0.0.0/0
4
Inter
10.2.1.1
10.2.1.1
0.0.0.1
10.2.1.0/24
3
Transit 10.2.1.2
10.2.1.1
0.0.0.1
10.3.1.0/24
7
Inter
10.2.1.1
10.2.1.1
0.0.0.1
10.4.1.0/24
3
Stub
10.4.1.1
10.4.1.1
0.0.0.1
10.5.1.0/24
17
Inter
10.2.1.1
10.2.1.1
0.0.0.1
10.1.1.0/24
5
Inter
10.2.1.1
10.2.1.1
0.0.0.1
Total Nets: 6
Intra Area: 2
Inter Area: 4
ASE: 0
NSSA: 0
After the area where Switch C resides is configured as a stub area, a default route takes the place
of the AS external route.
# Configure the area as a totally stub area by filtering Type-3 LSAs out of the stub area.
[SwitchA] ospf
[SwitchA-ospf-1] area 1
[SwitchA-ospf-1-area-0.0.0.1] stub no-summary
[SwitchA-ospf-1-area-0.0.0.1] quit
# Display OSPF routing information on Switch C.
[SwitchC] display ospf routing
OSPF Process 1 with Router ID 10.4.1.1
Routing Tables
Routing for Network
Destination
Cost
Type
NextHop
AdvRouter
Area
0.0.0.0/0
4
Inter
10.2.1.1
10.2.1.1
0.0.0.1
10.2.1.0/24
3
Transit 10.2.1.2
10.4.1.1
0.0.0.1
10.4.1.0/24
3
Stub
10.4.1.1
0.0.0.1
10.4.1.1
Total Nets: 3
Intra Area: 2
Inter Area: 1
ASE: 0
NSSA: 0
After this configuration, inter-area routes are removed, and only one external route (a default route)
exists.
Configuring an OSPF NSSA area
Network requirements
•
Configure OSPF on all switches and split AS into three areas.
•
Configure Switch A and Switch B as ABRs to forward routing information between areas.
•
Configure Area 1 as an NSSA area and configure Switch C as an ASBR to redistribute static routes
into the AS.
90
Figure 24 Network diagram
Configuration procedure
1.
Configure IP addresses for interfaces.
2.
Enable OSPF (see "Configuring basic OSPF").
3.
Configure Area 1 as an NSSA area:
# Configure Switch A.
<SwitchA> system-view
[SwitchA] ospf
[SwitchA-ospf-1] area 1
[SwitchA-ospf-1-area-0.0.0.1] nssa default-route-advertise no-summary
[SwitchA-ospf-1-area-0.0.0.1] quit
[SwitchA-ospf-1] quit
# Configure Switch C.
<SwitchC> system-view
[SwitchC] ospf
[SwitchC-ospf-1] area 1
[SwitchC-ospf-1-area-0.0.0.1] nssa
[SwitchC-ospf-1-area-0.0.0.1] quit
[SwitchC-ospf-1] quit
NOTE:
• To allow Switch C in the NSSA area to reach other areas within the AS, you must provide the keyword
default-route-advertise for the nssa command issued on Switch A (the ABR) so that Switch C can obtain
a default route.
• Configuring the nssa command with the keyword no-summary on Switch A can reduce the routing
table size on NSSA Switches. On other NSSA Switches, you only need to configure the nssa command.
# Display OSPF routing information on Switch C.
[SwitchC] display ospf routing
OSPF Process 1 with Router ID 10.4.1.1
Routing Tables
Routing for Network
Destination
Cost
Type
NextHop
91
AdvRouter
Area
0.0.0.0/0
65536
Inter
10.2.1.1
10.2.1.1
0.0.0.1
10.2.1.0/24
65535
Transit 10.2.1.2
10.4.1.1
0.0.0.1
10.4.1.0/24
3
Stub
10.4.1.1
0.0.0.1
10.4.1.1
Total Nets: 3
Intra Area: 2
4.
Inter Area: 1
ASE: 0
NSSA: 0
Configure route redistribution:
# Configure Switch C to redistribute static routes.
[SwitchC] ip route-static 3.1.3.1 24 10.4.1.2
[SwitchC] ospf
[SwitchC-ospf-1] import-route static
[SwitchC-ospf-1] quit
# Display OSPF routing information on Switch D.
<SwitchD> display ospf routing
OSPF Process 1 with Router ID 10.5.1.1
Routing Tables
Routing for Network
Destination
Cost
Type
NextHop
AdvRouter
Area
10.2.1.0/24
22
Inter
10.3.1.1
10.3.1.1
0.0.0.2
10.3.1.0/24
10
Transit 10.3.1.2
10.3.1.1
0.0.0.2
10.4.1.0/24
25
Inter
10.3.1.1
10.3.1.1
0.0.0.2
10.5.1.0/24
10
Stub
10.5.1.1
10.5.1.1
0.0.0.2
10.1.1.0/24
12
Inter
10.3.1.1
10.3.1.1
0.0.0.2
Destination
Cost
Type
Tag
NextHop
AdvRouter
3.1.3.0/24
1
Type2
1
10.3.1.1
10.2.1.1
Routing for ASEs
Total Nets: 6
Intra Area: 2
Inter Area: 3
ASE: 1
NSSA: 0
The output shows an external route imported from the NSSA area exists on Switch D.
Configuring OSPF DR election
Network requirements
•
Enable OSPF on Switches A, B, C, and D on the same network.
•
Configure Switch A as the DR, and configure Switch C as the BDR.
92
Figure 25 Network diagram
Configuration procedure
1.
Configure IP addresses for interfaces. (Details not shown.)
2.
Enable OSPF:
# Configure Switch A.
<SwitchA> system-view
[SwitchA] router id 1.1.1.1
[SwitchA] ospf
[SwitchA-ospf-1] area 0
[SwitchA-ospf-1-area-0.0.0.0] network 192.168.1.0 0.0.0.255
[SwitchA-ospf-1-area-0.0.0.0] quit
[SwitchA-ospf-1] quit
# Configure Switch B.
<SwitchB> system-view
[SwitchB] router id 2.2.2.2
[SwitchB] ospf
[SwitchB-ospf-1] area 0
[SwitchB-ospf-1-area-0.0.0.0] network 192.168.1.0 0.0.0.255
[SwitchB-ospf-1-area-0.0.0.0] quit
[SwitchB-ospf-1] quit
# Configure Switch C.
<SwitchC> system-view
[SwitchC] router id 3.3.3.3
[SwitchC] ospf
[SwitchC-ospf-1] area 0
[SwitchC-ospf-1-area-0.0.0.0] network 192.168.1.0 0.0.0.255
[SwitchC-ospf-1-area-0.0.0.0] quit
[SwitchC-ospf-1] quit
# Configure Switch D.
<SwitchD> system-view
[SwitchD] router id 4.4.4.4
[SwitchD] ospf
[SwitchD-ospf-1] area 0
[SwitchD-ospf-1-area-0.0.0.0] network 192.168.1.0 0.0.0.255
[SwitchD-ospf-1-area-0.0.0.0] quit
93
[SwitchD-ospf-1] return
# Display OSPF neighbor information of Switch A.
[SwitchA] display ospf peer verbose
OSPF Process 1 with Router ID 1.1.1.1
Neighbors
Area 0.0.0.0 interface 192.168.1.1(Vlan-interface1)'s neighbors
Router ID: 2.2.2.2
State: 2-Way
Address: 192.168.1.2
Mode: None
DR: 192.168.1.4
GR State: Normal
Priority: 1
BDR: 192.168.1.3
MTU: 0
Options is 0x02 (-|-|-|-|-|-|E|-)
Dead timer due in 38
sec
Neighbor is up for 00:01:31
Authentication Sequence: [ 0 ]
Router ID: 3.3.3.3
State: Full
Address: 192.168.1.3
Mode: Nbr is Master
DR: 192.168.1.4
GR State: Normal
Priority: 1
BDR: 192.168.1.3
MTU: 0
Options is 0x02 (-|-|-|-|-|-|E|-)
Dead timer due in 31
sec
Neighbor is up for 00:01:28
Authentication Sequence: [ 0 ]
Router ID: 4.4.4.4
State: Full
Address: 192.168.1.4
Mode: Nbr is Master
DR: 192.168.1.4
GR State: Normal
Priority: 1
BDR: 192.168.1.3
MTU: 0
Options is 0x02 (-|-|-|-|-|-|E|-)
Dead timer due in 31
sec
Neighbor is up for 00:01:28
Authentication Sequence: [ 0 ]
The output shows that Switch D is the DR and Switch C is the BDR.
3.
Configure router priorities on interfaces:
# Configure Switch A.
[SwitchA] interface vlan-interface 1
[SwitchA-Vlan-interface1] ospf dr-priority 100
[SwitchA-Vlan-interface1] quit
# Configure Switch B.
[SwitchB] interface vlan-interface 1
[SwitchB-Vlan-interface1] ospf dr-priority 0
[SwitchB-Vlan-interface1] quit
# Configure Switch C.
[SwitchC] interface vlan-interface 1
[SwitchC-Vlan-interface1] ospf dr-priority 2
[SwitchC-Vlan-interface1] quit
# Display neighbor information of Switch D.
<SwitchD> display ospf peer verbose
94
OSPF Process 1 with Router ID 4.4.4.4
Neighbors
Area 0.0.0.0 interface 192.168.1.4(Vlan-interface1)'s neighbors
Router ID: 1.1.1.1
State: Full
Address: 192.168.1.1
Mode:Nbr is
DR: 192.168.1.4
Slave
GR State: Normal
Priority: 100
BDR: 192.168.1.3
MTU: 0
Options is 0x02 (-|-|-|-|-|-|E|-)
Dead timer due in 31
sec
Neighbor is up for 00:11:17
Authentication Sequence: [ 0 ]
Router ID: 2.2.2.2
State: Full
Address: 192.168.1.2
Mode:Nbr is
DR: 192.168.1.4
Slave
GR State: Normal
Priority: 0
BDR: 192.168.1.3
MTU: 0
Options is 0x02 (-|-|-|-|-|-|E|-)
Dead timer due in 35
sec
Neighbor is up for 00:11:19
Authentication Sequence: [ 0 ]
Router ID: 3.3.3.3
State: Full
Address: 192.168.1.3
Mode:Nbr is
DR: 192.168.1.4
Slave
GR State: Normal
Priority: 2
BDR: 192.168.1.3
MTU: 0
Options is 0x02 (-|-|-|-|-|-|E|-)
Dead timer due in 33
sec
Neighbor is up for 00:11:15
Authentication Sequence: [ 0 ]
The output shows that the DR and BDR are not changed, because the priority settings do not take
effect immediately.
4.
Restart OSPF process:
# Restart the OSPF process of Switch D.
<SwitchD> reset ospf 1 process
Warning : Reset OSPF process? [Y/N]:y
# Display neighbor information of Switch D.
<SwitchD> display ospf peer verbose
OSPF Process 1 with Router ID 4.4.4.4
Neighbors
Area 0.0.0.0 interface 192.168.1.4(Vlan-interface1)'s neighbors
Router ID: 1.1.1.1
State: Full
Address: 192.168.1.1
Mode: Nbr is Slave
DR: 192.168.1.1
Priority: 100
BDR: 192.168.1.3
Options is 0x02 (-|-|-|-|-|-|E|-)
Dead timer due in 39
sec
Neighbor is up for 00:01:40
Authentication Sequence: [ 0 ]
95
MTU: 0
GR State: Normal
Router ID: 2.2.2.2
State: 2-Way
Address: 192.168.1.2
Mode: None
DR: 192.168.1.1
GR State: Normal
Priority: 0
BDR: 192.168.1.3
MTU: 0
Options is 0x02 (-|-|-|-|-|-|E|-)
Dead timer due in 35
sec
Neighbor is up for 00:01:44
Authentication Sequence: [ 0 ]
Router ID: 3.3.3.3
State: Full
Address: 192.168.1.3
Mode: Nbr is Slave
DR: 192.168.1.1
GR State: Normal
Priority: 2
BDR: 192.168.1.3
MTU: 0
Options is 0x02 (-|-|-|-|-|-|E|-)
Dead timer due in 39
sec
Neighbor is up for 00:01:41
Authentication Sequence: [ 0 ]
If the neighbor state is full, Switch D has established an adjacency with the neighbor. If the
neighbor state is 2-way, the two switches are not the DR or the BDR, and they do not exchange
LSAs.
# Display OSPF interface information.
[SwitchA] display ospf interface
OSPF Process 1 with Router ID 1.1.1.1
Interfaces
Area: 0.0.0.0
IP Address
Type
192.168.1.1
Broadcast DR
State
Cost
Pri
DR
BDR
1
100
192.168.1.1
192.168.1.3
[SwitchB] display ospf interface
OSPF Process 1 with Router ID 2.2.2.2
Interfaces
Area: 0.0.0.0
IP Address
Type
State
192.168.1.2
Broadcast DROther
Cost
Pri
DR
BDR
1
0
192.168.1.1
192.168.1.3
The interface state DROther means the interface is not the DR or BDR.
Configuring OSPF virtual links
Network requirements
Configure a virtual link between Switch B and Switch C to connect Area 2 to the backbone area. After
configuration, Switch B can learn routes to Area 2.
96
Figure 26 Network diagram
Configuration procedure
1.
Configure IP addresses for interfaces. (Details not shown.)
2.
Enable OSPF:
# Configure Switch A.
<SwitchA> system-view
[SwitchA] ospf 1 router-id 1.1.1.1
[SwitchA-ospf-1] area 0
[SwitchA-ospf-1-area-0.0.0.0] network 10.1.1.0 0.0.0.255
[SwitchA-ospf-1-area-0.0.0.0] quit
# Configure Switch B.
<SwitchB> system-view
[SwitchB] ospf 1 router-id 2.2.2.2
[SwitchB-ospf-1] area 0
[SwitchB-ospf-1-area-0.0.0.0] network 10.1.1.0 0.0.0.255
[SwitchB-ospf-1-area-0.0.0.0] quit
[SwitchB-ospf-1] area 1
[SwitchB–ospf-1-area-0.0.0.1] network 10.2.1.0 0.0.0.255
[SwitchB–ospf-1-area-0.0.0.1] quit
[SwitchB-ospf-1] quit
# Configure Switch C.
<SwitchC> system-view
[SwitchC] ospf 1 router-id 3.3.3.3
[SwitchC-ospf-1] area 1
[SwitchC-ospf-1-area-0.0.0.1] network 10.2.1.0 0.0.0.255
[SwitchC-ospf-1-area-0.0.0.1] quit
[SwitchC-ospf-1] area 2
[SwitchC–ospf-1-area-0.0.0.2] network 10.3.1.0 0.0.0.255
[SwitchC–ospf-1-area-0.0.0.2] quit
[SwitchC-ospf-1] quit
# Configure Switch D.
<SwitchD> system-view
[SwitchD] ospf 1 router-id 4.4.4.4
[SwitchD-ospf-1] area 2
[SwitchD-ospf-1-area-0.0.0.2] network 10.3.1.0 0.0.0.255
[SwitchD-ospf-1-area-0.0.0.2] quit
# Display the OSPF routing table of Switch B.
97
[SwitchB] display ospf routing
OSPF Process 1 with Router ID 2.2.2.2
Routing Tables
Routing for Network
Destination
Cost
Type
10.2.1.0/24
2
10.1.1.0/24
2
NextHop
AdvRouter
Area
Transit 10.2.1.1
3.3.3.3
0.0.0.1
Transit 10.1.1.2
2.2.2.2
0.0.0.0
Total Nets: 2
Intra Area: 2
Inter Area: 0
ASE: 0
NSSA: 0
Area 0 has no direct connection to Area 2, so the routing table of Switch B has no route to Area
2.
3.
Configure a virtual link:
# Configure Switch B.
[SwitchB] ospf
[SwitchB-ospf-1] area 1
[SwitchB-ospf-1-area-0.0.0.1] vlink-peer 3.3.3.3
[SwitchB-ospf-1-area-0.0.0.1] quit
[SwitchB-ospf-1] quit
# Configure Switch C.
[SwitchC] ospf 1
[SwitchC-ospf-1] area 1
[SwitchC-ospf-1-area-0.0.0.1] vlink-peer 2.2.2.2
[SwitchC-ospf-1-area-0.0.0.1] quit
# Display the OSPF routing table on Switch B.
[SwitchB] display ospf routing
OSPF Process 1 with Router ID 2.2.2.2
Routing Tables
Routing for Network
Destination
Cost
Type
AdvRouter
Area
10.2.1.0/24
2
Transit 10.2.1.1
NextHop
3.3.3.3
0.0.0.1
10.3.1.0/24
5
Inter
10.2.1.2
3.3.3.3
0.0.0.0
10.1.1.0/24
2
Transit 10.1.1.2
2.2.2.2
0.0.0.0
Total Nets: 3
Intra Area: 2
Inter Area: 1
ASE: 0
NSSA: 0
The output shows that Switch B has learned the route 10.3.1.0/24 to Area 2.
Configuring OSPF Graceful Restart
Network requirements
•
As shown in Figure 27, Switch A, Switch B, and Switch C that belong to the same AS and the same
OSPF routing domain are GR capable.
•
Switch A acts as the non-IETF GR Restarter; Switch B and Switch C are the GR Helpers and
re-synchronize their LSDB with Switch A through OOB communication of GR.
98
Figure 27 Network diagram
Configuration procedure
1.
Configure IP addresses for interfaces. (Details not shown.)
2.
Enable OSPF:
# Configure Switch A
SwitchA> system-view
[SwitchA] router id 1.1.1.1
[SwitchA] ospf 100
[SwitchA-ospf-100] area 0
[SwitchA-ospf-100-area-0.0.0.0] network 192.1.1.0 0.0.0.255
[SwitchA-ospf-100-area-0.0.0.0] quit
# Configure Switch B
<SwitchB> system-view
[SwitchB] router id 2.2.2.2
[SwitchB] ospf 100
[SwitchB-ospf-100] area 0
[SwitchB-ospf-100-area-0.0.0.0] network 192.1.1.0 0.0.0.255
[SwitchB-ospf-100-area-0.0.0.0] quit
# Configure Switch C
<SwitchC> system-view
[SwitchC] router id 3.3.3.3
[SwitchC] ospf 100
[SwitchC-ospf-100] area 0
[SwitchC-ospf-100-area-0.0.0.0] network 192.1.1.0 0.0.0.255
[SwitchC-ospf-100-area-0.0.0.0] quit
3.
Configure OSPF GR:
# Configure Switch A as the non-IETF OSPF GR Restarter: enable the link-local signaling capability,
the out-of-band re-synchronization capability, and non-IETF GRaceful Restart capability for OSPF
process 100.
[SwitchA-ospf-100] enable link-local-signaling
[SwitchA-ospf-100] enable out-of-band-resynchronization
[SwitchA-ospf-100] graceful-restart
[SwitchA-ospf-100] return
# Configure Switch B as the GR Helper: enable the link-local signaling capability and the
out-of-band re-synchronization capability for OSPF process 100.
99
[SwitchB-ospf-100] enable link-local-signaling
[SwitchB-ospf-100] enable out-of-band-resynchronization
# Configure Switch C as the GR Helper: enable the link-local signaling capability and the
out-of-band re-synchronization capability for OSPF process 100.
[SwitchC-ospf-100] enable link-local-signaling
[SwitchC-ospf-100] enable out-of-band-resynchronization
Verifying the configuration
# After the configurations on Switch A, Switch B, and Switch C are complete and the switches are
running steadily, enable OSPF Graceful Restart event debugging and then restart the OSPF process
using GR on Switch A.
<SwitchA> debugging ospf event graceful-restart
<SwitchA> terminal monitor
<SwitchA> terminal logging level 7
<SwitchA> reset ospf 100 process graceful-restart
Reset OSPF process? [Y/N]:y
%Oct 21 15:29:28:727 2011 SwitchA OSPF/5/OSPF_NBR_CHG: -MDC=1; OSPF 100 Neighbor
192.1.1.2(Vlan-interface100) from Full to Down.
%Oct 21 15:29:28:729 2011 SwitchA OSPF/5/OSPF_NBR_CHG: -MDC=1; OSPF 100 Neighbor
192.1.1.3(Vlan-interface100) from Full to Down.
*Oct 21 15:29:28:735 2011 SwitchA OSPF/7/DEBUG: -MDC=1;
OSPF 100 nonstandard GR Started for OSPF Router
*Oct 21 15:29:28:735 2011 SwitchA OSPF/7/DEBUG: -MDC=1;
OSPF 100 created GR wait timer,timeout interval is 40(s).
*Oct 21 15:29:28:735 2011 SwitchA OSPF/7/DEBUG: -MDC=1;
OSPF 100 created GR Interval timer,timeout interval is 120(s).
*Oct 21 15:29:28:758 2011 SwitchA OSPF/7/DEBUG: -MDC=1;
OSPF 100 created OOB Progress timer for neighbor 192.1.1.3.
*Oct 21 15:29:28:766 2011 SwitchA OSPF/7/DEBUG: -MDC=1;
OSPF 100 created OOB Progress timer for neighbor 192.1.1.2.
%Oct 21 15:29:29:902 2011 SwitchA OSPF/5/OSPF_NBR_CHG: -MDC=1; OSPF 100 Neighbor
192.1.1.2(Vlan-interface100) from Loading to Full.
*Oct 21 15:29:29:902 2011 SwitchA OSPF/7/DEBUG: -MDC=1;
OSPF 100 deleted OOB Progress timer for neighbor 192.1.1.2.
%Oct 21 15:29:30:897 2011 SwitchA OSPF/5/OSPF_NBR_CHG: -MDC=1; OSPF 100 Neighbor
192.1.1.3(Vlan-interface100) from Loading to Full.
*Oct 21 15:29:30:897 2011 SwitchA OSPF/7/DEBUG: -MDC=1;
OSPF 100 deleted OOB Progress timer for neighbor 192.1.1.3.
*Oct 21 15:29:30:911 2011 SwitchA OSPF/7/DEBUG: -MDC=1;
OSPF GR: Process 100 Exit Restart,Reason : DR or BDR change,for neighbor : 192.1.1.3.
*Oct 21 15:29:30:911 2011 SwitchA OSPF/7/DEBUG: -MDC=1;
OSPF 100 deleted GR Interval timer.
*Oct 21 15:29:30:912 2011 SwitchA OSPF/7/DEBUG: -MDC=1;
OSPF 100 deleted GR wait timer.
%Oct 21 15:29:30:920 2011 SwitchA OSPF/5/OSPF_NBR_CHG: -MDC=1; OSPF 100 Neighbor
192.1.1.2(Vlan-interface100) from Full to Down.
%Oct 21 15:29:30:921 2011 SwitchA OSPF/5/OSPF_NBR_CHG: -MDC=1; OSPF 100 Neighbor
192.1.1.3(Vlan-interface100) from Full to Down.
%Oct 21 15:29:33:815 2011 SwitchA OSPF/5/OSPF_NBR_CHG: -MDC=1; OSPF 100 Neighbor
192.1.1.3(Vlan-interface100) from Loading to Full.
100
%Oct 21 15:29:35:578 2011 SwitchA OSPF/5/OSPF_NBR_CHG: -MDC=1; OSPF 100 Neighbor
192.1.1.2(Vlan-interface100) from Loading to Full.
The output shows that Switch A completes GR.
Configuring BFD for OSPF
Network requirements
As shown in Figure 28, run OSPF on Switch A, Switch B, and Switch C so that they are reachable to each
other at the network layer. When the link over which Switch A and Switch B communicate through a Layer
2 switch fails, BFD can quickly detect the failure and notify OSPF of the failure. Switch A and Switch B
then communicate through Switch C.
Figure 28 Network diagram
Device
Interface
IP address
Device
Interface
IP address
Switch A
Vlan-int10
192.168.0.102/24
Switch B
Vlan-int10
192.168.0.100/24
Vlan-int11
10.1.1.102/24
Vlan-int13
13.1.1.1/24
Vlan-int11
10.1.1.100/24
Vlan-int13
13.1.1.2/24
Switch C
Configuration procedure
1.
Configure IP addresses for interfaces. (Details not shown.)
2.
Enable OSPF:
# Configure Switch A.
<SwitchA> system-view
[SwitchA] ospf
[SwitchA-ospf-1] area 0
[SwitchA-ospf-1-area-0.0.0.0] network 192.168.0.0 0.0.0.255
[SwitchA-ospf-1-area-0.0.0.0] network 10.1.1.0 0.0.0.255
[SwitchA-ospf-1-area-0.0.0.0] network 121.1.1.0 0.0.0.255
[SwitchA-ospf-1-area-0.0.0.0] quit
[SwitchA-ospf-1] quit
[SwitchA] interface vlan 11
[SwitchA-Vlan-interface11] ospf cost 2
[SwitchA-Vlan-interface11] quit
# Configure Switch B.
101
<SwitchB> system-view
[SwitchB] ospf
[SwitchB-ospf-1] area 0
[SwitchB-ospf-1-area-0.0.0.0] network 192.168.0.0 0.0.0.255
[SwitchB-ospf-1-area-0.0.0.0] network 13.1.1.0 0.0.0.255
[SwitchB-ospf-1-area-0.0.0.0] network 120.1.1.0 0.0.0.255
[SwitchB-ospf-1-area-0.0.0.0] quit
[SwitchB-ospf-1] quit
[SwitchB] interface vlan-interface 13
[SwitchB-Vlan-interface13] ospf cost 2
[SwitchA-Vlan-interface13] quit
# Configure Switch C.
<SwitchC> system-view
[SwitchC] ospf
[SwitchC-ospf-1] area 0
[SwitchC-ospf-1-area-0.0.0.0] network 10.1.1.0 0.0.0.255
[SwitchC-ospf-1-area-0.0.0.0] network 13.1.1.0 0.0.0.255
[SwitchC-ospf-1-area-0.0.0.0] quit
[SwitchC-ospf-1] quit
3.
Configure BFD:
# Enable BFD on Switch A and configure BFD parameters.
[SwitchA] bfd session init-mode active
[SwitchA] interface vlan-interface 10
[SwitchA-Vlan-interface10] ospf bfd enable
[SwitchA-Vlan-interface10] bfd min-transmit-interval 500
[SwitchA-Vlan-interface10] bfd min-receive-interval 500
[SwitchA-Vlan-interface10] bfd detect-multiplier 7
[SwitchA-Vlan-interface10] quit
[SwitchA] quit
# Enable BFD on Switch B and configure BFD parameters.
[SwitchB] bfd session init-mode active
[SwitchB] interface vlan-interface 10
[SwitchB-Vlan-interface10] ospf bfd enable
[SwitchB-Vlan-interface10] bfd min-transmit-interval 500
[SwitchB-Vlan-interface10] bfd min-receive-interval 500
[SwitchB-Vlan-interface10] bfd detect-multiplier 6
Verifying the configuration
# Display the BFD information on Switch A.
<SwitchA> display bfd session
Total Session Num: 1
Up Session Num: 1
Init Mode: Active
IPv4 Session Working Under Ctrl Mode:
LD/RD
SourceAddr
DestAddr
State
Holdtime
Interface
3/1
192.168.0.102
192.168.0.100
Up
1700ms
Vlan10
102
# Display routes destined for 120.1.1.0/24 on Switch A.
<SwitchA> display ip routing-table 120.1.1.0 verbose
Summary Count : 1
Destination: 120.1.1.0/24
Protocol: OSPF
SubProtID: 0x1
Cost: 2
Tag: 0
OrigTblID: 0x0
TableID: 0x2
NBRID: 0x26000002
AttrID: 0xffffffff
Process ID: 1
Age: 04h20m37s
Preference: 10
State: Active Adv
OrigVrf: default-vrf
OrigAs: 0
LastAs: 0
Neighbor: 0.0.0.0
Flags: 0x1008c
OrigNextHop: 192.168.0.100
Label: NULL
RealNextHop: 192.168.0.100
BkLabel: NULL
Tunnel ID: Invalid
BkTunnel ID: Invalid
BkNextHop: N/A
Interface: Vlan-interface10
BkInterface: N/A
The output shows that Switch A communicates with Switch B through VLAN-interface 10. Then the link
over VLAN-interface 10 fails.
# Display routes destined for 120.1.1.0/24 on Switch A.
<SwitchA> display ip routing-table 120.1.1.0 verbose
Summary Count : 1
Destination: 120.1.1.0/24
Protocol: OSPF
SubProtID: 0x1
Cost: 4
Tag: 0
OrigTblID: 0x0
TableID: 0x2
NBRID: 0x26000002
AttrID: 0xffffffff
Process ID: 1
Age: 04h20m37s
Preference: 10
State: Active Adv
OrigVrf: default-vrf
OrigAs: 0
LastAs: 0
Neighbor: 0.0.0.0
Flags: 0x1008c
OrigNextHop: 10.1.1.100
Label: NULL
RealNextHop: 10.1.1.100
BkLabel: NULL
Tunnel ID: Invalid
BkTunnel ID: Invalid
BkNextHop: N/A
Interface: Vlan-interface11
BkInterface: N/A
The output shows that Switch A communicates with Switch B through VLAN-interface 11.
103
Configuring OSPF FRR
Network requirements
As shown in Figure 29, Switch S, Switch A, and Switch D reside in the same OSPF domain. Configure
OSPF FRR so that when the link between Switch S and Switch D fails, traffic is immediately switched to
Link B.
Figure 29 Network diagram
Configuration procedure
1.
Configure IP addresses and subnet masks for interfaces on the switches. (Details not shown.)
2.
Configure OSPF on the switches to make sure Switch S, Switch A, and Switch D can communicate
with each other at the network layer. (Details not shown.)
3.
Configure OSPF FRR to automatically calculate the backup next hop:
You can enable OSPF FRR to either calculate a backup next hop by using the LFA algorithm, or
specify a backup next hop by using a routing policy.
{
(Method 1.) Enable OSPF FRR to calculate the backup next hop by using the LFA algorithm:
# Configure Switch S.
<SwitchS> system-view
[SwitchS] bfd echo-source-ip 1.1.1.1
[SwitchS] ospf 1
[SwitchS-ospf-1] fast-reroute lfa
[SwitchS-ospf-1] quit
# Configure Switch D.
<SwitchD> system-view
[SwitchD] bfd echo-source-ip 4.4.4.4
[SwitchD] ospf 1
[SwitchD-ospf-1] fast-reroute lfa
[SwitchD-ospf-1] quit
{
(Method 2.) Enable OSPF FRR to designate a backup next hop by using a routing policy.
# Configure Switch S.
<SwitchS> system-view
[SwitchS] bfd echo-source-ip 1.1.1.1
[SwitchS] ip prefix-list abc index 10 permit 4.4.4.4 32
[SwitchS] route-policy frr permit node 10
[SwitchS-route-policy-frr-10] if-match ip address prefix-list abc
[SwitchS-route-policy-frr-10] apply fast-reroute backup-interface vlan-interface
100 backup-nexthop 12.12.12.2
104
[SwitchS-route-policy-frr-10] quit
[SwitchS] ospf 1
[SwitchS-ospf-1] fast-reroute route-policy frr
[SwitchS-ospf-1] quit
# Configure Switch D.
<SwitchD> system-view
[SwitchD] bfd echo-source-ip 4.4.4.4
[SwitchD] ip prefix-list abc index 10 permit 1.1.1.1 32
[SwitchD] route-policy frr permit node 10
[SwitchD-route-policy-frr-10] if-match ip address prefix-list abc
[SwitchD-route-policy-frr-10] apply fast-reroute backup-interface vlan-interface
101 backup-nexthop 24.24.24.2
[SwitchD-route-policy-frr-10] quit
[SwitchD] ospf 1
[SwitchD-ospf-1] fast-reroute route-policy frr
[SwitchD-ospf-1] quit
Verifying the configuration
# Display route 4.4.4.4/32 on Switch S to view the backup next hop information.
[SwitchS] display ip routing-table 4.4.4.4 verbose
Summary Count : 1
Destination: 4.4.4.4/32
Protocol: OSPF
SubProtID: 0x1
Cost: 1
Tag: 0
OrigTblID: 0x0
TableID: 0x2
NBRID: 0x26000002
AttrID: 0xffffffff
Process ID: 1
Age: 04h20m37s
Preference: 10
State: Active Adv
OrigVrf: default-vrf
OrigAs: 0
LastAs: 0
Neighbor: 0.0.0.0
Flags: 0x1008c
OrigNextHop: 13.13.13.2
Label: NULL
RealNextHop: 13.13.13.2
BkLabel: NULL
BkNextHop: 12.12.12.2
Tunnel ID: Invalid
Interface: Vlan-interface200
BkTunnel ID: Invalid
BkInterface: Vlan-interface100
# Display route 1.1.1.1/32 on Switch D to view the backup next hop information.
[SwitchD] display ip routing-table 1.1.1.1 verbose
Summary Count : 1
Destination: 1.1.1.1/32
Protocol: OSPF
SubProtID: 0x1
Cost: 1
Tag: 0
OrigTblID: 0x0
Process ID: 1
Age: 04h20m37s
Preference: 10
State: Active Adv
OrigVrf: default-vrf
105
TableID: 0x2
NBRID: 0x26000002
AttrID: 0xffffffff
OrigAs: 0
LastAs: 0
Neighbor: 0.0.0.0
Flags: 0x1008c
OrigNextHop: 13.13.13.1
Label: NULL
RealNextHop: 13.13.13.1
BkLabel: NULL
BkNextHop: 24.24.24.2
Tunnel ID: Invalid
Interface: Vlan-interface200
BkTunnel ID: Invalid
BkInterface: Vlan-interface101
Troubleshooting OSPF configuration
No OSPF neighbor relationship established
Symptom
No OSPF neighbor relationship can be established.
Analysis
If the physical link and lower layer protocols work well, verify OSPF parameters configured on interfaces.
Two neighbors must have the same parameters, such as the area ID, network segment, and mask (a P2P
or virtual link can have different network segments and masks).
Solution
1.
Use the display ospf peer command to verify OSPF neighbor information.
2.
Use the display ospf interface command to verify OSPF interface information.
3.
Ping the neighbor router's IP address to verify that the connectivity is normal.
4.
Verify OSPF timers. The dead interval on an interface must be at least four times the hello interval.
5.
On an NBMA network, use the peer ip-address command to manually specify the neighbor.
6.
At least one interface must have a router priority higher than 0 on an NBMA or a broadcast
network.
Incorrect routing information
Symptom
OSPF cannot find routes to other areas.
Analysis
The backbone area must maintain connectivity to all other areas. If a router connects to more than one
area, at least one area must be connected to the backbone. The backbone cannot be configured as a
stub area.
In a stub area, all routers cannot receive external routes, and all interfaces connected to the stub area
must belong to the stub area.
Solution
1.
Use the display ospf peer command to verify neighbor information.
2.
Use the display ospf interface command to verify OSPF interface information.
3.
Use the display ospf lsdb command to verify the LSDB.
106
4.
Use the display current-configuration configuration ospf command to verify area configuration. If
more than two areas are configured, at least one area is connected to the backbone.
5.
In a stub area, all routers attached are configured with the stub command. In an NSSA area, all
routers attached are configured with the nssa command.
6.
If a virtual link is configured, use the display ospf vlink command to verify the state of the virtual
link.
107
Configuring IS-IS
This chapter describes how to configure IS-IS for IPv4 networks.
Overview
Intermediate System-to-Intermediate System (IS-IS) is a dynamic routing protocol designed by the ISO to
operate on the connectionless network protocol (CLNP).
IS-IS was modified and extended in RFC 1195 by the IETF for application in both TCP/IP and OSI
reference models, called "Integrated IS-IS" or "Dual IS-IS."
IS-IS is an IGP used within an AS. It uses the SPF algorithm for route calculation.
Terminology
•
Intermediate system—Similar to a router in TCP/IP, IS is the basic unit used in an IS-IS routing
domain to generate and propagate routing information. Throughout this chapter, an IS refers to a
router.
•
End system—Similar to a host in TCP/IP, an ES does not run IS-IS. ISO defines the ES-IS protocol for
communication between an ES and an IS.
•
Routing domain—An RD comprises a group of ISs that exchange routing information with each
other by using the same routing protocol.
•
Area—An IS-IS routing domain can be split into multiple areas.
•
Link State Database—All link states in the network form the LSDB. Each IS has at least one LSDB. An
IS uses the SPF algorithm and LSDB to generate IS-IS routes.
•
Link State Protocol Data Unit or Link State Packet —An IS advertises link state information in an LSP.
•
Network Protocol Data Unit—An NPDU is a network layer protocol packet in OSI, similar to an IP
packet in TCP/IP.
•
Designated IS—A DIS is elected on a broadcast network.
•
Network service access point—An NSAP is an OSI network layer address. The NSAP identifies an
abstract network service access point and describes the network address format in the OSI
reference model.
IS-IS address format
NSAP
As shown in Figure 30, an NSAP address comprises the Initial Domain Part (IDP) and the Domain
Specific Part (DSP). The IDP is analogous to the network ID of an IP address, and the DSP is analogous
to the subnet and host ID.
The IDP includes the Authority and Format Identifier (AFI) and the Initial Domain Identifier (IDI).
The DSP includes:
•
High Order Part of DSP (HO-DSP)—Identifies the area.
•
System ID—Identifies the host.
108
•
SEL—Identifies the type of service.
The IDP and DSP are variable in length. The length of an NSAP address ranges from 8 bytes to 20 bytes.
Figure 30 NSAP address format
Area address
The area address comprises the IDP and the HO-DSP of the DSP, which identify the area and the routing
domain. Different routing domains cannot have the same area address.
Typically, a router only needs one area address, and all nodes in the same area must have the same area
address. To support smooth area merging, partitioning, and switching, a router can have a maximum of
three area addresses.
System ID
A system ID uniquely identifies a host or router. It has a fixed length of 48 bits (6 bytes).
The system ID of a device can be generated from the router ID. For example, suppose a router uses the
IP address 168.10.1.1 of Loopback 0 as the router ID. The system ID can be obtained in the following
steps:
1.
Extend each decimal number of the IP address to three digits by adding 0s from the left, such as
168.010.001.001.
2.
Divide the extended IP address into three sections that each has four digits to get the system ID
1680.1000.1001.
If you use other methods to define a system ID, make sure that it can uniquely identify the host or router.
SEL
The N-SEL, or the NSAP selector (SEL), is similar to the protocol identifier in IP. Different transport layer
protocols correspond to different SELs. All SELs in IP are 00.
Routing method
The IS-IS address format identifies the area, so a Level-1 router can easily identify packets destined to
other areas. IS-IS routers perform routing as follows:
•
A Level-1 router performs intra-area routing according to the system ID. If the destination address of
a packet does not belong to the local area, the Level-1 router forwards it to the nearest Level-1-2
router.
•
A Level-2 router performs inter-area routing according to the area address.
NET
A network entity title (NET) identifies the network layer information of an IS. It does not include transport
layer information. A NET is a special NSAP address with the SEL being 0. The length of a NET ranges
from 8 bytes to 20 bytes, same as a NSAP address.
A NET includes the following parts:
•
Area ID—Has a length of 1 to 13 bytes.
109
•
System ID—A system ID uniquely identifies a host or router in the area and has a fixed length of 6
bytes.
•
SEL—Has a value of 0 and a fixed length of 1 byte.
For example, for a NET ab.cdef.1234.5678.9abc.00, the area ID is ab.cdef, the system ID is
1234.5678.9abc, and the SEL is 00.
Typically, a router only needs one NET, but it can have a maximum of three NETs for smooth area
merging and partitioning. When you configure multiple NETs, make sure the system IDs are the same.
IS-IS area
IS-IS has a 2-level hierarchy to support large-scale networks. A large-scale routing domain is divided into
multiple areas. Typically, a Level-1 router is deployed within an area, a Level-2 router is deployed
between areas, and a Level-1-2 router is deployed between Level-1 and Level-2 routers.
Level-1 and Level-2
•
Level-1 router—A Level-1 router establishes neighbor relationships with Level-1 and Level-1-2 routers
in the same area. It maintains a LSDB comprising intra-area routing information. A Level-1 router
forwards packets destined for external areas to the nearest Level-1-2 router. Level-1 routers in different
areas cannot establish neighbor relationships.
•
Level-2 router—A Level-2 router establishes neighbor relationships with Level-2 and Level-1-2 routers
in the same area or in different areas. It maintains a Level-2 LSDB containing inter-area routing
information. All the Level-2 and Level-1-2 routers must be contiguous to form the backbone of the IS-IS
routing domain. Level-2 routers can establish neighbor relationships regardless of the areas they
reside in.
•
Level-1-2 router—A router with both Level-1 and Level-2 router functions is a Level-1-2 router. It can
establish Level-1 neighbor relationships with Level-1 and Level-1-2 routers in the same area, and
establish Level-2 neighbor relationships with Level-2 and Level-1-2 routers in different areas. A Level-1
router can reach other areas only through a Level-1-2 router. The Level-1-2 router maintains two LSDBs,
a Level-1 LSDB for intra-area routing and a Level-2 LSDB for inter-area routing.
Figure 31 shows one IS-IS network topology. Area 1 is the backbone that comprises a set of Level-2
routers. The other four areas are non-backbone areas connected to the backbone through Level-1-2
routers.
110
Figure 31 IS-IS topology 1
Area 3
Area 2
L1/L2
L1/L2
L2
L1
L2
Area 1
L2
L2
Area 5
L1/L2
Area 4
L1
L1
L1/L2
L1
L1
L1
Figure 32 shows another IS-IS topology. The Level-1-2 routers connect to the Level-1 and Level-2 routers,
and form the IS-IS backbone together with the Level-2 routers. No area is defined as the backbone in this
topology. The backbone comprises all contiguous Level-2 and Level-1-2 routers in different areas. The IS-IS
backbone does not need to be a specific area.
Figure 32 IS-IS topology 2
Area 3
Area 2
L1/L2
L1/L2
L1
L2
L2
Area 1
L2
L2
Area 5
Area 4
L1
L1/L2
L1
L1/L2
L1
L1
L1
Both the Level-1 and Level-2 routers use the SPF algorithm to generate the shortest path tree.
111
Route leaking
Level-2 and Level-1-2 routers form a Level-2 area. An IS-IS routing domain comprises only one Level-2 area
and multiple Level-1 areas. A Level-1 area must connect to the Level-2 area rather than other Level-1 area.
The routing information of each Level-1 area is sent to the Level-2 area through a Level-1-2 router, so a
Level-2 router knows the routing information of the entire IS-IS routing domain. By default, a Level-2 router
does not advertise the routing information of other Level-1 areas and the Level-2 area to a Level-1 area, so
a Level-1 router simply sends packets destined for other areas to the nearest Level-1-2 router. The path
passing through the Level-1-2 router may not be the best. To solve this problem, IS-IS provides the route
leaking feature.
Route leaking enables a Level-1-2 router to advertise the routes of other Level-1 areas and the Level-2 area
to the connected Level-1 area so that the Level-1 routers can select the optimal routes for packets.
IS-IS network types
Network types
IS-IS supports the broadcast network (for example, Ethernet and Token Ring) and the point-to-point
network (for example, PPP and HDLC).
For an NBMA interface, such as an ATM interface, you must configure point-to-point or broadcast
subinterfaces. IS-IS cannot run on P2MP links.
DIS and pseudonodes
IS-IS routers on a broadcast network must elect a DIS.
The Level-1 and Level-2 DISs are elected separately. You can assign different priorities to a router for
different level DIS elections. The higher the router priority, the more likely the router becomes the DIS. If
multiple routers with the same highest DIS priority exist, the one with the highest SNPA (Subnetwork Point
of Attachment) address (MAC address on a broadcast network) will be elected. A router can be the DIS
for different levels.
IS-IS DIS election differs from OSPF DIS election in the following ways:
•
A router with priority 0 can also participate in the DIS election.
•
When a router with a higher priority is added to the network, an LSP flooding process is performed
to elect the router as the new DIS.
As shown in Figure 33, the same level routers on a network, including non-DIS routers, establish
adjacency with each other.
Figure 33 DIS in the IS-IS broadcast network
L1/L2
L2 adjacencies
L1 adjacencies
L1
DIS
L1/L2
L2
DIS
112
The DIS creates and updates pseudonodes, and generates LSPs for the pseudonodes, to describe all
routers on the network.
A pseudonode represents a virtual node on the broadcast network. It is not a real router. In IS-IS, it is
identified by the system ID of the DIS and a 1-byte Circuit ID (a non-zero value).
Using pseudonodes simplifies network topology and can reduce the amount of resources consumed by
SPF.
NOTE:
On an IS-IS broadcast network, all routers establish adjacency relationships, but they synchronize their
LSDBs through the DIS.
IS-IS PDUs
PDU
IS-IS PDUs are encapsulated into link layer frames. An IS-IS PDU has two parts, the headers and the
variable length fields. The headers comprise the PDU common header and the PDU specific header. All
PDUs have the same PDU common header. The specific headers vary by PDU type.
Figure 34 PDU format
Table 4 PDU types
Type
PDU Type
Acronym
15
Level-1 LAN IS-IS hello PDU
L1 LAN IIH
16
Level-2 LAN IS-IS hello PDU
L2 LAN IIH
17
Point-to-Point IS-IS hello PDU
P2P IIH
18
Level-1 Link State PDU
L1 LSP
20
Level-2 Link State PDU
L2 LSP
24
Level-1 Complete Sequence Numbers PDU
L1 CSNP
25
Level-2 Complete Sequence Numbers PDU
L2 CSNP
26
Level-1 Partial Sequence Numbers PDU
L1 PSNP
27
Level-2 Partial Sequence Numbers PDU
L2 PSNP
Hello PDU
IS-to-IS hello (IIH) PDUs are used by routers to establish and maintain neighbor relationships. On
broadcast networks, Level-1 routers use Level-1 LAN IIHs, and Level-2 routers use Level-2 LAN IIHs. The
P2P IIHs are used on point-to-point networks.
LSP
The LSPs carry link state information. LSPs include Level-1 LSPs and Level-2 LSPs. The Level-2 LSPs are sent
by the Level-2 routers, and the Level-1 LSPs are sent by the Level-1 routers. The Level-1-2 router can send
both types of LSPs.
113
SNP
A sequence number PDU (SNP) describes the complete or partial LSPs for LSDB synchronization.
SNPs include CSNP and PSNP, which are further divided into Level-1 CSNP, Level-2 CSNP, Level-1 PSNP,
and Level-2 PSNP.
A CSNP describes the summary of all LSPs for LSDB synchronization between neighboring routers. On
broadcast networks, CSNPs are sent by the DIS periodically (every 10 seconds by default). On
point-to-point networks, CSNPs are sent only during the first adjacency establishment.
A PSNP only contains the sequence numbers of one or multiple latest received LSPs. It can acknowledge
multiple LSPs at one time. When LSDBs are not synchronized, a PSNP is used to request missing LSPs from
a neighbor.
CLV
The variable fields of PDU comprise multiple Code-Length-Value (CLV) triplets.
Figure 35 CLV format
Table 5 shows that different PDUs contain different CLVs. Codes 1 through 10 are defined in ISO 10589
(code 3 and 5 are not shown in the table), and others are defined in RFC 1195.
Table 5 CLV codes and PDU types
CLV Code
Name
PDU Type
1
Area Addresses
IIH, LSP
2
IS Neighbors (LSP)
LSP
4
Partition Designated Level2 IS
L2 LSP
6
IS Neighbors (MAC Address)
LAN IIH
7
IS Neighbors (SNPA Address)
LAN IIH
8
Padding
IIH
9
LSP Entries
SNP
10
Authentication Information
IIH, LSP, SNP
128
IP Internal Reachability Information
LSP
129
Protocols Supported
IIH, LSP
130
IP External Reachability Information
L2 LSP
131
Inter-Domain Routing Protocol Information
L2 LSP
132
IP Interface Address
IIH, LSP
Protocols and standards
•
ISO 10589 ISO IS-IS Routing Protocol
114
•
ISO 9542 ES-IS Routing Protocol
•
ISO 8348/Ad2 Network Services Access Points
•
RFC 1195, Use of OSI IS-IS for Routing in TCP/IP and Dual Environments
•
RFC 2763, Dynamic Hostname Exchange Mechanism for IS-IS
•
RFC 2966, Domain-wide Prefix Distribution with Two-Level IS-IS
•
RFC 2973, IS-IS Mesh Groups
•
RFC 3277, IS-IS Transient Blackhole Avoidance
•
RFC 3358, Optional Checksums in ISIS
•
RFC 3373, Three-Way Handshake for IS-IS Point-to-Point Adjacencies
•
RFC 3567, Intermediate System to Intermediate System (IS-IS) Cryptographic Authentication
•
RFC 3719, Recommendations for Interoperable Networks using IS-IS
•
RFC 3786, Extending the Number of IS-IS LSP Fragments Beyond the 256 Limit
•
RFC 3787, Recommendations for Interoperable IP Networks using IS-IS
•
RFC 3847, Restart Signaling for IS-IS
IS-IS configuration task list
Tasks at a glance
Configuring basic IS-IS
• (Required.) Enabling IS-IS
• (Optional.) Configuring the IS level and circuit level
• (Optional.) Configuring P2P network type for an interface
(Optional.) Configuring IS-IS route control
•
•
•
•
•
•
•
•
Configuring IS-IS link cost
Specifying a preference for IS-IS
Configuring the maximum number of ECMP routes
Configuring IS-IS route summarization
Advertising a default route
Configuring IS-IS route redistribution
Configuring IS-IS route filtering
Configuring IS-IS route leaking
115
Tasks at a glance
(Optional.) Tuning and optimizing IS-IS networks
•
•
•
•
•
•
•
•
•
•
•
•
Specifying intervals for sending IS-IS hello and CSNP packets
Specifying the IS-IS hello multiplier
Configuring a DIS priority for an interface
Disabling an interface from sending/receiving IS-IS packets
Enabling an interface to send small hello packets
Configuring LSP parameters
Controlling SPF calculation interval
Configuring convergence priorities for specific routes
Setting the LSDB overload bit
Configuring system ID to host name mappings
Enabling the logging of neighbor state changes
Enabling IS-IS ISPF
(Optional.) Enhancing IS-IS network security
• Configuring neighbor relationship authentication
• Configuring area authentication
• Configuring routing domain authentication
(Optional.) Configuring IS-IS GR
(Optional.) Configuring BFD for IS-IS
(Optional.) Configuring IS-IS FRR
Configuring basic IS-IS
Configuration prerequisites
Before the configuration, complete the following tasks:
•
Configure the link layer protocol.
•
Configure IP addresses for interfaces to ensure IP connectivity between neighboring nodes.
Enabling IS-IS
Step
Command
Remarks
1.
Enter system view.
system-view
N/A
2.
Create an IS-IS process and enter
its view.
isis [ process-id ] [ vpn-instance
vpn-instance-name ]
By default, the IS-IS process is
disabled.
3.
Assign a NET.
network-entity net
By default, NET is not assigned.
4.
Return to system view.
quit
N/A
5.
Enter interface view.
interface interface-type
interface-number
N/A
6.
Enable an IS-IS process on the
interface.
isis enable [ process-id ]
By default, no IS-IS process is
enabled.
116
Configuring the IS level and circuit level
Follow these guidelines when you configure the IS level for routers in only one area:
•
Configure the IS level of all routers as Level-1 or Level-2 rather than different levels because the
routers do not need to maintain two identical LSDBs.
•
Configure the IS level as Level-2 on all routers in an IP network for good scalability.
For an interface of a Level-1 (or Level-2) router, the circuit level can only be Level-1 (or Level-2). For an
interface of a Level-1-2 router, the default circuit level is Level-1-2; if the router only needs to form Level-1 (or
Level-2) neighbor relationships, configure the circuit level for its interfaces as Level-1 (or Level-2) to limit
neighbor relationship establishment.
To configure the IS level and circuit level:
Step
Command
Remarks
1.
Enter system view.
system-view
N/A
2.
Enter IS-IS view.
isis [ process-id ] [ vpn-instance
vpn-instance-name ]
N/A
3.
Specify the IS level.
is-level { level-1 | level-1-2 |
level-2 }
By default, the IS level is Level-1-2.
4.
Return to system view.
quit
N/A
5.
Enter interface view.
interface interface-type
interface-number
N/A
6.
Specify the circuit level.
isis circuit-level [ level-1 | level-1-2
| level-2 ]
By default, an interface can establish
either the Level-1 or Level-2
adjacency.
Configuring P2P network type for an interface
Perform this task only for a broadcast network that has up to two attached routers.
Interfaces with different network types operate differently. For example, broadcast interfaces on a
network must elect the DIS and flood CSNP packets to synchronize the LSDBs, but P2P interfaces on a
network do not need to elect the DIS, and have a different LSDB synchronization mechanism.
If only two routers exist on a broadcast network, configure the network type of attached interfaces as P2P
to avoid DIS election and CSNP flooding, saving network bandwidth and speeding up network
convergence.
To configure P2P network type for an interface:
Step
Command
Remarks
1.
Enter system view.
system-view
N/A
2.
Enter interface view.
interface interface-type
interface-number
N/A
117
Step
Configure P2P network type for an
interface.
3.
Command
Remarks
isis circuit-type p2p
By default, the network type of an
interface depends on the physical
media. The network type of a
VLAN interface is broadcast.
Configuring IS-IS route control
Configuration prerequisites
Before the configuration, complete the following tasks:
•
Configure IP addresses for interfaces to ensure IP connectivity between neighboring nodes.
•
Enable IS-IS.
Configuring IS-IS link cost
The IS-IS cost of an interface is determined in the following order:
1.
IS-IS cost specified in interface view.
2.
IS-IS cost specified in system view. The cost is applied to the interfaces associated with the IS-IS
process.
3.
Automatically calculated cost. If the cost style is wide or wide-compatible, IS-IS automatically
calculates the cost using the formula: interface cost = (bandwidth reference value/interface
bandwidth) ×10, in the range of 1 to16777214. For other cost styles, Table 6 applies.
Table 6 Automatic cost calculation scheme for cost styles other than wide and wide-compatible
Interface bandwidth
Interface cost
≤ 10 Mbps
60
≤ 100 Mbps
50
≤ 155 Mbps
40
≤ 622 Mbps
30
≤ 2500 Mbps
20
> 2500 Mbps
10
4.
If none of the above costs is used, a default cost of 10 applies.
Configuring an IS-IS cost for an interface
Step
Command
Remarks
1.
Enter system view.
system-view
N/A
2.
Enter IS-IS view.
isis [ process-id ] [ vpn-instance
vpn-instance-name ]
N/A
118
Step
Command
Remarks
3.
(Optional.) Specify an
IS-IS cost style.
cost-style { narrow | wide | wide-compatible
| { compatible | narrow-compatible }
[ relax-spf-limit ] }
By default, the IS-IS cost type
is narrow.
4.
Return to system view.
quit
N/A
5.
Enter interface view.
interface interface-type interface-number
N/A
6.
(Optional.) Specify a cost
for the IS-IS interface.
isis cost value [ level-1 | level-2 ]
By default, no cost for the
interface is specified.
Configuring a global IS-IS cost
Step
Command
Remarks
1.
Enter system view.
system-view
N/A
2.
Enter IS-IS view.
isis [ process-id ] [ vpn-instance vpn-instance-name ]
N/A
3.
(Optional.) Specify
an IS-IS cost style.
cost-style { narrow | wide | wide-compatible |
{ compatible | narrow-compatible }
[ relax-spf-limit ] }
By default, the IS-IS cost style
is narrow.
4.
Specify a global
IS-IS cost.
circuit-cost value [ level-1 | level-2 ]
By default, no global cost is
specified.
Enabling automatic IS-IS cost calculation
Step
Command
Remarks
1.
Enter system view.
system-view
N/A
2.
Enter IS-IS view.
isis [ process-id ] [ vpn-instance
vpn-instance-name ]
N/A
3.
Specify an IS-IS cost style.
cost-style { wide | wide-compatible }
By default, the IS-IS cost is narrow.
4.
Enable automatic IS-IS cost
calculation.
auto-cost enable
By default, automatic IS-IS cost
calculation is disabled.
5.
(Optional.) Configure a
bandwidth reference value
for automatic IS-IS cost
calculation.
bandwidth-reference value
The default setting is100 Mbps.
Specifying a preference for IS-IS
If multiple routing protocols find routes to the same destination, the route found by the routing protocol
that has the highest preference is selected as the optimal route.
Perform this task to assign a preference to IS-IS directly or by using a routing policy. For more information
about the routing policy, see "Configuring routing policies."
To configure a preference for IS-IS:
119
Step
Command
Remarks
1.
Enter system view.
system-view
N/A
2.
Enter IS-IS view.
isis [ process-id ] [ vpn-instance
vpn-instance-name ]
N/A
3.
Configure a prefrence for
IS-IS.
preference { preference | route-policy
route-policy-name } *
The default setting is
15.
Configuring the maximum number of ECMP routes
Perform this task to implement load sharing over ECMP routes.
To configure the maximum number of ECMP routes:
Step
Command
Remarks
1.
Enter system view.
system-view
N/A
2.
Enter IS-IS view.
isis [ process-id ] [ vpn-instance
vpn-instance-name ]
N/A
maximum load-balancing number
By default, the maximum
number of ECMP routes
is the same as that
configured in the
max-ecmp-num
command. For more
information about the
max-ecmp-num
command, see IP Routing
Command Reference.
3.
Specify the maximum number
of ECMP routes.
Configuring IS-IS route summarization
Perform this task to summarize specific routes, including IS-IS routes and redistributed routes, into a single
route. Route summarization can reduce the routing table size and the LSDB scale.
Route summarization applies only to locally generated LSPs. The cost of the summary route is the lowest
one among the costs of the more-specific routes.
To configure route summarization:
Step
Command
Remarks
1.
Enter system view.
system-view
N/A
2.
Enter IS-IS view.
isis [ process-id ] [ vpn-instance
vpn-instance-name ]
N/A
3.
Configure IS-IS route
summarization.
summary ip-address { mask | mask-length }
[ avoid-feedback | generate_null0_route |
[ level-1 | level-1-2 | level-2 ] | tag tag ] *
By default, route summarization is
not configured.
120
Advertising a default route
IS-IS cannot redistribute a default route to its neighbors. This task enables IS-IS to advertise a default route
of 0.0.0.0/0 in an LSP to the same-level neighbors. Upon receiving the default route, the neighbors add
it into their routing table.
To advertise a default route:
Step
Command
Remarks
1.
Enter system view.
system-view
N/A
2.
Enter IS-IS view.
isis [ process-id ] [ vpn-instance
vpn-instance-name ]
N/A
Advertise a default
route.
default-route-advertise [ [ level-1 | level-1-2
| level-2 ] | route-policy route-policy-name ]
*
3.
By default, IS-IS does not advertise
a default route.
The generated routes are
advertised to only the same-level
neighbors.
Configuring IS-IS route redistribution
Perform this task to redistribute routes from other routing protocols into IS-IS. You can specify a cost for
redistributed routes and specify the maximum number of redistributed routes.
To configure IS-IS route redistribution from other routing protocols:
Step
Command
Remarks
1.
Enter system view.
system-view
N/A
2.
Enter IS-IS view.
isis [ process-id ] [ vpn-instance
vpn-instance-name ]
N/A
By default, no route is redistributed.
3.
4.
Redistribute routes from
other routing protocols
or other IS-IS processes.
import-route protocol [ process-id |
all-processes | allow-ibgp ] [ cost cost
| cost-type { external | internal } |
[ level-1 | level-1-2 | level-2 ] |
route-policy route-policy-name | tag
tag ] *
(Optional.) Configure
the maximum number of
redistributed Level
1/Level 2 IPv4 routes.
import-route limit number
By default, if no level is specified, this
command redistributes routes into the
Level-2 routing table.
This command redistributes only
active routes. To display active
routes, use the display ip
routing-table protocol command.
By default, the maximum number of
redistributed Level 1/Level 2 IPv4
routes is not configured.
Configuring IS-IS route filtering
You can use an ACL, IP prefix list, or routing policy to filter routes calculated using received LSPs and
routes redistributed from other routing protocols.
121
Filtering routes calculated from received LSPs
IS-IS saves LSPs received from neighbors in the LSDB, uses the SPF algorithm to calculate the shortest path
tree with itself as the root, and installs the routes to the IS-IS routing table.
Perform this task to filter calculated routes. Only routes that are not filtered can be added to the IS-IS
routing table.
To filter routes calculated using received LSPs:
Step
Command
Remarks
1.
Enter system view.
system-view
N/A
2.
Enter IS-IS view.
isis [ process-id ] [ vpn-instance
vpn-instance-name ]
N/A
3.
Filter routes calculated
using received LSPs.
filter-policy { acl-number | prefix-list
prefix-list-name | route-policy
route-policy-name } import
By default, IS-IS accepts all
routes calculated using
received LSPs.
Filtering redistributed routes
IS-IS can redistribute routes from other routing protocols or other IS-IS processes, add them to the IS-IS
routing table, and advertise them in LSPs.
Perform this task to filter redistributed routes. Only routes that are not filtered can be added to the IS-IS
routing table and advertised to neighbors.
To filter redistributed routes:
Step
Command
Remarks
1.
Enter system view.
system-view
N/A
2.
Enter IS-IS view.
isis [ process-id ] [ vpn-instance
vpn-instance-name ]
N/A
3.
Filter routes redistributed from
other routing protocols or IS-IS
processes.
filter-policy { acl-number | prefix-list
prefix-list-name | route-policy
route-policy-name } export [ protocol
[ process-id ] ]
By default, IS-IS accepts
all redistributed routes.
Configuring IS-IS route leaking
Perform this task to control route advertisement (route leaking) between Level-1 and Level-2.
You can configure IS-IS to advertise routes from Level-2 to Level-1, and to not advertise routes from Level-1
to Level-2.
To configure IS-IS route leaking:
Step
Command
Remarks
1.
Enter system view.
system-view
N/A
2.
Enter IS-IS view.
isis [ process-id ] [ vpn-instance
vpn-instance-name ]
N/A
122
Step
Command
Remarks
3.
Configure route
leaking from Level-1 to
Level-2.
import-route isis level-1 into level-2 [ filter-policy
{ acl-number | prefix-list prefix-list-name |
route-policy route-policy-name } | tag tag ] *
By default, IS-IS advertises
routes from Level-1 to
Level-2.
4.
Configure route
leaking from Level-2 to
Level-1.
import-route isis level-2 into level-1 [ filter-policy
{ acl-number | prefix-list prefix-list-name |
route-policy route-policy-name } | tag tag ] *
By default, IS-IS does not
advertise routes from
Level-2 to Level-1.
Tuning and optimizing IS-IS networks
Configuration prerequisites
Before you tune and optimize IS-IS networks, complete the following tasks:
•
Configure IP addresses for interfaces to ensure IP connectivity between neighboring nodes.
•
Enable IS-IS.
Specifying intervals for sending IS-IS hello and CSNP packets
Step
Command
Remarks
1.
Enter system view.
system-view
N/A
2.
Enter interface view.
interface interface-type
interface-number
N/A
The default setting is10 seconds.
3.
Specify the interval for
sending hello packets.
isis timer hello seconds [ level-1 |
level-2 ]
4.
Specify the interval for
sending CSNP packets on the
DIS of a broadcast network.
isis timer csnp seconds [ level-1 |
level-2 ]
The interval between hello packets
sent by the DIS is 1/3 the hello
interval set with the isis timer hello
command.
The default setting is10 seconds.
Specifying the IS-IS hello multiplier
If a neighbor receives no hello packets from the router within the advertised hold time, it considers the
router down and recalculates the routes. The hold time is the hello multiplier multiplied by the hello
interval.
On a broadcast link, Level-1 and Level-2 hello packets are advertised separately. You must set a hello
multiplier for each level.
On a P2P link, Level-1 and Level-2 hello packets are advertised in P2P hello packets. You do not need to
specify Level-1 or Level-2.
To specify the IS-IS hello multiplier:
Step
1.
Enter system view.
Command
Remarks
system-view
N/A
123
Step
Command
Remarks
2.
Enter interface view.
interface interface-type
interface-number
N/A
3.
Specify the number of hello packets a
neighbor must miss before declaring
the router is down.
isis timer holding-multiplier value
[ level-1 | level-2 ]
The default setting is
3.
Configuring a DIS priority for an interface
On a broadcast network, IS-IS must elect a router as the DIS at a routing level. You can specify a DIS
priority at a level for an interface. The greater the interface's priority, the more likely it becomes the DIS.
If multiple routers in the broadcast network have the same highest DIS priority, the router with the highest
MAC address becomes the DIS.
To configure a DIS priority for an interface:
Step
Command
Remarks
1.
Enter system view.
system-view
N/A
2.
Enter interface view.
interface interface-type
interface-number
N/A
3.
Configure a DIS priority for
the interface.
isis dis-priority value [ level-1 |
level-2 ]
The default setting is 64.
Disabling an interface from sending/receiving IS-IS packets
After being disabled from sending and receiving hello packets, an interface cannot form any neighbor
relationship, but can advertise directly connected networks in LSPs through other interfaces. This can save
bandwidth and CPU resources, and ensures that other routers know networks directly connected to the
interface.
To disable an interface from sending and receiving IS-IS packets:
Step
Command
Remarks
1.
Enter system view.
system-view
N/A
2.
Enter interface view.
interface interface-type
interface-number
N/A
3.
Disable the interface from
sending and receiving IS-IS
packets.
isis silent
By default, the interface can send
and receive IS-IS packets.
Enabling an interface to send small hello packets
IS-IS messages cannot be fragmented at the IP layer because they are directly encapsulated in frames.
Any two IS-IS neighboring routers must negotiate a common MTU. To avoid sending big hellos to save
bandwidth, enable the interface to send small hello packets without CLVs.
To enable an interface to send small hello packets:
124
Step
Command
Remarks
1.
Enter system view.
system-view
N/A
2.
Enter interface view.
interface interface-type
interface-number
N/A
3.
Enable the interface to send
small hello packets without
CLVs.
isis small-hello
By default, the interface can send
standard hello packets.
Configuring LSP parameters
Configuring LSP timers
1.
Specify the maximum age of LSPs.
Each LSP has an age that decreases in the LSDB. IS-IS runs a process to delete any LSP with an age
of 0 from the LSDB. You can adjust the age value based on the scale of a network.
To specify the maximum age of LSPs:
Step
Command
Remarks
1.
Enter system view.
system-view
N/A
2.
Enter IS-IS view.
isis [ process-id ] [ vpn-instance
vpn-instance-name ]
N/A
3.
Specify the maximum LSP
age.
timer lsp-max-age seconds
The default setting is1200
seconds.
2.
Specify the LSP refresh interval and generation interval.
Each router needs to refresh its LSPs at a configurable interval and send them to other routers to
prevent valid routes from aging out. A smaller refresh interval speeds up network convergence but
consumes more bandwidth.
When the network topology changes, for example, a neighbor is down or up, or the interface
metric, system ID, or area ID is changed, the router generates an LSP after a configurable interval.
If such a change occurs frequently, excessive LSPs are generated, consuming a large amount of
router resources and bandwidth. To solve the problem, you can adjust the LSP generation interval.
When network changes are not frequent, the minimum-interval is adopted. If network changes
become frequent, the LSP generation interval is incremented by incremental-interval × 2n-2 (n is the
number of calculation times) each time a generation occurs until the maximum-interval is reached.
To specify the LSP refresh interval and generation interval:
Step
Command
Remarks
1.
Enter system view.
system-view
N/A
2.
Enter IS-IS view.
isis [ process-id ] [ vpn-instance
vpn-instance-name ]
N/A
3.
Specify the LSP refresh
interval.
timer lsp-refresh seconds
By default, the LSP refresh
interval is 900 seconds.
125
Step
Command
Remarks
By default:
• The maximum interval is 2
Specify the LSP
generation interval.
4.
timer lsp-generation maximum-interval
[ minimum-interval [ incremental-interval ] ]
[ level-1 | level-2 ]
seconds.
• The minimum interval is 0
milliseconds.
• The incremental interval is
0 milliseconds.
3.
Specify LSP sending intervals.
If a change occurs in the LSDB, IS-IS advertises the changed LSP to neighbors. You can specify the
minimum interval for sending such LSPs.
To avoid unnecessary retransmissions, configure an LSP sending interval according to the number
of IS-IS interfaces or routes.
To configure LSP sending intervals:
Step
Command
Remarks
1.
Enter system view.
system-view
N/A
2.
Enter interface view.
interface interface-type
interface-number
N/A
3.
Specify the minimum interval
for sending LSPs and the
maximum LSP number that
can be sent at a time.
isis timer lsp time [ count count ]
By default, the minimum interval is 33
milliseconds, and the maximum LSP
number that can be sent at a time is 5.
Specifying LSP lengths
IS-IS messages cannot be fragmented at the IP layer because they are directly encapsulated in frames.
IS-IS routers in an area must send LSPs smaller than the smallest interface MTU in the area.
If the IS-IS routers have different interface MTUs, HP recommends configuring the maximum size of
generated LSP packets to be smaller than the smallest interface MTU in the area. Otherwise, the routers
must dynamically adjust the LSP packet size to fit the smallest interface MTU, which takes time and affects
other services.
To specify LSP lengths:
Step
Command
Remarks
1.
PreferenceEnter system view.
system-view
N/A
2.
Enter IS-IS view.
isis [ process-id ] [ vpn-instance
vpn-instance-name ]
N/A
3.
Specify the maximum length
of generated Level-1 LSPs or
Level-2 LSPs.
lsp-length originate size [ level-1 |
level-2 ]
By default, the maximum length
of generated Level-1 LSPs or
Level-2 LSPs is 1497 bytes.
4.
Specify the maximum length
of received LSPs.
lsp-length receive size
By default, the maximum length
of received LSPs is 1497 bytes.
126
Enabling LSP flash flooding
Changed LSPs can trigger SPF recalculation. To advertise the changed LSPs before the router recalculates
routes for faster network convergence, enable LSP flash flooding.
To enable LSP flash flooding:
Step
Command
Remarks
1.
Enter system view.
system-view
N/A
2.
Enter IS-IS view.
isis [ process-id ] [ vpn-instance vpn-instance-name ]
N/A
3.
Enable LSP flash
flooding.
flash-flood [ flood-count flooding-count |
max-timer-interval flooding-interval | [ level-1 |
level-2 ] ] *
By default, LSP flash
flooding is disabled.
Enabling LSP fragment extension
Perform this task to enable IS-IS fragment extension for an IS-IS process. The MTUs of all interfaces
running the IS-IS process must not be less than 512. Otherwise, LSP fragment extension does not take
effect.
To enable LSP fragment extension:
Step
Command
Remarks
1.
Enter system view.
system-view
N/A
2.
Enter IS-IS view.
isis [ process-id ] [ vpn-instance
vpn-instance-name ]
N/A
3.
Enable LSP fragment
extension.
lsp-fragments-extend [ level-1 |
level-1-2 | level-2 ]
By default, this feature is disabled.
4.
Configure a virtual system
ID.
virtual-system virtual-system-id
By default, no virtual system ID is
configured.
Configure at least one virtual system to
generate extended LSP fragments.
Controlling SPF calculation interval
Based on the LSDB, an IS-IS router uses the SPF algorithm to calculate the shortest path tree with itself
being the root, and uses the shortest path tree to determine the next hop to a destination network. By
adjusting the SPF calculation interval, you can prevent bandwidth and router resources from being
overconsumed due to frequent topology changes.
When network changes are not frequent, the minimum-interval is adopted. If network changes become
frequent, the SPF calculation interval is incremented by incremental-interval × 2n-2 (n is the number of
calculation times) each time a calculation occurs until the maximum-interval is reached.
To control SPF calculation interval:
Step
Command
Remarks
1.
Enter system view.
system-view
N/A
2.
Enter IS-IS view.
isis [ process-id ] [ vpn-instance
vpn-instance-name ]
N/A
127
Step
Command
Remarks
By default:
• The maximum interval is 5
3.
Configure the SPF
calculation interval.
timer spf maximum-interval
[ minimum-interval [ incremental-interval ] ]
seconds.
• The minimum interval is 50
milliseconds.
• The incremental interval is
200 milliseconds.
Configuring convergence priorities for specific routes
A topology change causes IS-IS routing convergence. To improve convergence speed, you can assign
different convergence priorities to specific IS-IS routes, including critical, high, medium, and low. The
higher the convergence priority, the faster the convergence speed.
IS-IS host routes have the medium convergence priority.
To assign convergence priorities to specific IS-IS routes:
Step
Command
Remarks
1.
Enter system view.
system-view
N/A
2.
Enter IS-IS view.
isis [ process-id ] [ vpn-instance
vpn-instance-name ]
N/A
3.
Assign convergence priorities
to specific IS-IS routes.
priority { critical | high | medium }
{ prefix-list prefix-list-name | tag
tag-value }
By default, IS-IS routes have the
lowest convergence priority.
Setting the LSDB overload bit
By setting the overload bit in sent LSPs, a router informs other routers of failures that make it unable to
select routes and forward packets.
When an IS-IS router cannot record the complete LSDB, for example, because of memory insufficiency,
it will calculate wrong routes. To make troubleshooting easier, temporarily isolate the router from the IS-IS
network by setting the overload bit.
To set the LSDB overload bit:
Step
Command
Remarks
1.
Enter system view.
system-view
N/A
2.
Enter IS-IS view.
isis [ process-id ] [ vpn-instance vpn-instance-name ]
N/A
3.
Set the overload bit.
set-overload [ on-startup [ [ start-from-nbr system-id
[ timeout1 [ nbr-timeout ] ] ] | timeout2 ] [ allow { external
| interlevel } * ]
By default, the
overload bit is not
set.
128
Configuring system ID to host name mappings
A 6-byte system ID in hexadecimal notation uniquely identifies a router or host in an IS-IS network. To
make a system ID easy to read, the system allows you to use host names to identify devices and provides
mappings between system IDs and host names.
The mappings can be configured manually or dynamically. Follow these guidelines when you configure
the mappings:
•
To view host names rather than system IDs by using the display isis lsdb command, you must enable
dynamic system ID to host name mapping.
•
If you configure both dynamic mapping and static mapping on a router, the host name specified for
dynamic mapping applies.
Configuring a static system ID to host name mapping
Step
Command
Remarks
1.
Enter system view.
system-view
N/A
2.
Enter IS-IS view.
isis [ process-id ] [ vpn-instance
vpn-instance-name ]
N/A
3.
Configure a system ID to host
name mapping for a remote
IS.
is-name map sys-id map-sys-name
A system ID can correspond to only
one host name.
Configuring dynamic system ID to host name mapping
Static system ID to host name mapping requires you to manually configure a mapping for each router in
the network. When a new router is added to the network or a mapping must be modified, you must
configure all routers manually.
When you use dynamic system ID to host name mapping, you only need to configure a host name for
each router in the network. Each router advertises the host name in a dynamic host name CLV to other
routers so all routers in the network can have all mappings.
To help check the origin of LSPs in the LSDB, you can configure a name for the DIS in a broadcast
network.
To configure dynamic system ID to host name mapping:
Step
Command
Remarks
1.
Enter system view.
system-view
N/A
2.
Enter IS-IS view.
isis [ process-id ] [ vpn-instance
vpn-instance-name ]
N/A
3.
Specify a host name
for the IS and enable
dynamic system ID to
host name mapping.
is-name sys-name
By default, no host name is specified for
the router.
4.
Return to system view.
quit
N/A
5.
Enter interface view.
interface interface-type
interface-number
N/A
129
Step
Command
Remarks
By default, no DIS name is configured.
Configure a DIS name.
6.
isis dis-name symbolic-name
This command takes effect only on a
router enabled with dynamic system ID to
host name mapping.
This command is not available on P2P
interfaces.
Enabling the logging of neighbor state changes
With this feature enabled, the router delivers information about neighbor state changes to the terminal
for display.
To enable the logging of neighbor state changes:
Step
Command
Remarks
1.
Enter system view.
system-view
N/A
2.
Enter IS-IS view.
isis [ process-id ] [ vpn-instance
vpn-instance-name ]
N/A
3.
Enable the logging of
neighbor state changes.
log-peer-change
By default, the logging of
neighbor state is enabled.
Enabling IS-IS ISPF
When the network topology changes, Incremental Shortest Path First (ISPF) computes only the affected
part of the SPT, instead of the entire SPT.
To enable IS-IS ISPF:
Step
Command
Remarks
1.
Enter system view.
system-view
N/A
2.
Enter IS-IS view.
isis [ process-id ] [ vpn-instance vpn-instance-name ]
N/A
3.
Enable IS-IS ISPF.
ispf enable
By default, IS-IS is disabled.
Enhancing IS-IS network security
To enhance the security of an IS-IS network, you can configure IS-IS authentication. IS-IS authentication
involves neighbor relationship authentication, area authentication, and routing domain authentication.
Configuration prerequisites
Before the configuration, complete the following tasks:
•
Configure IP addresses for interfaces to ensure IP connectivity between neighboring nodes.
•
Enable IS-IS.
130
Configuring neighbor relationship authentication
With neighbor relationship authentication configured, an interface adds the password in the specified
mode into hello packets to the peer and checks the password in the received hello packets. If the
authentication succeeds, it forms the neighbor relationship with the peer.
The authentication mode and password at both ends must be identical.
To configure neighbor relationship authentication:
Step
Command
Remarks
1.
Enter system view.
system-view
N/A
2.
Enter interface view.
interface interface-type interface-number
N/A
3.
Specify the authentication
mode and password.
isis authentication-mode { md5 | simple }
{ cipher cipher-string | plain plain-string }
[ level-1 | level-2 ] [ ip | osi ]
By default, no authentication
is configured.
Configuring area authentication
Area authentication prevents the router from installing routing information from untrusted routers into the
Level-1 LSDB. The router encapsulates the authentication password in the specified mode in Level-1
packets (LSP, CSNP, and PSNP) and checks the password in received Level-1 packets.
Routers in a common area must have the same authentication mode and password.
To configure area authentication:
Step
Command
Remarks
1.
Enter system view.
system-view
N/A
2.
Enter IS-IS view.
isis [ process-id ] [ vpn-instance
vpn-instance-name ]
N/A
3.
Specify the area
authentication mode and
password.
area-authentication-mode { md5 |
simple } { cipher cipher-string | plain
plain-string } [ ip | osi ]
By default, no area authentication
is configured.
Configuring routing domain authentication
Routing domain authentication prevents untrusted routing information from entering into a routing
domain. A router with the authentication configured encapsulates the password in the specified mode
into Level-2 packets (LSP, CSNP, and PSNP) and check the password in received Level-2 packets.
All the routers in the backbone must have the same authentication mode and password.
To configure routing domain authentication:
Step
Command
Remarks
1.
Enter system view.
system-view
N/A
2.
Enter IS-IS view.
isis [ process-id ] [ vpn-instance
vpn-instance-name ]
N/A
131
Step
Specify the routing domain
authentication mode and
password.
3.
Command
Remarks
domain-authentication-mode
{ md5 | simple } { cipher
cipher-string | plain plain-string }
[ ip | osi ]
By default, no routing domain
authentication is configured.
Configuring IS-IS GR
GR ensures the continuity of packet forwarding when a routing protocol restarts.
•
GR Restarter—Graceful restarting router. It must have GR capability.
•
GR Helper—A neighbor of the GR Restarter. It assists the GR Restarter to complete the GR process.
By default, a device acts as the GR Helper. Configure IS-IS GR on the GR Restarter.
GR Restarter uses the following timers:
•
T1 timer—Specifies the times that GR Restarter can send a Restart TLV with the RR bit set. After
restart, the GR Restarter sends a Restart TLV with the RR bit set to its neighbor. If the restarting router
receives a Restart TLV with the RA set from its neighbor before the T1 timer expires, the GR process
starts. Otherwise, the GR process fails.
•
T2 timer—Specifies the LSDB synchronization interval. Each LSDB has a T2 timer. The Level-1-2 router
has two T2 timers: a Level-1 timer and a Level-2 timer. If the LSDBs have not achieved
synchronization before the two timers expire, the GR process fails.
•
T3 timer—Specifies the GR interval. The GR interval is set as the holdtime in hello PDUs. Within the
interval, the neighbors maintain their adjacency with the GR Restarter. If the GR process has not
completed within the holdtime, the neighbors tear down the neighbor relationship and the GR
process fails.
To configure GR on the GR Restarter:
Step
Command
Remarks
1.
Enter system view.
system-view
N/A
2.
Enable IS-IS and
enter IS-IS view.
isis [ process-id ] [ vpn-instance
vpn-instance-name ]
N/A
3.
Enable IS-IS GR.
graceful-restart
By default, the GR capability for IS-IS is
disabled.
4.
(Optional.) Suppress
the SA bit during
restart.
graceful-restart suppress-sa
5.
(Optional.) Configure
the T1 timer.
graceful-restart t1 seconds count
count
By default, the T1 timer is 3 seconds and can
expire 10 times.
6.
(Optional.) Configure
the T2 timer.
graceful-restart t2 seconds
By default, the T2 timer is 60 seconds.
7.
(Optional.) Configure
the T3 timer.
graceful-restart t3 seconds
By default, the T2 timer is 300 seconds.
By default, the SA bit is not suppressed.
132
By enabling the GR Restarter to suppress the
Suppress-Advertisement (SA) bit in the hello
PDUs, the neighbors will still advertise their
adjacency with the GR Restarter.
Configuring BFD for IS-IS
BFD provides a single mechanism to quickly detect and monitor the connectivity of links between OSPF
neighbors, reducing network convergence time. For more information about BFD, see High Availability
Configuration Guide.
To configure BFD for IS-IS:
Step
Command
Remarks
1.
Enter system view.
system-view
N/A
2.
Enter interface view.
interface interface-type interface-number
N/A
3.
Enable IS-IS on an interface.
isis enable [ process-id ]
N/A
4.
Enable BFD on an IS-IS
interface.
isis bfd enable
By default, an IS-IS interface
is not enabled with BFD.
Configuring IS-IS FRR
A link or router failure on a path can cause packet loss and even routing loop. Such problems arise until
IS-IS completes the routing convergence based on the new network topology. IS-IS FRR enables fast
rerouting to minimize the impact of link or node failures.
Figure 36 Network diagram for IS-IS FRR
In Figure 36, after you enable FRR on Router B, IS-IS automatically calculates or designates a backup next
hop when a link failure is detected. In this way, packets are directed to the backup next hop to reduce
traffic recovery time. Meanwhile, IS-IS calculates the shortest path based on the new network topology,
and forwards packets over the path after network convergence.
You can either enable IS-IS FRR to calculate a backup next hop automatically, or designate a backup next
hop with a routing policy for routes matching specific criteria.
Configuration prerequisites
Before you configure IS-IS FRR, complete the following tasks:
•
Configure IP addresses for interfaces to ensure IP connectivity between neighboring nodes.
•
Enable IS-IS.
133
Configuration guidelines
Do not use FRR and BFD at the same time. Otherwise, FRR may fail to take effect.
Configuring IS-IS FRR to automatically calculate a backup next
hop
Step
Command
Remarks
1.
Enter system view.
system-view
N/A
2.
Configure the source address
of echo packets.
bfd echo-source-ip ip-address
By default, the source address of
echo packets is not configured.
3.
Enter IS-IS view.
isis [ process-id ] [ vpn-instance
vpn-instance-name ]
N/A
4.
Enable IS-IS FRR to
automatically calculate a
backup next hop.
fast-reroute auto
By default, IS-IS FRR is disabled.
Configuring IS-IS FRR using a routing policy
You can use the apply fast-reroute backup-interface command to specify a backup next hop in a routing
policy for routes matching specific criteria, and perform this task to reference the routing policy for IS-IS
FRR. For more information about the apply fast-reroute backup-interface command and routing policy
configurations, see "Configuring routing policies."
To configure IS-IS FRR using a routing policy:
Step
Command
Remarks
1.
Enter system view.
system-view
N/A
2.
Configure the source address
of echo packets.
bfd echo-source-ip ip-address
By default, the source address of
echo packets is not configured.
3.
Enter IS-IS view.
isis [ process-id ] [ vpn-instance
vpn-instance-name ]
N/A
4.
Enable IS-IS FRR using a
routing policy.
fast-reroute route-policy
route-policy-name
By default, this feature is not
enabled.
Displaying and maintaining IS-IS
Execute display commands in any view and the reset command in user view.
Task
Command
Display brief IS-IS configuration
information.
display isis brief [ process-id ]
Display the IS-IS GR status.
display isis graceful-restart status [ level-1 | level-2 ] [ process-id ]
134
Task
Command
Display information about IS-IS enabled
interfaces.
display isis interface [ [ interface-type interface-number ] [ verbose ]
| statistics] [ process-id ]
Display IS-IS LSDB information.
display isis lsdb [ [ level-1 | level-2 ] | local | lsp-id lspid |
[ lsp-name lspname ] | verbose ] * [ process-id ]
Display the host name to system ID
mapping table.
display isis name-table [ process-id ]
Display IS-IS neighbor information.
display isis peer [ statistics | verbose ] [ process-id ]
Display IS-IS redistributed route
information
display isis redistribute [ ipv4 [ ip-address mask-length ] ] [ level-1 |
level-2 ] [ process-id ]
Display IS-IS IPv4 routing information.
display isis route [ ipv4 [ ip-address mask-length ] ] [ [ level-1 |
level-2 ] | verbose ] * [ process-id ]
Display IS-IS statistics.
display isis statistics [ level-1 | level-1-2 | level-2 ] [ process-id ]
Clear IS-IS process data structure
information.
reset isis all [ process-id ] [ graceful-restart ]
Clear the data structure information of an
IS-IS neighbor.
reset isis peer system-id [ process-id ]
IS-IS configuration examples
Basic IS-IS configuration example
Network requirements
As shown in Figure 37, Switch A, Switch B, Switch C, and Switch D reside in an IS-IS AS.
Switch A and B are Level-1 switches, Switch D is a Level-2 switch, and Switch C is a Level-1-2 switch. Switch
A, Switch B, and Switch C are in Area 10, and Switch D is in Area 20.
Figure 37 Network diagram
Configuration procedure
1.
Configure IP addresses for interfaces. (Details not shown.)
135
2.
Configure IS-IS:
# Configure Switch A.
<SwitchA> system-view
[SwitchA] isis 1
[SwitchA-isis-1] is-level level-1
[SwitchA-isis-1] network-entity 10.0000.0000.0001.00
[SwitchA-isis-1] quit
[SwitchA] interface vlan-interface 100
[SwitchA-Vlan-interface100] isis enable 1
[SwitchA-Vlan-interface100] quit
# Configure Switch B.
<SwitchB> system-view
[SwitchB] isis 1
[SwitchB-isis-1] is-level level-1
[SwitchB-isis-1] network-entity 10.0000.0000.0002.00
[SwitchB-isis-1] quit
[SwitchB] interface vlan-interface 200
[SwitchB-Vlan-interface200] isis enable 1
[SwitchB-Vlan-interface200] quit
# Configure Switch C.
<SwitchC> system-view
[SwitchC] isis 1
[SwitchC-isis-1] network-entity 10.0000.0000.0003.00
[SwitchC-isis-1] quit
[SwitchC] interface vlan-interface 100
[SwitchC-Vlan-interface100] isis enable 1
[SwitchC-Vlan-interface100] quit
[SwitchC] interface vlan-interface 200
[SwitchC-Vlan-interface200] isis enable 1
[SwitchC-Vlan-interface200] quit
[SwitchC] interface vlan-interface 300
[SwitchC-Vlan-interface300] isis enable 1
[SwitchC-Vlan-interface300] quit
# Configure Switch D.
<SwitchD> system-view
[SwitchD] isis 1
[SwitchD-isis-1] is-level level-2
[SwitchD-isis-1] network-entity 20.0000.0000.0004.00
[SwitchD-isis-1] quit
[SwitchD] interface vlan-interface 100
[SwitchD-Vlan-interface100] isis enable 1
[SwitchD-Vlan-interface100] quit
[SwitchD] interface vlan-interface 300
[SwitchD-Vlan-interface300] isis enable 1
[SwitchD-Vlan-interface300] quit
Verifying the configuration
# Display the IS-IS LSDB on each switch to verify the LSPs.
136
[SwitchA] display isis lsdb
Database information for IS-IS(1)
---------------------------------
Level-1 Link State Database
---------------------------
LSPID
Seq Num
Checksum
Holdtime
Length
ATT/P/OL
-------------------------------------------------------------------------0000.0000.0001.00-00* 0x00000004
0xdf5e
1096
68
0/0/0
0000.0000.0002.00-00
0x00000004
0xee4d
1102
68
0/0/0
0000.0000.0002.01-00
0x00000001
0xdaaf
1102
55
0/0/0
0000.0000.0003.00-00
0x00000009
0xcaa3
1161
111
1/0/0
0000.0000.0003.01-00
0x00000001
0xadda
1112
55
0/0/0
*-Self LSP, +-Self LSP(Extended), ATT-Attached, P-Partition, OL-Overload
[SwitchB] display isis lsdb
Database information for IS-IS(1)
---------------------------------
Level-1 Link State Database
---------------------------
LSPID
Seq Num
Checksum
Holdtime
Length
ATT/P/OL
-------------------------------------------------------------------------0000.0000.0001.00-00
0x00000006
0xdb60
988
68
0/0/0
0000.0000.0002.00-00* 0x00000008
0xe651
1189
68
0/0/0
0000.0000.0002.01-00* 0x00000005
0xd2b3
1188
55
0/0/0
0000.0000.0003.00-00
0x00000014
0x194a
1190
111
1/0/0
0000.0000.0003.01-00
0x00000002
0xabdb
995
55
0/0/0
*-Self LSP, +-Self LSP(Extended), ATT-Attached, P-Partition, OL-Overload
[SwitchC] display isis lsdb
Database information for IS-IS(1)
--------------------------------Level-1 Link State Database
--------------------------LSPID
Seq Num
Checksum
Holdtime
Length
ATT/P/OL
-------------------------------------------------------------------------0000.0000.0001.00-00
0x00000006
0xdb60
847
68
0/0/0
0000.0000.0002.00-00
0x00000008
0xe651
1053
68
0/0/0
0000.0000.0002.01-00
0x00000005
0xd2b3
1052
55
0/0/0
0000.0000.0003.00-00* 0x00000014
0x194a
1051
111
1/0/0
137
0000.0000.0003.01-00* 0x00000002
0xabdb
854
55
0/0/0
*-Self LSP, +-Self LSP(Extended), ATT-Attached, P-Partition, OL-Overload
Level-2 Link State Database
---------------------------
LSPID
Seq Num
Checksum
Holdtime
Length
ATT/P/OL
-------------------------------------------------------------------------0000.0000.0003.00-00* 0x00000012
0xc93c
842
100
0/0/0
0000.0000.0004.00-00
0x00000026
0x331
1173
84
0/0/0
0000.0000.0004.01-00
0x00000001
0xee95
668
55
0/0/0
*-Self LSP, +-Self LSP(Extended), ATT-Attached, P-Partition, OL-Overload
[SwitchD] display isis lsdb
Database information for IS-IS(1)
---------------------------------
Level-2 Link State Database
---------------------------
LSPID
Seq Num
Checksum
Holdtime
Length
ATT/P/OL
------------------------------------------------------------------------------0000.0000.0003.00-00
0x00000013
0xc73d
1003
100
0/0/0
0000.0000.0004.00-00* 0x0000003c
0xd647
1194
84
0/0/0
0000.0000.0004.01-00* 0x00000002
0xec96
1007
55
0/0/0
*-Self LSP, +-Self LSP(Extended), ATT-Attached, P-Partition, OL-Overload
# Display the IS-IS routing information on each switch.
[SwitchA] display isis route
Route information for IS-IS(1)
------------------------------
Level-1 IPv4 Forwarding Table
-----------------------------
IPv4 Destination
IntCost
ExtCost ExitInterface
NextHop
Flags
------------------------------------------------------------------------------10.1.1.0/24
10
NULL
Vlan100
Direct
D/L/-
10.1.2.0/24
20
NULL
Vlan100
10.1.1.1
R/-/-
192.168.0.0/24
20
NULL
Vlan100
10.1.1.1
R/-/-
0.0.0.0/0
10
NULL
Vlan100
10.1.1.1
R/-/-
Flags: D-Direct, R-Added to Rib, L-Advertised in LSPs, U-Up/Down Bit Set
[SwitchC] display isis route
138
Route information for IS-IS(1)
-----------------------------Level-1 IPv4 Forwarding Table
----------------------------IPv4 Destination
IntCost
ExtCost ExitInterface
NextHop
Flags
------------------------------------------------------------------------------192.168.0.0/24
10
NULL
Vlan300
Direct
D/L/-
10.1.1.0/24
10
NULL
Vlan100
Direct
D/L/-
10.1.2.0/24
10
NULL
Vlan200
Direct
D/L/-
Flags: D-Direct, R-Added to Rib, L-Advertised in LSPs, U-Up/Down Bit Set
Level-2 IPv4 Forwarding Table
-----------------------------
IPv4 Destination
IntCost
ExtCost ExitInterface
NextHop
Flags
------------------------------------------------------------------------------192.168.0.0/24
10
NULL
Vlan300
Direct
D/L/-
10.1.1.0/24
10
NULL
Vlan100
Direct
D/L/-
10.1.2.0/24
10
NULL
Vlan200
Direct
D/L/-
172.16.0.0/16
20
NULL
Vlan300
192.168.0.2
R/-/-
Flags: D-Direct, R-Added to Rib, L-Advertised in LSPs, U-Up/Down Bit Set
[SwitchD] display isis route
Route information for IS-IS(1)
-----------------------------Level-2 IPv4 Forwarding Table
----------------------------IPv4 Destination
IntCost
ExtCost ExitInterface
NextHop
Flags
------------------------------------------------------------------------------192.168.0.0/24
10
NULL
Vlan300
Direct
D/L/-
10.1.1.0/24
20
NULL
Vlan300
192.168.0.1
R/-/-
10.1.2.0/24
20
NULL
Vlan300
192.168.0.1
R/-/-
172.16.0.0/16
10
NULL
Vlan100
Direct
D/L/-
Flags: D-Direct, R-Added to Rib, L-Advertised in LSPs, U-Up/Down Bit Set
The output shows that the routing table of Level-1 switches contains a default route with the next hop as
the Level-1-2 switch. The routing table of Level-2 switch contains both routing information of Level-1 and
Level-2.
139
DIS election configuration example
Network requirements
As shown in Figure 38, Switches A, B, C, and D reside in IS-IS area 10 on a broadcast network (Ethernet).
Switch A and Switch B are Level-1-2 switches, Switch C is a Level-1 switch, and Switch D is a Level-2 switch.
Change the DIS priority of Switch A to make it elected as the Level-1-2 DIS router.
Figure 38 Network diagram
Configuration procedure
1.
Configure IP addresses for interfaces. (Details not shown.)
2.
Enable IS-IS:
# Configure Switch A.
<SwitchA> system-view
[SwitchA] isis 1
[SwitchA-isis-1] network-entity 10.0000.0000.0001.00
[SwitchA-isis-1] quit
[SwitchA] interface vlan-interface 100
[SwitchA-Vlan-interface100] isis enable 1
[SwitchA-Vlan-interface100] quit
# Configure Switch B.
<SwitchB> system-view
[SwitchB] isis 1
[SwitchB-isis-1] network-entity 10.0000.0000.0002.00
[SwitchB-isis-1] quit
[SwitchB] interface vlan-interface 100
[SwitchB-Vlan-interface100] isis enable 1
[SwitchB-Vlan-interface100] quit
# Configure Switch C.
<SwitchC> system-view
[SwitchC] isis 1
[SwitchC-isis-1] network-entity 10.0000.0000.0003.00
[SwitchC-isis-1] is-level level-1
[SwitchC-isis-1] quit
140
[SwitchC] interface vlan-interface 100
[SwitchC-Vlan-interface100] isis enable 1
[SwitchC-Vlan-interface100] quit
# Configure Switch D.
<SwitchD> system-view
[SwitchD] isis 1
[SwitchD-isis-1] network-entity 10.0000.0000.0004.00
[SwitchD-isis-1] is-level level-2
[SwitchD-isis-1] quit
[SwitchD] interface vlan-interface 100
[SwitchD-Vlan-interface100] isis enable 1
[SwitchD-Vlan-interface100] quit
# Display information about IS-IS neighbors on Switch A.
[SwitchA] display isis peer
Peer information for IS-IS(1)
---------------------------System Id: 0000.0000.0002
Interface: Vlan-interface100
Circuit Id: 0000.0000.0003.01
State: Up
Type: L1(L1L2)
HoldTime: 21s
PRI: 64
System Id: 0000.0000.0003
Interface: Vlan-interface100
Circuit Id: 0000.0000.0003.01
State: Up
Type: L1
HoldTime: 27s
PRI: 64
System Id: 0000.0000.0002
Interface: Vlan-interface100
Circuit Id: 0000.0000.0004.01
State: Up
Type: L2(L1L2)
HoldTime: 28s
PRI: 64
System Id: 0000.0000.0004
Interface: Vlan-interface100
Circuit Id: 0000.0000.0004.01
State: Up
Type: L2
HoldTime: 30s
PRI: 64
# Display information about IS-IS interfaces on Switch A.
[SwitchA] display isis interface
Interface information for IS-IS(1)
----------------------------------
Interface: Vlan-interface100
Id
IPv4.State
IPv6.State
MTU
Type
DIS
001
Up
Down
1497
L1/L2
No/No
# Display information about IS-IS interfaces on Switch C.
[SwitchC] display isis interface
Interface information for IS-IS(1)
----------------------------------
Interface: Vlan-interface100
141
Id
IPv4.State
IPv6.State
MTU
Type
DIS
001
Up
Down
1497
L1/L2
Yes/No
# Display information about IS-IS interfaces on Switch D.
[SwitchD] display isis interface
Interface information for IS-IS(1)
---------------------------------Interface: Vlan-interface100
Id
IPv4.State
IPv6.State
MTU
Type
DIS
001
Up
Down
1497
L1/L2
No/Yes
The output shows that when the default DIS priority is used, Switch C is the DIS for Level-1, and
Switch D is the DIS for Level-2. The pseudonodes of Level-1 and Level-2 are 0000.0000.0003.01
and 0000.0000.0004.01.
#Configure the DIS priority of Switch A.
[SwitchA] interface vlan-interface 100
[SwitchA-Vlan-interface100] isis dis-priority 100
[SwitchA-Vlan-interface100] quit
# Display IS-IS neighbors on Switch A.
[SwitchA] display isis peer
Peer information for IS-IS(1)
---------------------------System Id: 0000.0000.0002
Interface: Vlan-interface100
Circuit Id: 0000.0000.0001.01
State: Up
Type: L1(L1L2)
HoldTime: 21s
PRI: 64
System Id: 0000.0000.0003
Interface: Vlan-interface100
Circuit Id: 0000.0000.0001.01
State: Up
Type: L1
HoldTime: 27s
PRI: 64
System Id: 0000.0000.0002
Interface: Vlan-interface100
Circuit Id: 0000.0000.0001.01
State: Up
Type: L2(L1L2)
HoldTime: 28s
PRI: 64
System Id: 0000.0000.0004
Interface: Vlan-interface100
Circuit Id: 0000.0000.0001.01
State: Up
Type: L2
HoldTime: 30s
PRI: 64
# Display information about IS-IS interfaces on Switch A.
[SwitchA] display isis interface
Interface information for IS-IS(1)
----------------------------------
Interface: Vlan-interface100
Id
IPv4.State
IPv6.State
142
MTU
Type
DIS
001
Up
Down
1497
L1/L2
Yes/Yes
The output shows that after the DIS priority configuration, Switch A becomes the DIS for Level-1-2,
and the pseudonode is 0000.0000.0001.01.
# Display information about IS-IS neighbors and interfaces on Switch C.
[SwitchC] display isis peer
Peer information for IS-IS(1)
---------------------------System Id: 0000.0000.0002
Interface: Vlan-interface100
Circuit Id: 0000.0000.0001.01
State: Up
Type: L1
HoldTime: 25s
PRI: 64
System Id: 0000.0000.0001
Interface: Vlan-interface100
Circuit Id: 0000.0000.0001.01
State: Up
Type: L1
HoldTime: 7s
PRI: 100
[SwitchC] display isis interface
Interface information for IS-IS(1)
----------------------------------
Interface: Vlan-interface100
Id
IPv4.State
IPv6.State
MTU
Type
DIS
001
Up
Down
1497
L1/L2
No/No
# Display information about IS-IS neighbors and interfaces on Switch D.
[SwitchD] display isis peer
Peer information for IS-IS(1)
---------------------------System Id: 0000.0000.0001
Interface: Vlan-interface100
Circuit Id: 0000.0000.0001.01
State: Up
Type: L2
HoldTime: 9s
PRI: 100
System Id: 0000.0000.0002
Interface: Vlan-interface100
Circuit Id: 0000.0000.0001.01
State: Up
Type: L2
HoldTime: 28s
PRI: 64
[SwitchD] display isis interface
Interface information for IS-IS(1)
----------------------------------
Interface: Vlan-interface100
Id
IPv4.State
IPv6.State
MTU
Type
DIS
001
Up
Down
1497
L1/L2
No/No
143
IS-IS route redistribution configuration example
Network requirements
As shown in Figure 39, Switch A, Switch B, Switch C, and Switch D reside in the same AS. They use IS-IS
to interconnect. Switch A and Switch B are Level-1 routers, Switch D is a Level-2 router, and Switch C is a
Level-1-2 router.
Redistribute RIP routes into IS-IS on Switch D.
Figure 39 Network diagram
Configuration procedure
1.
Configure IP addresses for interfaces. (Details not shown.)
2.
Configure basic IS-IS:
# Configure Switch A.
<SwitchA> system-view
[SwitchA] isis 1
[SwitchA-isis-1] is-level level-1
[SwitchA-isis-1] network-entity 10.0000.0000.0001.00
[SwitchA-isis-1] quit
[SwitchA] interface vlan-interface 100
[SwitchA-Vlan-interface100] isis enable 1
[SwitchA-Vlan-interface100] quit
# Configure Switch B.
<SwitchB> system-view
[SwitchB] isis 1
[SwitchB-isis-1] is-level level-1
[SwitchB-isis-1] network-entity 10.0000.0000.0002.00
[SwitchB-isis-1] quit
[SwitchB] interface vlan-interface 200
[SwitchB-Vlan-interface200] isis enable 1
[SwitchB-Vlan-interface200] quit
# Configure Switch C.
<SwitchC> system-view
[SwitchC] isis 1
144
[SwitchC-isis-1] network-entity 10.0000.0000.0003.00
[SwitchC-isis-1] quit
[SwitchC] interface vlan-interface 200
[SwitchC-Vlan-interface200] isis enable 1
[SwitchC-Vlan-interface200] quit
[SwitchC] interface vlan-interface 100
[SwitchC-Vlan-interface100] isis enable 1
[SwitchC-Vlan-interface100] quit
[SwitchC] interface vlan-interface 300
[SwitchC-Vlan-interface300] isis enable 1
[SwitchC-Vlan-interface300] quit
# Configure Switch D.
<SwitchD> system-view
[SwitchD] isis 1
[SwitchD-isis-1] is-level level-2
[SwitchD-isis-1] network-entity 20.0000.0000.0004.00
[SwitchD-isis-1] quit
[SwitchD] interface interface vlan-interface 300
[SwitchD-Vlan-interface300] isis enable 1
[SwitchD-Vlan-interface300] quit
# Display IS-IS routing information on each switch.
[SwitchA] display isis route
Route information for IS-IS(1)
------------------------------
Level-1 IPv4 Forwarding Table
-----------------------------
IPv4 Destination
IntCost
ExtCost ExitInterface
NextHop
Flags
------------------------------------------------------------------------------10.1.1.0/24
10
NULL
VLAN100
Direct
D/L/-
10.1.2.0/24
20
NULL
VLAN100
10.1.1.1
R/-/-
192.168.0.0/24
20
NULL
VLAN100
10.1.1.1
R/-/-
0.0.0.0/0
10
NULL
VLAN100
10.1.1.1
R/-/-
Flags: D-Direct, R-Added to Rib, L-Advertised in LSPs, U-Up/Down Bit Set
[SwitchC] display isis route
Route information for IS-IS(1)
-----------------------------Level-1 IPv4 Forwarding Table
----------------------------IPv4 Destination
IntCost
ExtCost ExitInterface
NextHop
Flags
------------------------------------------------------------------------------10.1.1.0/24
10
NULL
145
VLAN100
Direct
D/L/-
10.1.2.0/24
10
NULL
VLAN200
Direct
D/L/-
192.168.0.0/24
10
NULL
VLAN300
Direct
D/L/-
Flags: D-Direct, R-Added to Rib, L-Advertised in LSPs, U-Up/Down Bit Set
Level-2 IPv4 Forwarding Table
-----------------------------
IPv4 Destination
IntCost
ExtCost ExitInterface
NextHop
Flags
------------------------------------------------------------------------------10.1.1.0/24
10
NULL
VLAN100
Direct
D/L/-
10.1.2.0/24
10
NULL
VLAN200
Direct
D/L/-
192.168.0.0/24
10
NULL
VLAN300
Direct
D/L/-
Flags: D-Direct, R-Added to Rib, L-Advertised in LSPs, U-Up/Down Bit Set
[SwitchD] display isis route
Route information for IS-IS(1)
------------------------------
Level-2 IPv4 Forwarding Table
-----------------------------
IPv4 Destination
IntCost
ExtCost ExitInterface
NextHop
Flags
------------------------------------------------------------------------------192.168.0.0/24
10
NULL
VLAN300
Direct
D/L/-
10.1.1.0/24
20
NULL
VLAN300
192.168.0.1
R/-/-
10.1.2.0/24
20
NULL
VLAN300
192.168.0.1
R/-/-
Flags: D-Direct, R-Added to Rib, L-Advertised in LSPs, U-Up/Down Bit Set
3.
Run RIPv2 between Switch D and Switch E, and configure IS-IS to redistribute RIP routes on Switch
D:
# Configure RIPv2 on Switch D.
[SwitchD] rip 1
[SwitchD-rip-1] network 10.0.0.0
[SwitchD-rip-1] version 2
[SwitchD-rip-1] undo summary
# Configure RIPv2 on Switch E.
[SwitchE] rip 1
[SwitchE-rip-1] network 10.0.0.0
[SwitchE-rip-1] version 2
[SwitchE-rip-1] undo summary
# Configure IS-IS to redistribute RIP routes on Switch D.
[SwitchD-rip-1] quit
[SwitchD] isis 1
[SwitchD–isis-1] import-route rip level-2
# Display IS-IS routing information on Switch C.
146
[SwitchC] display isis route
Route information for IS-IS(1)
------------------------------
Level-1 IPv4 Forwarding Table
-----------------------------
IPv4 Destination
IntCost
ExtCost ExitInterface
NextHop
Flags
------------------------------------------------------------------------------10.1.1.0/24
10
NULL
VLAN100
Direct
D/L/-
10.1.2.0/24
10
NULL
VLAN200
Direct
D/L/-
192.168.0.0/24
10
NULL
VLAN300
Direct
D/L/-
Flags: D-Direct, R-Added to Rib, L-Advertised in LSPs, U-Up/Down Bit Set
Level-2 IPv4 Forwarding Table
-----------------------------
IPv4 Destination
IntCost
ExtCost ExitInterface
NextHop
Flags
------------------------------------------------------------------------------10.1.1.0/24
10
NULL
VLAN100
Direct
D/L/-
10.1.2.0/24
10
NULL
VLAN200
Direct
D/L/-
192.168.0.0/24
10
NULL
VLAN300
Direct
D/L/-
10.1.4.0/24
10
NULL
VLAN300
192.168.0.2
R/L/-
10.1.5.0/24
20
NULL
VLAN300
192.168.0.2
R/L/-
10.1.6.0/24
20
NULL
VLAN300
192.168.0.2
R/L/-
Flags: D-Direct, R-Added to Rib, L-Advertised in LSPs, U-Up/Down Bit Set
IS-IS authentication configuration example
Network requirements
As shown in Figure 40, Switch A, Switch B, Switch C, and Switch D reside in the same IS-IS routing
domain. Run IS-IS among them.
Switch A, Switch B, and Switch C belong to Area 10, and Switch D belongs to Area 20.
Configure neighbor relationship authentication between neighbors. Configure area authentication in
Area 10 to prevent untrusted routes from entering into the area. Configure routing domain authentication
on Switch C and Switch D to prevent untrusted routes from entering the routing domain.
147
Figure 40 Network diagram
Configuration procedure
1.
Configure IP addresses for interfaces. (Details not shown.)
2.
Configure basic IS-IS:
# Configure Switch A.
<SwitchA> system-view
[SwitchA] isis 1
[SwitchA-isis-1] network-entity 10.0000.0000.0001.00
[SwitchA-isis-1] quit
[SwitchA] interface vlan-interface 100
[SwitchA-Vlan-interface100] isis enable 1
[SwitchA-Vlan-interface100] quit
# Configure Switch B.
<SwitchB> system-view
[SwitchB] isis 1
[SwitchB-isis-1] network-entity 10.0000.0000.0002.00
[SwitchB-isis-1] quit
[SwitchB] interface vlan-interface 200
[SwitchB-Vlan-interface200] isis enable 1
[RouterB--Vlan-interface200] quit
# Configure Switch C.
<SwitchC> system-view
[SwitchC] isis 1
[SwitchC-isis-1] network-entity 10.0000.0000.0003.00
[SwitchC-isis-1] quit
[SwitchC] interface vlan-interface 200
[SwitchC-Vlan-interface200] isis enable 1
[SwitchC-Vlan-interface200] quit
[SwitchC] interface vlan-interface 300
[SwitchC-Vlan-interface300] isis enable 1
[SwitchC-Vlan-interface300] quit
[SwitchC] interface vlan-interface 300
[SwitchC-Vlan-interface300] isis enable 1
148
[SwitchC-Vlan-interface300] quit
# Configure Switch D.
<SwitchD> system-view
[SwitchD] isis 1
[SwitchD-isis-1] network-entity 20.0000.0000.0001.00
[SwitchD-isis-1] quit
[SwitchD] interface vlan-interface 300
[SwitchD-Vlan-interface300] isis enable 1
[SwitchD-Vlan-interface300] quit
3.
Configure neighbor relationship authentication between neighbors:
# Configure the authentication mode as MD5 and set the plaintext password to eRq on
VLAN-interface 100 of Switch A and on VLAN-interface 100 of Switch C.
[SwitchA] interface vlan-interface 100
[SwitchA-Vlan-interface100] isis authentication-mode md5 plain eRg
[SwitchA-Vlan-interface100] quit
[SwitchC] interface vlan-interface 100
[SwitchC-Vlan-interface100] isis authentication-mode md5 plain eRg
[SwitchC-Vlan-interface100] quit
# Configure the authentication mode as MD5 and set the plaintext password to t5Hr on
VLAN-interface 200 of Switch B and on VLAN-interface 200 of Switch C.
[SwitchB] interface vlan-interface 200
[SwitchB-Vlan-interface200] isis authentication-mode md5 plain t5Hr
[SwitchB-Vlan-interface200] quit
[SwitchC] interface vlan-interface 200
[SwitchC-Vlan-interface200] isis authentication-mode md5 plain t5Hr
[SwitchC-Vlan-interface200] quit
# Configure the authentication mode as MD5 and set the plaintext password to hSec on
VLAN-interface 300 of Switch D and on VLAN-interface 300 of Switch C.
[SwitchC] interface vlan-interface 300
[SwitchC-Vlan-interface300] isis authentication-mode md5 plain hSec
[SwitchC-Vlan-interface300] quit
[SwitchD] interface vlan-interface 300
[SwitchD-Vlan-interface300] isis authentication-mode md5 plain hSec
[SwitchD-Vlan-interface300] quit
4.
Configure the area authentication mode as MD5 and set the plaintext password to 10Sec on
Switch A, Switch B, and Switch C.
[SwitchA] isis 1
[SwitchA-isis-1] area-authentication-mode md5 plain 10Sec
[SwitchA-isis-1] quit
[SwitchB] isis 1
[SwitchB-isis-1] area-authentication-mode md5 plain 10Sec
[SwitchB-isis-1] quit
[SwitchC] isis 1
[SwitchC-isis-1] area-authentication-mode md5 plain 10Sec
[SwitchC-isis-1] quit
5.
Configure routing domain authentication mode as MD5 and set the plaintext password to
1020Sec on Switch C and Switch D.
149
[SwitchC] isis 1
[SwitchC-isis-1] domain-authentication-mode md5 plain 1020Sec
[SwitchC-isis-1] quit
[SwitchD] isis 1
[SwitchD-isis-1] domain-authentication-mode md5 plain 1020Sec
IS-IS Graceful Restart configuration example
Network requirements
As shown in Figure 41, Switch A, Switch B, and Switch C belong to the same IS-IS routing domain.
Figure 41 Network diagram
Configuration procedure
1.
Configure IP addresses and subnet masks for interfaces. (Details not shown.)
2.
Configure IS-IS on the switches to make sure Switch A, Switch B, and Switch C can communicate
with each other at layer 3 and dynamic route update can be implemented among them with IS-IS.
(Details not shown.)
3.
Configure IS-IS GR:
# Enable IS-IS GR on Switch A.
<SwitchA> system-view
[SwitchA] isis 1
[SwitchA-isis-1] graceful-restart
[SwitchA-isis-1] return
Verifying the configuration
After Switch A establishes adjacencies with Switch B and Switch C, they begin to exchange routing
information. Restart IS-IS on Switch A, which enters the restart state and sends connection requests to its
neighbors through the Graceful Restart mechanism to synchronize the LSDB. To display the IS-IS GR status
on Switch A, use the display isis graceful-restart status command.
# Restart the IS-IS process on Switch A.
<SwitchA> reset isis all 1 graceful-restart
Reset IS-IS process? [Y/N]:y
# Check the Graceful Restart status of IS-IS on Switch A.
<SwitchA> display isis graceful-restart status
Restart information for IS-IS(1)
--------------------------------
150
Restart status: COMPLETE
Restart phase: Finish
Restart t1: 3, count 10; Restart t2: 60; Restart t3: 300
SA Bit: supported
Level-1 restart information
--------------------------Total number of interfaces: 1
Number of waiting LSPs: 0
Level-2 restart information
--------------------------Total number of interfaces: 1
Number of waiting LSPs: 0
BFD for IS-IS configuration example
Network requirements
•
As shown in Figure 42, run IS-IS on Switch A, Switch B and Switch C so that can reach each other
at the network layer.
•
After the link over which Switch A and Switch B communicate through the Layer-2 switch fails, BFD
can quickly detect the failure and notify IS-IS of the failure. Switch A and Switch B then communicate
through Switch C.
Figure 42 Network diagram
Device
Interface
IP address
Device
Interface
IP address
Switch A
Vlan-int10
10.1.0.102/24
Switch B
Vlan-int10
10.1.0.100/24
Vlan-int11
11.1.1.1/24
Vlan-int13
13.1.1.1/24
Vlan-int11
11.1.1.2/24
Vlan-int13
13.1.1.2/24
Switch C
Configuration procedure
1.
Configure IP addresses for interfaces. (Details not shown.)
2.
Configure basic IS-IS:
# Configure Switch A.
<SwitchA> system-view
151
[SwitchA] isis
[SwitchA-isis-1] network-entity 10.0000.0000.0001.00
[SwitchA-isis-1] quit
[SwitchA] interface vlan-interface 10
[SwitchA-Vlan-interface10] isis enable
[SwitchA-Vlan-interface10] quit
[SwitchA] interface vlan-interface 11
[SwitchA-Vlan-interface11] isis enable
[SwitchA-Vlan-interface11] quit
# Configure Switch B.
<SwitchB> system-view
[SwitchB] isis
[SwitchB-isis-1] network-entity 10.0000.0000.0002.00
[SwitchB-isis-1] quit
[SwitchB] interface vlan-interface 10
[SwitchB-Vlan-interface10] isis enable
[SwitchB-Vlan-interface10] quit
[SwitchB] interface vlan-interface 13
[SwitchB-Vlan-interface13] isis enable
[SwitchB-Vlan-interface13] quit
# Configure Switch C.
<SwitchC> system-view
[SwitchC] isis
[SwitchC-isis-1] network-entity 10.0000.0000.0003.00
[SwitchC-isis-1] quit
[SwitchC] interface vlan-interface 11
[SwitchC-Vlan-interface11] isis enable
[SwitchC-Vlan-interface11] quit
[SwitchC] interface vlan-interface 13
[SwitchC-Vlan-interface13] isis enable
[SwitchC-Vlan-interface13] quit
3.
Configure BFD functions:
# Enable BFD and configure BFD parameters on Switch A.
[SwitchA] bfd session init-mode passive
[SwitchA] interface vlan-interface 10
[SwitchA-Vlan-interface10] isis bfd enable
[SwitchA-Vlan-interface10] bfd min-receive-interval 500
[SwitchA-Vlan-interface10] bfd min-transmit-interval 500
[SwitchA-Vlan-interface10] bfd detect-multiplier 7
# Enable BFD and configure BFD parameters on Switch B.
[SwitchB] bfd session init-mode active
[SwitchB] interface vlan-interface 10
[SwitchB-Vlan-interface10] isis bfd enable
[SwitchB-Vlan-interface10] bfd min-receive-interval 500
[SwitchB-Vlan-interface10] bfd min-transmit-interval 500
[SwitchB-Vlan-interface10] bfd detect-multiplier 8
[SwitchB-Vlan-interface10] return
152
Verifying the configuration
# Display the BFD session information on Switch A.
<SwitchA> display bfd session
Total Session Num: 1
Up Session Num: 1
Init Mode: Active
IPv4 Session Working Under Ctrl Mode:
LD/RD
SourceAddr
DestAddr
State
Holdtime
Interface
3/1
192.168.0.102
192.168.0.100
Up
1700ms
Vlan10
# Display routes destined for 120.1.1.0/24 on Switch A.
<SwitchA> display ip routing-table 120.1.1.0 verbose
Summary Count : 1
Destination: 120.1.1.0/24
Protocol: ISIS
SubProtID: 0x1
Cost: 10
Tag: 0
OrigTblID: 0x0
TableID: 0x2
NBRID: 0x26000002
AttrID: 0xffffffff
Process ID: 1
Age: 04h20m37s
Preference: 10
State: Active Adv
OrigVrf: default-vrf
OrigAs: 0
LastAs: 0
Neighbor: 0.0.0.0
Flags: 0x1008c
OrigNextHop: 192.168.0.100
Label: NULL
RealNextHop: 192.168.0.100
BkLabel: NULL
Tunnel ID: Invalid
BkTunnel ID: Invalid
BkNextHop: N/A
Interface: Vlan-interface10
BkInterface: N/A
The output shows that Switch A and Switch B communicate through VLAN-interface 10. Then the link over
VLAN-interface 10 fails.
# Display routes destined for 120.1.1.0/24 on Switch A.
<SwitchA> display ip routing-table 120.1.1.0 verbose
Summary Count : 1
Destination: 120.1.1.0/24
Protocol: ISIS
SubProtID: 0x1
Cost: 20
Tag: 0
OrigTblID: 0x0
TableID: 0x2
NBRID: 0x26000002
AttrID: 0xffffffff
Process ID: 1
Age: 04h20m37s
Preference: 10
State: Active Adv
OrigVrf: default-vrf
OrigAs: 0
LastAs: 0
Neighbor: 0.0.0.0
Flags: 0x1008c
OrigNextHop: 10.1.1.100
Label: NULL
RealNextHop: 10.1.1.100
153
BkLabel: NULL
BkNextHop: N/A
Tunnel ID: Invalid
Interface: Vlan-interface11
BkTunnel ID: Invalid
BkInterface: N/A
The output shows that Switch A and Switch B communicate through VLAN-interface 11.
IS-IS FRR configuration example
Network requirements
As shown in Figure 43, Switch S, Switch A, and Switch D belong to the same IS-IS routing domain.
Configure IS-IS FRR so that when the Link A fails, traffic can be switched to Link B immediately.
Figure 43 Network diagram
Switch A
0
4
t10
-in 2.1/2
n
a
1
Vl .12.
12
Loop 0
1.1.1.1/32
Switch S
0
t10
-in 2/24
n
a
.
Vl .12
.12
12
Link B
Vla
24 n-in
.24 t10
.24 1
.2/
24
Link A
Vlan-int200
13.13.13.1/24
V
24 lan.24 int
.24 101
.4/
24
Vlan-int200
13.13.13.2/24
Loop 0
4.4.4.4/32
Switch D
Configuration procedure
1.
Configure IP addresses and subnet masks for interfaces on the switches. (Details not shown.)
2.
Configure IS-IS on the switches to make sure Switch A, Switch D, and Switch S can communicate
with each other at Layer 3. (Details not shown.)
3.
Configure IS-IS FRR:
Enable IS-IS FRR to automatically calculate a backup next hop, or designate a backup next hop by
using a referenced routing policy.
{
(Method 1.) Enable IS-IS FRR to automatically calculate a backup next hop:
# Configure Switch S.
<SwitchS> system-view
[SwitchS] bfd echo-source-ip 1.1.1.1
[SwitchS] isis 1
[SwitchS-isis-1] fast-reroute auto
[SwitchS-isis-1] quit
# Configure Switch D.
<SwitchD> system-view
[SwitchD] bfd echo-source-ip 4.4.4.4
[SwitchD] isis 1
[SwitchD-isis-1] fast-reroute auto
[SwitchD-isis-1] quit
{
(Method 2.) Enable IS-IS FRR to designate a backup next hop by using a referenced routing
policy:
# Configure Switch S.
<SwitchS> system-view
[SwitchS] bfd echo-source-ip 1.1.1.1
154
[SwitchS] ip prefix-list abc index 10 permit 4.4.4.4 32
[SwitchS] route-policy frr permit node 10
[SwitchS-route-policy-frr-10] if-match ip address prefix-list abc
[SwitchS-route-policy-frr-10] apply fast-reroute backup-interface vlan-interface
100 backup-nexthop 12.12.12.2
[SwitchS-route-policy-frr-10] quit
[SwitchS] isis 1
[SwitchS-isis-1] fast-reroute route-policy frr
[SwitchS-isis-1] quit
# Configure Switch D.
<SwitchD> system-view
[SwitchD] bfd echo-source-ip 4.4.4.4
[SwitchD] ip prefix-list abc index 10 permit 1.1.1.1 32
[SwitchD] route-policy frr permit node 10
[SwitchD-route-policy-frr-10] if-match ip address prefix-list abc
[SwitchD-route-policy-frr-10] apply fast-reroute backup-interface vlan-interface
101 backup-nexthop 24.24.24.2
[SwitchD-route-policy-frr-10] quit
[SwitchD] isis 1
[SwitchD-isis-1] fast-reroute route-policy frr
[SwitchD-isis-1] quit
Verifying the configuration
# Display route 4.4.4.4/32 on Switch S to view the backup next hop information.
[SwitchS] display ip routing-table 4.4.4.4 verbose
Summary Count : 1
Destination: 4.4.4.4/32
Protocol: ISIS
SubProtID: 0x1
Cost: 10
Tag: 0
OrigTblID: 0x0
TableID: 0x2
NBRID: 0x26000002
AttrID: 0xffffffff
Process ID: 1
Age: 04h20m37s
Preference: 10
State: Active Adv
OrigVrf: default-vrf
OrigAs: 0
LastAs: 0
Neighbor: 0.0.0.0
Flags: 0x1008c
OrigNextHop: 13.13.13.2
Label: NULL
RealNextHop: 13.13.13.2
BkLabel: NULL
BkNextHop: 12.12.12.2
Tunnel ID: Invalid
Interface: Vlan-interface200
BkTunnel ID: Invalid
BkInterface: Vlan-interface100
# Display route 1.1.1.1/32 on Switch D to view the backup next hop information.
[SwitchD] display ip routing-table 1.1.1.1 verbose
Summary Count : 1
Destination: 1.1.1.1/32
155
Protocol: ISIS
SubProtID: 0x1
Cost: 10
Tag: 0
OrigTblID: 0x0
TableID: 0x2
NBRID: 0x26000002
AttrID: 0xffffffff
Process ID: 1
Age: 04h20m37s
Preference: 10
State: Active Adv
OrigVrf: default-vrf
OrigAs: 0
LastAs: 0
Neighbor: 0.0.0.0
Flags: 0x1008c
OrigNextHop: 13.13.13.1
Label: NULL
RealNextHop: 13.13.13.1
BkLabel: NULL
BkNextHop: 24.24.24.2
Tunnel ID: Invalid
Interface: Vlan-interface200
BkTunnel ID: Invalid
BkInterface: Vlan-interface101
156
Configuring BGP
Overview
Border Gateway Protocol (BGP) is an exterior gateway protocol (EGP). It is called internal BGP (IBGP)
when it runs within an AS and called external BGP (EBGP) when it runs between ASs.
The current version in use is BGP-4 (RFC 4271).
BGP has the following characteristics:
•
Focuses on route control and selection rather than route discovery and calculation.
•
Uses TCP to enhance reliability.
•
Measures the distance of a route by using a list of ASs that the route must travel through to reach the
destination. BGP is also called a path-vector protocol.
•
Supports CIDR.
•
Reduces bandwidth consumption by advertising only incremental updates. BGP is very suitable to
advertise large numbers of routes on the Internet.
•
Eliminates routing loops by adding AS path information to BGP route updates.
•
Uses policies to implement flexible route filtering and selection.
•
Has good scalability.
BGP speaker and BGP peer
A router running BGP is a BGP speaker. A BGP speaker establishes peer relationships with other BGP
speakers to exchange routing information over TCP connections.
BGP peers fall into the following types:
•
IBGP peers—Reside in the same AS as the local router.
•
EBGP peers—Reside in different ASs from the local router.
BGP message types
BGP uses the following message types:
•
Open—After establishing a TCP connection, BGP sends an Open message to establish a session
with the peer.
•
Update—BGP sends update messages to exchange routing information between peers. Each
update message can advertise a group of feasible routes with identical attributes and multiple
withdrawn routes.
•
Keepalive—BGP sends Keepalive messages between peers to maintain connectivity.
•
Route-refresh—BGP sends a Route-refresh message to request the routing information of a specified
address family from a peer.
•
Notification—BGP sends a Notification message upon detecting an error and immediately closes
the connection.
157
BGP path attributes
BGP uses the following path attributes in update messages for route filtering and selection:
•
ORIGIN
The ORIGIN attribute specifies the origin of BGP routes. This attribute has the following types:
{
IGP—Has the highest priority. Routes generated in the local AS have the IGP attribute.
{
EGP—Has the second highest priority. Routes obtained through EGP have the EGP attribute.
{
•
INCOMPLETE—Has the lowest priority. The source of routes with this attribute is unknown.
Routes redistributed from other routing protocols have the INCOMPLETE attribute.
AS_PATH
The AS_PATH attribute identifies the ASs through which a route has passed. Before advertising a
route to another AS, BGP adds the local AS number into the AS_PATH attribute, so the receiver can
determine ASs to route the message back.
The AS_PATH attribute has the following types:
{
{
AS_SEQUENCE—Arranges AS numbers in sequence. As shown in Figure 44, the number of the
AS closest to the receiver's AS is leftmost.
AS_SET—Arranges AS numbers randomly.
Figure 44 AS_PATH attribute
BGP uses the AS_PATH attribute to implement the following functions:
{
{
Avoid routing loops—A BGP router does not receive routes containing the local AS number to
avoid routing loops.
Affect route selection—BGP gives priority to the route with the shortest AS_PATH length if other
factors are the same. As shown in Figure 44, the BGP router in AS 50 gives priority to the route
passing AS40 for sending data to the destination 8.0.0.0. In some applications, you can
apply a routing policy to control BGP route selection by modifying the AS_PATH length. For
more information about routing policy, see "Configuring routing policies."
158
{
•
Filter routes—By using an AS path list, you can filter routes based on AS numbers contained in
the AS_PATH attribute. For more information about AS path list, see "Configuring routing
policies."
NEXT_HOP
The NEXT_HOP attribute may not be the IP address of a directly-connected router. Its value is
determined as follows:
{
{
{
When a BGP speaker advertises a self-originated route to a BGP peer, it sets the address of the
sending interface as the NEXT_HOP.
When a BGP speaker sends a received route to an EBGP peer, it sets the address of the
sending interface as the NEXT_HOP.
When a BGP speaker sends a route received from an EBGP peer to an IBGP peer, it does not
modify the NEXT_HOP attribute. If load balancing is configured, BGP modifies the NEXT_HOP
attribute for the equal-cost routes. For load balancing information, see "BGP load balancing."
Figure 45 NEXT_HOP attribute
•
MED (Multi-Exit Discriminator)
BGP advertises the MED attribute between two neighboring ASs, each of which does not advertise
the attribute to any other AS.
Similar to metrics used by IGPs, MED is used to determine the best route for traffic going into an AS.
When a BGP router obtains multiple routes to the same destination, but with different next hops
from different EBGP peers, it considers the route with the smallest MED value the best route given
that other conditions are the same. As shown in Figure 46, traffic from AS 10 to AS 20 travels
through Router B that is selected according to MED.
159
Figure 46 MED attribute
MED = 0
Router B
2.1.1.1
D = 9.0.0.0
Next_hop = 2.1.1.1
MED = 0
EBGP
IBGP
9.0.0.0
IBGP
Router A
D = 9.0.0.0
Next_hop = 3.1.1.1
MED = 100
AS 10
EBGP
Router D
IBGP
3.1.1.1
Router C
AS 20
MED = 100
Generally BGP only compares MEDs of routes received from the same AS. You can also use the
compare-different-as-med command to force BGP to compare MED values of routes received from
different ASs.
•
LOCAL_PREF
The LOCAL_PREF attribute is exchanged between IBGP peers only, and is not advertised to any
other AS. It indicates the priority of a BGP router.
BGP uses LOCAL_PREF to determine the best route for traffic leaving the local AS. When a BGP
router obtains from several IBGP peers multiple routes to the same destination but with different
next hops, it considers the route with the highest LOCAL_PREF value as the best route. As shown
in Figure 47, traffic from AS 20 to AS 10 travels through Router C that is selected according to
LOCAL_PREF.
160
Figure 47 LOCAL_PREF attribute
•
COMMUNITY
The COMMUNITY attribute identifies the community of BGP routes. A BGP community is a group
of routes with the same characteristics. It has no geographical boundaries. Routes of different ASs
can belong to the same community.
A route can carry one or more COMMUNITY attribute values (each of which is represented by a
4-byte integer). A router uses the COMMUNITY attribute to determine whether to advertise the
route and the advertising scope without using complex filters such as ACLs. This mechanism
simplifies routing policy configuration, management, and maintenance.
Well-known COMMUNITY attributes involve the following:
{
{
{
{
INTERNET—By default, all routes belong to the Internet community. Routes with this attribute
can be advertised to all BGP peers.
NO_EXPORT—Routes with this attribute cannot be advertised out of the local AS or out of the
local confederation, but can be advertised to other sub-ASs in the confederation. For
confederation information, see "Settlements for problems in large-scale BGP networks."
No_ADVERTISE—Routes with this attribute cannot be advertised to other BGP peers.
No_EXPORT_SUBCONFED—Routes with this attribute cannot be advertised out of the local AS
or other sub-ASs in the local confederation.
You can configure BGP community lists to filter BGP routes based on the BGP COMMUNITY
attribute.
•
Extended community attribute
To satisfy new demands, BGP defines the extended community attribute. The extended community
attribute has the following advantages over the COMMUNITY attribute:
{
{
Provides more attribute values by extending the attribute length to eight bytes.
Allows for using different types of extended community attributes in different scenarios to
enhance route filtering and control and simplify configuration and management.
161
BGP route selection
BGP discards routes with unreachable NEXT_HOPs. If multiple routes to the same destination are
available, BGP selects the best route in the following sequence:
1.
The route with the highest Preferred_value
2.
The route with the highest LOCAL_PREF
3.
The route generated by the network command, the route redistributed by the importe-route
command, or the summary route in turn.
4.
The route with the shortest AS_PATH
5.
The IGP, EGP, or INCOMPLETE route in turn
6.
The route with the lowest MED value
7.
The route learned from EBGP, confederation EBGP, confederation IBGP, or IBGP in turn
8.
The route with the smallest next hop metric
9.
The route with the shortest CLUSTER_LIST
10.
The route with the smallest ORIGINATOR_ID
11.
The route advertised by the router with the smallest router ID
12.
The route advertised by the peer with the lowest IP address
CLUSTER_IDs of route reflectors form a CLUSTER_LIST. If a route reflector receives a route that contains its
own CLUSTER ID in the CLUSTER_LIST, the router discards the route to avoid routing loops.
If load balancing is configured, the system selects available routes to implement load balancing.
BGP route advertisement rules
BGP follow these rules for route advertisement:
•
When multiple feasible routes to a destination exist, BGP advertises only the best route to its peers.
If the advertise-rib-active command is configured, BGP advertises the best route in the IP routing
table; if not, BGP advertise the best route in the BGP routing table.
•
BGP advertises only routes that it uses.
•
BGP advertises routes learned from an EBGP peer to all BGP peers, including both EBGP and IBGP
peers.
•
BGP advertises routes learned from an IBGP peer to EBGP peers, rather than other IBGP peers.
•
After establishing a session with a new BGP peer, BGP advertises all the routes matching the above
rules to the peer. After that, BGP advertises only incremental updates to the peer.
BGP load balancing
BGP implements load balancing through route recursion and route selection.
•
BGP load balancing through route recursion.
The next hop of a BGP route may not be directly connected. One of the reasons is next hops in
routing information exchanged between IBGP peers are not modified. The BGP router must find the
directly-connected next hop through IGP. The matching route with the direct next hop is called the
"recursive route." The process of finding a recursive route is route recursion.
The system supports BGP load balancing based on route recursion. If multiple recursive routes to
the same destination are load balanced (suppose three direct next hop addresses), BGP generates
162
the same number of next hops to forward packets. BGP load balancing based on route recursion
is always enabled by the system rather than configured by using commands.
•
BGP load balancing through route selection.
BGP differs from IGP in the implementation of load balancing in the following ways:
{
{
IGP routing protocols, such as RIP and OSPF, compute metrics of routes, and then implement
load balancing over routes with the same metric and to the same destination. The route
selection criterion is metric.
BGP has no route computation algorithm, so it cannot implement load balancing according to
metrics of routes. However, BGP has abundant route selection rules, through which, it selects
available routes for load balancing and adds load balancing to route selection rules.
BGP implements load balancing only on routes that have the same AS_PATH, ORIGIN,
LOCAL_PREF and MED, rather than using the route selection rules as described in "BGP route
selection."
Figure 48 Network diagram
In Figure 48, Router A and Router B are IBGP peers of Router C. Router D and Router E both advertise a
route 9.0.0.0 to Router C. If load balancing with a maximum number of two routes is configured on
Router C, and the two routes have the same AS_PATH, ORIGIN, LOCAL_PREF, and MED, Router C
installs both the two routes to its routing table for load balancing. After that, Router C forwards to Router
A and Router B a single route that has NEXT_HOP changed to Router C and other attributes changed to
those of the best route.
NOTE:
BGP load balancing is applicable between EBGP peers, between IBGP peers, and between
confederations.
Settlements for problems in large-scale BGP networks
You can use the following methods to facilitate management and improve route distribution efficiency on
a large-scale BGP network.
•
Route summarization
Route summarization can reduce the BGP routing table size by advertising summary routes rather
than more specific routes.
163
The system supports both manual and automatic route summarization. Manual route
summarization allows you to determine the attribute of a summary route and whether to advertise
more specific routes.
•
Route dampening
Route frapping (a route comes up and disappears in the routing table frequently) causes BGP to
send many routing updates. It can consume too many resources and affect other operations.
In most cases, BGP runs in complex networks where route changes are more frequent. To solve the
problem caused by route flapping, you can use BGP route dampening to suppress unstable routes.
BGP route dampening uses a penalty value to judge the stability of a route. The bigger the value,
the less stable the route. Each time a route state change (from reachable to unreachable) occurs,
or a reachable route's attribute changes, BGP adds a penalty value (1000, which is a fixed
number and cannot be changed) to the route. When the penalty value of the route exceeds the
suppress value, the route is suppressed and cannot become the optimal route. When the penalty
value reaches the upper limit, no penalty value is added.
If the suppressed route does not flap, its penalty value gradually decreases to half of the suppress
value after a period of time. This period is called "Half-life." When the value decreases to the
reusable threshold value, the route is usable again.
Figure 49 BGP route dampening
Penalty
value
Suppress
threshold
Reusable
threshold
Suppress time
Time
Half-life
•
Peer group
You can organize BGP peers with the same attributes into a group to simplify their configurations.
When a peer joins the peer group, the peer obtains the same configuration as the peer group. If
the configuration of the peer group is changed, the configuration of group members is changed.
•
Community
You can apply a community list or an extended community list to a routing policy for route control.
For more information, see "BGP path attributes."
•
Route reflector
IBGP peers must be fully meshed to maintain connectivity. If n routers exist in an AS, the number of
IBGP connections is n(n-1)/2. If a large number of IBGP peers exist, large amounts of network and
CPU resources are consumed to maintain sessions.
164
Using route reflectors can solve this issue. In an AS, a router acts as a route reflector, and other
routers act as clients connecting to the route reflector. The route reflector forwards routing
information received from a client to other clients. In this way, all clients can receive routing
information from one another without establishing BGP sessions.
A router that is neither a route reflector nor a client is a non-client, which, as shown in Figure 50,
must establish BGP sessions to the route reflector and other non-clients.
Figure 50 Network diagram for a route reflector
The route reflector and clients form a cluster. Typically a cluster has one route reflector. The ID of
the route reflector is the Cluster_ID. You can configure more than one route reflector in a cluster to
improve availability, as shown in Figure 51. The configured route reflectors must have the same
Cluster_ID to avoid routing loops.
Figure 51 Network diagram for route reflectors
When the BGP routers in an AS are fully meshed, route reflection is unnecessary because it
consumes more bandwidth resources. You can use commands to disable route reflection instead of
modifying network configuration or changing network topology.
After route reflection is disabled between clients, routes can still be reflected between a client and
a non-client.
•
Confederation
165
Confederation is another method to manage growing IBGP connections in an AS. It splits an AS
into multiple sub-ASs. In each sub-AS, IBGP peers are fully meshed. As shown in Figure 52,
intra-confederation EBGP connections are established between sub-ASs in AS 200.
Figure 52 Confederation network diagram
A non-confederation BGP speaker does not need to know sub-ASs in the confederation. It
considers the confederation as one AS, and the confederation ID as the AS number. In the above
figure, AS 200 is the confederation ID.
Confederation has a deficiency. When you change an AS into a confederation, you must
reconfigure the routers, and the topology will be changed.
In large-scale BGP networks, you can use both route reflector and confederation.
MP-BGP
BGP-4 carries only IPv4 unicast routing information. IETF extended BGP-4 by introducing Multiprotocol
Extensions for BGP-4 (MP-BGP). MP-BGP can carry routing information for multiple address families,
including IPv4 multicast, IPv6 unicast, and IPv6 multicast.
MP-BGP is backward compatible with BGP.
MP-BGP extended attributes
Prefixes and next hops are key routing information. BGP-4 uses update messages to carry feasible route
prefixes in the Network Layer Reachability Information (NLRI) field, unfeasible route prefixes in the
withdrawn routes field, and next hops in the NEXT_HOP attribute. These attributes cannot carry routing
information for multiple network layer protocols.
To support multiple network layer protocols, MP-BGP defines the following path attributes:
•
MP_REACH_NLRI—Carries feasible route prefixes and next hops for multiple network layer
protocols.
•
MP_UNREACH_NLRI—Carries unfeasible route prefixes for multiple network layer protocols.
MP-BGP uses these two attributes to advertise feasible and unfeasible routes for different network layer
protocols. BGP speakers not supporting MP-BGP ignore updates containing these attributes and do not
forward them to its peers.
166
The current MP-BGP implementation supports multiple protocol extensions, including VPN, IPv6, and
multicast. For more information about VPN, see MCE Configuration Guide.
Address family
MP-BGP uses address families and subsequent address families to identify different network layer
protocols for routes contained in the MP_REACH_NLRI and MP_UNREACH_NLRI attributes. For example,
an Address Family Identifier (AFI) of 2 and a Subsequent Address Family Identifier (SAFI) of 1 identify
IPv6 unicast routing information carried in the MP_REACH_NLRI attribute. For address family values, see
RFC 1700.
BGP configuration views
BGP uses different views to manage routing information for different address families and different VPN
instances. Most BGP commands are available in all BGP views. BGP supports multiple VPN instances by
establishing a separate routing table for each VPN.
Table 7 describes different BGP views.
Table 7 BGP views
View names
Ways to enter the views
<Sysname> system-view
BGP view
[Sysname] bgp 100
[Sysname-bgp]
Remarks
Configurations in this view are
effective for routes of all address
families on the public network and in
all VPN instances (such as
confederation, GR, and logging
configurations), or only for routes of
all address families on the public
network.
<Sysname> system-view
BGP IPv4 unicast instance
view
[Sysname] bgp 100
[Sysname-bgp] ipv4-family
unicast
Configurations in this view are
effective for IPv4 unicast routes on the
public network.
[Sysname-bgp-ipv4]
<Sysname> system-view
BGP IPv6 unicast instance
view
[Sysname] bgp 100
[Sysname-bgp] ipv6-family
unicast
Configurations in this view are
effective for IPv6 unicast routes on the
public network.
[Sysname-bgp-ipv6]
<Sysname> system-view
[Sysname] bgp 100
BGP-VPN view
[Sysname-bgp] ip vpn-instance
vpn1
[Sysname-bgp-vpn1]
Configurations in this view are
effective for routes of all address
families in the specified VPN
instance.
<Sysname> system-view
[Sysname] bgp 100
BGP-VPN IPv4 unicast
instance view
[Sysname-bgp] ip vpn-instance
vpn1
[Sysname-bgp-vpn1]
ipv4-family unicast
[Sysname-bgp-ipv4-vpn1]
167
Configurations in this view are
effective for IPv4 unicast routes in the
specified VPN instance.
View names
Ways to enter the views
Remarks
<Sysname> system-view
[Sysname] bgp 100
BGP-VPN IPv6 unicast
instance view
[Sysname-bgp] ip vpn-instance
vpn1
[Sysname-bgp-vpn1]
ipv6-family unicast
Configurations in this view are
effective for IPv6 unicast routes in the
specified VPN instance.
[Sysname-bgp-ipv6-vpn1]
Protocols and standards
•
RFC 1700, ASSIGNED NUMBERS
•
RFC 1771, A Border Gateway Protocol 4 (BGP-4)
•
RFC 2858, Multiprotocol Extensions for BGP-4
•
RFC 3392, Capabilities Advertisement with BGP-4
•
RFC 2918, Route Refresh Capability for BGP-4
•
RFC 2439, BGP Route Flap Damping
•
RFC 1997, BGP Communities Attribute
•
RFC 2796, BGP Route Reflection
•
RFC 3065, Autonomous System Confederations for BGP
•
RFC 4271, A Border Gateway Protocol 4 (BGP-4)
•
RFC 4724, Graceful Restart Mechanism for BGP
•
RFC 4360, BGP Extended Communities Attribute
•
RFC 4760, Multiprotocol Extensions for BGP-4
BGP configuration task list
In a basic BGP network, you only need to perform the following configurations:
•
Enable BGP.
•
Configure BGP peers or peer groups. If you configure a BGP setting at both the peer group and the
peer level, the most recent configuration takes effect on the peer.
•
Control BGP route generation.
To control BGP route distribution and path selection, you must perform additional configuration tasks.
To configure BGP, perform the following tasks (IPv4):
Tasks at a glance
Remarks
Configuring basic BGP:
• (Required.) Enabling BGP
• (Required.) Perform one of the following tasks:
{
Configuring a BGP peer
{
Configuring a BGP peer group
• (Optional.) Specifying the source interface for TCP connections
168
HP recommends
configuring BGP peer
groups on large scale
BGP networks for easy
configuration and
maintenance.
Tasks at a glance
Remarks
Generating BGP routes:
• Perform at least one of the following tasks:
{
Injecting a local network
{
Redistributing IGP routes
N/A
(Optional.) Controlling route distribution and reception:
•
•
•
•
•
•
Configuring BGP route summarization
Advertising optimal routes in the IP routing table
Advertising a default route to a peer or peer group
N/A
Limiting routes received from a peer or peer group
Configuring BGP route filtering policies
Configuring BGP route dampening
(Optional.) Controlling BGP path selection:
•
•
•
•
•
•
Specifying a preferred value for routes received
Configuring preferences for BGP routes
N/A
Configuring the default local preference
Configuring the MED attribute
Configuring the NEXT_HOP attribute
Configuring the AS_PATH attribute
(Optional.) Tuning and optimizing BGP networks:
•
•
•
•
•
•
•
•
•
•
Configuring the keepalive interval and hold time
Configuring the interval for sending updates for the same route
Enabling BGP to establish an EBGP session over multiple hops
Enabling immediate reestablishment of direct EBGP connections upon link failure
N/A
Enabling 4-byte AS number suppression
Configuring MD5 authentication for BGP
Configuring BGP load balancing
Disabling BGP to establish a session to a peer or peer group
Configuring BGP soft-reset
Protecting an EBGP peer when memory usage reaches level 2 threshold
(Optional.) Configuring a large-scale BGP network:
• Configuring BGP community
• Configuring a BGP route reflector
• Configuring a BGP confederation
N/A
(Optional.) Configuring BGP GR
N/A
(Optional.) Enabling trap
N/A
(Optional.) Enabling logging of session state changes
N/A
(Optional.) Configuring BFD for BGP
N/A
To configure BGP, perform the following tasks (IPv6):
169
Tasks at a glance
Remarks
Configuring basic BGP:
• (Required.) Enabling BGP
• (Required.) Perform one of the following tasks:
{
Configuring a BGP peer
{
Configuring a BGP peer group
• (Optional.) Specifying the source interface for TCP connections
HP recommends
configuring BGP peer
groups on large scale
BGP networks for easy
configuration and
maintenance.
Generating BGP routes:
• Perform at least one of the following tasks:
{
Injecting a local network
{
Redistributing IGP routes
N/A
(Optional.) Controlling route distribution and reception:
•
•
•
•
•
•
Configuring BGP route summarization
Advertising optimal routes in the IP routing table
Advertising a default route to a peer or peer group
N/A
Limiting routes received from a peer or peer group
Configuring BGP route filtering policies
Configuring BGP route dampening
(Optional.) Controlling BGP path selection:
•
•
•
•
•
•
Specifying a preferred value for routes received
Configuring preferences for BGP routes
N/A
Configuring the default local preference
Configuring the MED attribute
Configuring the NEXT_HOP attribute
Configuring the AS_PATH attribute
(Optional.) Tuning and optimizing BGP networks:
•
•
•
•
•
•
•
•
•
•
Configuring the keepalive interval and hold time
Configuring the interval for sending updates for the same route
Enabling BGP to establish an EBGP session over multiple hops
Enabling immediate reestablishment of direct EBGP connections upon link failure
N/A
Enabling 4-byte AS number suppression
Configuring MD5 authentication for BGP
Configuring BGP load balancing
Disabling BGP to establish a session to a peer or peer group
Configuring BGP soft-reset
Protecting an EBGP peer when memory usage reaches level 2 threshold
(Optional.) Configuring a large-scale BGP network:
• Configuring BGP community
• Configuring a BGP route reflector
• Configuring a BGP confederation
N/A
(Optional.) Configuring BGP GR
N/A
(Optional.) Enabling trap
N/A
(Optional.) Enabling logging of session state changes
N/A
(Optional.) Configuring BFD for BGP
N/A
170
Configuring basic BGP
This section describes the basic settings required for a BGP network to run.
Enabling BGP
A router ID is the unique identifier of a BGP router in an AS.
•
To ensure the uniqueness of a router ID and enhance availability, specify in BGP view the IP address
of a local loopback interface as the router ID.
•
If no router ID is specified in BGP view, the global router ID is used.
•
To modify a router ID, use the router-id command in BGP view, rather than the router id command
in system view.
•
If you specify a router ID in BGP view and then remove the interface that owns the router ID, the
router does not select a new router ID. To select a new router ID, use the undo router-id command
in BGP view.
To enable BGP:
Step
1.
2.
Enter system view.
Configure a global router ID.
Command
Remarks
system-view
N/A
router id router-id
By default, no global router ID is
configured, and BGP uses the
highest loopback interface IP
address—if any—as the router ID. If
no loopback interface IP address is
available, BGP uses the highest
physical interface IP address as the
route ID regardless of the interface
status.
• Enable BGP and enter BGP
view:
bgp as-number
3.
Enable BGP and enter BGP
view or BGP-VPN view.
• Enable BGP and enter
BGP-VPN view:
a. bgp as-number
b. ip vpn-instance
vpn-instance-name
4.
Specify a router ID.
router-id router-id
Configuring a BGP peer
Configuring an IPv4 BGP peer
171
By default, BGP is not enabled.
A router can reside in only one AS,
so the router can run only one BGP
process.
To enter BGP-VPN view, the
specified VPN instance must already
exist and have the route distinguisher
(RD) configured. For more
information about VPN, see MCE
Configuration Guide.
By default, the global router ID is
used.
Step
1.
Enter system view.
Command
Remarks
system-view
N/A
• Enter BGP view:
bgp as-number
2.
Enter BGP view or BGP-VPN
view.
• Enter BGP-VPN view:
a. bgp as-number
N/A
b. ip vpn-instance
vpn-instance-name
3.
Create an IPv4 BGP peer and
specify its AS number.
peer ip-address as-number
as-number
By default, no IPv4 BGP peer is
created.
4.
(Optional.) Configure a
description for a peer.
peer ip-address description
description-text
By default, no description is
configured for a peer.
5.
Create and enter BGP IPv4
unicast instance view or
BGP-VPN IPv4 unicast
instance view.
ipv4-family [ unicast ]
By default, the BGP IPv4 unicast
instance view and BGP-VPN IPv4
unicast instance view are not
created.
Enable the router to exchange
IPv4 unicast routing
information with the specified
peer.
peer ip-address enable
By default, the router cannot
exchange IPv4 unicast routing
information with the peer.
Command
Remarks
system-view
N/A
6.
Configuring an IPv6 BGP peer
Step
1.
Enter system view.
• Enter BGP view:
bgp as-number
2.
Enter BGP view or BGP-VPN
view.
• Enter BGP-VPN view:
a. bgp as-number
N/A
b. ip vpn-instance
vpn-instance-name
3.
Create an IPv6 BGP peer and
specify its AS number.
peer ipv6-address as-number
as-number
By default, no IPv6 BGP peer is
created.
4.
(Optional.) Configure a
description for a peer.
peer ipv6-address description
description-text
By default, no description is
configured for a peer.
5.
Create and enter BGP IPv6
unicast instance view or
BGP-VPN IPv6 unicast
instance view.
ipv6-family [ unicast ]
By default, the BGP IPv6 unicast
instance view and BGP-VPN IPv6
unicast instance view are not
created.
Enable the router to exchange
IPv6 unicast routing
information with the specified
peer.
peer ipv6-address enable
By default, the router cannot
exchange IPv6 unicast routing
information with the peer.
6.
172
Configuring a BGP peer group
The peers in a peer group use the same route selection policy.
In a large-scale network, many peers can use the same route selection policy. You can configure a peer
group and add these peers into this group. When you change the policy for the group, the modification
also applies to the peers in the group.
A peer group is an IBGP peer group if peers in it belong to the local AS, and is an EBGP peer group if
peers in it belong to different ASs.
Configuring an IBGP peer group
After you create an IBGP peer group and then add a peer into it, the system creates the peer in BGP view
and specifies the local AS number for the peer.
To configure an IBGP peer group (IPv4):
Step
1.
Enter system view.
Command
Remarks
system-view
N/A
• Enter BGP view:
bgp as-number
2.
Enter BGP view or BGP-VPN
view.
• Enter BGP-VPN view:
a. bgp as-number
N/A
b. ip vpn-instance
vpn-instance-name
3.
Create an IBGP peer group.
group group-name [ internal ]
By default, no IBGP peer group is
created.
By default, no peer exists in the
peer group.
4.
Add a peer into the IBGP peer
group.
peer ip-address group group-name
[ as-number as-number ]
5.
(Optional.) Configure a
description for a peer group.
peer group-name description
description-text
By default, no description is
configured for the peer group.
6.
Create and enter BGP IPv4
unicast instance view or
BGP-VPN IPv4 unicast
instance view.
ipv4-family [ unicast ]
By default, the BGP IPv4 unicast
instance view and BGP-VPN IPv4
unicast instance view are not
created.
Enable the router to exchange
IPv4 unicast routing
information with peers in the
specified peer group.
peer group-name enable
By default, the router cannot
exchange IPv4 unicast routing
information with the peers.
7.
To use the as-number as-number
option, you must specify the local
AS number.
To configure an IBGP peer group (IPv6):
Step
1.
Enter system view.
Command
Remarks
system-view
N/A
173
Step
Command
Remarks
• Enter BGP view:
bgp as-number
Enter BGP view or BGP-VPN
view.
2.
• Enter BGP-VPN view:
a. bgp as-number
N/A
b. ip vpn-instance
vpn-instance-name
Create an IBGP peer group.
3.
group group-name [ internal ]
By default, no IBGP peer group is
created.
By default, no peer exists in the
peer group.
4.
Add a peer into the IBGP peer
group.
peer ipv6-address group
group-name [ as-number
as-number ]
5.
(Optional.) Configure a
description for a peer group.
peer group-name description
description-text
By default, no description is
configured for the peer group.
6.
Create and enter BGP IPv6
unicast instance view or
BGP-VPN IPv6 unicast
instance view.
ipv6-family [ unicast ]
By default, the BGP IPv6 unicast
instance view and BGP-VPN IPv6
unicast instance view are not
created.
Enable the router to exchange
IPv6 unicast routing
information with peers in the
specified peer group.
peer group-name enable
By default, the router cannot
exchange IPv6 unicast routing
information with the peers.
7.
To use the as-number as-number
option, you must specify the local
AS number.
Configuring an EBGP peer group
If peers in an EBGP group belong to the same external AS, the EBGP peer group is a pure EBGP peer
group. If not, it is a mixed EBGP peer group.
Use one of the following approaches to configure an EBGP peer group:
•
Approach 1—Create an EBGP peer group, specify its AS number, and add peers into it. All the
added peers have the same AS number. All peers in the peer group have the same AS number as
the peer group. You can specify an AS number for a peer before adding it into the peer group. The
AS number must be the same as that of the peer group.
•
Approach 2—Create an EBGP peer group, specify an AS number for a peer, and add the peer into
the peer group. Peers added in the group can have different AS numbers.
•
Approach 3—Create an EBGP peer group and add a peer with an AS number into it. Peers added
in the group can have different AS numbers.
To configure an EBGP peer group by using Approach 1 (IPv4):
Step
1.
Enter system view.
Command
Remarks
system-view
N/A
174
Step
Command
Remarks
• Enter BGP view:
bgp as-number
2.
Enter BGP view or BGP-VPN
view.
• Enter BGP-VPN view:
a. bgp as-number
N/A
b. ip vpn-instance
vpn-instance-name
3.
4.
Create an EBGP peer group.
Specify the AS number for the
group.
group group-name external
peer group-name as-number
as-number
By default, no EBGP peer group is
created.
By default, no AS number is
specified.
If a peer group contains peers, you
cannot remove or change its AS
number.
By default, no peer exists in the
peer group.
5.
Add a peer into the EBGP
peer group.
peer ip-address group group-name
[ as-number as-number ]
The as-number as-number option,
if used, must specify the same AS
number as the peer group-name
as-number as-number command.
6.
(Optional.) Configure a
description for a peer group.
peer group-name description
description-text
By default, no description is
configured for the peer group.
7.
Create and enter BGP IPv4
unicast instance view or
BGP-VPN IPv4 unicast
instance view.
ipv4-family [ unicast ]
By default, the BGP IPv4 unicast
instance view and BGP-VPN IPv4
unicast instance view are not
created.
Enable the router to exchange
IPv4 unicast routing
information with peers in the
specified peer group.
peer group-name enable
By default, the router cannot
exchange IPv4 unicast routing
information with the peers.
8.
To configure an EBGP peer group by using Approach 1 (IPv6):
Step
1.
Enter system view.
Command
Remarks
system-view
N/A
• Enter BGP view:
bgp as-number
2.
Enter BGP view or BGP-VPN
view.
• Enter BGP-VPN view:
a. bgp as-number
N/A
b. ip vpn-instance
vpn-instance-name
3.
4.
Create an EBGP peer group.
Specify the AS number for the
group.
group group-name external
peer group-name as-number
as-number
175
By default, no EBGP peer group is
created.
By default, no AS number is
specified.
If a peer group contains peers, you
cannot remove or change its AS
number.
Step
Command
Remarks
By default, no peer exists in the
peer group.
5.
Add a peer into the EBGP
peer group.
peer ipv6-address group
group-name [ as-number
as-number ]
6.
(Optional.) Configure a
description for a peer group.
peer group-name description
description-text
By default, no description is
configured for the peer group.
7.
Create and enter BGP IPv6
unicast instance view or
BGP-VPN IPv6 unicast
instance view.
ipv6-family [ unicast ]
By default, the BGP IPv6 unicast
instance view and BGP-VPN IPv6
unicast instance view are not
created.
Enable the router to exchange
IPv6 unicast routing
information with peers in the
specified peer group.
peer group-name enable
By default, the router cannot
exchange IPv6 unicast routing
information with the peers.
8.
The as-number as-number option,
if used, must specify the same AS
number as the peer group-name
as-number as-number command.
To configure an EBGP peer group by using Approach 2 (IPv4):
Step
1.
Enter system view.
Command
Remarks
system-view
N/A
• Enter BGP view:
bgp as-number
2.
Enter BGP view or BGP-VPN
view.
• Enter BGP-VPN view:
a. bgp as-number
N/A
b. ip vpn-instance
vpn-instance-name
3.
Create an EBGP peer group.
group group-name external
By default, no EBGP peer group is
created.
4.
Create an IPv4 BGP peer and
specify its AS number.
peer ip-address as-number
as-number
By default, no IPv4 BGP peer is
created.
By default, no peer exists in the
peer group.
5.
Add the peer into the EBGP
peer group.
peer ip-address group group-name
[ as-number as-number ]
The as-number as-number option,
if used, must specify the same AS
number as the peer ip-address
as-number as-number command.
6.
(Optional.) Configure a
description for a peer group.
peer group-name description
description-text
By default, no description is
configured for the peer group.
7.
Create and enter BGP IPv4
unicast instance view or
BGP-VPN IPv4 unicast
instance view.
ipv4-family [ unicast ]
By default, the BGP IPv4 unicast
instance view and BGP-VPN IPv4
unicast instance view are not
created.
Enable the router to exchange
IPv4 unicast routing
information with peers in the
specified peer group.
peer group-name enable
By default, the router cannot
exchange IPv4 unicast routing
information with the peers.
8.
176
To configure an EBGP peer group by using Approach 2 (IPv6):
Step
1.
Enter system view.
Command
Remarks
system-view
N/A
• Enter BGP view:
bgp as-number
2.
Enter BGP view or BGP-VPN
view.
• Enter BGP-VPN view:
a. bgp as-number
N/A
b. ip vpn-instance
vpn-instance-name
3.
Create an EBGP peer group.
group group-name external
By default, no EBGP peer group is
created.
4.
Create an IPv6 BGP peer and
specify its AS number.
peer ipv6-address as-number
as-number
By default, no IPv6 BGP peer is
created.
By default, no peer exists in the
peer group.
5.
Add the peer into the EBGP
peer group.
peer ipv6-address group
group-name [ as-number
as-number ]
6.
(Optional.) Configure a
description for the peer group.
peer group-name description
description-text
By default, no description is
configured for the peer group.
7.
Create and enter BGP IPv6
unicast instance view or
BGP-VPN IPv6 unicast
instance view.
ipv6-family [ unicast ]
By default, the BGP IPv6 unicast
instance view and BGP-VPN IPv6
unicast instance view are not
created.
Enable the router to exchange
IPv6 unicast routing
information with peers in the
specified peer group.
peer group-name enable
By default, the router cannot
exchange IPv6 unicast routing
information with the peers.
8.
The as-number as-number option,
if used, must specify the same AS
number as the peer ip-address
as-number as-number command.
To configure an EBGP peer group by using Approach 3 (IPv4):
Step
1.
Enter system view.
Command
Remarks
system-view
N/A
• Enter BGP view:
bgp as-number
2.
Enter BGP view or BGP-VPN
view.
• Enter BGP-VPN view:
a. bgp as-number
N/A
b. ip vpn-instance
vpn-instance-name
3.
Create an EBGP peer group.
group group-name external
By default, no EBGP peer group is
created.
4.
Add a peer into the EBGP
peer group.
peer ip-address group group-name
as-number as-number
By default, no peer exists in the
peer group.
5.
(Optional.) Configure a
description for the peer group.
peer group-name description
description-text
By default, no description is
configured for the peer group.
177
Step
6.
7.
Command
Remarks
Create and enter BGP IPv4
unicast instance view or
BGP-VPN IPv4 unicast
instance view.
ipv4-family [ unicast ]
By default, the BGP IPv4 unicast
instance view and BGP-VPN IPv4
unicast instance view are not
created.
Enable the router to exchange
IPv4 unicast routing
information with peers in the
specified peer group.
peer group-name enable
By default, the router cannot
exchange IPv4 unicast routing
information with the peers.
To configure an EBGP peer group by using Approach 3 (IPv6):
Step
1.
Enter system view.
Command
Remarks
system-view
N/A
• Enter BGP view:
bgp as-number
2.
Enter BGP view or BGP-VPN
view.
• Enter BGP-VPN view:
a. bgp as-number
N/A
b. ip vpn-instance
vpn-instance-name
3.
Create an EBGP peer group.
group group-name external
By default, no EBGP peer group is
created.
4.
Add a peer into the EBGP
peer group.
peer ipv6-address group
group-name as-number as-number
By default, no peer exists in the
peer group.
5.
(Optional.) Configure a
description for the peer group.
peer group-name description
description-text
By default, no description is
configured for the peer group.
6.
Create and enter BGP IPv6
unicast instance view or
BGP-VPN IPv6 unicast
instance view.
ipv6-family [ unicast ]
By default, the BGP IPv6 unicast
instance view and BGP-VPN IPv6
unicast instance view are not
created.
Enable the router to exchange
IPv6 unicast routing
information with peers in the
specified peer group.
peer group-name enable
By default, the router cannot
exchange IPv6 unicast routing
information with the peers.
7.
Specifying the source interface for TCP connections
By default, BGP uses the output interface of the optimal route to a peer or peer group as the source
interface for establishing TCP connections to the peer or peer group, and it uses the IP address/IPv6
address of the output interface as the source IP address/IPv6 address of TCP connections. You can
change the source interface in the following scenarios:
•
If the peer’s IP address/IPv4 address belongs to an interface indirectly connected to the local router,
you must specify that interface as the source interface for TCP connections on the peer. For example,
interface A on the local end is directly connected to interface B on the peer. If you use the peer
x.x.x.x as-number as-number command in which x.x.x.x is not the IP address of interface B on the
local end, you must use the peer connect-interface command on the peer to specify the interface
whose IP address is x.x.x.x as the source interface for establishing a TCP connection.
178
•
On a BGP router that has multiple links to a peer, if the source interface fails, BGP has to reestablish
TCP connections. To avoid this problem, use a loopback interface as the source interface.
•
To establish multiple BGP sessions between two routers, specify the source interface for establishing
TCP connections to each peer on the local router. Otherwise, the local BGP router may fail to
establish a TCP connection to a peer when using the outbound interface of the best route to the peer
as the source interface.
To specify the source interface for TCP connections (IPv4):
Step
Enter system view.
1.
Command
Remarks
system-view
N/A
• Enter BGP view:
bgp as-number
Enter BGP view or BGP-VPN
view.
2.
• Enter BGP-VPN view:
a. bgp as-number
N/A
b. ip vpn-instance
vpn-instance-name
Specify the source interface
for establishing TCP
connections to a peer or peer
group.
3.
peer { group-name | ip-address }
connect-interface interface-type
interface-number
By default, BGP uses the outbound
interface of the best route to the
BGP peer or peer group as the
source interface for establishing a
TCP connection to the peer or peer
group.
To specify the source interface for TCP connections (IPv6):
Step
1.
Enter system view.
Command
Remarks
system-view
N/A
• Enter BGP view:
bgp as-number
2.
Enter BGP view or BGP-VPN
view.
• Enter BGP-VPN view:
a. bgp as-number
N/A
b. ip vpn-instance
vpn-instance-name
3.
Specify the source interface
for establishing TCP
connections to a peer or peer
group.
peer { group-name |
ipv6-address } connect-interface
interface-type interface-number
Generating BGP routes
BGP can generate routes in the following ways:
•
Advertise local networks.
•
Redistribute IGP routes.
179
By default, BGP uses the outbound
interface of the best route to the
BGP peer or peer group as the
source interface for establishing a
TCP connection to the peer or peer
group.
Injecting a local network
Perform this task to inject a network in the local routing table to the BGP routing table, so BGP can
advertise the network to BGP peers. The ORIGIN attribute of BGP routes advertised in this way is IGP.
You can also use a routing policy to control route advertisement.
The specified network must be available and active in the local IP routing table.
To inject a local network (IPv4):
Step
1.
Enter system view.
Command
Remarks
system-view
N/A
• Enter BGP view:
bgp as-number
2.
Enter BGP view or BGP-VPN
view.
• Enter BGP-VPN view:
a. bgp as-number
N/A
b. ip vpn-instance
vpn-instance-name
3.
4.
Enter BGP IPv4 unicast
instance view or BGP-VPN
IPv4 unicast instance view.
ipv4-family [ unicast ]
N/A
Inject a local network to the
BGP routing table.
network ip-address [ mask |
mask-length ] [ route-policy
route-policy-name ]
By default, BGP does not advertise
any local network.
Command
Remarks
system-view
N/A
To inject a local network (IPv6):
Step
1.
Enter system view.
• Enter BGP view:
bgp as-number
2.
Enter BGP view or BGP-VPN
view.
• Enter BGP-VPN view:
a. bgp as-number
N/A
b. ip vpn-instance
vpn-instance-name
3.
4.
Enter BGP IPv6 unicast
instance view or BGP-VPN
IPv6 unicast instance view.
ipv6-family [ unicast ]
N/A
Inject a local network to the
IPv6 BGP routing table.
network ipv6-address prefix-length
[ route-policy route-policy-name ]
By default, BGP does not advertise
any local network.
Redistributing IGP routes
Perform this task to configure route redistribution from an IGP to BGP.
By default, BGP does not redistribute default IGP routes. You can use the default-route imported
command to redistribute default IGP routes into the BGP routing table.
Only active routes can be redistributed. To view route state information, use the display ip routing-table
protocol or display ipv6 routing-table protocol command.
180
The ORIGIN attribute of BGP routes redistributed from IGPs is INCOMPLETE.
To configure BGP to redistribute IGP routes (IPv4):
Step
1.
Enter system view.
Command
Remarks
system-view
N/A
• Enter BGP view:
bgp as-number
2.
Enter BGP view or BGP-VPN
view.
• Enter BGP-VPN view:
a. bgp as-number
N/A
b. ip vpn-instance
vpn-instance-name
Enter BGP IPv4 unicast
instance view or BGP-VPN
IPv4 unicast instance view.
ipv4-family [ unicast ]
N/A
4.
Enable route redistribution
from the specified IGP into
BGP.
import-route protocol [ { process-id
| all-processes } [ med med-value |
route-policy route-policy-name ] * ]
By default, BGP does not
redistribute IGP routes.
5.
(Optional.) Enable default
route redistribution into BGP.
default-route imported
By default, BGP does not
redistribute default routes.
3.
To configure BGP to redistribute IGP routes (IPv6):
Step
1.
Enter system view.
Command
Remarks
system-view
N/A
• Enter BGP view:
bgp as-number
2.
Enter BGP view or BGP-VPN
view.
• Enter BGP-VPN view:
a. bgp as-number
N/A
b. ip vpn-instance
vpn-instance-name
Enter BGP IPv6 unicast
instance view or BGP-VPN
IPv6 unicast instance view.
ipv6-family [ unicast ]
N/A
4.
Enable route redistribution
from the specified IGP into
BGP.
import-route protocol [ process-id
[ med med-value | route-policy
route-policy-name ] * ]
By default, BGP does not
redistribute IGP routes.
5.
(Optional.) Enable default
route redistribution into BGP.
default-route imported
By default, BGP does not
redistribute default routes.
3.
Controlling route distribution and reception
This section describes how to control route distribution and reception.
181
Configuring BGP route summarization
Route summarization can reduce the number of redistributed routes and the routing table size. IPv4 BGP
supports automatic route summarization and manual route summarization. Manual summarization takes
precedence over automatic summarization. IPv6 BGP supports only manual route summarization.
The output interface of a BGP summary route is Null 0 on the originating router. Therefore, a summary
route must not be an optimal route on the originating router. Otherwise, BGP will fail to forward packets
matching the route. If a summarized specific route has the same mask as the summary route, but has a
lower priority, the summary route becomes the optimal route. In this case, you must change the priority
of the summary or the specific route to make the specific route as the optimal route.
Configuring automatic route summarization
Automatic route summarization enables BGP to summarize IGP subnet routes redistributed by the
import-route command so BGP advertises only natural network routes.
To configure automatic route summarization (IPv4):
Step
1.
Enter system view.
Command
Remarks
system-view
N/A
• Enter BGP view:
bgp as-number
2.
Enter BGP view or BGP-VPN
view.
• Enter BGP-VPN view:
a. bgp as-number
N/A
b. ip vpn-instance
vpn-instance-name
3.
4.
Enter BGP IPv4 unicast
instance view or BGP-VPN
IPv4 unicast instance view.
ipv4-family [ unicast ]
N/A
Configure automatic route
summarization.
summary automatic
By default, automatic route
summarization is not configured.
Configuring manual route summarization
By configuring manual route summarization, you can summarize both redistributed routes and routes
injected using the network command and determine the mask length for a summary route as needed.
To configure BGP manual route summarization (IPv4):
Step
1.
Enter system view.
Command
Remarks
system-view
N/A
• Enter BGP view:
bgp as-number
2.
Enter BGP view or BGP-VPN
view.
• Enter BGP-VPN view:
a. bgp as-number
N/A
b. ip vpn-instance
vpn-instance-name
3.
Enter BGP IPv4 unicast
instance view or BGP-VPN
IPv4 unicast instance view.
ipv4-family [ unicast ]
182
N/A
Step
4.
Create a summary route in the
BGP routing table.
Command
Remarks
aggregate ip-address { mask |
mask-length } [ as-set |
attribute-policy route-policy-name
| detail-suppressed | origin-policy
route-policy-name |
suppress-policy
route-policy-name ] *
By default, no summary route is
configured.
To configure BGP manual route summarization (IPv6):
Step
Command
Remarks
1.
Enter system view.
system-view
N/A
2.
Enter BGP view.
bgp as-number
N/A
3.
Enter BGP IPv6 unicast
instance view.
ipv4-family [ unicast ]
N/A
Create a summary route in the
IPv6 BGP routing table.
aggregate ipv6-address
prefix-length [ as-set |
attribute-policy route-policy-name
| detail-suppressed | origin-policy
route-policy-name |
suppress-policy
route-policy-name ] *
By default, no summary route is
configured.
4.
Advertising optimal routes in the IP routing table
By default, BGP advertises optimal routes in the BGP routing table, which may not be optimal in the IP
routing table. This task allows you to advertise BGP routes that are optimal in the IP routing table to all
BGP peers.
To enable BGP to advertise optimal routes in the IP routing table:
Step
Command
Remarks
1.
Enter system view.
system-view
N/A
2.
Enter BGP view.
bgp as-number
N/A
3.
Enable BGP to advertise
optimal routes in the IP routing
table.
advertise-rib-active
By default, BGP advertises optimal
routes in the BGP routing table.
Advertising a default route to a peer or peer group
Perform this task to advertise a default BGP route with the next hop being the advertising router to a peer
or peer group.
To advertise a default route to a peer or peer group (IPv4):
Step
1.
Enter system view.
Command
Remarks
system-view
N/A
183
Step
Command
Remarks
• Enter BGP view:
bgp as-number
Enter BGP view or BGP-VPN
view.
2.
• Enter BGP-VPN view:
a. bgp as-number
N/A
b. ip vpn-instance
vpn-instance-name
3.
4.
Enter BGP IPv4 unicast
instance view or BGP-VPN
IPv4 unicast instance view.
ipv4-family [ unicast ]
N/A
Advertise a default route to a
peer or peer group.
peer { group-name | ip-address }
default-route-advertise
[ route-policy route-policy-name ]
By default, no default route is
advertised.
To advertise a default route to a peer or peer group (IPv6):
Step
Command
Remarks
1.
Enter system view.
system-view
N/A
2.
Enter BGP view.
bgp as-number
N/A
3.
Enter BGP IPv6 unicast
instance view.
ipv6-family [ unicast ]
N/A
4.
Advertise a default route to a
peer or peer group.
peer { group-name |
ipv6-address }
default-route-advertise
[ route-policy route-policy-name ]
By default, no default route is
advertised.
Limiting routes received from a peer or peer group
This feature can prevent attacks that send a large number of BGP routes to the router.
If the number of routes received from a peer or peer group exceeds the upper limit, the router takes one
of the following actions based on your configuration:
•
Tear down the BGP session to the peer or peer group.
•
Display an alarm message.
•
Tear down the BGP session to the peer or peer group and, after a specified period of time,
reestablishes a BGP session to the peer or peer group.
You can specify a percentage threshold for the router to display an alarm message. When the ratio of the
number of received routes to the maximum number reaches the percentage value, the router displays an
alarm message.
To limit routes that a router can receive from a peer or peer group (IPv4):
Step
1.
Enter system view.
Command
Remarks
system-view
N/A
184
Step
Command
Remarks
• Enter BGP view:
bgp as-number
Enter BGP view or BGP-VPN
view.
2.
• Enter BGP-VPN view:
a. bgp as-number
N/A
b. ip vpn-instance
vpn-instance-name
3.
4.
Enter BGP IPv4 unicast
instance view or BGP-VPN
IPv4 unicast instance view.
ipv4-family [ unicast ]
N/A
Specify the maximum number
of routes that a router can
receive from a peer or peer
group.
peer { group-name | ip-address }
route-limit prefix-number
[ { alert-only | reconnect
reconnect-time } |
percentage-value ] *
By default, the number of routes
that a router can receive from a
peer or peer group is not limited.
To limit routes that a router can receive from a peer or peer group (IPv6):
Step
Command
Remarks
1.
Enter system view.
system-view
N/A
2.
Enter BGP view.
bgp as-number
N/A
3.
Enter BGP IPv6 unicast
instance view.
ipv6-family [ unicast ]
N/A
4.
Specify the maximum number
of routes that a router can
receive from a peer or peer
group.
peer { group-name |
ipv6-address } route-limit
prefix-number [ { alert-only |
reconnect reconnect-time } |
percentage-value ] *
By default, the number of routes
that a router can receive from a
peer or peer group is not limited.
Configuring BGP route filtering policies
Configuration prerequisites
Before you configure BGP routing filtering policies, configure the following filters used for route filtering
as needed:
•
ACL (see ACL and QoS Configuration Guide)
•
Prefix list (see "Configuring routing policies")
•
Routing policy (see "Configuring routing policies")
•
AS path list (see "Configuring routing policies")
Configuring BGP route distribution filtering policies
To configure BGP route distribution filtering policies, use the following methods:
•
Use an ACL or prefix list to filter routing information advertised to all peers.
•
Use a routing policy, ACL, AS path list, or prefix list to filter routing information advertised to a peer
or peer group.
If you configure multiple filtering policies, apply them in the following sequence:
185
1.
filter-policy export
2.
peer filter-policy export
3.
peer as-path-acl export
4.
peer prefix-list export
5.
peer route-policy export
Only routes passing all the configured policies can be advertised.
To configure BGP route distribution filtering policies (IPv4):
Step
1.
Enter system view.
Command
Remarks
system-view
N/A
• Enter BGP view:
bgp as-number
2.
Enter BGP view or BGP-VPN
view.
• Enter BGP-VPN view:
a. bgp as-number
N/A
b. ip vpn-instance
vpn-instance-name
3.
Enter BGP IPv4 unicast
instance view or BGP-VPN
IPv4 unicast instance view.
ipv4-family [ unicast ]
186
N/A
Step
Command
Remarks
• Reference an ACL or IP prefix
list to filter routes redistributed
to all peers:
filter-policy { acl-number |
prefix-list prefix-list-name }
export [ direct | isis process-id
| ospf process-id | rip
process-id | static ]
• Reference a routing policy to
filter advertisements to a peer
or peer group:
peer { group-name |
ip-address } route-policy
route-policy-name export
4.
Configure BGP route
distribution filtering policies.
• Reference an ACL to filter
advertisements to a peer or
peer group:
peer { group-name |
ip-address } filter-policy
acl-number export
Use at least one approach.
By default, no BGP distribution
filtering policy is configured.
• Reference an AS path list to
filter routing information sent to
a peer or peer group:
peer { group-name |
ip-address } as-path-acl
as-path-acl-number export
• Reference an IPv4 prefix list to
filter routing information sent to
a peer or peer group:
peer { group-name |
ip-address } prefix-list
prefix-list-name export
To configure BGP route distribution filtering policies (IPv6):
Step
1.
Enter system view.
Command
Remarks
system-view
N/A
• Enter BGP view:
bgp as-number
2.
Enter BGP view or BGP-VPN
view.
• Enter BGP-VPN view:
a. bgp as-number
N/A
b. ip vpn-instance
vpn-instance-name
3.
Enter BGP IPv6 unicast
instance view or BGP-VPN
IPv6 unicast instance view.
Ipv6-family [ unicast ]
187
N/A
Step
Command
Remarks
• Reference an ACL or IPv6 prefix
list to filter routes redistributed
to all peers:
filter-policy { acl6-number |
prefix-list ipv6-prefix-name }
export [ direct | isisv6
process-id | ospfv3 process-id
| ripng process-id | static ]
• Reference a routing policy to
filter advertisements to a peer
or peer group:
peer { group-name |
ipv6-address } route-policy
route-policy-name export
4.
Configure BGP route
distribution filtering policies.
• Reference an ACL to filter
advertisements to a peer or
peer group:
peer { group-name |
ipv6-address } filter-policy
acl6-number export
Use at least one approach.
Not configured by default.
• Reference an AS path list to
filter routing information sent to
a peer or peer group:
peer { group-name |
ipv6-address } as-path-acl
as-path-acl-number export
• Reference an IPv6 prefix list to
filter routing information sent to
peer { group-name |
ipv6-address } prefix-list
ipv6-prefix-name export
Configuring BGP route reception filtering policies
You can use the following methods to configure BGP route reception filtering policies:
•
Use an ACL or prefix list to filter routing information received from all peers.
•
Use a routing policy, ACL, AS path list, or prefix list to filter routing information received from a peer
or peer group.
If you configure multiple filtering policies, apply them in the following sequence:
1.
filter-policy import
2.
peer filter-policy import
3.
peer as-path-acl import
4.
peer prefix-list import
5.
peer route-policy import
Only routes passing all the configured policies can be received.
To configure BGP route reception filtering policies (IPv4):
188
Step
1.
Enter system view.
Command
Remarks
system-view
N/A
• Enter BGP view:
bgp as-number
2.
Enter BGP view or BGP-VPN
view.
• Enter BGP-VPN view:
a. bgp as-number
N/A
b. ip vpn-instance
vpn-instance-name
3.
Enter BGP IPv4 unicast
instance view or BGP-VPN
IPv4 unicast instance view.
ipv4-family [ unicast ]
N/A
• Reference an ACL or IP prefix list to
filter routes from all peers:
filter-policy { acl-number | prefix-list
prefix-list-name } import
• Reference a routing policy to filter
routing information from a peer or
peer group:
peer { group-name | ip-address }
route-policy route-policy-name
import
• Reference an ACL to filter routing
4.
Configure BGP route
reception filtering policies.
information from a peer or peer
group:
peer { group-name | ip-address }
filter-policy acl-number import
Use at least one approach.
By default, no route reception
filtering is configured.
• Reference an AS path list to filter
routing information from a peer or
peer group:
peer { group-name | ip-address }
as-path-acl as-path-acl-number
import
• Reference an IPv4 prefix list to filter
routing information from a peer or
peer group:
peer { group-name | ip-address }
prefix-list prefix-list-name import
To configure BGP route reception filtering policies (IPv6):
Step
1.
Enter system view.
Command
Remarks
system-view
N/A
• Enter BGP view:
bgp as-number
2.
Enter BGP view or BGP-VPN
view.
• Enter BGP-VPN view:
a. bgp as-number
b. ip vpn-instance
vpn-instance-name
189
N/A
Step
3.
Enter BGP IPv6 unicast
instance view or BGP-VPN
IPv6 unicast instance view.
Command
Remarks
ipv6-family [ unicast ]
N/A
• Reference ACL or IPv6 prefix list to
filter routes from all peers:
filter-policy { acl6-number |
prefix-list ipv6-prefix-name } import
• Reference a routing policy to filter
routing information from a peer or
peer group:
peer { group-name | ipv6-address }
route-policy route-policy-name
import
• Reference an ACL to filter routing
4.
Configure BGP route
reception filtering policies.
information from a peer or peer
group:
peer { group-name | ipv6-address }
filter-policy acl6-number import
Use at least one approach.
By default, no route reception
filtering is configured.
• Reference an AS path list to filter
routing information from a peer or
peer group:
peer { group-name | ipv6-address }
as-path-acl as-path-acl-number
import
• Reference an IPv6 prefix list to filter
routing information from a peer or
peer group:
peer { group-name | ipv6-address }
prefix-list ipv6-prefix-name import
Configuring BGP route dampening
Route dampening enables BGP to not select unstable routes as optimal routes.
To configure BGP route dampening (IPv4):
Step
1.
Enter system view.
Command
Remarks
system-view
N/A
• Enter BGP view:
bgp as-number
2.
Enter BGP view or BGP-VPN
view.
• Enter BGP-VPN view:
a. bgp as-number
N/A
b. ip vpn-instance
vpn-instance-name
3.
Enter BGP IPv4 unicast
instance view or BGP-VPN
IPv4 unicast instance view.
ipv4-family [ unicast ]
190
N/A
Step
4.
Configure BGP route
dampening.
Command
Remarks
dampening [ half-life-reachable
half-life-unreachable reuse suppress
ceiling | route-policy
route-policy-name ] *
By default, BGP route dampening
is not configured.
To configure BGP route dampening (IPv6):
Step
1.
Enter system view.
Command
Remarks
system-view
N/A
• Enter BGP view:
bgp as-number
2.
Enter BGP view or BGP-VPN
view.
• Enter BGP-VPN view:
a. bgp as-number
N/A
b. ip vpn-instance
vpn-instance-name
3.
4.
Enter BGP IPv6 unicast
instance view or BGP-VPN
IPv6 unicast instance view.
ipv6-family [ unicast ]
N/A
Configure IPv6 BGP route
dampening.
dampening [ half-life-reachable
half-life-unreachable reuse suppress
ceiling | route-policy
route-policy-name ] *
By default, IPv6 BGP route
dampening is not configured.
Controlling BGP path selection
By configuring BGP path attributes, you can control BGP path selection.
Specifying a preferred value for routes received
Perform this task to set a preferred value for specific routes to control BGP path selection.
Among multiple routes that have the same destination/mask and are learned from different peers, the
one with the greatest preferred value is selected as the optimal route.
To specify a preferred value for routes from a peer or peer group (IPv4):
Step
1.
Enter system view.
Command
Remarks
system-view
N/A
• Enter BGP view:
bgp as-number
2.
Enter BGP view or BGP-VPN
view.
• Enter BGP-VPN view:
a. bgp as-number
N/A
b. ip vpn-instance
vpn-instance-name
3.
Enter BGP IPv4 unicast
instance view or BGP-VPN
IPv4 unicast instance view.
ipv4-family [ unicast ]
191
N/A
Step
4.
Specify a preferred value for
routes received from a peer or
peer group.
Command
Remarks
peer { group-name | ip-address }
preferred-value value
The default preferred value is 0.
To specify a preferred value for routes from a peer or peer group (IPv6):
Step
1.
Enter system view.
Command
Remarks
system-view
N/A
• Enter BGP view:
bgp as-number
2.
Enter BGP view or BGP-VPN
view.
• Enter BGP-VPN view:
a. bgp as-number
N/A
b. ip vpn-instance
vpn-instance-name
3.
4.
Enter BGP IPv6 unicast
instance view or BGP-VPN
IPv6 unicast instance view.
ipv6-family [ unicast ]
N/A
Specify a preferred value for
routes received from a peer or
peer group.
peer { group-name |
ipv6-address } preferred-value
value
The default preferred value is 0.
Configuring preferences for BGP routes
Routing protocols each have a default preference. If they find multiple routes destined for the same
network, the route found by the routing protocol with the highest preference is selected as the optimal
route.
You can use the preference command to modify preferences for EBGP, IBGP, and local BGP routes, or
reference a routing policy to set a preference for matching routes (for routes not matching the routing
policy, the default preference applies).
If a device has an EBGP route and a local BGP route to reach the same destination, it does not select the
EBGP route because the EBGP route has a lower preference than the local BGP route by default. You can
use the network short-cut command to configure the EBGP route as a shortcut route that has the same
preference as the local BGP route so that the EBGP route will more likely become the optimal route.
To configure preferences for BGP routes (IPv4):
Step
1.
Enter system view.
Command
Remarks
system-view
N/A
• Enter BGP view:
bgp as-number
2.
Enter BGP view or BGP-VPN
view.
• Enter BGP-VPN view:
a. bgp as-number
b. ip vpn-instance
vpn-instance-name
192
N/A
Step
Command
Remarks
Enter BGP IPv4 unicast
instance view or BGP-VPN
IPv4 unicast instance view.
ipv4-family [ unicast ]
N/A
4.
Configure preferences for
EBGP, IBGP, and local BGP
routes.
preference { external-preference
internal-preference
local-preference | route-policy
route-policy-name }
The default preferences for EBGP,
IBGP, and local BGP routes are
255, 255, and 130.
5.
Configure an EBGP route as a
shortcut route.
network ip-address [ mask |
mask-length ] short-cut
By default, an EBGP route has a
preference of 255.
3.
To configure preferences for BGP routes (IPv6):
Step
1.
Enter system view.
Command
Remarks
system-view
N/A
• Enter BGP view:
bgp as-number
2.
Enter BGP view or BGP-VPN
view.
• Enter BGP-VPN view:
a. bgp as-number
N/A
b. ip vpn-instance
vpn-instance-name
Enter BGP IPv6 unicast
instance view or BGP-VPN
IPv6 unicast instance view.
ipv6-family [ unicast ]
N/A
4.
Configure preferences for
EBGP, IBGP, and local BGP
routes.
preference { external-preference
internal-preference
local-preference | route-policy
route-policy-name }
The default preferences for EBGP,
IBGP, and local BGP routes are
255, 255, and 130.
5.
Configure an EBGP route as a
shortcut route.
network ipv6-address prefix-length
short-cut
By default, an EBGP route has a
preference of 255.
3.
Configuring the default local preference
The local preference is used to determine the best route for traffic leaving the local AS. When a BGP
router obtains from several IBGP peers multiple routes to the same destination, but with different next
hops, it considers the route with the highest local preference as the best route.
This task allows you to specify the default local preference for routes sent to IBGP peers.
To specify the default local preference (IPv4):
Step
1.
Enter system view.
Command
Remarks
system-view
N/A
193
Step
Command
Remarks
• Enter BGP view:
bgp as-number
2.
Enter BGP view or BGP-VPN
view.
• Enter BGP-VPN view:
a. bgp as-number
N/A
b. ip vpn-instance
vpn-instance-name
3.
4.
Enter BGP IPv4 unicast
instance view or BGP-VPN
IPv4 unicast instance view.
ipv4-family [ unicast ]
N/A
Configure the default local
preference.
default local-preference value
The default local preference is
100.
To specify the default local preference (IPv6):
Step
1.
Enter system view.
Command
Remarks
system-view
N/A
• Enter BGP view:
bgp as-number
2.
Enter BGP view or BGP-VPN
view.
• Enter BGP-VPN view:
a. bgp as-number
N/A
b. ip vpn-instance
vpn-instance-name
3.
4.
Enter BGP IPv6 unicast
instance view or BGP-VPN
IPv6 unicast instance view.
ipv6-family [ unicast ]
N/A
Configure the default local
preference.
default local-preference value
The default local preference is
100.
Configuring the MED attribute
BGP uses MED to determine the best route for traffic going into an AS. When a BGP router obtains from
EBGP peers multiple routes to the same destination but with different next hops, it considers the route with
the smallest MED value as the best route if other conditions are the same.
Configuring the default MED value
To configure the default MED value (IPv4):
Step
1.
Enter system view.
Command
Remarks
system-view
N/A
• Enter BGP view:
bgp as-number
2.
Enter BGP view or BGP-VPN
view.
• Enter BGP-VPN view:
a. bgp as-number
b. ip vpn-instance
vpn-instance-name
194
N/A
Step
3.
4.
Command
Remarks
Enter BGP IPv4 unicast
instance view or BGP-VPN
IPv4 unicast instance view.
ipv4-family [ unicast ]
N/A
Configure the default MED
value.
default med med-value
The default MED value is 0.
To configure the default MED value (IPv6):
Step
1.
Enter system view.
Command
Remarks
system-view
N/A
• Enter BGP view:
bgp as-number
2.
Enter BGP view or BGP-VPN
view.
• Enter BGP-VPN view:
a. bgp as-number
N/A
b. ip vpn-instance
vpn-instance-name
3.
4.
Enter BGP IPv6 unicast
instance view or BGP-VPN
IPv6 unicast instance view.
ipv6-family [ unicast ]
N/A
Configure the default MED
value.
default med med-value
The default MED value is 0.
Enabling MED comparison for routes from different ASs
This task enables BGP to compare the MEDs of routes from different ASs.
To enable MED comparison for routes from different ASs (IPv4):
Step
1.
Enter system view.
Command
Remarks
system-view
N/A
• Enter BGP view:
bgp as-number
2.
Enter BGP view or BGP-VPN
view.
• Enter BGP-VPN view:
a. bgp as-number
N/A
b. ip vpn-instance
vpn-instance-name
3.
4.
Enter BGP IPv4 unicast
instance view or BGP-VPN
IPv4 unicast instance view.
ipv4-family [ unicast ]
N/A
Enable MED comparison for
routes from different ASs.
compare-different-as-med
By default, this feature is disabled.
To enable MED comparison for routes from different ASs (IPv6):
Step
Command
Remarks
1.
Enter system view.
system-view
N/A
2.
Enter BGP view.
bgp as-number
N/A
195
Step
Command
Remarks
3.
Enter BGP IPv6 unicast
instance view.
ipv6-family [ unicast ]
N/A
4.
Enable MED comparison for
routes from different ASs.
compare-different-as-med
By default, this feature is disabled.
Enabling MED comparison for routes on a per-AS basis
This task enables BGP to compare the MEDs of routes from an AS.
Figure 53 Route selection based on MED (in an IPv4 network)
AS 400
Router E
10.0.0.0
AS 300
AS 200
Router ID : 3.3.3.3
Router ID : 2.2.2.2
Router ID : 1.1.1.1
Router B
Router C
Router A
Eth1/1
3.3.3.3/24
AS 100
Eth1/1
2.2.2.2/24
Eth1/1
1.1.1.1
Router D
As shown in Figure 53, Router D learns network 10.0.0.0 from both Router A and Router B. Because
Router B has a smaller router ID, the route learned from Router B is optimal.
Network
*>i
10.0.0.0
* i
NextHop
MED
2.2.2.2
50
LocPrf
PrefVal Path/Ogn
0
300e
3.3.3.3
50
0
200e
When Router D learns network 10.0.0.0 from Router C, it compares the route with the optimal route in
its routing table. Because Router C and Router B reside in different ASs, BGP does not compare the MEDs
of the two routes. Router C has a smaller router ID than Router B so the route from Router C becomes
optimal.
Network
NextHop
MED
LocPrf
PrefVal Path/Ogn
*>i
10.0.0.0
1.1.1.1
60
0
200e
* i
10.0.0.0
2.2.2.2
50
0
300e
3.3.3.3
50
0
200e
* i
However, Router C and Router A reside in the same AS, and Router C has a greater MED, so network
10.0.0.0 learned from Router C should not be optimal.
You can configure the bestroute compare-med command to enable MED comparison for routes from the
same AS on Router D. After that, Router D puts the routes received from each AS into a group, selects the
route with the lowest MED from each group, and compares routes from different groups. This mechanism
avoids the above-mentioned problem. The following output shows the BGP routing table on Router D after
this feature is enabled. Network 10.0.0.0 learned from Router B is the optimal route.
196
Network
NextHop
MED
2.2.2.2
50
0
300e
* i
3.3.3.3
50
0
200e
* i
1.1.1.1
60
0
200e
*>i
10.0.0.0
LocPrf
PrefVal Path/Ogn
To enable MED comparison for routes on a per-AS basis (IPv4):
Step
1.
Enter system view.
Command
Remarks
system-view
N/A
• Enter BGP view:
bgp as-number
2.
Enter BGP view or BGP-VPN
view.
• Enter BGP-VPN view:
a. bgp as-number
N/A
b. ip vpn-instance
vpn-instance-name
3.
4.
Enter BGP IPv4 unicast
instance view or BGP-VPN
IPv4 unicast instance view.
ipv4-family [ unicast ]
N/A
Enable MED comparison for
routes on a per-AS basis.
bestroute compare-med
By default, this feature is disabled.
To enable MED comparison for routes on a per-AS basis (IPv6):
Step
Command
Remarks
1.
Enter system view.
system-view
N/A
2.
Enter BGP view.
bgp as-number
N/A
3.
Enter BGP IPv6 unicast
instance view.
ipv6-family [ unicast ]
N/A
4.
Enable MED comparison for
routes on a per-AS basis.
bestroute compare-med
By default, this feature is disabled.
Enabling MED comparison for routes from confederation peers
This task enables BGP to compare the MEDs of routes received from confederation peers. However, if a
route received from a confederation peer has an AS number that does not belong to the confederation,
BGP does not compare the route with other routes. For example, a confederation has three AS numbers
65006, 65007, and 65009. BGP receives three routes from different confederation peers. The AS_PATH
attributes of these routes are 65006 65009, 65007 65009, and 65008 65009, and the MED values of
them are 2, 3, and 1. Because the third route's AS_PATH attribute contains AS number 65008 that does
not belong to the confederation, BGP does not compare it with other routes. As a result, the first route
becomes the optimal route.
To enable MED comparison for routes from confederation peers (IPv4):
Step
1.
Enter system view.
Command
Remarks
system-view
N/A
197
Step
Command
Remarks
• Enter BGP view:
bgp as-number
2.
Enter BGP view or BGP-VPN
view.
• Enter BGP-VPN instance view:
a. bgp as-number
N/A
b. ip vpn-instance
vpn-instance-name
3.
4.
Enter BGP IPv4 unicast
instance view or BGP-VPN
IPv4 unicast instance view.
ipv4-family [ unicast ]
N/A
Enable MED comparison for
routes from confederation
peers.
bestroute med-confederation
By default, this feature is disabled.
To enable MED comparison for routes from confederation peers (IPv6):
Step
Command
Remarks
1.
Enter system view.
system-view
N/A
2.
Enter BGP view.
bgp as-number
N/A
3.
Enter BGP IPv6 unicast
instance view.
ipv6-family [ unicast ]
N/A
4.
Enable MED comparison for
routes from confederation
peers.
bestroute med-confederation
By default, this feature is disabled.
Configuring the NEXT_HOP attribute
By default, a BGP router does not set itself as the next hop for routes advertised to an IBGP peer or peer
group. In some cases, however, you must configure the advertising router as the next hop to make sure
the BGP peer can find the correct next hop.
For example, as shown in Figure 54, Router A and Router B establish an EBGP neighbor relationship, and
Router B and Router C establish an IBGP neighbor relationship. If Router C has no route destined for IP
address 1.1.1.1/24, you must configure Router B to set itself 3.1.1.1/24 as the next hop for the network
2.1.1.1/24 advertised to Router C.
Figure 54 NEXT_HOP attribute configuration
If a BGP router has two peers on a broadcast network, it does not set itself as the next hop for routes sent
to an EBGP peer by default. As shown in Figure 55, Router A and Router B establish an EBGP neighbor
relationship, and Router B and Router C establish an IBGP neighbor relationship. They are on the same
broadcast network 1.1.1.0/24. When Router B sends EBGP routes to Router A, it does not set itself as the
198
next hop by default. However, you can configure Router B to set it (1.1.1.2/24) as the next hop for routes
sent to Router A by using the peer next-hop-local command as needed.
Figure 55 NEXT_HOP attribute configuration
IMPORTANT:
If you have configured BGP load balancing, the router sets itself as the next hop for routes sent to an IBGP
peer or peer group regardless of whether the peer next-hop-local command is configured.
To configure the NEXT_HOP attribute (IPv4):
Step
1.
Enter system view.
Command
Remarks
system-view
N/A
• Enter BGP view:
bgp as-number
2.
Enter BGP view or BGP-VPN
view.
• Enter BGP-VPN view:
a. bgp as-number
N/A
b. ip vpn-instance
vpn-instance-name
3.
4.
Enter BGP IPv4 unicast
instance view or BGP-VPN
IPv4 unicast instance view.
Specify the router as the next
hop for routes sent to a peer
or peer group.
ipv4-family [ unicast ]
N/A
peer { group-name | ip-address }
next-hop-local
By default, the router sets itself as
the next hop for routes sent to an
EBGP peer or peer group, but does
not set itself as the next hop for
routes sent to an IBGP peer or peer
group.
To configure the NEXT_HOP attribute (IPv6):
Step
Command
Remarks
1.
Enter system view.
system-view
N/A
2.
Enter BGP view.
bgp as-number
N/A
3.
Enter BGP IPv6 unicast
instance view.
ipv6-family [ unicast ]
N/A
199
Step
4.
Specify the router as the next
hop for routes sent to a peer
or peer group.
Command
Remarks
peer { group-name |
ipv6-address } next-hop-local
By default, the router sets itself as
the next hop for routes sent to an
EBGP peer or peer group, but does
not set itself as the next hop for
routes sent to an IBGP peer or peer
group.
Configuring the AS_PATH attribute
Permitting local AS number to appear in routes from a peer or peer group
In general, BGP checks whether the AS_PATH attribute of a route from a peer contains the local AS
number. If yes, it discards the route to avoid routing loops.
In certain network environments (for example, a Hub&Spoke network in MPLS L3VPN), however, the
AS_PATH attribute of a route from a peer must be allowed to contain the local AS number. Otherwise, the
route cannot be advertised correctly.
To permit the local AS number to appear in routes from a peer or peer group and specify the
appearance times (IPv4):
Step
1.
Enter system view.
Command
Remarks
system-view
N/A
• Enter BGP view:
bgp as-number
2.
Enter BGP view or BGP-VPN
view.
• Enter BGP-VPN view:
a. bgp as-number
N/A
b. ip vpn-instance
vpn-instance-name
3.
4.
Enter BGP IPv4 unicast
instance view or BGP-VPN
IPv4 unicast instance view.
ipv4-family [ unicast ]
N/A
Permit the local AS number to
appear in routes from a peer
or peer group and specify the
appearance times.
peer { group-name | ip-address }
allow-as-loop [ number ]
By default, the local AS number is
not allowed in routes from a peer
or peer group.
To permit the local AS number to appear in routes from a peer or peer group and specify the
appearance times (IPv6):
Step
1.
Enter system view.
Command
Remarks
system-view
N/A
• Enter BGP view:
bgp as-number
2.
Enter BGP view or BGP-VPN
view.
• Enter BGP-VPN view:
a. bgp as-number
b. ip vpn-instance
vpn-instance-name
200
N/A
Step
3.
4.
Command
Remarks
Enter BGP IPv6 unicast
instance view or BGP-VPN
IPv6 unicast instance view.
ipv6-family [ unicast ]
N/A
Permit the local AS number to
appear in routes from a peer
or peer group and specify the
appearance times.
peer { group-name |
ipv6-address } allow-as-loop
[ number ]
By default, the local AS number is
not allowed in routes from a peer
or peer group.
Disabling BGP from considering AS_PATH during best route selection
To disable BGP from considering AS_PATH during best route selection (IPv4):
Step
1.
Enter system view.
Command
Remarks
system-view
N/A
• Enter BGP view:
bgp as-number
2.
Enter BGP view or BGP-VPN
view.
• Enter BGP-VPN view:
a. bgp as-number
N/A
b. ip vpn-instance
vpn-instance-name
3.
4.
Enter BGP IPv4 unicast
instance view or BGP-VPN
IPv4 unicast instance view.
ipv4-family [ unicast ]
N/A
Disable BGP from considering
AS_PATH during best route
selection.
bestroute as-path-neglect
By default, BGP considers
AS_PATH during best route
selection.
To disable BGP from considering AS_PATH during best route selection (IPv6):
Step
1.
Enter system view.
Command
Remarks
system-view
N/A
• Enter BGP view:
bgp as-number
2.
Enter BGP view or BGP-VPN
view.
• Enter BGP-VPN view:
a. bgp as-number
N/A
b. ip vpn-instance
vpn-instance-name
3.
4.
Enter BGP IPv6 unicast
instance view or BGP-VPN
IPv6 unicast instance view.
ipv6-family [ unicast ]
N/A
Disable BGP from considering
AS_PATH during best route
selection.
bestroute as-path-neglect
By default, BGP considers
AS_PATH during best route
selection.
Advertising a fake AS number to a peer or peer group
After you move a BGP router from an AS to another AS (from AS 2 to AS 3 for example), you have to
modify the AS number of the router on all its EBGP peers. To avoid such modifications, you can configure
201
the router to advertise a fake AS number 2 to its EBGP peers so that the EBGP peers still think that Router
A is in AS 2.
To advertise a fake AS number to a peer or peer group (IPv4):
Step
1.
Enter system view.
Command
Remarks
system-view
N/A
• Enter BGP view:
bgp as-number
2.
Enter BGP view or BGP-VPN
view.
• Enter BGP-VPN view:
a. bgp as-number
N/A
b. ip vpn-instance
vpn-instance-name
3.
Advertise a fake AS number to
a peer or peer group.
peer { group-name | ip-address }
fake-as as-number
By default, no fake AS number is
advertised to a peer or peer group.
This command applies to only
EBGP peers or EBGP peer groups.
To advertise a fake AS number to a peer or peer group (IPv6):
Step
1.
Enter system view.
Command
Remarks
system-view
N/A
• Enter BGP view:
bgp as-number
2.
Enter BGP view or BGP-VPN
view.
• Enter BGP-VPN view:
a. bgp as-number
N/A
b. ip vpn-instance
vpn-instance-name
3.
Advertise a fake AS number to
a peer or peer group.
peer { group-name |
ipv6-address } fake-as as-number
By default, no fake AS number is
advertised to a peer or peer group.
This command applies to only
EBGP peers or EBGP peer groups.
Configuring AS number substitution
IMPORTANT:
Do not configure AS number substitution in normal circumstances. Otherwise, routing loops might occur.
To use BGP between PE and CE in MPLS L3VPN, VPN sites in different geographical areas should have
different AS numbers. Otherwise, BGP discards route updates containing the local AS number. If two CEs
connected to different PEs use the same AS number, you must configure AS number substitution on each
PE to replace the AS number in route updates originated by the remote CE as its own AS number before
advertising them to the connected CE.
202
Figure 56 AS number substitution configuration (in an IPv4 network)
For example, as shown in Figure 56, CE 1 and CE 2 use the same AS number 800. To implement
bidirectional communication between the two sites, configure AS number substitution on PE 2 to replace
AS 800 as AS 100 for the BGP route update originated from CE 1 before advertising it to CE2, and
perform the same configuration on PE1.
To configure AS number substitution for a peer or peer group (IPv4):
Step
1.
Enter system view.
Command
Remarks
system-view
N/A
• Enter BGP view:
bgp as-number
2.
Enter BGP view or BGP-VPN
view.
• Enter BGP-VPN view:
a. bgp as-number
N/A
b. ip vpn-instance
vpn-instance-name
3.
Configure AS number
substitution for a peer or peer
group.
peer { group-name | ip-address }
substitute-as
By default, AS number substitution
is not configured.
To configure AS number substitution for a peer or peer group (IPv6):
Step
1.
Enter system view.
Command
Remarks
system-view
N/A
• Enter BGP view:
bgp as-number
2.
Enter BGP view or BGP-VPN
view.
• Enter BGP-VPN view:
a. bgp as-number
N/A
b. ip vpn-instance
vpn-instance-name
3.
Configure AS number
substitution for a peer or peer
group.
peer { group-name |
ipv6-address } substitute-as
By default, AS number substitution
is not configured.
Removing private AS numbers from updates sent to an EBGP peer or peer group
Private AS numbers are typically used in test networks, and should not be transmitted in public networks.
The range of private AS numbers is from 64512 to 65535.
To remove private AS numbers from updates sent to an EBGP peer or peer group (IPv4):
203
Step
1.
Enter system view.
Command
Remarks
system-view
N/A
• Enter BGP view:
bgp as-number
2.
Enter BGP view or BGP-VPN
view.
• Enter BGP-VPN view:
a. bgp as-number
N/A
b. ip vpn-instance
vpn-instance-name
3.
4.
Enter BGP IPv4 unicast
instance view or BGP-VPN
IPv4 unicast instance view.
ipv4-family [ unicast ]
Configure BGP to remove
private AS numbers from the
AS_PATH attribute of updates
sent to an EBGP peer or peer
group.
peer { group-name | ip-address }
public-as-only
N/A
By default, this feature is not
configured.
This command is only applicable to
EBGP peers or peer groups.
To remove private AS numbers from updates sent to an EBGP peer or peer group (IPv6):
Step
1.
Enter system view.
Command
Remarks
system-view
N/A
• Enter BGP view:
bgp as-number
2.
Enter BGP view or BGP-VPN
view.
• Enter BGP-VPN view:
a. bgp as-number
N/A
b. ip vpn-instance
vpn-instance-name
3.
4.
Enter BGP IPv6 unicast
instance view or BGP-VPN
IPv6 unicast instance view.
ipv6-family [ unicast ]
Configure BGP to remove
private AS numbers from the
AS_PATH attribute of updates
sent to an EBGP peer or peer
group.
peer { group-name |
ipv6-address } public-as-only
N/A
By default, this feature is not
configured.
This command is only applicable to
EBGP peers or peer groups.
Ignoring the first AS number of EBGP route updates
By default, BGP checks whether the first AS number in the AS_PATH attribute of a route update received
from a peer is the AS number of that peer. If not, BGP discards the route update.
To ignore the first AS number of EBGP route updates:
Step
Command
Remarks
1.
Enter system view.
system-view
N/A
2.
Enter BGP view.
bgp as-number
N/A
3.
Configure BGP to ignore the first AS
number of EBGP route updates.
ignore-first-as
By default, BGP checks the
first AS number of EBGP
route updates.
204
Tuning and optimizing BGP networks
This section describes how to tune and optimize BGP networks.
Configuring the keepalive interval and hold time
BGP sends keepalive messages at a specific interval to keep the BGP session between two routers.
If a router receives no keepalive or update message from a peer within the hold time, it tears down the
session.
You can configure the keepalive interval and hold time globally or for a specific peer or peer group. The
individual settings take precedence over the global settings.
The actual keepalive interval and hold time are determined as follows:
•
If the hold time settings on the local and peer routers are different, the smaller setting is used. If the
hold time is 0, BGP does not send keepalive messages to its peers and never tears down the
session.
•
If the keepalive interval is 0 and the negotiated hold time is not 0, the actual keepalive interval
equals 1/3 of the hold time. If the keepalive interval is not 0, the actual keepalive interval is the
smaller one between 1/3 of the hold time and the keepalive interval.
To configure the keepalive interval and hold time (IPv4):
Step
1.
Enter system view.
Command
Remarks
system-view
N/A
• Enter BGP view:
bgp as-number
2.
Enter BGP view or BGP-VPN
view.
• Enter BGP-VPN view:
a. bgp as-number
N/A
b. ip vpn-instance
vpn-instance-name
Use either approach.
• Configure the global keepalive
interval and hold time:
timer keepalive keepalive hold
holdtime
3.
Configure the keepalive
interval and hold time.
• Configure the keepalive
interval and hold time for a
peer or peer group:
peer { group-name |
ip-address } timer keepalive
keepalive hold holdtime
To configure the keepalive interval and hold time (IPv6):
205
By default, the keepalive interval is
60 seconds, and hold time is 180
seconds.
The timer command takes effect for
new BGP sessions and does not
affect existing sessions.
If you modify the timers with the
peer timer command, BGP
immediately closes the existing
BGP session and creates a new
session to the peer by using the
new settings.
Step
1.
Enter system view.
Command
Remarks
system-view
N/A
• Enter BGP view:
bgp as-number
2.
Enter BGP view or BGP-VPN
view.
• Enter BGP-VPN view:
a. bgp as-number
N/A
b. ip vpn-instance
vpn-instance-name
Use either approach.
• Configure the global keepalive
interval and hold time:
timer keepalive keepalive hold
holdtime
3.
Configure the keepalive
interval and hold time.
• Configure the keepalive
interval and hold time for a
peer or peer group:
peer { group-name |
ipv6-address } timer keepalive
keepalive hold holdtime
By default, the keepalive interval is
60 seconds, and hold time is 180
seconds.
The timer command takes effect for
new BGP sessions and does not
affect existing sessions.
If you modify the timers with the
peer timer command, BGP
immediately closes the existing
BGP session and creates a new
session to the peer by using the
new settings.
Configuring the interval for sending updates for the same route
A BGP router sends an update message to its peers when a route is changed. If the route changes
frequently, the BGP router keeps sending updates for the same route, resulting route flapping. To prevent
this situation, perform this task to configure the interval for sending updates for the same route to a peer
or peer group.
To configure the interval for sending the same update to a peer or peer group (IPv4):
Step
1.
Enter system view.
Command
Remarks
system-view
N/A
• Enter BGP view:
bgp as-number
2.
Enter BGP view or BGP-VPN
view.
• Enter BGP-VPN view:
a. bgp as-number
N/A
b. ip vpn-instance
vpn-instance-name
3.
Configure the interval for
sending updates for the same
route to a peer or peer group.
peer { group-name | ip-address }
route-update-interval interval
By default, the interval is 15
seconds for an IBGP peer and 30
seconds for an EBGP peer.
To configure the interval for sending the same update to a peer or peer group (IPv6):
Step
1.
Enter system view.
Command
Remarks
system-view
N/A
206
Step
Command
Remarks
• Enter BGP view:
bgp as-number
2.
Enter BGP view or BGP-VPN
view.
• Enter BGP-VPN view:
a. bgp as-number
N/A
b. ip vpn-instance
vpn-instance-name
3.
Configure the interval for
sending updates for the same
route to a peer or peer group.
peer { group-name |
ipv6-address }
route-update-interval interval
By default, the interval is 15
seconds for an IBGP peer and 30
seconds for an EBGP peer.
Enabling BGP to establish an EBGP session over multiple hops
To establish an EBGP connection, two routers must have a direct physical link. If no direct link is available,
you must use the peer ebgp-max-hop command to enable BGP to establish an EBGP session over
multiple hops and specify the maximum hops.
If directly connected EBGP peers use loopback interfaces to establish a BGP session, you do not need to
configure the peer ebgp-max-hop command.
To enable BGP to establish an indirect EBGP session (IPv4):
Step
1.
Enter system view.
Command
Remarks
system-view
N/A
• Enter BGP view:
bgp as-number
2.
Enter BGP view or BGP-VPN
view.
• Enter BGP-VPN view:
a. bgp as-number
N/A
b. ip vpn-instance
vpn-instance-name
3.
Enable BGP to establish an
EBGP session to an
indirectly-connected peer or
peer group and specify the
maximum hop count.
peer { group-name | ip-address }
ebgp-max-hop [ hop-count ]
By default, BGP cannot establish
an EBGP session to an
indirectly-connected peer or peer
group.
To enable BGP to establish an indirect EBGP session (IPv6):
Step
1.
Enter system view.
Command
Remarks
system-view
N/A
• Enter BGP view:
bgp as-number
2.
Enter BGP view or BGP-VPN
view.
• Enter BGP-VPN view:
a. bgp as-number
b. ip vpn-instance
vpn-instance-name
207
N/A
Step
3.
Enable BGP to establish an
EBGP session to an
indirectly-connected peer or
peer group and specify the
maximum hop count.
Command
Remarks
peer { group-name |
ipv6-address } ebgp-max-hop
[ hop-count ]
By default, BGP cannot establish
an EBGP session to an
indirectly-connected peer or peer
group.
Enabling immediate reestablishment of direct EBGP
connections upon link failure
When the link to a directly-connected EBGP peer goes down, the router does not reestablish a session to
the peer until the hold time timer expires. This feature enables BGP to immediately recreate the session
in that situation. When this feature is disabled, route flapping does not affect EBGP session state.
To enable immediate reestablishment of direct EBGP connections:
Step
Command
Remarks
1.
Enter system view.
system-view
N/A
2.
Enter BGP view.
bgp as-number
N/A
3.
Enable immediate reestablishment of
direct EBGP connections upon link
failure.
ebgp-interface-sensitive
By default, this feature is
enabled.
Enabling 4-byte AS number suppression
BGP supports 4-byte AS numbers. The 4-byte AS number occupies four bytes, in the range of 1 to
4294967295. By default, a device sends an Open message to the peer device for session establishment.
The Open message indicates that the device supports 4-byte AS numbers. If the peer device does not
support 4-byte AS numbers (supports only 2-byte AS numbers), the session cannot be established. To
resolve this issue, enable the 4-byte AS number suppression function. The device then sends an Open
message to inform the peer that it does not support 4-byte AS numbers, so the BGP session can be
established.
If the peer device supports 4-byte AS numbers, do not enable the 4-byte AS number suppression function.
Otherwise, the BGP session cannot be established.
To enable 4-byte AS number suppression (IPv4):
Step
1.
Enter system view.
Command
Remarks
system-view
N/A
• Enter BGP view:
bgp as-number
2.
Enter BGP view or BGP-VPN
instance view.
• Enter BGP-VPN instance view:
a. bgp as-number
b. ip vpn-instance
vpn-instance-name
208
N/A
Step
3.
Enable 4-byte AS number
suppression.
Command
Remarks
peer { group-name | ip-address }
capability-advertise
suppress-4-byte-as
By default, 4-byte AS number
suppression is not enabled.
To enable 4-byte AS number suppression (IPv6):
Step
1.
Enter system view.
Command
Remarks
system-view
N/A
• Enter BGP view:
bgp as-number
2.
Enter BGP view or BGP-VPN
instance view.
• Enter BGP-VPN instance view:
a. bgp as-number
N/A
b. ip vpn-instance
vpn-instance-name
3.
Enable 4-byte AS number
suppression.
peer { group-name |
ipv6-address } capability-advertise
suppress-4-byte-as
By default, 4-byte AS number
suppression is not enabled.
Configuring MD5 authentication for BGP
Perform this task to configure MD5 authentication between BGP peers. MD5 authentication verifies each
segment sent on the TCP connection between the peers. The BGP peers must be configured with the same
key to establish a TCP connection.
To configure MD5 authentication for BGP (IPv4):
Step
1.
Enter system view.
Command
Remarks
system-view
N/A
• Enter BGP view:
bgp as-number
2.
Enter BGP view or BGP-VPN
instance view.
• Enter BGP-VPN instance view:
a. bgp as-number
N/A
b. ip vpn-instance
vpn-instance-name
3.
Configure MD5
authentication for a peer or
peer group.
peer { group-name | ip-address }
password { cipher | simple }
password
By default, MD5 authentication is
not configured for any BGP peer.
To configure MD5 authentication for BGP (IPv6):
Step
1.
Enter system view.
Command
Remarks
system-view
N/A
209
Step
Command
Remarks
• Enter BGP view:
bgp as-number
2.
Enter BGP view or BGP-VPN
instance view.
• Enter BGP-VPN instance view:
a. bgp as-number
N/A
b. ip vpn-instance
vpn-instance-name
3.
Configure MD5
authentication for a peer or
peer group.
peer { group-name |
ipv6-address } password { cipher |
simple } password
By default, MD5 authentication is
not configured for any BGP peer.
Configuring BGP load balancing
If multiple BGP routes with the same AS_PATH, ORIGIN, LOCAL_PREF, and MED attributes to a
destination exist, you can use the balance command to enable load balancing over these ECMP routes
and specify the maximum number of ECMP routes.
To configure the maximum number of ECMP routes (IPv4):
Step
1.
Enter system view.
Command
Remarks
system-view
N/A
• Enter BGP view:
bgp as-number
2.
Enter BGP view or BGP-VPN
view.
• Enter BGP-VPN view:
a. bgp as-number
N/A
b. ip vpn-instance
vpn-instance-name
3.
4.
Enter BGP IPv4 unicast
instance view or BGP-VPN
IPv4 unicast instance view.
ipv4-family [ unicast ]
N/A
Configure the maximum
number of ECMP routes for
load balancing.
balance number
By default, load balancing is
disabled.
To configure the maximum number of ECMP routes (IPv6):
Step
1.
Enter system view.
Command
Remarks
system-view
N/A
• Enter BGP view:
bgp as-number
2.
Enter BGP view or BGP-VPN
view.
• Enter BGP-VPN view:
a. bgp as-number
N/A
b. ip vpn-instance
vpn-instance-name
3.
Enter BGP IPv6 unicast
instance view or BGP-VPN
IPv6 unicast instance view.
ipv6-family [ unicast ]
210
N/A
Step
4.
Configure the maximum
number of ECMP routes for
load balancing.
Command
Remarks
balance number
By default, load balancing is
disabled.
Disabling BGP to establish a session to a peer or peer group
This task enables you to temporarily tear down the BGP session to a specific peer or peer group so that
you can perform network upgrade and maintenance without needing to delete and reconfigure the peer
or peer group. To recover the session, execute the undo peer ignore command.
To disable BGP to establish a session to a peer or peer group (IPv4):
Step
1.
Enter system view.
Command
Remarks
system-view
N/A
• Enter BGP view:
bgp as-number
2.
Enter BGP view or BGP-VPN
view.
• Enter BGP-VPN view:
a. bgp as-number
N/A
b. ip vpn-instance
vpn-instance-name
3.
Disable BGP to establish a
session to a peer or peer
group.
peer { group-name | ip-address }
ignore
By default, BGP can establish a
session to a peer or peer group.
To disable BGP to establish a session to a peer or peer group (IPv6):
Step
1.
Enter system view.
Command
Remarks
system-view
N/A
• Enter BGP view:
bgp as-number
2.
Enter BGP view or BGP-VPN
view.
• Enter BGP-VPN view:
a. bgp as-number
N/A
b. ip vpn-instance
vpn-instance-name
3.
Disable BGP to establish a
session to a peer or peer
group.
peer { group-name |
ipv6-address } ignore
By default, BGP can establish a
session to a peer.
Configuring BGP soft-reset
After you modify the route selection policy (for example, modify the preferred value), you must reset BGP
sessions to apply the new policy. The reset operation tears down and re-establishes BGP sessions.
To avoid tearing down BGP sessions, you can use one of the following soft-reset methods to apply the
new policy:
211
Enabling route-refresh—The BGP router advertises a route-refresh message to the specified peer,
and the peer resends its routing information to the router. After receiving the routing information, the
router filters the routing information by using the new policy.
•
This method requires that both the local router and the peer support route refresh.
Saving updates—Use the peer keep-all-routes command to save all route updates from the
specified peer. After modifying the route selection policy, filter routing information by using the new
policy.
•
This method does not require that the local router and the peer support route refresh but it uses
more memory resources to save routes.
Manual soft-reset—Use the refresh bgp command to enable BGP to send local routing information
or advertise a route-refresh message to the specified peer so the peer resends its routing information.
After receiving the routing information, the router filters the routing information by using the new
policy.
•
This method requires that both the local router and the peer support route refresh.
Enabling route-refresh
To enable BGP route refresh for a peer or peer group (IPv4):
Step
1.
Enter system view.
Command
Remarks
system-view
N/A
• Enter BGP view:
bgp as-number
2.
Enter BGP view or BGP-VPN
view.
• Enter BGP-VPN view:
a. bgp as-number
N/A
b. ip vpn-instance
vpn-instance-name
• Enable BGP route refresh for the
specified peer or peer group:
peer { group-name |
ip-address }
capability-advertise
route-refresh
3.
Enable BGP route refresh for a
peer or peer group.
• Enable BGP route refresh and
multi-protocol extension
capability for the specified peer
or peer group:
undo peer { group-name |
ip-address }
capability-advertise
conventional
Use either approach.
By default, BGP route refresh is
enabled.
To enable BGP route refresh for a peer or peer group (IPv6):
Step
1.
Enter system view.
Command
Remarks
system-view
N/A
212
Step
Command
Remarks
• Enter BGP view:
bgp as-number
2.
Enter BGP view or BGP-VPN
view.
• Enter BGP-VPN view:
a. bgp as-number
N/A
b. ip vpn-instance
vpn-instance-name
• Enable BGP route refresh for the
specified peer or peer group:
peer { group-name |
ipv6-address }
capability-advertise
route-refresh
3.
Enable BGP route refresh for a
peer or peer group.
• Enable BGP route refresh and
multi-protocol extension
capability for the specified peer
or peer group:
undo peer { group-name |
ipv6-address }
capability-advertise
conventional
Use either approach.
By default, BGP route refresh is
enabled.
Saving updates
To save all route updates from the specified peer or peer group (IPv4):
Step
1.
Enter system view.
Command
Remarks
system-view
N/A
• Enter BGP view:
bgp as-number
2.
Enter BGP view or BGP-VPN
view.
• Enter BGP-VPN view:
a. bgp as-number
N/A
b. ip vpn-instance
vpn-instance-name
3.
4.
Enter BGP IPv4 unicast
instance view or BGP-VPN
IPv4 unicast instance view.
Save all route updates from
the peer or peer group.
ipv4-family [ unicast ]
peer { group-name | ip-address }
keep-all-routes
N/A
By default, the routes are not
saved.
This command takes effect only for
the routes received after this
command is executed.
To save all route updates from the specified peer or peer group (IPv6):
Step
Command
Remarks
1.
Enter system view.
system-view
N/A
2.
Enter BGP view
bgp as-number
N/A
213
Step
3.
4.
Enter BGP IPv6 unicast
instance view.
Save all route updates from
the peer or peer group.
Command
Remarks
ipv6-family [ unicast ]
N/A
peer { group-name |
ipv6-address } keep-all-routes
By default, the routes are not
saved.
This command takes effect only for
the routes received after this
command is executed.
Configuring manual soft-reset
To configure manual soft-reset (IPv4):
Step
1.
Enter system view.
Command
Remarks
system-view
N/A
• Enter BGP view:
bgp as-number
2.
Enter BGP view or BGP-VPN
view.
• Enter BGP-VPN view:
a. bgp as-number
N/A
b. ip vpn-instance
vpn-instance-name
• Enable BGP route refresh for the
specified peer or peer group:
peer { group-name |
ip-address }
capability-advertise
route-refresh
3.
4.
5.
Enable BGP route refresh for a
peer or peer group.
• Enable BGP route refresh and
By default, BGP route refresh is
enabled.
Return to user view.
return
N/A
Perform manual soft-reset.
refresh bgp { ip-address | all |
external | group group-name |
internal } { export | import } ipv4
[ unicast ] [ vpn-instance
vpn-instance-name ]
N/A
multi-protocol extension
capability for the specified peer
or peer group:
undo peer { group-name |
ip-address }
capability-advertise
conventional
To configure manual soft-reset (IPv6):
Step
1.
Enter system view.
Command
Remarks
system-view
N/A
214
Step
Command
Remarks
• Enter BGP view:
bgp as-number
2.
Enter BGP view or BGP-VPN
view.
• Enter BGP-VPN view:
a. bgp as-number
N/A
b. ip vpn-instance
vpn-instance-name
• Enable BGP route refresh for the
specified peer or peer group:
peer { group-name |
ipv6-address }
capability-advertise
route-refresh
3.
4.
5.
Enable BGP route refresh for a
peer or peer group.
• Enable BGP route refresh and
By default, BGP route refresh is
enabled.
Return to user view.
return
N/A
Perform manual soft-reset.
refresh bgp { ipv6-address | all |
external | group group-name |
internal } { export | import } ipv6
[ unicast ] [ vpn-instance
vpn-instance-name ]
N/A
multi-protocol extension
capability for the specified peer
or peer group:
undo peer { group-name |
ipv6-address }
capability-advertise
conventional
Protecting an EBGP peer when memory usage reaches level 2
threshold
Memory usage includes the following levels of thresholds: normal, level 1, level 2, and level 3. When
level 2 threshold is reached, BGP tears down an EBGP session to release memory resources periodically
until the memory usage is exempt from level 2 threshold. You can configure this feature to avoid tearing
down the BGP session with a specific EBGP peer when memory usage reaches level 2 threshold.
For more information about thresholds, see Fundamentals Configuration Guide.
To configure BGP to protect EBGP peer or peer group when the memory usage reaches level 2 threshold
(IPv4):
Step
1.
Enter system view.
Command
Remarks
system-view
N/A
• Enter BGP view:
bgp as-number
2.
Enter BGP view or BGP-VPN
view.
• Enter BGP-VPN view:
a. bgp as-number
b. ip vpn-instance
vpn-instance-name
215
N/A
Step
3.
Configure BGP to protect
EBGP peer or peer group
when the memory usage
reaches level 2 threshold.
Command
Remarks
peer { group-name | ip-address }
low-memory-exempt
By default, BGP tears down an
EBGP session to release memory
resources periodically when level
2 threshold is reached.
To configure BGP to protect EBGP peer or peer group when the memory usage reaches level 2 threshold
(IPv6):
Step
1.
Enter system view.
Command
Remarks
system-view
N/A
• Enter BGP view:
bgp as-number
2.
Enter BGP view or BGP-VPN
view.
• Enter BGP-VPN view:
a. bgp as-number
N/A
b. ip vpn-instance
vpn-instance-name
3.
Configure BGP to protect
EBGP peer or peer group
when the memory usage
reaches level 2 threshold.
peer { group-name |
ipv6-address }
low-memory-exempt
By default, BGP tears down an
EBGP session to release memory
resources periodically when level
2 threshold is reached.
Configuring a large-scale BGP network
In a large network, the number of BGP connections is huge and BGP configuration and maintenance are
complicated. To simply BGP configuration, you can use the peer group, community, route reflector, and
confederation features as needed. For more information about configuring peer groups, see
"Configuring a BGP peer group."
Configuring BGP community
By default, a router does not advertise the COMMUNITY or extended community attribute to its peers or
peer groups. When the router receives a route carrying the COMMUNITY or extended community
attribute, it removes the attribute before advertising the route to other peers or peer groups.
Perform this task to enable a router to advertise the COMMUNITY or extended community attribute to its
peers for route filtering and control. You can also reference a routing policy to add or modify the
COMMUNITY or extended community attribute for specific routes. For more information about routing
policy, see "Configuring routing policies."
To configure BGP community (IPv4):
Step
1.
Enter system view.
Command
Remarks
system-view
N/A
216
Step
Command
Remarks
• Enter BGP view:
bgp as-number
2.
Enter BGP view or BGP-VPN
view.
• Enter BGP-VPN view:
a. bgp as-number
N/A
b. ip vpn-instance
vpn-instance-name
3.
Enter BGP IPv4 unicast
instance view or BGP-VPN
IPv4 unicast instance view.
ipv4-family [ unicast ]
N/A
• Advertise the COMMUNITY
4.
5.
Advertise the COMMUNITY
or extended community
attribute to a peer or peer
group.
(Optional.) Apply a routing
policy to routes advertised to
a peer or peer group.
attribute to a peer or peer
group:
peer { group-name |
ip-address }
advertise-community
• Advertise the extended
community attribute to a peer
or peer group:
peer { group-name |
ip-address }
advertise-ext-community
peer { group-name | ip-address }
route-policy route-policy-name
export
By default, the COMMUNITY or
extended community attribute is
not advertised.
By default, no routing policy is
applied.
To configure BGP community (IPv6):
Step
Command
Remarks
1.
Enter system view.
system-view
N/A
2.
Enter BGP view.
bgp as-number
N/A
3.
Enter BGP IPv6 unicast
instance view.
ipv6-family [ unicast ]
N/A
• Advertise the COMMUNITY
4.
5.
Advertise the COMMUNITY
or extended community
attribute to a peer or peer
group.
(Optional.) Apply a routing
policy to routes advertised to
a peer or peer group.
attribute to a peer or peer
group:
peer { group-name |
ipv6-address }
advertise-community
• Advertise the extended
community attribute to a peer
or peer group:
peer { group-name |
ipv6-address }
advertise-ext-community
peer { group-name |
ipv6-address } route-policy
route-policy-name export
217
By default, the COMMUNITY or
extended community attribute is
not advertised.
By default, no routing policy is
applied.
Configuring a BGP route reflector
If an AS has many BGP routers, configure them as a cluster. To reduce IBGP connections, configure one
of them as a route reflector and others as clients.
To improve availability, you can specify multiple route reflectors for a cluster. The route reflectors in the
cluster must have the same cluster ID to avoid routing loops.
To configure a BGP route reflector (IPv4):
Step
1.
Enter system view.
Command
Remarks
system-view
N/A
• Enter BGP view:
bgp as-number
2.
Enter BGP view or BGP-VPN
view.
• Enter BGP-VPN view:
a. bgp as-number
N/A
b. ip vpn-instance
vpn-instance-name
Enter BGP IPv4 unicast
instance view or BGP-VPN
IPv4 unicast instance view.
ipv4-family [ unicast ]
N/A
4.
Configure the router as a route
reflector and specify a peer or
peer group as its client.
peer { group-name | ip-address }
reflect-client
By default, no route reflector or
client is configured.
5.
Enable route reflection
between clients.
reflect between-clients
By default, route reflection
between clients is enabled.
6.
(Optional.) Configure the
cluster ID of the route reflector.
reflector cluster-id { cluster-id |
ip-address }
By default, a route reflector uses its
own router ID as the cluster ID.
3.
To configure a BGP route reflector (IPv6):
Step
Command
Remarks
1.
Enter system view.
system-view
N/A
2.
Enter BGP view.
bgp as-number
N/A
3.
Enter BGP IPv6 unicast
instance view.
ipv6-family [ unicast ]
N/A
4.
Configure the router as a route
reflector and specify a peer or
peer group as its client.
peer { group-name |
ipv6-address } reflect-client
By default, no route reflector or
client is configured.
5.
Enable route reflection
between clients.
reflect between-clients
By default, route reflection
between clients is enabled.
6.
(Optional.) Configure the
cluster ID of the route reflector.
reflector cluster-id { cluster-id |
ip-address }
By default, a route reflector uses its
own router ID as the cluster ID.
Configuring a BGP confederation
BGP confederation provides another way to reduce IBGP connections in an AS.
218
A confederation contains sub-ASs. In each sub-AS, IBGP peers are fully meshed. Sub-ASs establish EBGP
connections in between.
Configuring a BGP confederation
After you split an AS into multiple sub-ASs, configure a router in a sub-AS as follows:
1.
Enable BGP and specify the AS number of the router. For more information, see "Enabling BGP."
2.
Specify the confederation ID. From an outsider’s perspective, the sub-ASs of the confederation is
a single AS, which is identified by the confederation ID.
3.
If the router needs to establish EBGP connections to other sub-ASs, you must specify the peering
sub-ASs in the confederation.
A confederation can contain a maximum of 32 sub-ASs. The AS number of a sub-AS is effective only in
the confederation.
To configure a BGP confederation:
Step
Command
Remarks
1.
Enter system view.
system-view
N/A
2.
Enter BGP view.
bgp as-number
N/A
3.
Configure a confederation ID.
confederation id as-number
By default, no confederation ID is
configured.
4.
Specify peering sub-ASs in the
confederation.
confederation peer-as
as-number-list
By default, no peering sub-AS is
specified.
Configuring confederation compatibility
If any routers in the confederation do not comply with RFC 3065, enable confederation compatibility to
allow the router to work with those routers.
To configure confederation compatibility:
Step
Command
Remarks
1.
Enter system view.
system-view
N/A
2.
Enter BGP view.
bgp as-number
N/A
3.
Enable confederation
compatibility.
confederation nonstandard
By default, confederation
compatibility is disabled.
Configuring BGP GR
Graceful Restart (GR) ensures continuous forwarding when BGP restarts or an active/standby switchover
occurs. GR defines the following types of GR-capable devices:
•
GR restarter—Performs GR upon a BGP restart or active/standby switchover.
•
GR helper—Helps the GR restarter to complete the GR process.
A device can act as a GR restarter and GR helper at the same time.
BGP GR works as follows:
219
1.
The BGP GR restarter and helper exchange Open messages for GR capability negotiation. If both
parties have the GR capability, they establish a GR-capable session. The GR restarter sends the GR
timer set by the graceful-restart timer restart command to the GR helper in an Open message.
2.
When an active/standby switchover occurs or BGP restarts, the GR restarter does not remove
existing BGP routes, and it still uses these routes for packet forwarding. The GR helper marks all
routes learned from the GR restarter as stale instead of deleting them, and it still uses these routes
for packet forwarding. During the GR process, packet forwarding is not interrupted.
3.
After the active/standby switchover or BGP restart completes, the GR restarter reestablishes a BGP
session with the GR helper. If the BGP session fails to be established within the GR timer advertised
by the GR Restarater, the GR helper removes the stale routes.
4.
If the BGP session is established, routing information is exchanged for the GR Restarter to retrieve
route entries and for the GR Helper to recover stale routes. You can use the graceful-restart timer
wait-for-rib command to configure the time for the local router to wait for the End-Of-RIB (End of
Routing-Information-Base) marker, and control the route convergence speed. If routing information
exchange is not completed within the time, the GR restarter does not receive new routes. Instead,
the GR restarter updates its routing table and forwarding table with the BGP routes already
learned to complete BGP route convergence. The GR helper removes the stale routes.
Follow these guidelines when you configure BGP GR:
•
The End-Of-RIB indicates the end of route updates.
•
The maximum time to wait for the End-of-RIB marker configured on the local end is not advertised
to the peer. It controls the time for the local end to receive updates from the peer.
Perform the following configuration on the GR restarter and GR helper.
To configure BGP GR:
Step
Command
Remarks
1.
Enter system view.
system-view
N/A
2.
Enter BGP view.
bgp as-number
N/A
3.
Enable GR capability for BGP.
graceful-restart
By default, GR capability is
disabled for BGP.
The default setting is 150 seconds.
4.
Configure the GR timer.
graceful-restart timer restart
timer
5.
Configure the maximum time to
wait for the End-of-RIB marker.
graceful-restart timer
wait-for-rib timer
The time that a peer waits to
reestablish a session must be less
than the hold time.
The default setting is 180 seconds.
Enabling trap
After trap is enabled for BGP, BGP generates Level-4 traps to report important events. The generated
traps are sent to the information center of the device. The output rules of the traps (whether to output the
traps and where to output) are determined according to the information center configuration. For
information center configuration, see Network Management and Monitoring Configuration Guide.
To enable trap:
220
Step
1.
Enter system view.
Command
Remarks
system-view
N/A
By default, trap for BGP is enabled.
2.
Enable trap for BGP.
snmp-agent trap enable bgp
For more information about this
command, see Network Management
and Monitoring Configuration Guide.
Enabling logging of session state changes
Perform this task to enable BGP to log BGP session establishment and disconnection events. To view the
log information, use the display bgp peer ipv4 log-info command.
To enable the logging of session state changes:
Step
Command
Remarks
1.
Enter system view.
system-view
N/A
2.
Enter BGP view.
bgp as-number
N/A
3.
Enable the logging of session
state changes globally.
log-peer-change
By default, logging of session state
changes is enabled globally.
Configuring BFD for BGP
IMPORTANT:
If you have enabled GR, use BFD with caution because BFD might detect a failure before the system
performs GR, which will result in GR failure. If you have enabled both BFD and GR for BGP, do not disable
BFD during a GR process to avoid GR failure.
BGP maintains neighbor relationships based on the keepalive timer and hold timer in seconds. It requires
that the hold time must be at least three times the keepalive interval. This mechanism makes link failure
detection slow. Once a failure occurs on a high-speed link, a large quantity of packets will be dropped
before routing convergence completes. BFD for BGP can solve this problem by fast detecting link failures
to reduce convergence time.
For more information about BFD, see High Availability Configuration Guide.
Before you can enable BFD for the BGP peer, establish a BGP session between the local router and the
peer.
To enable BFD for a BGP peer (IPv4):
Step
1.
Enter system view.
Command
Remarks
system-view
N/A
221
Step
Command
Remarks
• Enter BGP view:
bgp as-number
2.
Enter BGP view or BGP-VPN view.
• Enter BGP-VPN view:
N/A
a. bgp as-number
b. ip vpn-instance vpn-instance-name
3.
Enable BFD to detect the link to the
specified BGP peer.
peer ip-address bfd
By default, BFD is
not enabled.
To enable BFD for a BGP peer (IPv6):
Step
1.
Enter system view.
Command
Remarks
system-view
N/A
• Enter BGP view:
bgp as-number
2.
Enter BGP view or BGP-VPN view.
• Enter BGP-VPN view:
N/A
a. bgp as-number
b. ip vpn-instance vpn-instance-name
3.
Enable BFD to detect the link to the
specified IPv6 BGP peer.
peer ipv6-address bfd
By default, BFD is
not enabled.
Displaying and maintaining BGP
Execute display commands in any view and reset commands in user view (IPv4).
Task
Command
Display BGP IPv4 unicast peer group
information.
display bgp group ipv4 [ unicast ] [ vpn-instance
vpn-instance-name ] [ group-name ]
Display BGP IPv4 unicast peer or peer
group information.
display bgp peer ipv4 [ unicast ] [ vpn-instance
vpn-instance-name ] [ ip-address { log-info | verbose } |
group-name log-info | verbose ]
Display BGP IPv4 unicast routing
information.
display bgp routing-table ipv4 [ unicast ] [ vpn-instance
vpn-instance-name ] [ network-address [ { mask | mask-length }
[ longest-match ] ] ]
Display BGP IPv4 unicast route
advertisement information.
display bgp routing-table ipv4 [ unicast ] [ vpn-instance
vpn-instance-name ] network-address [ mask | mask-length ]
advertise-info
Display BGP IPv4 unicast routing
information sent to/received from the
specified BGP peer.
display bgp routing-table ipv4 [ unicast ] [ vpn-instance
vpn-instance-name ] peer ip-address { advertised-routes |
received-routes } [ network-address [ mask | mask-length ] |
statistic ]
Display BGP IPv4 unicast routing statistics.
display bgp routing-table ipv4 [ unicast ] [ vpn-instance
vpn-instance-name ] statistic
222
Task
Command
Display BGP IPv4 unicast routing
information matching the specified AS
path list.
display bgp routing-table ipv4 [ unicast ] [ vpn-instance
vpn-instance-name ] as-path-acl as-path-acl-number
Display BGP IPv4 unicast routing
information matching the specified BGP
community list.
display bgp routing-table ipv4 [ unicast ] [ vpn-instance
vpn-instance-name ] community-list
{ { basic-community-list-number | comm-list-name }
[ whole-match ] | adv-community-list-number }
Display dampened BGP IPv4 unicast
routing information.
display bgp routing-table dampened ipv4 [ unicast ]
[ vpn-instance vpn-instance-name ]
Display BGP dampening parameter
information.
display bgp dampening parameter ipv4 [ unicast ] [ vpn-instance
vpn-instance-name ]
Display BGP IPv4 unicast routing flap
statistics.
display bgp routing-table flap-info ipv4 [ unicast ] [ vpn-instance
vpn-instance-name ] [ network-address [ { mask | mask-length }
[ longest-match ] ] | as-path-acl as-path-acl-number ]
Display information about routes
advertised by the network command and
shortcut routes configured by the network
short-cut command.
display bgp network ipv4 [ unicast ] [ vpn-instance
vpn-instance-name ]
Display BGP path attribute information.
display bgp paths [ as-regular-expression ]
Reset all BGP sessions.
reset bgp all
Reset IPv4 unicast BGP sessions.
reset bgp { as-number | ip-address | all | external | group
group-name | internal } ipv4 [ unicast ] [ vpn-instance
vpn-instance-name ]
Clear dampened BGP IPv4 unicast routing
information and release suppressed
routes.
reset bgp dampening ipv4 [ unicast ] [ vpn-instance
vpn-instance-name ] [ network-address [ mask | mask-length ] ]
Clear BGP IPv4 unicast route flap
information.
reset bgp flap-info ipv4 [ unicast ] [ vpn-instance
vpn-instance-name ] [ network-address [ mask | mask-length ] |
as-path-acl as-path-acl-number | peer peer-address ]
Execute display commands in any view and reset commands in user view (IPv6).
Task
Command
Display BGP IPv6 unicast peer group
information.
display bgp group ipv6 [ unicast ] [ vpn-instance
vpn-instance-name ] [ group-name ]
Display BGP IPv6 unicast peer or peer
group information.
Display BGP IPv6 unicast routing
information.
display bgp peer ipv6 [ unicast ] [ group-name log-info |
ipv6-address { log-info | verbose } | verbose ]
display bgp peer ipv6 [ unicast ] vpn-instance vpn-instance-name
[ group-name log-info | ipv6-address { log-info | verbose } |
verbose ]
display bgp routing-table ipv6 [ unicast ] [ vpn-instance
vpn-instance-name ] [ network-address prefix-length
[ advertise-info ] ]
223
Task
Display BGP IPv6 unicast routing
information sent to/received from the
specified BGP peer.
Command
display bgp routing-table ipv6 [ unicast ] peer ipv6-address
{ advertised-routes | received-routes } [ network-address
prefix-length | statistics ]
display bgp routing-table ipv6 [ unicast ] vpn-instance
vpn-instance-name peer ipv6-address { advertised-routes |
received-routes } [ network-address prefix-length | statistics ]
Display BGP IPv6 unicast routing statistics.
display bgp routing-table ipv6 [ unicast ] [ vpn-instance
vpn-instance-name ] statistics
Display BGP IPv6 unicast routing
information matching the specified AS
path list.
display bgp routing-table ipv6 [ unicast ] [ vpn-instance
vpn-instance-name ] as-path-acl as-path-acl-number
Display BGP IPv6 unicast routing
information matching the specified BGP
community list.
display bgp routing-table ipv6 [ unicast ] [ vpn-instance
vpn-instance-name ] community-list
{ { basic-community-list-number | comm-list-name }
[ whole-match ] | adv-community-list-number }
Display dampened BGP IPv6 unicast
routing information.
display bgp routing-table dampened ipv6 [ unicast ]
[ vpn-instance vpn-instance-name ]
Display BGP dampening parameter
information.
display bgp dampening parameter ipv6 [ unicast ] [ vpn-instance
vpn-instance-name ]
Display BGP IPv6 unicast routing flap
statistics.
display bgp routing-table flap-info ipv6 [ unicast ] [ vpn-instance
vpn-instance-name ] [ network-address prefix-length | as-path-acl
as-path-acl-number ]
Display the incoming label of BGP IPv6
unicast routing information.
display bgp routing-table ipv6 [ unicast ] inlabel
Display the outgoing label of BGP IPv6
unicast routing information.
display bgp routing-table ipv6 [ unicast ] outlabel
Display information about routes
advertised by the network command and
shortcut routes configured by the network
short-cut command.
display bgp network ipv6 [ unicast ] [ vpn-instance
vpn-instance-name ]
Display BGP path attribute information.
display bgp paths [ as-regular-expression ]
Reset IPv6 unicast BGP sessions.
reset bgp { as-number | ipv6-address | all | external | group
group-name | internal } ipv6 [ unicast ] [ vpn-instance
vpn-instance-name ]
reset bgp ip-address ipv6 [ unicast ]
Clear dampened BGP IPv6 unicast routing
information and release suppressed
routes.
reset bgp dampening ipv6 [ unicast ] [ vpn-instance
vpn-instance-name ] [ network-address prefix-length ]
Clear BGP IPv6 unicast route flap
information.
reset bgp flap-info ipv6 [ unicast ] [ vpn-instance
vpn-instance-name ] [ network-address prefix-length | as-path-acl
as-path-acl-number | peer ipv6-address ]
224
IPv4 BGP configuration examples
Basic BGP configuration example
Network requirements
In Figure 57, run EBGP between Switch A and Switch B, and run IBGP between Switch B and Switch C
so that Switch C can access the network 8.1.1.0/24 connected to Switch A.
Figure 57 Network diagram
Configuration considerations
To prevent route flapping caused by port state changes, this example uses loopback interfaces to
establish IBGP connections. Because loopback interfaces are virtual interfaces, use the peer
connect-interface command to specify the loopback interface as the source interface for establishing
BGP connections. Enable OSPF in AS 65009 to make sure that Switch B can communicate with Switch
C through loopback interfaces.
The EBGP peers, Switch A and Switch B (usually belong to different carriers), are located in different ASs.
Typically, their loopback interfaces are not reachable to each other, so directly connected interfaces are
used for establishing BGP sessions. To enable Switch C to access the network 8.1.1.0/24 connected
directly to Switch A, inject network 8.1.1.0/24 to the BGP routing table of Switch A.
Configuration procedure
1.
Configure IP addresses for interfaces. (Details not shown.)
2.
Configure IBGP:
# Configure Switch B.
<SwitchB> system-view
[SwitchB] bgp 65009
[SwitchB-bgp] router-id 2.2.2.2
[SwitchB-bgp] peer 3.3.3.3 as-number 65009
[SwitchB-bgp] peer 3.3.3.3 connect-interface loopback 0
[SwitchB-bgp] ipv4-family unicast
[SwitchB-bgp-ipv4] peer 3.3.3.3 enable
[SwitchB-bgp-ipv4] quit
[SwitchB-bgp] quit
[SwitchB] ospf 1
[SwitchB-ospf-1] area 0
[SwitchB-ospf-1-area-0.0.0.0] network 2.2.2.2 0.0.0.0
[SwitchB-ospf-1-area-0.0.0.0] network 9.1.1.1 0.0.0.255
[SwitchB-ospf-1-area-0.0.0.0] quit
225
[SwitchB-ospf-1] quit
# Configure Switch C.
<SwitchC> system-view
[SwitchC] bgp 65009
[SwitchC-bgp] router-id 3.3.3.3
[SwitchC-bgp] peer 2.2.2.2 as-number 65009
[SwitchC-bgp] peer 2.2.2.2 connect-interface loopback 0
[SwitchC-bgp] ipv4-family unicast
[SwitchC-bgp-ipv4] peer 2.2.2.2 enable
[SwitchC-bgp-ipv4] quit
[SwitchC-bgp] quit
[SwitchC] ospf 1
[SwitchC-ospf-1] area 0
[SwitchC-ospf-1-area-0.0.0.0] network 3.3.3.3 0.0.0.0
[SwitchC-ospf-1-area-0.0.0.0] network 9.1.1.0 0.0.0.255
[SwitchC-ospf-1-area-0.0.0.0] quit
[SwitchC-ospf-1] quit
[SwitchC] display bgp peer ipv4
BGP local router ID : 3.3.3.3
Local AS number : 65009
Total number of peers : 1
Peer
2.2.2.2
Peers in established state : 1
AS
MsgRcvd
65009
2
MsgSent OutQ PrefRcv Up/Down
2
0
State
0 00:00:13 Established
The output shows that Switch C has established an IBGP peer relationship with Switch B.
3.
Configure EBGP:
# Configure Switch A.
<SwitchA> system-view
[SwitchA] bgp 65008
[SwitchA-bgp] router-id 1.1.1.1
[SwitchA-bgp] peer 3.1.1.1 as-number 65009
[SwitchA-bgp] ipv4-family unicast
[SwitchA-bgp-ipv4] peer 3.1.1.1 enable
[SwitchA-bgp-ipv4] network 8.1.1.0 24
[SwitchA-bgp-ipv4] quit
[SwitchA-bgp] quit
# Configure Switch B.
[SwitchB] bgp 65009
[SwitchB-bgp] peer 3.1.1.2 as-number 65008
[SwitchB-bgp] ipv4-family unicast
[SwitchB-bgp-ipv4] peer 3.1.1.2 enable
[SwitchB-bgp-ipv4] quit
[SwitchB-bgp] quit
# Display BGP peer information on Switch B.
[SwitchB] display bgp peer ipv4
226
BGP local router ID : 2.2.2.2
Local AS number : 65009
Total number of peers : 2
Peer
Peers in established state : 2
AS
MsgRcvd
MsgSent OutQ PrefRcv Up/Down
State
3.3.3.3
65009
4
4
0
0 00:02:49 Established
3.1.1.2
65008
2
2
0
0 00:00:05 Established
The output shows that Switch B has established an IBGP peer relationship with Switch C and an
EBGP peer relationship with Switch A.
# Display the BGP routing table on Switch A.
[SwitchA] display bgp routing-table ipv4
Total number of routes: 1
BGP local router ID is 1.1.1.1
Status codes: * - valid, > - best, d - damped, h - history,
s - suppressed, S - Stale, i - internal, e - external
Origin: i - IGP, e - EGP, ? - incomplete
>
Network
NextHop
MED
8.1.1.0/24
8.1.1.1
0
LocPrf
PrefVal Path/Ogn
0
i
# Display the BGP routing table on Switch B.
[SwitchB] display bgp routing-table ipv4
Total number of routes: 1
BGP local router ID is 2.2.2.2
Status codes: * - valid, > - best, d - damped, h - history,
s - suppressed, S - Stale, i - internal, e - external
Origin: i - IGP, e - EGP, ? - incomplete
Network
NextHop
MED
>e 8.1.1.0/24
3.1.1.2
0
LocPrf
PrefVal Path/Ogn
0
65008i
# Display the BGP routing table on Switch C.
[SwitchC] display bgp routing-table ipv4
Total number of routes: 1
BGP local router ID is 3.3.3.3
Status codes: * - valid, > - best, d - damped, h - history,
s - suppressed, S - Stale, i - internal, e - external
Origin: i - IGP, e - EGP, ? - incomplete
Network
NextHop
MED
227
LocPrf
PrefVal Path/Ogn
i 8.1.1.0/24
3.1.1.2
0
100
0
65008i
The outputs show that Switch A has learned no route to AS65009, and Switch C has learned
network 8.1.1.0, but the next hop 3.1.1.2 is unreachable. As a result, the route is invalid.
4.
Redistribute direct routes:
Configure BGP to redistribute direct routes on Switch B, so that Switch A can obtain the route to
9.1.1.0/24, and Switch C can obtain the route to 3.1.1.0/24.
# Configure Switch B.
[SwitchB] bgp 65009
[SwitchB-bgp] ipv4-family unicast
[SwitchB-bgp-ipv4] import-route direct
[SwitchB-bgp-ipv4] quit
[SwitchB-bgp] quit
# Display the BGP routing table on Switch A.
[SwitchA] display bgp routing-table ipv4
Total number of routes: 4
BGP local router ID is 1.1.1.1
Status codes: * - valid, > - best, d - damped, h - history,
s - suppressed, S - Stale, i - internal, e - external
Origin: i - IGP, e - EGP, ? - incomplete
Network
NextHop
MED
>e 2.2.2.2/32
3.1.1.1
0
0
65009?
e 3.1.1.0/24
3.1.1.1
0
0
65009?
8.1.1.0/24
8.1.1.1
0
0
i
>e 9.1.1.0/24
3.1.1.1
0
0
65009?
>
LocPrf
PrefVal Path/Ogn
Two routes, 2.2.2.2/32 and 9.1.1.0/24, have been added in Switch A’s routing table.
# Display the BGP routing table on Switch C.
[SwitchC] display bgp routing-table ipv4
Total number of routes: 4
BGP local router ID is 3.3.3.3
Status codes: * - valid, > - best, d - damped, h - history,
s - suppressed, S - Stale, i - internal, e - external
Origin: i - IGP, e - EGP, ? - incomplete
Network
NextHop
MED
LocPrf
PrefVal Path/Ogn
i 2.2.2.2/32
2.2.2.2
0
100
0
?
>i 3.1.1.0/24
2.2.2.2
0
100
0
?
>i 8.1.1.0/24
3.1.1.2
0
100
0
65008i
>i 9.1.1.0/24
2.2.2.2
0
100
0
?
The output shows that the route 8.1.1.0 becomes valid with the next hop as Switch A.
228
Verifying the configuration
# Ping 8.1.1.1 on Switch C.
[SwitchC] ping 8.1.1.1
PING 8.1.1.1 (8.1.1.1): 56 data bytes
56 bytes from 8.1.1.1: icmp_seq=0 ttl=254 time=10.000 ms
56 bytes from 8.1.1.1: icmp_seq=1 ttl=254 time=4.000 ms
56 bytes from 8.1.1.1: icmp_seq=2 ttl=254 time=4.000 ms
56 bytes from 8.1.1.1: icmp_seq=3 ttl=254 time=3.000 ms
56 bytes from 8.1.1.1: icmp_seq=4 ttl=254 time=3.000 ms
--- 8.1.1.1 ping statistics --5 packet(s) transmitted, 5 packet(s) received, 0.0% packet loss
round-trip min/avg/max/stddev = 3.000/4.800/10.000/2.638 ms
BGP and IGP route redistribution configuration example
Network requirements
As shown in Figure 58, all devices of company A belong to AS 65008, and all devices of company B
belong to AS 65009. AS 65008 and AS 65009 are connected through Switch A and Switch B. It is
required that Switch A can access network 9.1.2.0/24 in AS 65009, and Switch C can access network
8.1.1.0/24 in AS 65008.
Figure 58 Network diagram
Configuration considerations
Configure BGP to redistribute routes from OSPF on Switch B, so Switch A can obtain the route to
9.1.2.0/24. Configure OSPF to redistribute routes from BGP on Switch B, so Switch C can obtain the route
to 8.1.1.0/24.
Configuration procedure
1.
Configure IP addresses for interfaces. (Details not shown.)
2.
Configure OSPF:
Enable OSPF in AS 65009, so Switch B can obtain the route to 9.1.2.0/24.
# Configure Switch B.
<SwitchB> system-view
[SwitchB] ospf 1
[SwitchB-ospf-1] area 0
[SwitchB-ospf-1-area-0.0.0.0] network 2.2.2.2 0.0.0.0
[SwitchB-ospf-1-area-0.0.0.0] network 9.1.1.0 0.0.0.255
[SwitchB-ospf-1-area-0.0.0.0] quit
[SwitchB-ospf-1] quit
229
# Configure Switch C.
<SwitchC> system-view
[SwitchC] ospf 1
[SwitchC-ospf-1] import-route direct
[SwitchC-ospf-1] area 0
[SwitchC-ospf-1-area-0.0.0.0] network 9.1.1.0 0.0.0.255
[SwitchC-ospf-1-area-0.0.0.0] quit
[SwitchC-ospf-1] quit
3.
Configure the EBGP connection:
Configure the EBGP connection and inject network 8.1.1.0/24 to the BGP routing table of Switch
A, so that Switch B can obtain the route to 8.1.1.0/24.
# Configure Switch A.
<SwitchA> system-view
[SwitchA] bgp 65008
[SwitchA-bgp] router-id 1.1.1.1
[SwitchA-bgp] peer 3.1.1.1 as-number 65009
[SwitchA-bgp] ipv4-family unicast
[SwitchA-bgp-ipv4] peer 3.1.1.1 enable
[SwitchA-bgp-ipv4] network 8.1.1.0 24
[SwitchA-bgp-ipv4] quit
[SwitchA-bgp] quit
# Configure Switch B.
[SwitchB] bgp 65009
[SwitchB-bgp] router-id 2.2.2.2
[SwitchB-bgp] peer 3.1.1.2 as-number 65008
[SwitchB-bgp] ipv4-family unicast
[SwitchB-bgp-ipv4] peer 3.1.1.2 enable
4.
Configure BGP and IGP route redistribution:
# Configure route redistribution between BGP and OSPF on Switch B.
[SwitchB-bgp-ipv4] import-route ospf 1
[SwitchB-bgp-ipv4] quit
[SwitchB-bgp] quit
[SwitchB] ospf 1
[SwitchB-ospf-1] import-route bgp
[SwitchB-ospf-1] quit
# Display the BGP routing table on Switch A.
[SwitchA] display bgp routing-table ipv4
Total number of routes: 3
BGP local router ID is 1.1.1.1
Status codes: * - valid, > - best, d - damped, h - history,
s - suppressed, S - Stale, i - internal, e - external
Origin: i - IGP, e - EGP, ? - incomplete
Network
NextHop
MED
230
LocPrf
PrefVal Path/Ogn
>e 3.3.3.3/32
3.1.1.1
1
0
65009?
>
8.1.1.0/24
8.1.1.1
0
0
i
>e 9.1.2.0/24
3.1.1.1
1
0
65009?
# Display the OSPF routing table on Switch C.
[SwitchC] display ospf routing
OSPF Process 1 with Router ID 3.3.3.3
Routing Tables
Routing for Network
Destination
Cost
Type
9.1.1.0/24
1
2.2.2.2/32
1
Destination
8.1.1.0/24
NextHop
AdvRouter
Area
Transit 9.1.1.2
3.3.3.3
0.0.0.0
Stub
9.1.1.1
2.2.2.2
0.0.0.0
Cost
Type
Tag
NextHop
AdvRouter
1
Type2
1
9.1.1.1
2.2.2.2
Routing for ASEs
Total Nets: 3
Intra Area: 2
Inter Area: 0
ASE: 1
NSSA: 0
Verifying the configuration
# Use ping for verification.
[SwitchA] ping -a 8.1.1.1 9.1.2.1
PING 9.1.2.1 (9.1.2.1) from 8.1.1.1: 56 data bytes
56 bytes from 9.1.2.1: icmp_seq=0 ttl=254 time=10.000 ms
56 bytes from 9.1.2.1: icmp_seq=1 ttl=254 time=12.000 ms
56 bytes from 9.1.2.1: icmp_seq=2 ttl=254 time=2.000 ms
56 bytes from 9.1.2.1: icmp_seq=3 ttl=254 time=7.000 ms
56 bytes from 9.1.2.1: icmp_seq=4 ttl=254 time=9.000 ms
--- 9.1.2.1 ping statistics --5 packet(s) transmitted, 5 packet(s) received, 0.0% packet loss
round-trip min/avg/max/stddev = 2.000/8.000/12.000/3.406 ms
[SwitchC] ping -a 9.1.2.1 8.1.1.1
PING 8.1.1.1 (8.1.1.1) from 9.1.2.1: 56 data bytes
56 bytes from 8.1.1.1: icmp_seq=0 ttl=254 time=9.000 ms
56 bytes from 8.1.1.1: icmp_seq=1 ttl=254 time=4.000 ms
56 bytes from 8.1.1.1: icmp_seq=2 ttl=254 time=3.000 ms
56 bytes from 8.1.1.1: icmp_seq=3 ttl=254 time=3.000 ms
56 bytes from 8.1.1.1: icmp_seq=4 ttl=254 time=3.000 ms
--- 8.1.1.1 ping statistics --5 packet(s) transmitted, 5 packet(s) received, 0.0% packet loss
round-trip min/avg/max/stddev = 3.000/4.400/9.000/2.332 ms
231
BGP route summarization configuration example
Network requirements
As shown in Figure 59, run EBGP between Switch C and Switch D, so the internal network and external
network can communicate with each other.
In AS 65106, configure static routing between Switch A and Switch B, configure OSPF between Switch
B and Switch C, and configure OSPF to redistribute static routes, so the devices in the internal network
can communicate with each other.
Configure route summarization on Switch C so BGP advertises a summary route instead of the specific
networks 192.168.64.0/24, 192.168.74.0/24, and 192.168.99.0/24 to Switch D.
Figure 59 Network diagram
Configuration procedure
1.
Configure IP addresses for interfaces. (Details not shown.)
2.
Configure static routing between Switch A and Switch B:
# Configure a default route with the next hop 192.168.212.1 on Switch A.
<SwitchA> system-view
[SwitchA] ip route-static 0.0.0.0 0 192.168.212.1
# Configure static routes to 192.168.64.0/24, 192.168.74.0/24, and 192.168.99.0/24 with
the same next hop 192.168.212.161 on Switch B.
<SwitchB> system-view
[SwitchB] ip route-static 192.168.64.0 24 192.168.212.161
[SwitchB] ip route-static 192.168.74.0 24 192.168.212.161
[SwitchB] ip route-static 192.168.99.0 24 192.168.212.161
3.
Configure OSPF between Switch B and Switch C and configure OSPF on Switch B to redistribute
static routes:
# Configure OSPF to advertise the local network and enable OSPF to redistribute static routes on
Switch B.
[SwitchB] ospf
[SwitchB-ospf-1] area 0
[SwitchB-ospf-1-area-0.0.0.0] network 172.17.100.0 0.0.0.255
[SwitchB-ospf-1-area-0.0.0.0] quit
[SwitchB-ospf-1] import-route static
232
[SwitchB-ospf-1] quit
# Configure OSPF to advertise the local networks on Switch C.
[SwitchC] ospf
[SwitchC-ospf-1] area 0
[SwitchC-ospf-1-area-0.0.0.0] network 172.17.100.0 0.0.0.255
[SwitchC-ospf-1-area-0.0.0.0] network 10.220.2.0 0.0.0.255
[SwitchC-ospf-1-area-0.0.0.0] quit
[SwitchC-ospf-1] quit
# Display the IP routing table on Switch C.
[SwitchC] display ip routing-table protocol ospf
Summary Count : 5
OSPF Routing table Status : <Active>
Summary Count : 3
Destination/Mask
Proto
Pre
Cost
NextHop
Interface
192.168.64.0/24
OSPF
150
1
172.17.100.1
Vlan100
192.168.74.0/24
OSPF
150
1
172.17.100.1
Vlan100
192.168.99.0/24
OSPF
150
1
172.17.100.1
Vlan100
OSPF Routing table Status : <Inactive>
Summary Count : 2
Destination/Mask
Proto
Pre
Cost
NextHop
Interface
10.220.2.0/24
OSPF
10
1
10.220.2.16
Vlan200
172.17.100.0/24
OSPF
10
1
172.17.100.2
Vlan100
The output shows that Switch C has learned routes to 192.168.64.0/24, 192.168.99.0/24, and
192.168.64.0/18 through OSPF.
4.
Configure BGP between Switch C and Switch D and configure BGP on Switch C to redistribute
OSPF routes:
# On Switch C, enable BGP, specify Switch D as an EBGP peer, and configure BGP to redistribute
OSPF routes.
[SwitchC] bgp 65106
[SwitchC-bgp] router-id 3.3.3.3
[SwitchC-bgp] peer 10.220.2.217 as-number 64631
[SwitchC-bgp] ipv4-family unicast
[SwitchC-bgp-ipv4] peer 10.220.2.217 enable
[SwitchC-bgp-ipv4] import-route ospf
# Enable BGP, and configure Switch C as an EBGP peer on Switch D.
[SwitchD] bgp 64631
[SwitchD-bgp] router-id 4.4.4.4
[SwitchD-bgp] peer 10.220.2.16 as-number 65106
[SwitchD-bgp] ipv4-family unicast
[SwitchD-bgp-ipv4] peer 10.220.2.16 enable
[SwitchD-bgp-ipv4] quit
[SwitchD-bgp] quit
233
# Display the IP routing table on Switch D.
[SwitchD] display ip routing-table protocol bgp
Summary Count : 3
BGP Routing table Status : <Active>
Summary Count : 3
Destination/Mask
Proto
Pre
Cost
NextHop
Interface
192.168.64.0/24
BGP
255
1
10.220.2.16
Vlan200
192.168.74.0/24
BGP
255
1
10.220.2.16
Vlan200
192.168.99.0/24
BGP
255
1
10.220.2.16
Vlan200
BGP Routing table Status : <Inactive>
Summary Count : 0
The output shows that Switch D has learned routes to 192.168.64.0/24, 192.168.74.0/24, and
192.168.99.0/24 through BGP.
After the above configurations, ping hosts on networks 192.168.74.0/24, 192.168.99.0/24,
and 192.168.64.0/18 from Switch D. The ping operations succeed.
5.
Configure route summarization on Switch C to summarize 192.168.64.0/24,
192.168.74.0/24, and 192.168.99.0/24 into a single route 192.168.64.0/18 on Switch C,
and disable advertisement of the specific routes.
[SwitchC-bgp-ipv4] aggregate 192.168.64.0 18 detail-suppressed
[SwitchC-bgp-ipv4] quit
[SwitchC-bgp] quit
Verifying the configuration
# Display IP routing table on Switch C.
[SwitchC] display ip routing-table | include 192.168
192.168.64.0/18
BGP
130
0
127.0.0.1
NULL0
192.168.64.0/24
OSPF
150
1
172.17.100.1
Vlan100
192.168.74.0/24
OSPF
150
1
172.17.100.1
Vlan100
192.168.99.0/24
OSPF
150
1
172.17.100.1
Vlan100
The output shows that Switch C has a summary route 192.168.64.0/18 with the output interface Null0.
# Display IP routing table on Switch D.
[SwitchD] display ip routing-table protocol bgp
Summary Count : 1
BGP Routing table Status : <Active>
Summary Count : 1
Destination/Mask
Proto
Pre
Cost
NextHop
Interface
192.168.64.0/18
BGP
255
0
10.220.2.16
Vlan200
BGP Routing table Status : <Inactive>
Summary Count : 0
234
The output shows that Switch D has only one route 192.168.64.0/18 to AS 65106.
After the above configurations, ping the hosts on networks 192.168.64.0/24, 192.168.74.0/24 and
192.168.99.0/24 from Switch D. The ping operations succeed.
BGP load balancing configuration example
Network requirements
As shown in Figure 60, run EBGP between Switch A and Switch B and between Switch A and Switch C.
Run IBGP between Switch B and Switch C. Configure load balancing over the two EBGP links on Switch
A.
Figure 60 Network diagram
Configuration considerations
On Switch A, establish EBGP connections with Switch B and Switch C. Configure BGP to advertise
network 8.1.1.0/24 to Switch B and Switch C, so that Switch B and Switch C can access the internal
network connected to Switch A.
On Switch B, establish an EBGP connection with Switch A and an IBGP connection with Switch C.
Configure BGP to advertise network 9.1.1.0/24 to Switch A, so that Switch A can access the intranet
through Switch B. Configure a static route to interface loopback 0 on Switch C (or use a routing protocol
like OSPF) to establish the IBGP connection.
On Switch C, establish an EBGP connection with Switch A and an IBGP connection with Switch B.
Configure BGP to advertise network 9.1.1.0/24 to Switch A, so that Switch A can access the intranet
through Switch C. Configure a static route to interface loopback 0 on Switch B (or use another protocol
like OSPF) to establish the IBGP connection.
Configure load balancing on Switch A.
Configuration procedure
1.
Configure IP addresses for interfaces. (Details not shown.)
2.
Configure BGP connections:
# Configure Switch A.
<SwitchA> system-view
[SwitchA] bgp 65008
235
[SwitchA-bgp] router-id 1.1.1.1
[SwitchA-bgp] peer 3.1.1.1 as-number 65009
[SwitchA-bgp] peer 3.1.2.1 as-number 65009
[SwitchA-bgp] ipv4-family unicast
[SwitchA-bgp-ipv4] peer 3.1.1.1 enable
[SwitchA-bgp-ipv4] peer 3.1.2.1 enable
[SwitchA-bgp-ipv4] network 8.1.1.1 24
[SwitchA-bgp-ipv4] quit
[SwitchA-bgp] quit
# Configure Switch B.
<SwitchB> system-view
[SwitchB] bgp 65009
[SwitchB-bgp] router-id 2.2.2.2
[SwitchB-bgp] peer 3.1.1.2 as-number 65008
[SwitchB-bgp] peer 3.3.3.3 as-number 65009
[SwitchB-bgp] peer 3.3.3.3 connect-interface loopback 0
[SwitchB-bgp] ipv4-family unicast
[SwitchB-bgp-ipv4] peer 3.1.1.2 enable
[SwitchB-bgp-ipv4] peer 3.3.3.3 enable
[SwitchB-bgp-ipv4] network 9.1.1.0 24
[SwitchB-bgp-ipv4] quit
[SwitchB-bgp] quit
[SwitchB] ip route-static 3.3.3.3 32 9.1.1.2
# Configure Switch C.
<SwitchC> system-view
[SwitchC] bgp 65009
[SwitchC-bgp] router-id 3.3.3.3
[SwitchC-bgp] peer 3.1.2.2 as-number 65008
[SwitchC-bgp] peer 2.2.2.2 as-number 65009
[SwitchC-bgp] peer 2.2.2.2 connect-interface loopback 0
[SwitchC-bgp] ipv4-family unicast
[SwitchC-bgp-ipv4] peer 3.1.2.2 enable
[SwitchC-bgp-ipv4] peer 2.2.2.2 enable
[SwitchC-bgp-ipv4] network 9.1.1.0 24
[SwitchC-bgp-ipv4] quit
[SwitchC-bgp] quit
[SwitchC] ip route-static 2.2.2.2 32 9.1.1.1
# Display the BGP routing table on Switch A.
[SwitchA] display bgp routing-table ipv4
Total number of routes: 3
BGP local router ID is 1.1.1.1
Status codes: * - valid, > - best, d - damped, h - history,
s - suppressed, S - Stale, i - internal, e - external
Origin: i - IGP, e - EGP, ? - incomplete
Network
NextHop
MED
236
LocPrf
PrefVal Path/Ogn
>
*
{
{
8.1.1.0/24
8.1.1.1
0
0
i
>e 9.1.1.0/24
3.1.1.1
0
0
65009i
3.1.2.1
0
0
65009i
e
The output shows two valid routes to destination 9.1.1.0/24. The route with next hop 3.1.1.1 is
marked with a greater-than sign (>), indicating it is the best route (because the ID of Switch B
is smaller). The route with next hop 3.1.2.1 is marked with an asterisk (*), indicating it is a valid
route, but not the best.
By using the display ip routing-table command, you can find only one route to 9.1.1.0/24 with
next hop 3.1.1.1 and outbound interface VLAN-interface 200.
Configure loading balancing:
3.
Because Switch A has two routes to reach AS 65009, configuring load balancing over the two
BGP routes on Switch A can improve link usage.
# Configure Switch A.
[SwitchA] bgp 65008
[SwitchA-bgp] ipv4-family unicast
[SwitchA-bgp-ipv4] balance 2
[SwitchA-bgp-ipv4] quit
[SwitchA-bgp] quit
Verifying the configuration
# Display the BGP routing table on Switch A.
[SwitchA] display bgp routing-table ipv4
Total number of routes: 3
BGP local router ID is 1.1.1.1
Status codes: * - valid, > - best, d - damped, h - history,
s - suppressed, S - Stale, i - internal, e - external
Origin: i - IGP, e - EGP, ? - incomplete
Network
NextHop
MED
8.1.1.0/24
8.1.1.1
0
0
i
>e 9.1.1.0/24
3.1.1.1
0
0
65009i
>e
3.1.2.1
0
0
65009i
>
LocPrf
PrefVal Path/Ogn
•
The route 9.1.1.0/24 has two next hops, 3.1.1.1 and 3.1.2.1, both of which are marked with a
greater-than sign (>), indicating they are the best routes.
•
By using the display ip routing-table command, you can find two routes to 9.1.1.0/24. One has next
hop 3.1.1.1 and outbound interface VLAN-interface 200, and the other has next hop 3.1.2.1 and
outbound interface VLAN-interface 300.
237
BGP community configuration example
Network requirements
As shown in Figure 61, Switch B establishes EBGP connections with Switch A and C. Configure
NO_EXPORT community attribute on Switch A to make routes from AS 10 not advertised by AS 20 to any
other AS.
Figure 61 Network diagram
Configuration procedure
1.
Configure IP addresses for interfaces. (Details not shown.)
2.
Configure EBGP:
# Configure Switch A.
<SwitchA> system-view
[SwitchA] bgp 10
[SwitchA-bgp] router-id 1.1.1.1
[SwitchA-bgp] peer 200.1.2.2 as-number 20
[SwitchA-bgp] ipv4-family unicast
[SwitchA-bgp-ipv4] peer 200.1.2.2 enable
[SwitchA-bgp-ipv4] network 9.1.1.0 255.255.255.0
[SwitchA-bgp] quit
# Configure Switch B.
<SwitchB> system-view
[SwitchB] bgp 20
[SwitchB-bgp] router-id 2.2.2.2
[SwitchB-bgp] peer 200.1.2.1 as-number 10
[SwitchB-bgp] peer 200.1.3.2 as-number 30
[SwitchB-bgp] ipv4-family unicast
[SwitchB-bgp-ipv4] peer 200.1.2.1 enable
[SwitchB-bgp-ipv4] peer 200.1.3.2 enable
[SwitchB-bgp-ipv4] quit
[SwitchB-bgp] quit
# Configure Switch C.
<SwitchC> system-view
[SwitchC] bgp 30
[SwitchC-bgp] router-id 3.3.3.3
238
[SwitchC-bgp] peer 200.1.3.1 as-number 20
[SwitchC-bgp] ipv4-family unicast
[SwitchC-bgp-ipv4] peer 200.1.3.1 enable
[SwitchC-bgp-ipv4] quit
[SwitchC-bgp] quit
# Display the BGP routing table on Switch B.
[SwitchB] display bgp routing-table ipv4 9.1.1.0
BGP local router ID: 2.2.2.2
Local AS number: 20
Paths:
1 available, 1 best
BGP routing table information of 9.1.1.0/24:
From
: 200.1.2.1 (1.1.1.1)
Relay nexthop
: 200.1.2.1
Original nexthop: 200.1.2.1
OutLabel
: NULL
AS-path
: 10
Origin
: igp
Attribute value : pref-val 0
State
: valid, external, best,
# Display advertisement information of network 9.1.1.0 on Switch B.
[SwitchB] display bgp routing-table ipv4 9.1.1.0 advertise-info
BGP local router ID: 2.2.2.2
Local AS number: 20
Paths:
1 best
BGP routing table information of 9.1.1.0/24:
Advertised to peers (1 in total):
200.1.3.2
The output shows that Switch B can advertise the route with the destination 9.1.1.0/24 to other
ASs through BGP.
# Display the BGP routing table on Switch C.
[SwitchC] display bgp routing-table ipv4
Total number of routes: 1
BGP local router ID is 3.3.3.3
Status codes: * - valid, > - best, d - dampened, h - history,
s - suppressed, S - stale, i - internal, e - external
Origin: i - IGP, e - EGP, ? - incomplete
Network
>e 9.1.1.0/24
NextHop
MED
200.1.3.1
239
LocPrf
PrefVal Path/Ogn
0
20 10i
The output shows that Switch C has learned route 9.1.1.0/24 from Switch B.
3.
Configure BGP community:
# Configure a routing policy.
[SwitchA] route-policy comm_policy permit node 0
[SwitchA-route-policy-comm_policy-0] apply community no-export
[SwitchA-route-policy-comm_policy-0] quit
# Apply the routing policy.
[SwitchA] bgp 10
[SwitchA-bgp] ipv4-family unicast
[SwitchA-bgp-ipv4] peer 200.1.2.2 route-policy comm_policy export
[SwitchA-bgp-ipv4] peer 200.1.2.2 advertise-community
Verifying the configuration
# Display the routing table on Switch B.
[SwitchB] display bgp routing-table ipv4 9.1.1.0
BGP local router ID: 2.2.2.2
Local AS number: 20
Paths:
1 available, 1 best
BGP routing table information of 9.1.1.0/24:
From
: 200.1.2.1 (1.1.1.1)
Relay nexthop
: 200.1.2.1
Original nexthop: 200.1.2.1
OutLabel
: NULL
Community
: No-Export
AS-path
: 10
Origin
: igp
Attribute value : pref-val 0
State
: valid, external, best,
# Display advertisement information for the route 9.1.1.0 on Switch B.
[SwitchB] display bgp routing-table ipv4 9.1.1.0 advertise-info
BGP local router ID: 2.2.2.2
Local AS number: 20
Paths:
1 best
BGP routing table information of 9.1.1.0/24:
Not advertised to any peers yet
# Display the BGP routing table on Switch C.
[SwitchC] display bgp routing-table ipv4
Total number of routes: 0
You can see the NO_EXPORT community attribute in the output. In this case, Switch B does not advertise
the route 9.1.1.0/24 through BGP.
240
BGP route reflector configuration example
Network requirements
In Figure 62, all switches run BGP.
•
Between Switch A and Switch B is an EBGP connection, between Switch C and Switch B, and
between Switch C and Switch D are IBGP connections.
•
Switch C is a route reflector with clients Switch B and D.
•
Switch D can learn route 20.0.0.0/8 from Switch C.
Figure 62 Network diagram
Configuration procedure
1.
Configure IP addresses for interfaces. (Details not shown.)
2.
Configure BGP connections:
# Configure Switch A.
<SwitchA> system-view
[SwitchA] bgp 100
[SwitchA-bgp] router-id 1.1.1.1
[SwitchA-bgp] peer 192.1.1.2 as-number 200
[SwitchA-bgp] ipv4-family unicast
[SwitchA-bgp-ipv4] peer 192.1.1.2 enable
# Inject network 20.0.0.0/8 to the BGP routing table.
[SwitchA-bgp-ipv4] network 20.0.0.0
[SwitchA-bgp-ipv4] quit
[SwitchA-bgp] quit
# Configure Switch B.
<SwitchB> system-view
[SwitchB] bgp 200
[SwitchB-bgp] router-id 2.2.2.2
[SwitchB-bgp] peer 192.1.1.1 as-number 100
[SwitchB-bgp] peer 193.1.1.1 as-number 200
[SwitchB-bgp] ipv4-family unicast
[SwitchB-bgp-ipv4] peer 192.1.1.1 enable
[SwitchB-bgp-ipv4] peer 193.1.1.1 enable
[SwitchB-bgp-ipv4] peer 193.1.1.1 next-hop-local
241
[SwitchB-bgp-ipv4] quit
[SwitchB-bgp] quit
# Configure Switch C.
<SwitchC> system-view
[SwitchC] bgp 200
[SwitchC-bgp] router-id 3.3.3.3
[SwitchC-bgp] peer 193.1.1.2 as-number 200
[SwitchC-bgp] peer 194.1.1.2 as-number 200
[SwitchC-bgp] ipv4-family unicast
[SwitchC-bgp-ipv4] peer 193.1.1.2 enable
[SwitchC-bgp-ipv4] peer 194.1.1.2 enable
[SwitchC-bgp-ipv4] quit
[SwitchC-bgp] quit
# Configure Switch D.
<SwitchD> system-view
[SwitchD] bgp 200
[SwitchD-bgp] router-id 4.4.4.4
[SwitchD-bgp] peer 194.1.1.1 as-number 200
[SwitchD-bgp] ipv4-family unicast
[SwitchD-bgp-ipv4] peer 194.1.1.1 enable
[SwitchD-bgp-ipv4] quit
[SwitchD-bgp] quit
3.
Configure Switch C as the route reflector.
[SwitchC] bgp 200
[SwitchC-bgp] ipv4-family unicast
[SwitchC-bgp-ipv4] peer 193.1.1.2 reflect-client
[SwitchC-bgp-ipv4] peer 194.1.1.2 reflect-client
[SwitchC-bgp-ipv4] quit
[SwitchC-bgp] quit
Verifying the configuration
# Display the BGP routing table on Switch B.
[SwitchB] display bgp routing-table ipv4
Total number of routes: 1
BGP local router ID is 2.2.2.2
Status codes: * - valid, > - best, d - damped, h - history,
s - suppressed, S - Stale, i - internal, e - external
Origin: i - IGP, e - EGP, ? - incomplete
Network
>e 20.0.0.0
NextHop
MED
192.1.1.1
0
# Display the BGP routing table on Switch D.
[SwitchD] display bgp routing-table ipv4
Total number of routes: 1
242
LocPrf
PrefVal Path/Ogn
0
100i
BGP local router ID is 4.4.4.4
Status codes: * - valid, > - best, d - damped, h - history,
s - suppressed, S - Stale, i - internal, e - external
Origin: i - IGP, e - EGP, ? - incomplete
Network
i 20.0.0.0
NextHop
MED
LocPrf
PrefVal Path/Ogn
193.1.1.2
0
100
0
100i
Switch D has learned route 20.0.0.0/8 from Switch C.
BGP confederation configuration example
Network requirements
As shown in Figure 63, to reduce IBGP connections, AS 200 is split into three sub-ASs: AS65001,
AS65002, and AS65003. Switches in AS65001 are fully meshed.
Figure 63 Network diagram
Switch C
Switch B
Switch F
Vlan-int600
Vlan-int300
Vlan-int200
AS 65002
AS 65003
t3
00
Vlan-int100
Vlan-int100
Switch D
Vl
an
-in
AS 100
Vlan-int400
Vlan-int400
Switch A
Vlan-int200
Vlan-int500
AS 65001
Vlan-int200
Vlan-int500
Switch E
AS 200
Device
Interface
IP address
Device
Interface
IP address
Switch A
Vlan-int100
200.1.1.1/24
Switch D
Vlan-int200
10.1.5.1/24
Vlan-int200
10.1.1.1/24
Vlan-int400
10.1.3.2/24
Vlan-int300
10.1.2.1/24
Vlan-int200
10.1.5.2/24
Vlan-int400
10.1.3.1/24
Vlan-int500
10.1.4.2/24
Vlan-int100
200.1.1.2/24
Vlan-int600
9.1.1.1/24
Vlan-int500
10.1.4.1/24
Switch B
Vlan-int200
10.1.1.2/24
Switch C
Vlan-int300
10.1.2.2/24
Switch E
Switch F
Configuration procedure
1.
Configure IP addresses for interfaces. (Details not shown.)
2.
Configure BGP confederation:
# Configure Switch A.
<SwitchA> system-view
[SwitchA] bgp 65001
[SwitchA-bgp] router-id 1.1.1.1
243
[SwitchA-bgp] confederation id 200
[SwitchA-bgp] confederation peer-as 65002 65003
[SwitchA-bgp] peer 10.1.1.2 as-number 65002
[SwitchA-bgp] peer 10.1.2.2 as-number 65003
[SwitchA-bgp] ipv4-family unicast
[SwitchA-bgp-ipv4] peer 10.1.1.2 enable
[SwitchA-bgp-ipv4] peer 10.1.2.2 enable
[SwitchA-bgp-ipv4] peer 10.1.1.2 next-hop-local
[SwitchA-bgp-ipv4] peer 10.1.2.2 next-hop-local
[SwitchA-bgp-ipv4] quit
[SwitchA-bgp] quit
# Configure Switch B.
<SwitchB> system-view
[SwitchB] bgp 65002
[SwitchB-bgp] router-id 2.2.2.2
[SwitchB-bgp] confederation id 200
[SwitchB-bgp] confederation peer-as 65001 65003
[SwitchB-bgp] peer 10.1.1.1 as-number 65001
[SwitchB-bgp] ipv4-family unicast
[SwitchB-bgp-ipv4] peer 10.1.1.1 enable
[SwitchB-bgp-ipv4] quit
[SwitchB-bgp] quit
# Configure Switch C.
<SwitchC> system-view
[SwitchC] bgp 65003
[SwitchC-bgp] router-id 3.3.3.3
[SwitchC-bgp] confederation id 200
[SwitchC-bgp] confederation peer-as 65001 65002
[SwitchC-bgp] peer 10.1.2.1 as-number 65001
[SwitchC-bgp] ipv4-family unicast
[SwitchC-bgp-ipv4] peer 10.1.2.1 enable
[SwitchC-bgp-ipv4] quit
[SwitchC-bgp] quit
3.
Configure IBGP connections in AS 65001:
# Configure Switch A.
[SwitchA] bgp 65001
[SwitchA-bgp] peer 10.1.3.2 as-number 65001
[SwitchA-bgp] peer 10.1.4.2 as-number 65001
[SwitchA-bgp] ipv4-family unicast
[SwitchA-bgp-ipv4] peer 10.1.3.2 enable
[SwitchA-bgp-ipv4] peer 10.1.4.2 enable
[SwitchA-bgp-ipv4] peer 10.1.3.2 next-hop-local
[SwitchA-bgp-ipv4] peer 10.1.4.2 next-hop-local
[SwitchA-bgp-ipv4] quit
[SwitchA-bgp] quit
# Configure Switch D.
<SwitchD> system-view
244
[SwitchD] bgp 65001
[SwitchD-bgp] router-id 4.4.4.4
[SwitchD-bgp] confederation id 200
[SwitchD-bgp] peer 10.1.3.1 as-number 65001
[SwitchD-bgp] peer 10.1.5.2 as-number 65001
[SwitchD-bgp] ipv4-family unicast
[SwitchD-bgp-ipv4] peer 10.1.3.1 enable
[SwitchD-bgp-ipv4] peer 10.1.5.2 enable
[SwitchD-bgp-ipv4] quit
[SwitchD-bgp] quit
# Configure Switch E.
<SwitchE> system-view
[SwitchE] bgp 65001
[SwitchE-bgp] router-id 5.5.5.5
[SwitchE-bgp] confederation id 200
[SwitchE-bgp] peer 10.1.4.1 as-number 65001
[SwitchE-bgp] peer 10.1.5.1 as-number 65001
[SwitchE-bgp] ipv4-family unicast
[SwitchE-bgp-ipv4] peer 10.1.4.1 enable
[SwitchE-bgp-ipv4] peer 10.1.5.1 enable
[SwitchE-bgp-ipv4] quit
[SwitchE-bgp] quit
4.
Configure the EBGP connection between AS 100 and AS 200:
# Configure Switch A.
[SwitchA] bgp 65001
[SwitchA-bgp] peer 200.1.1.2 as-number 100
[SwitchA-bgp] ipv4-family unicast
[SwitchA-bgp-ipv4] peer 200.1.1.2 enable
[SwitchA-bgp-ipv4] quit
[SwitchA-bgp] quit
# Configure Switch F.
<SwitchF> system-view
[SwitchF] bgp 100
[SwitchF-bgp] router-id 6.6.6.6
[SwitchF-bgp] peer 200.1.1.1 as-number 200
[SwitchF-bgp] ipv4-family unicast
[SwitchF-bgp-ipv4] peer 200.1.1.1 enable
[SwitchF-bgp-ipv4] network 9.1.1.0 255.255.255.0
[SwitchF-bgp-ipv4] quit
[SwitchF-bgp] quit
Verifying the configuration
# Display the routing table on Switch B, which is similar to that on Switch C.
[SwitchB] display bgp routing-table ipv4
Total number of routes: 1
BGP local router ID is 2.2.2.2
245
Status codes: * - valid, > - best, d - damped, h - history,
s - suppressed, S - Stale, i - internal, e - external
Origin: i - IGP, e - EGP, ? - incomplete
Network
NextHop
MED
LocPrf
PrefVal Path/Ogn
>i 9.1.1.0/24
10.1.1.1
0
100
0
(65001)
100i
[SwitchB] display bgp routing-table ipv4 9.1.1.0
BGP local router ID: 2.2.2.2
Local AS number: 65002
Paths:
1 available, 1 best
BGP routing table information of 9.1.1.0/24:
From
: 10.1.1.1 (1.1.1.1)
Relay nexthop
: 10.1.1.1
Original nexthop: 10.1.1.1
OutLabel
: NULL
AS-path
: (65001) 100
Origin
: igp
Attribute value : MED 0, localpref 100, pref-val 0, pre 255
State
: valid, external-confed, best,
# Display the BGP routing table on Switch D.
[SwitchD] display bgp routing-table ipv4
Total number of routes: 1
BGP local router ID is 4.4.4.4
Status codes: * - valid, > - best, d - damped, h - history,
s - suppressed, S - Stale, i - internal, e - external
Origin: i - IGP, e - EGP, ? - incomplete
Network
NextHop
MED
LocPrf
PrefVal Path/Ogn
>i 9.1.1.0/24
10.1.3.1
0
100
0
[SwitchD] display bgp routing-table ipv4 9.1.1.0
BGP local router ID: 4.4.4.4
Local AS number: 65001
Paths:
1 available, 1 best
BGP routing table information of 9.1.1.0/24:
From
: 10.1.3.1 (1.1.1.1)
Relay nexthop
: 10.1.3.1
Original nexthop: 10.1.3.1
246
100i
OutLabel
: NULL
AS-path
: 100
Origin
: igp
Attribute value : MED 0, localpref 100, pref-val 0, pre 255
State
: valid, internal-confed, best,
The output indicates the following:
•
Switch F can send route information to Switch B and Switch C through the confederation by
establishing only an EBGP connection with Switch A.
•
Switch B and Switch D are in the same confederation, but belong to different sub-ASs. They obtain
external route information from Switch A and generate the same BGP route entries. It is likely that
they reside in the same AS, although they have no direct connection in between.
BGP path selection configuration example
Network requirements
In Figure 64, all switches run BGP. EBGP runs between Switch A and Switch B, and between Switch A
and Switch C. IBGP runs between Switch B and Switch D, and between Switch D and Switch C. OSPF is
the IGP protocol in AS 200.
Configure routing policies, making Switch D use the route 1.0.0.0/8 from Switch C as the optimal.
Figure 64 Network diagram
Device
Interface
IP address
Device
Interface
IP address
Switch A
Vlan-int101
1.0.0.1/8
Switch D
Vlan-int400
195.1.1.1/24
Vlan-int100
192.1.1.1/24
Vlan-int300
194.1.1.1/24
Vlan-int200
193.1.1.1/24
Vlan-int400
195.1.1.2/24
Vlan-int100
192.1.1.2/24
Vlan-int200
193.1.1.2/24
Vlan-int300
194.1.1.2/24
Switch B
Switch C
Configuration procedure
1.
Configure IP addresses for interfaces. (Details not shown.)
2.
Configure OSPF on Switch B, Switch C, and Switch D:
# Configure Switch B.
<SwitchB> system-view
[SwitchB] ospf
[SwitchB-ospf] area 0
[SwitchB-ospf-1-area-0.0.0.0] network 192.1.1.0 0.0.0.255
247
[SwitchB-ospf-1-area-0.0.0.0] network 194.1.1.0 0.0.0.255
[SwitchB-ospf-1-area-0.0.0.0] quit
[SwitchB-ospf-1] quit
# Configure Switch C.
<SwitchC> system-view
[SwitchC] ospf
[SwitchC-ospf] area 0
[SwitchC-ospf-1-area-0.0.0.0] network 193.1.1.0 0.0.0.255
[SwitchC-ospf-1-area-0.0.0.0] network 195.1.1.0 0.0.0.255
[SwitchC-ospf-1-area-0.0.0.0] quit
[SwitchC-ospf-1] quit
# Configure Switch D.
<SwitchD> system-view
[SwitchD] ospf
[SwitchD-ospf] area 0
[SwitchD-ospf-1-area-0.0.0.0] network 194.1.1.0 0.0.0.255
[SwitchD-ospf-1-area-0.0.0.0] network 195.1.1.0 0.0.0.255
[SwitchD-ospf-1-area-0.0.0.0] quit
[SwitchD-ospf-1] quit
3.
Configure BGP connections:
# Configure Switch A.
<SwitchA> system-view
[SwitchA] bgp 100
[SwitchA-bgp] peer 192.1.1.2 as-number 200
[SwitchA-bgp] peer 193.1.1.2 as-number 200
[SwitchA-bgp] ipv4-family unicast
[SwitchA-bgp-ipv4] peer 192.1.1.2 enable
[SwitchA-bgp-ipv4] peer 193.1.1.2 enable
# Inject network 1.0.0.0/8 to the BGP routing table on Switch A.
[SwitchA-bgp-ipv4] network 1.0.0.0 8
[SwitchA-bgp-ipv4] quit
[SwitchA-bgp] quit
# Configure Switch B.
[SwitchB] bgp 200
[SwitchB-bgp] peer 192.1.1.1 as-number 100
[SwitchB-bgp] peer 194.1.1.1 as-number 200
[SwitchB-bgp] ipv4-family unicast
[SwitchB-bgp-ipv4] peer 192.1.1.1 enable
[SwitchB-bgp-ipv4] peer 194.1.1.1 enable
[SwitchB-bgp-ipv4] quit
[SwitchB-bgp] quit
# Configure Switch C.
[SwitchC] bgp 200
[SwitchC-bgp] peer 193.1.1.1 as-number 100
[SwitchC-bgp] peer 195.1.1.1 as-number 200
[SwitchC-bgp] ipv4-family unicast
[SwitchC-bgp-ipv4] peer 193.1.1.1 enable
248
[SwitchC-bgp-ipv4] peer 195.1.1.1 enable
[SwitchC-bgp-ipv4] quit
[SwitchC-bgp] quit
# Configure Switch D.
[SwitchD] bgp 200
[SwitchD-bgp] peer 194.1.1.2 as-number 200
[SwitchD-bgp] peer 195.1.1.2 as-number 200
[SwitchD-bgp] ipv4-family unicast
[SwitchD-bgp-ipv4] peer 194.1.1.2 enable
[SwitchD-bgp-ipv4] peer 195.1.1.2 enable
[SwitchD-bgp-ipv4] quit
[SwitchD-bgp] quit
4.
Configure attributes for route 1.0.0.0/8, making Switch D give priority to the route learned from
Switch C:
{
(Method 1.) Configure a higher MED value for the route 1.0.0.0/8 advertised from Switch A to
peer 192.1.1.2:
# Define an ACL numbered 2000 to permit route 1.0.0.0/8.
[SwitchA] acl number 2000
[SwitchA-acl-basic-2000] rule permit source 1.0.0.0 0.255.255.255
[SwitchA-acl-basic-2000] quit
# Define two routing policies, apply_med_50, which sets the MED for route 1.0.0.0/8 to 50,
and apply_med_100, which sets the MED for route 1.0.0.0/8 to 100.
[SwitchA] route-policy apply_med_50 permit node 10
[SwitchA-route-policy-apply_med_50-10] if-match ip address acl 2000
[SwitchA-route-policy-apply_med_50-10] apply cost 50
[SwitchA-route-policy-apply_med_50-10] quit
[SwitchA] route-policy apply_med_100 permit node 10
[SwitchA-route-policy-apply_med_100-10] if-match ip address acl 2000
[SwitchA-route-policy-apply_med_100-10] apply cost 100
[SwitchA-route-policy-apply_med_100-10] quit
# Apply routing policy apply_med_50 to the route advertised to peer 193.1.1.2 (Switch C),
and apply_med_100 to the route advertised to peer 192.1.1.2 (Switch B).
[SwitchA] bgp 100
[SwitchA-bgp] ipv4-family unicast
[SwitchA-bgp-ipv4] peer 193.1.1.2 route-policy apply_med_50 export
[SwitchA-bgp-ipv4] peer 192.1.1.2 route-policy apply_med_100 export
[SwitchA-bgp-ipv4] quit
[SwitchA-bgp] quit
# Display the BGP routing table on Switch D.
[SwitchD] display bgp routing-table ipv4
Total number of routes: 2
BGP local router ID is 195.1.1.1
Status codes: * - valid, > - best, d - dampened, h - history,
s - suppressed, S - stale, i - internal, e - external
Origin: i - IGP, e - EGP, ? - incomplete
249
Network
>i 1.0.0.0
*
i
NextHop
MED
LocPrf
PrefVal Path/Ogn
193.1.1.1
50
100
0
100i
192.1.1.1
100
100
0
100i
Route 1.0.0.0/8 is the optimal.
{
(Method 2.) Configure different local preferences on Switch B and C for route 1.0.0.0/8,
making Switch D give priority to the route from Switch C:
# Define an ACL numbered 2000 on Router C, permitting route 1.0.0.0/8.
[SwitchC] acl number 2000
[SwitchC-acl-basic-2000] rule permit source 1.0.0.0 0.255.255.255
[SwitchC-acl-basic-2000] quit
# Configure a routing policy named localpref on Switch C, setting the local preference of route
1.0.0.0/8 to 200 (the default is 100).
[SwitchC] route-policy localpref permit node 10
[SwitchC-route-policy-localpref-10] if-match ip address acl 2000
[SwitchC-route-policy-localpref-10] apply local-preference 200
[SwitchC-route-policy-localpref-10] quit
# Apply routing policy localpref to routes from peer 193.1.1.1.
[SwitchC] bgp 200
[SwitchC-bgp] ipv4-family unicast
[SwitchC-bgp-ipv4] peer 193.1.1.1 route-policy localpref import
[SwitchC-bgp-ipv4] quit
[SwitchC-bgp] quit
# Display the BGP routing table on Switch D.
[SwitchD] display bgp routing-table ipv4
Total number of routes: 2
BGP local router ID is 195.1.1.1
Status codes: * - valid, > - best, d - dampened, h - history,
s - suppressed, S - stale, i - internal, e - external
Origin: i - IGP, e - EGP, ? - incomplete
Network
>i 1.0.0.0
*
i
NextHop
MED
LocPrf
PrefVal Path/Ogn
193.1.1.1
200
0
100i
192.1.1.1
100
0
100i
Route 1.0.0.0/8 learned from Switch C is the optimal.
BGP GR configuration example
Network requirements
In Figure 65 are all BGP switches. EBGP runs between Switch A and Switch B. IBGP runs between Switch
B and Switch C. Enable GR capability for BGP so that the communication between Switch A and Switch
C is not affected when an active/standby switchover occurs on Switch B.
250
Figure 65 Network diagram
Configuration procedure
1.
Configure Switch A:
# Configure IP addresses for interfaces. (Details not shown.)
# Configure the EBGP connection.
<SwitchA> system-view
[SwitchA] bgp 65008
[SwitchA-bgp] router-id 1.1.1.1
[SwitchA-bgp] peer 200.1.1.1 as-number 65009
# Enable GR capability for BGP.
[SwitchA-bgp] graceful-restart
# Inject network 8.0.0.0/8 to the BGP routing table.
[SwitchA-bgp] ipv4-family
[SwitchA-bgp-ipv4] network 8.0.0.0
# Enable Switch A to exchange IPv4 unicast routing information with Switch B.
[SwitchA-bgp-ipv4] peer 200.1.1.1 enable
2.
Configure Switch B:
# Configure IP addresses for interfaces. (Details not shown.)
# Configure the EBGP connection.
<SwitchB> system-view
[SwitchB] bgp 65009
[SwitchB-bgp] router-id 2.2.2.2
[SwitchB-bgp] peer 200.1.1.2 as-number 65008
# Configure the IBGP connection.
[SwitchB-bgp] peer 9.1.1.2 as-number 65009
# Enable GR capability for BGP.
[SwitchB-bgp] graceful-restart
# Inject networks 200.1.1.0/24 and 9.1.1.0/24 to the BGP routing table.
[SwitchB-bgp] ipv4-family
[SwitchB-bgp-ipv4] network 200.1.1.0 24
[SwitchB-bgp-ipv4] network 9.1.1.0 24
# Enable Switch B to exchange IPv4 unicast routing information with Switch A and Switch C.
[SwitchB-bgp-ipv4] peer 200.1.1.2 enable
[SwitchB-bgp-ipv4] peer 9.1.1.2 enable
3.
Configure Switch C:
# Configure IP addresses for interfaces. (Details not shown.)
# Configure the IBGP connection.
251
<SwitchC> system-view
[SwitchC] bgp 65009
[SwitchC-bgp] router-id 3.3.3.3
[SwitchC-bgp] peer 9.1.1.1 as-number 65009
# Enable GR capability for BGP.
[SwitchC-bgp] graceful-restart
# Enable Switch C to exchange IPv4 unicast routing information with Switch B.
[SwitchC-bgp-ipv4] peer 9.1.1.1 enable
Verifying the configuration
Ping Switch C on Switch A. Meanwhile, perform an active/standby switchover on Switch B. The ping
operation is successful during the whole switchover process.
BFD for BGP configuration example
Network requirements
As shown in Figure 66,
•
Configure OSPF as the IGP in AS 200.
•
Establish two IBGP connections between Switch A and Switch C. When both paths are working,
Switch C adopts the path Switch A<—>Switch B<—>Switch C to exchange packets with network
1.1.1.0/24. Configure BFD over the path. If the path fails, BFD can quickly detect the failure and
notify it to BGP. Then the path Switch A<—>Switch D<—>Switch C takes effect immediately.
Figure 66 Network diagram
Device
Interface
IP address
Device
Interface
IP address
Switch A
Vlan-int100
3.0.1.1/24
Switch C
Vlan-int101
3.0.2.2/24
Vlan-int200
2.0.1.1/24
Vlan-int201
2.0.2.2/24
Vlan-int100
3.0.1.2/24
Vlan-int101
3.0.2.1/24
Switch B
252
Switch D
Vlan-int200
2.0.1.2/24
Vlan-int201
2.0.2.1/24
Configuration procedure
1.
Configure IP addresses for interfaces. (Details not shown.)
2.
Configure OSPF to make sure that Switch A and Switch C are reachable to each other. (Details not
shown.)
3.
Configure BGP on Switch A:
# Establish two IBGP connections to Switch C.
<SwitchA> system-view
[SwitchA] bgp 200
[SwitchA-bgp] peer 3.0.2.2 as-number 200
[SwitchA-bgp] peer 2.0.2.2 as-number 200
[SwitchA-bgp] ipv4-family unicast
[SwitchA-bgp-ipv4] peer 3.0.2.2 enable
[SwitchA-bgp-ipv4] peer 2.0.2.2 enable
[SwitchA-bgp-ipv4] quit
[SwitchA-bgp] quit
# Create ACL 2000 to permit 1.1.1.0/24 to pass.
[SwitchA] acl number 2000
[SwitchA-acl-basic-2000] rule permit source 1.1.1.0 0.0.0.255
[SwitchA-acl-basic-2000] quit
# Create two route policies, apply_med_50 and apply_med_100. Policy apply_med_50 sets the
MED for route 1.1.1.0/24 to 50. Policy apply_med_100 sets that to 100.
[SwitchA] route-policy apply_med_50 permit node 10
[SwitchA-route-policy-apply_med_50-10] if-match ip address acl 2000
[SwitchA-route-policy-apply_med_50-10] apply cost 50
[SwitchA-route-policy-apply_med_50-10] quit
[SwitchA] route-policy apply_med_100 permit node 10
[SwitchA-route-policy-apply_med_100-10] if-match ip address acl 2000
[SwitchA-route-policy-apply_med_100-10] apply cost 100
[SwitchA-route-policy-apply_med_100-10] quit
# Apply routing policy apply_med_50 to routes outgoing to peer 3.0.2.2, and apply routing
policy apply_med_100 to routes outgoing to peer 2.0.2.2.
[SwitchA] bgp 200
[SwitchA-bgp] ipv4-family unicast
[SwitchA-bgp-ipv4] peer 3.0.2.2 route-policy apply_med_50 export
[SwitchA-bgp-ipv4] peer 2.0.2.2 route-policy apply_med_100 export
[SwitchA-bgp-ipv4] quit
# Enable BFD for peer 3.0.2.2.
[SwitchA-bgp] peer 3.0.2.2 bfd
[SwitchA-bgp] quit
4.
Configure BGP on Switch C:
# Establish two IBGP connections to Switch A.
<SwitchC> system-view
[SwitchC] bgp 200
[SwitchC-bgp] peer 3.0.1.1 as-number 200
[SwitchC-bgp] peer 2.0.1.1 as-number 200
[SwitchC-bgp] ipv4-family unicast
253
[SwitchC-bgp-ipv4] peer 3.0.1.1 enable
[SwitchC-bgp-ipv4] peer 2.0.1.1 enable
[SwitchC-bgp-ipv4] quit
[SwitchC-bgp] quit
# Enable BFD for peer 3.0.1.1.
[SwitchC-bgp] peer 3.0.1.1 bfd
[SwitchC-bgp] quit
[SwitchC] quit
Verifying the configuration
# Display detailed BFD session information on Router C.
<SwitchC> display bfd session verbose
Total Session Num: 1
Up Session Num: 1
Init Mode: Active
IPv4 Session Working Under Ctrl Mode:
Local Discr: 513
Remote Discr: 513
Source IP: 3.0.2.2
Destination IP: 3.0.1.1
Session State: Up
Interface: N/A
Min Tx Inter: 500ms
Act Tx Inter: 500ms
Min Rx Inter: 500ms
Detect Inter: 2500ms
Rx Count: 135
Tx Count: 135
Connect Type: Indirect
Running Up for: 00:00:58
Hold Time: 2457ms
Auth mode: None
Detect Mode: Async
Slot: 0
Protocol: BGP
Diag Info: No Diagnostic
The output shows that a BFD session has been established between Switch A and Switch C and
that BFD runs properly.
# Display BGP peer information on Switch C.
<SwitchC> display bgp peer ipv4
BGP local router ID: 3.3.3.3
Local AS number: 200
Total number of peers: 2
Peer
Peers in established state: 2
AS
MsgRcvd
MsgSent OutQ PrefRcv Up/Down
State
2.0.1.1
200
4
5
0
0 00:01:55 Established
3.0.1.1
200
4
5
0
0 00:01:52 Established
The output shows that Switch C has established two BGP connections with Switch A, and both
connections are in Established state.
# Display route 1.1.1.0/24 on Switch C.
<SwitchC> display ip routing-table 1.1.1.0 24 verbose
Summary Count : 1
254
Destination: 1.1.1.0/24
Protocol: BGP
Process ID: 0
SubProtID: 0x1
Age: 00h00m09s
Cost: 50
Preference: 255
Tag: 0
State: Active Adv
OrigTblID: 0x1
OrigVrf: default-vrf
TableID: 0x2
OrigAs: 0
NBRID: 0x15000001
LastAs: 0
AttrID: 0x1
Neighbor: 3.0.1.1
Flags: 0x10060
OrigNextHop: 3.0.1.1
Label: NULL
RealNextHop: 3.0.2.1
BkLabel: NULL
BkNextHop: N/A
Tunnel ID: Invalid
BkTunnel ID: Invalid
Interface: Vlan-interface101
BkInterface: N/A
The output shows that Switch C communicates with network 1.1.1.0/24 through the path Switch
C<—>Switch B<—>Switch A. Then the path Switch C<—>Switch B<—>Switch A fails.
# Enable debugging on Switch C.
<SwitchC> debugging bgp event
<SwitchC> terminal monitor
<SwitchC> terminal logging level 7
%Mar 12 19:02:59:241 2012 SwitchC BFD/6/FSM: -VDC=1; Sess[3.0.2.2/3.0.1.1, LD/RD:
513/513, Interface:N/A, SessType:Ctrl, LinkType:INET], Sta: UP->DOWN, Diag: 1
*Mar 12 19:02:59:242 2012 SwitchC BGP/7/DEBUG: -VDC=1;
BGP.: 3.0.1.1 Receive ManualStop event in ESTABLISHED state.
*Mar 12 19:02:59:242 2012 SwitchC BGP/7/DEBUG: -VDC=1;
BGP.: 3.0.1.1 Send NOTIFICATION
Err/SubErr: 6/0 (Cease/ErrSubCode Unspecified)
Error data NULL.
*Mar 12 19:02:59:243 2012 SwitchC BGP/7/DEBUG: -VDC=1;
BGP.: 3.0.1.1 State is changed from ESTABLISHED to IDLE.
The output shows that Switch C can quickly detect the link failure and notify BGP to change the
relevant IBGP session state.
# Display route 1.1.1.0/24 on Switch C.
<SwitchC> display ip routing-table 1.1.1.0 24 verbose
Summary Count : 1
Destination: 1.1.1.0/24
Protocol: BGP
Process ID: 0
SubProtID: 0x1
Cost: 100
Tag: 0
OrigTblID: 0x1
TableID: 0x2
NBRID: 0x15000000
AttrID: 0x0
Age: 00h03m08s
Preference: 255
State: Active Adv
OrigVrf: default-vrf
OrigAs: 0
LastAs: 0
Neighbor: 2.0.1.1
255
Flags: 0x10060
OrigNextHop: 2.0.1.1
Label: NULL
RealNextHop: 2.0.2.1
BkLabel: NULL
Tunnel ID: Invalid
BkTunnel ID: Invalid
BkNextHop: N/A
Interface: Vlan-interface201
BkInterface: N/A
The output shows that Switch C communicates with network 1.1.1.0/24 through the path Switch
C<—>Switch D<—>Switch A.
IPv6 BGP configuration examples
IPv6 BGP basic configuration example
Network requirements
In Figure 67, run EBGP between Switch A and Switch B, and run IBGP between Switch B and Switch C
so that Switch C can access the network 50::/64 connected to Switch A.
Figure 67 Network diagram
Configuration procedure
1.
Configure IP addresses for interfaces. (Details not shown.)
2.
Configure IBGP:
# Configure Switch B.
<SwitchB> system-view
[SwitchB] bgp 65009
[SwitchB-bgp] router-id 2.2.2.2
[SwitchB-bgp] peer 9::2 as-number 65009
[SwitchB-bgp] ipv6-family
[SwitchB-bgp-ipv6] peer 9::2 enable
[SwitchB-bgp-ipv6] quit
# Configure Switch C.
<SwitchC> system-view
[SwitchC] bgp 65009
[SwitchC-bgp] router-id 3.3.3.3
[SwitchC-bgp] peer 9::1 as-number 65009
[SwitchC-bgp] ipv6-family
[SwitchC-bgp-ipv6] peer 9::1 enable
3.
Configure EBGP:
# Configure Switch A.
<SwitchA> system-view
256
[SwitchA] bgp 65008
[SwitchA-bgp] router-id 1.1.1.1
[SwitchA-bgp] peer 10::1 as-number 65009
[SwitchA-bgp] ipv6-family
[SwitchA-bgp-ipv6] peer 10::1 enable
# Configure Switch B.
[SwitchB-bgp] peer 10::2 as-number 65008
[SwitchB-bgp] ipv6-family
[SwitchB-bgp-ipv6] peer 10::2 enable
4.
Inject network routes to the BGP routing table:
# Configure Switch A.
[SwitchA-bgp-ipv6] network 10:: 64
[SwitchA-bgp-ipv6] network 50:: 64
[SwitchA-bgp-ipv6] quit
[SwitchA-bgp] quit
# Configure Switch B.
[SwitchB-bgp-ipv6] network 10:: 64
[SwitchB-bgp-ipv6] network 9:: 64
[SwitchB-bgp-ipv6] quit
[SwitchB-bgp] quit
# Configure Switch C.
[SwitchC-bgp-ipv6] network 9:: 64
[SwitchC-bgp-ipv6] quit
[SwitchC-bgp] quit
Verifying the configuration
# Display IPv6 BGP peer information on Switch B.
[SwitchB] display bgp peer ipv6
BGP local router ID: 2.2.2.2
Local AS number: 65009
Total number of peers: 2
Peers in established state: 2
Peer
AS
MsgRcvd
MsgSent OutQ PrefRcv Up/Down
State
9::2
65009
41
43
0
1 00:29:00 Established
10::2
65008
38
38
0
2 00:27:20 Established
The output shows that Switch A and Switch B have established an EBGP connection, and Switch B and
Switch C have established an IBGP connection.
# Display IPv6 BGP routing table information on Switch A.
[SwitchA] display bgp routing-table ipv6
Total number of routes: 4
BGP local router ID is 1.1.1.1
Status codes: * - valid, > - best, d - dampened, h - history,
s - suppressed, S - stale, i - internal, e - external
257
Origin: i - IGP, e - EGP, ? - incomplete
>e Network : 9::
PrefixLen : 64
NextHop : 10::1
LocPrf
:
PrefVal : 0
OutLabel
: NULL
MED
: 0
Path/Ogn: 65009i
>
Network : 10::
PrefixLen : 64
NextHop : ::
LocPrf
:
PrefVal : 32768
OutLabel
: NULL
MED
: 0
Path/Ogn: i
*
e Network : 10::
PrefixLen : 64
NextHop : 10::1
LocPrf
:
PrefVal : 0
OutLabel
: NULL
MED
: 0
Path/Ogn: 65009i
>
Network : 50::
PrefixLen : 64
NextHop : ::
LocPrf
:
PrefVal : 32768
OutLabel
: NULL
MED
: 0
Path/Ogn: i
The output shows that Switch A has learned routing information of AS 65009.
# Display IPv6 BGP routing table information on Switch C.
[SwitchC] display bgp routing-table ipv6
Total number of routes: 4
BGP local router ID is 3.3.3.3
Status codes: * - valid, > - best, d - dampened, h - history,
s - suppressed, S - stale, i - internal, e - external
Origin: i - IGP, e - EGP, ? - incomplete
>
Network : 9::
PrefixLen : 64
NextHop : ::
LocPrf
:
PrefVal : 32768
OutLabel
: NULL
MED
: 0
Path/Ogn: i
*
i Network : 9::
PrefixLen : 64
NextHop : 9::1
LocPrf
: 100
PrefVal : 0
OutLabel
: NULL
MED
: 0
Path/Ogn: i
258
>i Network : 10::
PrefixLen : 64
NextHop : 9::1
LocPrf
: 100
PrefVal : 0
OutLabel
: NULL
MED
: 0
Path/Ogn: i
>i Network : 50::
PrefixLen : 64
NextHop : 10::2
LocPrf
: 100
PrefVal : 0
OutLabel
: NULL
MED
: 0
Path/Ogn: 65008i
The output shows that Switch C has learned the route 50::/64.
# Ping hosts on network 50::/64 on Switch C. The ping operations succeed.
IPv6 BGP route reflector configuration example
Network requirements
In Figure 68, run EBGP between Switch A and Switch B, run IBGP between Switch C and Switch B, and
between Switch C and Switch D. Switch C is a route reflector with clients Switch B and D.
Figure 68 Network diagram
Configuration procedure
1.
Configure IPv6 addresses for interfaces and IPv4 addresses for loopback interfaces. (Details not
shown.)
2.
Configure IBGP and EBGP connections and advertise network routes through IPv6 BGP:
# Configure Switch A.
<SwitchA> system-view
[SwitchA] bgp 100
[SwitchA-bgp] router-id 1.1.1.1
[SwitchA-bgp] peer 100::2 as-number 200
[SwitchA-bgp] ipv6-family
[SwitchA-bgp-ipv6] peer 100::2 enable
[SwitchA-bgp-ipv6] network 1:: 64
[SwitchA-bgp-ipv6] network 100:: 96
[SwitchA-bgp-ipv6] quit
259
[SwitchA-bgp] quit
# Configure Switch B
<SwitchB> system-view
[SwitchB] bgp 200
[SwitchB-bgp] router-id 2.2.2.2
[SwitchB-bgp] peer 100::1 as-number 100
[SwitchB-bgp] peer 101::1 as-number 200
[SwitchB-bgp] ipv6-family
[SwitchB-bgp-ipv6] peer 100::1 enable
[SwitchB-bgp-ipv6] peer 101::1 enable
[SwitchB-bgp-ipv6] peer 101::1 next-hop-local
[SwitchB-bgp-ipv6] network 100:: 96
[SwitchB-bgp-ipv6] network 101:: 96
[SwitchB-bgp-ipv6] quit
[SwitchB-bgp] quit
# Configure Switch C.
<SwitchC> system-view
[SwitchC] bgp 200
[SwitchC-bgp] router-id 3.3.3.3
[SwitchC-bgp] peer 101::2 as-number 200
[SwitchC-bgp] peer 102::2 as-number 200
[SwitchC-bgp] ipv6-family
[SwitchC-bgp-ipv6] peer 101::2 enable
[SwitchC-bgp-ipv6] peer 102::2 enable
[SwitchC-bgp-ipv6] network 101:: 96
[SwitchC-bgp-ipv6] network 102:: 96
# Configure Switch D.
<SwitchD> system-view
[SwitchD] bgp 200
[SwitchD-bgp] router-id 4.4.4.4
[SwitchD-bgp] peer 102::1 as-number 200
[SwitchD-bgp] ipv6-family
[SwitchD-bgp-ipv6] peer 102::1 enable
[SwitchD-bgp-ipv6] network 102:: 96
3.
Configure Switch C as a route reflector, and configure Switch B and Switch D as its clients.
[SwitchC-bgp-ipv6] peer 101::2 reflect-client
[SwitchC-bgp-ipv6] peer 102::2 reflect-client
[SwitchC-bgp-ipv6] quit
[SwitchC-bgp] quit
Verifying the configuration
# Execute the display bgp routing-table ipv6 command on Switch D.
[SwitchD] display bgp routing-table ipv6
Total number of routes: 5
BGP local router ID is 4.4.4.4
Status codes: * - valid, > - best, d - dampened, h - history,
260
s - suppressed, S - stale, i - internal, e - external
Origin: i - IGP, e - EGP, ? - incomplete
>i Network : 1::
PrefixLen : 64
NextHop : 101::2
LocPrf
: 100
PrefVal : 0
OutLabel
: NULL
MED
: 0
Path/Ogn: 100i
>i Network : 100::
PrefixLen : 96
NextHop : 101::2
LocPrf
: 100
PrefVal : 0
OutLabel
: NULL
MED
: 0
Path/Ogn: i
>i Network : 101::
PrefixLen : 96
NextHop : 102::1
LocPrf
: 100
PrefVal : 0
OutLabel
: NULL
MED
: 0
Path/Ogn: i
>
Network : 102::
PrefixLen : 96
NextHop : ::
LocPrf
:
PrefVal : 32768
OutLabel
: NULL
MED
: 0
Path/Ogn: i
*
i Network : 102::
PrefixLen : 96
NextHop : 102::1
LocPrf
: 100
PrefVal : 0
OutLabel
: NULL
MED
: 0
Path/Ogn: i
The output shows that Switch D has learned the network 1::/64 from Switch C through route reflection.
BFD for IPv6 BGP configuration example
Network requirements
As shown in Figure 69, configure OSPFv3 as the IGP in AS 200.
Establish two IBGP connections between Switch A and Switch C. When both paths are working, Switch
C adopts the path Switch A<—>Switch B<—>Switch C to exchange packets with network 1200::0/64.
Configure BFD over the path. Then if the path fails, BFD can quickly detect the failure and notify it to IPv6
BGP. Then the path Switch A<—>Switch D<—>Switch C takes effect immediately.
261
Figure 69 Network diagram
Switch B
Vlan-int100
Vlan-int101
Vlan-int100
AS 100
Vlan-int101
1200::0/64
AS 200
Vlan-int200
AS 300
Vlan-int201
Switch A
Switch C
Vlan-int200
Vlan-int201
Switch D
Device
Interface
IP address
Device
Interface
IP address
Switch A
Vlan-int100
3000::1/64
Switch C
Vlan-int101
3001::3/64
Vlan-int200
2000::1/64
Vlan-int201
2001::3/64
Vlan-int100
3000::2/64
Vlan-int200
2000::2/64
Vlan-int101
3001::2/64
Vlan-int201
2001::2/64
Switch B
Switch D
Configuration procedure
1.
Configure IPv6 addresses for interfaces. (Details not shown.)
2.
Configure OSPFv3 so that Switch A and Switch C can reach each other. (Details not shown.)
3.
Configure IPv6 BGP on Switch A:
# Establish two IBGP connections to Switch C.
<SwitchA> system-view
[SwitchA] bgp 200
[SwitchA-bgp] router-id 1.1.1.1
[SwitchA-bgp] peer 3001::3 as-number 200
[SwitchA-bgp] peer 2001::3 as-number 200
[SwitchA-bgp] ipv6-family
[SwitchA-bgp-ipv6] peer 3001::3 enable
[SwitchA-bgp-ipv6] peer 2001::3 enable
[SwitchA-bgp-ipv6] quit
# Create IPv6 ACL 2000 to permit 1200::0/64 to pass.
[SwitchA] acl ipv6 number 2000
[SwitchA-acl6-basic-2000] rule permit source 1200:: 64
[SwitchA-acl6-basic-2000] quit
# Create two route policies, apply_med_50 and apply_med_100. Policy apply_med_50 sets the
MED for route 1200::0/64 to 50. Policy apply_med_100 sets that to 100.
[SwitchA] route-policy apply_med_50 permit node 10
[SwitchA-route-policy-apply_med_50-10] if-match ipv6 address acl 2000
[SwitchA-route-policy-apply_med_50-10] apply cost 50
[SwitchA-route-policy-apply_med_50-10] quit
262
[SwitchA] route-policy apply_med_100 permit node 10
[SwitchA-route-policy-apply_med_100-10] if-match ipv6 address acl 2000
[SwitchA-route-policy-apply_med_100-10] apply cost 100
[SwitchA-route-policy-apply_med_100-10] quit
# Apply routing policy apply_med_50 to routes outgoing to peer 3001::3, and apply routing
policy apply_med_100 to routes outgoing to peer 2001::3.
[SwitchA] bgp 200
[SwitchA-bgp] ipv6-family unicast
[SwitchA-bgp-ipv6] peer 3001::3 route-policy apply_med_50 export
[SwitchA-bgp-ipv6] peer 2001::3
route-policy apply_med_100 export
[SwitchA-bgp-ipv6] quit
# Enable BFD for peer 3001::3.
[SwitchA-bgp] peer 3001::3 bfd
[SwitchA-bgp] quit
4.
Configure IPv6 BGP on Switch C:
# Establish two IBGP connections to Switch A.
<SwitchC> system-view
[SwitchC] bgp 200
[SwitchC-bgp] router-id 3.3.3.3
[SwitchC-bgp] peer 3000::1 as-number 200
[SwitchC-bgp] peer 2000::1 as-number 200
[SwitchC-bgp] ipv6-family
[SwitchC-bgp-ipv6] peer 3000::1 enable
[SwitchC-bgp-ipv6] peer 2000::1 enable
[SwitchC-bgp-ipv6] quit
# Enable BFD for peer 3001::1.
[SwitchC-bgp] peer 3000::1 bfd
[SwitchC-bgp] quit
[SwitchC] quit
Verifying the configuration
# Display detailed BFD session information on Switch C.
<SwitchC> display bfd session verbose
Total Session Num: 1
Up Session Num: 1
Init Mode: Active
IPv6 Session Working Under Ctrl Mode:
Local Discr: 513
Remote Discr: 513
Source IP: 3001::3
Destination IP: 3000::1
Session State: Up
Interface: N/A
Min Tx Inter: 500ms
Act Tx Inter: 500ms
Min Rx Inter: 500ms
Detect Inter: 2500ms
Rx Count: 13
Tx Count: 14
Connect Type: Indirect
Running Up for: 00:00:05
Hold Time: 2243ms
Auth mode: None
Detect Mode: Async
Slot: 0
Protocol: BGP6
263
Diag Info: No Diagnostic
The output shows that a BFD session has been established between Switch A and Switch C and that BFD
runs properly.
# Display BGP peer information on Switch C.
<SwitchC> display bgp peer ipv6
BGP local router ID: 3.3.3.3
Local AS number: 200
Total number of peers: 2
Peer
Peers in established state: 2
AS
MsgRcvd
MsgSent OutQ PrefRcv Up/Down
State
2000::1
200
8
8
0
0 00:04:45 Established
3000::1
200
5
4
0
0 00:01:53 Established
The output shows that Switch C has established two BGP connections with Switch A, and both
connections are in Established state.
# Display route 1200::0/64 on Switch C.
<SwitchC> display ipv6 routing-table 1200::0 64 verbose
Summary Count : 1
Destination: 1200::/64
Protocol: BGP4+
Process ID: 0
SubProtID: 0x1
Age: 00h01m07s
Cost: 50
Preference: 255
Tag: 0
State: Active Adv
OrigTblID: 0x1
OrigVrf: default-vrf
TableID: 0xa
OrigAs: 0
NBRID: 0x25000001
LastAs: 0
AttrID: 0x1
Neighbor: 3000::1
Flags: 0x10060
OrigNextHop: 3000::1
Label: NULL
RealNextHop: FE80::20C:29FF:FE4A:3873
BkLabel: NULL
BkNextHop: N/A
Tunnel ID: Invalid
BkTunnel ID: Invalid
Interface: Vlan-interface101
BkInterface: N/A
The output shows that Switch C communicates with network 1200::0/64 through the path Switch
C<—>Switch B<—>Switch A. Then the path Switch C<—>Switch B<—>Switch A fails.
# Enable debugging on Switch C.
<SwitchC> debugging bgp event
<SwitchC> terminal monitor
<SwitchC> terminal logging level 7
%Mar 14 15:00:24:256 2012 SwitchC BFD/6/FSM: -VDC=1; Sess[3002::2/3001::1, LD/RD:
513/513, Interface:N/A, SessType:Ctrl, LinkType:INET], Sta: UP->DOWN, Diag: 1
*Mar 14 15:00:24:257 2012 SwitchC BGP/7/DEBUG: -VDC=1;
BGP.: 3001::1 Receive ManualStop event in ESTABLISHED state.
264
*Mar 14 15:00:24:257 2012 SwitchC BGP/7/DEBUG: -VDC=1;
BGP.: 3001::1 Send NOTIFICATION
Err/SubErr: 6/0 (Cease/ErrSubCode Unspecified)
Error data NULL.
*Mar 14 15:00:24:258 2012 SwitchC BGP/7/DEBUG: -VDC=1;
BGP.: 3001::1 State is changed from ESTABLISHED to IDLE.
The output shows that Switch C can quickly detect the link failure and notify BGP to change the relevant
IBGP session state.
# Display route 1200::0/64 on Switch C.
<SwitchC> display ipv6 routing-table 1200::0 64 verbose
Summary Count : 1
Destination: 1200::/64
Protocol: BGP4+
Process ID: 0
SubProtID: 0x1
Cost: 100
Age: 00h00m57s
Preference: 255
Tag: 0
State: Active Adv
OrigTblID: 0x1
OrigVrf: default-vrf
TableID: 0xa
OrigAs: 0
NBRID: 0x25000000
LastAs: 0
AttrID: 0x0
Neighbor: 2000::1
Flags: 0x10060
OrigNextHop: 2000::1
Label: NULL
RealNextHop: FE80::20C:29FF:FE40:715
BkLabel: NULL
Tunnel ID: Invalid
BkTunnel ID: Invalid
BkNextHop: N/A
Interface: Vlan-interface201
BkInterface: N/A
The output shows that Switch C communicates with network 1200::0/64 through the path Switch
C<—>Switch D<—>Switch A.
Troubleshooting BGP
Symptom
Display BGP peer information by using the display bgp peer ipv4 unicast or display bgp peer ipv6
unicast command. The state of the connection to a peer cannot become established.
Analysis
To become BGP peers, any two routers must establish a TCP connection using port 179 and exchange
Open messages successfully.
Solution
1.
Use the display current-configuration command to verify the current configuration, and verify that
the peer's AS number is correct.
265
2.
Use the display bgp peer ipv4 unicast or display bgp peer ipv6 unicast command to verify that the
peer's IP address/IPv6 address is correct.
3.
If a loopback interface is used, verify that the loopback interface is specified with the peer
connect-interface command.
4.
If the peer is a non-direct EBGP peer, verify that the peer ebgp-max-hop command is configured.
5.
Verify that a valid route to the peer is available.
6.
Use the ping command to verify the connectivity to the peer.
7.
Use the display tcp verbose or display ipv6 tcp verbose command to verify the TCP connection.
8.
Verify that no ACL rule is applied to disable TCP port 179.
266
Configuring PBR
Introduction to PBR
Different from destination-based routing, policy-based routing (PBR) uses user-defined policies to route
packets. A policy can specify the next hop and other parameters for packets that match specific criteria,
such as ACLs.
A device uses PBR to forward matching packets and uses the routing table to forward other packets. If
PBR is not configured, the device uses the routing table to forward packets.
The device supports only interface PBR, which guides the forwarding of packets received on an interface
only.
Policy
A policy comprises match criteria and actions to be taken on the matching packets. A policy can have
one or multiple nodes as follows:
•
Each node is identified by a node number. A smaller node number has a higher priority.
•
A node comprises if-match and apply clauses. An if-match clause specifies a match criterion, and
an apply clause specifies an action.
•
A node has a match mode of permit or deny.
A policy matches nodes in priority order against packets. If a packet satisfies the match criteria on a node,
it is processed by the action on the node. Otherwise, it goes to the next node for a match. If the packet
does not match the criteria on any node, it is forwarded according to the routing table.
if-match clause
PBR supports only the if-match acl clause, which sets an ACL match criterion.
You can specify only one if-match clause of each type for a node.
apply clause
PBR supports only the apply next-hop clause, which sets the next hop for packets.
Relationship between the match mode and clauses on the node
Does a packet match all
the if-match clauses on
the node?
Match mode
permit
Deny
• If the node is configured with an
Yes.
apply clause, PBR executes the apply
clause on the node.
• If the node is configured with no
The packet is forwarded according
to the routing table.
PBR matches the packet against the next
node.
PBR matches the packet against the
next node.
apply clause, the packet is forwarded
according to the routing table.
No.
267
A node that has no if-match clauses matches any packet.
PBR and track
PBR can work with the Track feature to dynamically adapt the availability status of a node configured
with an apply clause to the link status of a tracked next hop.
When the track entry associated with the node changes to negative because the next hop is detected as
being unavailable, the node cannot be used for forwarding. When the track entry changes to positive or
NotReady because the next hop is detected as being available, the node can be used for forwarding.
For more information about track-PBR collaboration, see High Availability Configuration Guide.
PBR configuration task list
Tasks at a glance
(Required.) Configuring a policy:
• Creating a node
• Configuring match criteria for a node
• Configuring actions for a node
(Required.) Configuring PBR
Configuring a policy
Creating a node
Step
Command
Remarks
1.
Enter system view.
system-view
N/A
2.
Create a node for a policy, and
enter policy node view.
policy-based-route policy-name
[ deny | permit ] node node-number
By default, no policy node is
created.
Configuring match criteria for a node
Step
Command
Remarks
1.
Enter system
view.
system-view
N/A
2.
Enter policy
node view.
policy-based-route policy-name [ deny | permit ] node
node-number
N/A
3.
Configure an
ACL match
criterion.
if-match acl acl-number
By default, no ACL
match criterion is
configured.
268
NOTE:
If an ACL match criterion is defined, packets are matched against the ACL rules, and the permit or deny
action and the time range of the specified ACL are ignored. If the specified ACL does not exist, no packet
is matched.
Configuring actions for a node
Step
Command
Remarks
1.
Enter system
view.
system-view
N/A
2.
Enter policy
node view.
policy-based-route policy-name [ deny |
permit ] node node-number
N/A
By default, no next hop is specified.
3.
Set next hops.
apply next-hop [ vpn-instance
vpn-instance-name ] { ip-address [ direct ]
[ track track-entry-number ] }&<1-n>
You can specify multiple next hops for
backup, which are executed in the
order they are configured.
The value of n is 2.
Configuring PBR
Configure PBR by applying a policy to an interface. PBR uses the policy to guide the forwarding of
packets received on the interface. The specified policy must exist. Otherwise, the interface PBR
configuration fails.
You can apply only one policy on an interface. Before you apply a new policy, you must first remove the
current policy from the interface.
You can apply the same policy on multiple interfaces.
To configure interface PBR:
Step
Command
Remarks
1.
Enter system
view.
system-view
N/A
2.
Enter interface
view.
interface interface-type interface-number
N/A
3.
Apply a policy
on the interface.
ip policy-based-route policy-name
By default, no policy is applied on the
interface.
Displaying and maintaining PBR
Execute display commands in any view and reset commands in user view.
Task
Command
Display PBR policy information.
display ip policy-based-route [ policy policy-name ]
Display PBR configuration.
display ip policy-based-route setup
269
Task
Command
Display interface PBR configuration and
statistics.
display ip policy-based-route interface interface-type
interface-number [ slot slot-number ]
Clear PBR statistics.
reset ip policy-based-route statistics [ policy policy-name ]
Packet type-based interface PBR configuration
example
Network requirements
As shown in Figure 70, configure PBR on Switch A to forward all TCP packets received on VLAN-interface
11 to the next hop 1.1.2.2. Switch A forwards other packets according to the routing table.
Figure 70 Network diagram
Configuration procedure
1.
Configure Switch A:
# Configure ACL 3101 to match TCP packets.
<SwitchA> system-view
[SwitchA] acl number 3101
[SwitchA-acl-adv-3101] rule permit tcp
[SwitchA-acl-adv-3101] quit
# Configure Node 5 for policy aaa to forward TCP packets to next hop 1.1.2.2.
[SwitchA] policy-based-route aaa permit node 5
[SwitchA-pbr-aaa-5] if-match acl 3101
[SwitchA-pbr-aaa-5] apply next-hop 1.1.2.2
[SwitchA-pbr-aaa-5] quit
270
# Configure interface PBR by applying the policy aaa on VLAN-interface 11.
[SwitchA] interface vlan-interface 11
[SwitchA-Vlan-interface11] ip address 10.110.0.10 255.255.255.0
[SwitchA-Vlan-interface11] ip policy-based-route aaa
[SwitchA-Vlan-interface11] quit
# Configure the IP addresses of VLAN-interface 10 and VLAN-interface 20.
[SwitchA] interface vlan-interface 10
[SwitchA-Vlan-interface10] ip address 1.1.2.1 255.255.255.0
[SwitchA-Vlan-interface10] quit
[SwitchA] interface vlan-interface 20
[SwitchA-Vlan-interface20] ip address 1.1.3.1 255.255.255.0
2.
Configure Switch B:
# Configure a static route to subnet 10.110.0.0/24.
<SwitchB> system-view
[SwitchB] ip route-static 10.110.0.0 24 1.1.2.1
# Configure the IP address of VLAN-interface 10.
[SwitchB] interface vlan-interface 10
[SwitchB-Vlan-interface10] ip address 1.1.2.2 255.255.255.0
3.
Configure Switch C:
# Configure a static route to subnet 10.110.0.0/24.
<SwitchC> system-view
[SwitchC] ip route-static 10.110.0.0 24 1.1.3.1
# Configure the IP address of VLAN-interface 20.
[SwitchC] interface vlan-interface 20
[SwitchC-Vlan-interface20] ip address 1.1.3.2 255.255.255.0
Verifying the configuration
# Configure the IP address 10.110.0.20/24 for Host A, and specify its gateway address as 10.110.0.10.
# On Host A, Telnet to Switch B that is directly connected to Switch A. The operation succeeds.
# On Host A, Telnet to Switch C that is directly connected to Switch A. The operation fails.
# Ping Switch C from Host A. The operation succeeds.
Telnet uses TCP and ping uses ICMP. The preceding results show that all TCP packets arriving on
VLAN-interface 11 of Switch A are forwarded to next hop 1.1.2.2, and other packets are forwarded
through VLAN-interface 20. The interface PBR configuration is effective.
271
Configuring IPv6 static routing
Static routes are manually configured and cannot adapt to network topology changes. If a fault or a
topological change occurs in the network, the network administrator must modify the static routes
manually. IPv6 static routing works well in a simple IPv6 network.
Configuring an IPv6 static route
Before you configure an IPv6 static route, complete the following tasks:
•
Configure parameters for the related interfaces.
•
Configure link layer attributes for the related interfaces.
•
Ensure that the neighboring nodes can reach each other.
To configure an IPv6 static route:
Step
1.
Enter system view.
Command
Remarks
system-view
N/A
• Approach 1:
2.
3.
4.
ipv6 route-static ipv6-address prefix-length
{ interface-type interface-number
[ next-hop-address ] | next-hop-address |
vpn-instance d-vpn-instance-name
next-hop-address } [ permanent ] [ preference
preference-value ] [ tag tag-value ]
[ description description-text ]
Use either approach.
Configure an IPv6 static
route.
• Approach 2:
(Optional.) Configure the
default preference for IPv6
static routes.
ipv6 route-static default-preference
default-preference-value
The default setting is 60.
(Optional.) Delete all IPv6
static routes, including the
default route.
delete ipv6 [ vpn-instance vpn-instance-name ]
static-routes all
The undo ipv6
route-static command
deletes one IPv6 static
route.
ipv6 route-static vpn-instance
s-vpn-instance-name ipv6-address
prefix-length { interface-type interface-number
[ next-hop-address ] | next-hop-address
[ public ] | vpn-instance d-vpn-instance-name
next-hop-address } [ permanent ] [ preference
preference-value ] [ tag tag-value ]
[ description description-text ]
By default, no IPv6 static
route is configured.
Configuring BFD for IPv6 static routes
BFD provides a general purpose, standard, and medium- and protocol-independent fast failure detection
mechanism. It can uniformly and quickly detect the failures of the bidirectional forwarding paths between
272
two routers for protocols, such as routing protocols and MPLS. For more information about BFD, see High
Availability Configuration Guide.
IMPORTANT:
Enabling BFD for a flapping route could worsen the situation.
Bidirectional control mode
To use BFD bidirectional control detection between two devices, enable BFD control mode for each
device's static route destined to the peer.
To configure a static route and enable BFD control mode for it, specify an output interface and a direct
next hop, or specify an indirect next hop and a specific BFD packet source address for the static route.
To configure BFD control mode for an IPv6 static route (direct next hop):
Step
1.
Enter system view.
Command
Remarks
system-view
N/A
• Approach 1:
2.
Configure BFD
control mode for an
IPv6 static route.
ipv6 route-static ipv6-address prefix-length
interface-type interface-number next-hop-address bfd
control-packet [ preference preference-value ] [ tag
tag-value ] [ description description-text ]
• Approach 2:
ipv6 route-static vpn-instance s-vpn-instance-name
ipv6-address prefix-length interface-type
interface-number next-hop-address bfd control-packet
[ preference preference-value ] [ tag tag-value ]
[ description description-text ]
Use either
approach.
By default, BFD
control mode for an
IPv6 static route is
not configured.
To configure BFD control mode for an IPv6 static route (indirect next hop):
Step
1.
Enter system view.
Command
Remarks
system-view
N/A
• Approach 1:
2.
Configure BFD
control mode for an
IPv6 static route.
ipv6 route-static ipv6-address prefix-length
{ next-hop-address bfd control-packet bfd-source
ipv6-address | vpn-instance d-vpn-instance-name
next-hop-address bfd control-packet bfd-source ip-address }
[ preference preference-value ] [ tag tag-value ] [ description
description-text ]
• Approach 2:
ipv6 route-static vpn-instance s-vpn-instance-name
ipv6-address prefix-length { next-hop-address bfd
control-packet bfd-source ipv6-address | vpn-instance
d-vpn-instance-name next-hop-address bfd control-packet
bfd-source ipv6-address } [ preference preference-value ]
[ tag tag-value ] [ description description-text ]
273
Use either
approach.
By default, BFD
control mode
for an IPv6
static route is
not configured.
Single-hop echo mode
With BFD echo mode enabled for a static route, the output interface sends BFD echo packets to the
destination device, which loops the packets back to test the link reachability.
IMPORTANT:
Do not use BFD for a static route with the output interface in spoofing state.
To configure BFD echo mode for an IPv6 static route:
Step
1.
Enter system view.
Command
Remarks
system-view
N/A
By default, the source address
of echo packets is not
configured.
2.
Configure the source
address of echo
packets.
bfd echo-source-ipv6 ipv6-address
The source address of echo
packets must be a global
unicast address.
For more information about this
command, see High
Availability Command
Reference.
• Approach 1:
3.
Configure BFD echo
mode for an IPv6
static route.
ipv6 route-static ipv6-address prefix-length
interface-type interface-number
next-hop-address bfd echo-packet
[ preference preference-value ] [ tag
tag-value ] [ description description-text ]
• Approach 2:
ipv6 route-static vpn-instance
s-vpn-instance-name ipv6-address
prefix-length interface-type
interface-number next-hop-address bfd
echo-packet [ preference preference-value ]
[ tag tag-value ] [ description
description-text ]
Use either approach.
By default, BFD echo mode for
an IPv6 static route is not
configured.
The next hop IPv6 address must
be a global unicast address.
Displaying and maintaining IPv6 static routes
Execute display commands in any view.
Task
Command
Display IPv6 static route information.
display ipv6 routing-table protocol static [ inactive | verbose ]
274
IPv6 static routing configuration examples
Basic IPv6 static route configuration example
Network requirements
As shown in Figure 71, configure IPv6 static routes so that hosts can reach one another.
Figure 71 Network diagram
Host B 2::2/64
Vlan-int400
2::1/64
Vlan-int200
4::2/64
Vlan-int300
5::2/64
Switch B
Vlan-int200
4::1/64
Vlan-int300
5::1/64
Vlan-int100
1::1/64
Host A 1::2/64
Vlan-int500
3::1/64
Switch C
Switch A
Host C 3::2/64
Configuration procedure
1.
Configure the IPv6 addresses for all VLAN interfaces. (Details not shown.)
2.
Configure IPv6 static routes:
# Configure a default IPv6 static route on Switch A.
<SwitchA> system-view
[SwitchA] ipv6 route-static :: 0 4::2
# Configure two IPv6 static routes on Switch B.
<SwitchB> system-view
[SwitchB] ipv6 route-static 1:: 64 4::1
[SwitchB] ipv6 route-static 3:: 64 5::1
# Configure a default IPv6 static route on Switch C.
<SwitchC> system-view
[SwitchC] ipv6 route-static :: 0 5::2
3.
Configure the IPv6 addresses for all the hosts and configure the default gateway of Host A, Host
B, and Host C as 1::1, 2::1, and 3::1.
4.
Verify the configuration:
# Display the IPv6 static route information on Switch A.
[SwitchA] display ipv6 routing-table protocol static
Summary Count : 1
Static Routing table Status : <Active>
Summary Count : 1
275
Destination: ::
Protocol
NextHop
: 4::2
Preference: 60
: Static
Interface
: Vlan-interface200
Cost
: 0
Destination: 1::/64
Protocol
: Static
NextHop
: 4::1
Preference: 60
Interface
: Vlan-interface200
Cost
: 0
Destination: 3::/64
Protocol
: Static
NextHop
: 5::1
Preference: 60
Interface
: Vlan-interface300
Cost
Static Routing table Status : <Inactive>
Summary Count : 0
# Display the IPv6 static route information on Switch B.
[SwitchB] display ipv6 routing-table protocol static
Summary Count : 2
Static Routing table Status : <Active>
Summary Count : 2
: 0
Static Routing table Status : <Inactive>
Summary Count : 0
# Use the ping command to test the reachability.
[SwitchA] ping ipv6 3::1
PING6(104=40+8+56 bytes) 4::1 --> 3::1
56 bytes from 3::1, icmp_seq=0 hlim=62 time=4.000 ms
56 bytes from 3::1, icmp_seq=1 hlim=62 time=3.000 ms
56 bytes from 3::1, icmp_seq=2 hlim=62 time=2.000 ms
56 bytes from 3::1, icmp_seq=3 hlim=62 time=2.000 ms
56 bytes from 3::1, icmp_seq=4 hlim=62 time=2.000 ms
--- 3::1 ping6 statistics --5 packet(s) transmitted, 5 packet(s) received, 0.0% packet loss
round-trip min/avg/max/std-dev = 2.000/10.200/42.000/15.905 ms
BFD for IPv6 static routes configuration example (direct next
hop)
Network requirements
In Figure 72, configure an IPv6 static route to subnet 120::/64 on Switch A, and configure an IPv6 static
route to subnet 121::/64 on Switch B. Enable BFD for both routes. Configure an IPv6 static route to subnet
120::/64 and an IPv6 static route to subnet 121::/64 on Switch C. When the link between Switch A and
Switch B through the Layer 2 switch fails, BFD can detect the failure immediately, and Switch A and
Switch B can communicate through Switch C.
276
Figure 72 Network diagram
Device
Interface
IPv6 address
Device
Interface
IPv6 address
Switch A
Vlan-int10
12::1/64
Switch B
Vlan-int10
12::2/64
Vlan-int11
10::102/64
Vlan-int13
13::1/64
Switch C
Vlan-int11
10:: 100/64
Vlan-int13
13::2/64
Configuration procedure
1.
Configure IPv6 addresses for interfaces. (Details not shown.)
2.
Configure IPv6 static routes and BFD:
# Configure IPv6 static routes on Switch A and enable BFD control mode for the static route that
traverses the Layer 2 switch.
<SwitchA> system-view
[SwitchA] interface vlan-interface 10
[SwitchA-vlan-interface10] bfd min-transmit-interval 500
[SwitchA-vlan-interface10] bfd min-receive-interval 500
[SwitchA-vlan-interface10] bfd detect-multiplier 9
[SwitchA-vlan-interface10] quit
[SwitchA] ipv6 route-static 120:: 64 vlan-interface 10 FE80::2E0:FCFF:FE58:123E bfd
control-packet
[SwitchA] ipv6 route-static 120:: 64 10::100 preference 65
[SwitchA] quit
# Configure IPv6 static routes on Switch B and enable BFD control mode for the static route that
traverses the Layer 2 switch.
<SwitchB> system-view
[SwitchB] interface vlan-interface 10
[SwitchB-vlan-interface10] bfd min-transmit-interval 500
[SwitchB-vlan-interface10] bfd min-receive-interval 500
[SwitchB-vlan-interface10] bfd detect-multiplier 9
[SwitchB-vlan-interface10] quit
[SwitchB] ipv6 route-static 121:: 64 vlan-interface 10 FE80::2A0:FCFF:FE00:580A bfd
control-packet
[SwitchB] ipv6 route-static 121:: 64 vlan-interface 13 13::2 preference 65
[SwitchB] quit
# Configure IPv6 static routes on Switch C.
<SwitchC> system-view
[SwitchC] ipv6 route-static 120:: 64 13::1
[SwitchC] ipv6 route-static 121:: 64 10::102
277
Verifying the configuration
# Display the BFD sessions on Switch A.
<SwitchA> display bfd session
Total Session Num: 1
Up Session Num: 1
Init Mode: Active
IPv6 Session Working Under Ctrl Mode:
Local Discr: 513
Remote Discr: 33
Source IP: FE80::2A0:FCFF:FE00:580A (link-local address of VLAN-interface 10 on
Switch A)
Destination IP: FE80::2E0:FCFF:FE58:123E (link-local address of VLAN-interface 10 on
Switch B)
Session State: Up
Interface: Vlan10
Hold Time: 2012ms
The output shows that the BFD session has been created.
# Display IPv6 static routes on Switch A.
<SwitchA> display ipv6 routing-table protocol static
Summary Count : 1
Static Routing table Status : <Active>
Summary Count : 1
Destination: 12::/64
Protocol
: Static
NextHop
: 12::2
Preference: 60
Interface
: Vlan10
Cost
: 0
Direct Routing table Status : <Inactive>
Summary Count : 0
The output shows that Switch A communicates with Switch B through VLAN-interface 10. Then the link
over VLAN-interface 10 fails.
# Display IPv6 static routes on Switch A again.
<SwitchA> display ipv6 routing-table protocol static
Summary Count : 1
Static Routing table Status : <Active>
Summary Count : 1
Destination: 120::/64
Protocol
NextHop
: 10::100
Preference: 65
Interface
: Vlan11
Cost
Static Routing table Status : < Inactive>
Summary Count : 0
278
: Static
: 0
The output shows that Switch A communicates with Switch B through VLAN-interface 11.
BFD for IPv6 static routes configuration example (indirect next
hop)
Network requirements
In Figure 73, Switch A has a route to interface Loopback 1 (2::9/128) on Switch B, with the output
interface being VLAN-interface 10. Switch B has a route to interface Loopback 1 (1::9/128) on Switch A,
with the output interface being VLAN-interface 12. Switch D has a route to 1::9/128, with the output
interface being VLAN-interface 10, and a route to 2::9/128, with the output interface being
VLAN-interface 12.
Configure an IPv6 static route to subnet 120::/64 on Switch A, and configure an IPv6 static route to
subnet 121::/64 on Switch B. Enable BFD for both routes. Configure an IPv6 static route to subnet
120::/64 and an IPv6 static route to subnet 121::/64 on both Switch C and Switch D. When the link
between Switch A and Switch B through Switch D fails, BFD can detect the failure immediately and
Switch A and Switch B can communicate through Switch C.
Figure 73 Network diagram
Loop1
2::9/128
Loop1
1::9/128
121::/64
120::/64
Switch D
Vlan-int10
Vlan-int12
Vlan-int10
Vlan-int12
BFD
1
t1
Vlan-int11
Switch B
Vl
an
-in
t1
3
-in
an
Vl
Switch A
Vlan-int13
Switch C
Device
Interface
IPv6 address
Device
Interface
IPv6 address
Switch A
Vlan-int10
12::1/64
Switch B
Vlan-int12
11::1/64
Vlan-int11
10::102/64
Vlan-int13
13::1/64
Switch C
Loop1
1::9/128
Vlan-int11
10::100/64
Vlan-int13
13::2/64
Switch D
Loop1
2::9/128
Vlan-int10
12::2/64
Vlan-int12
11::2/64
Configuration procedure
1.
Configure IPv6 addresses for interfaces. (Details not shown.)
2.
Configure IPv6 static routes and BFD:
# Configure IPv6 static routes on Switch A and enable BFD control packet mode for the IPv6 static
route that traverses Switch D.
<SwitchA> system-view
[SwitchA] interface loopback 1
[SwitchA-LoopBack1] bfd min-transmit-interval 500
[SwitchA-LoopBack1] bfd min-receive-interval 500
[SwitchA-LoopBack1] bfd detect-multiplier 9
[SwitchA-LoopBack1] quit
279
[SwitchA] ipv6 route-static 120:: 64 2::9 bfd control-packet bfd-source 1::9
[SwitchA] ipv6 route-static 120:: 64 10::100 preference 65
[SwitchA] quit
# Configure IPv6 static routes on Switch B and enable BFD control packet mode for the static route
that traverses Switch D.
<SwitchB> system-view
[SwitchB] interface loopback 1
[SwitchB-LoopBack1] bfd min-transmit-interval 500
[SwitchB-LoopBack1] bfd min-receive-interval 500
[SwitchB-LoopBack1] bfd detect-multiplier 9
[SwitchB-LoopBack1] quit
[SwitchB] ipv6 route-static 121:: 64 1::9 bfd control-packet bfd-source 2::9
[SwitchB] ipv6 route-static 121:: 64 13::2 preference 65
[SwitchB] quit
# Configure IPv6 static routes on Switch C.
<SwitchC> system-view
[SwitchC] ipv6 route-static 120:: 64 13::2
[SwitchC] ipv6 route-static 121:: 64 10::102
# Configure IPv6 static routes on Switch D.
<SwitchD> system-view
[SwitchD] ipv6 route-static 120:: 64 11::2
[SwitchD] ipv6 route-static 121:: 64 12::1
Verifying the configuration
# Display the BFD sessions on Switch A.
<SwitchA> display bfd session
Total Session Num: 1
Up Session Num: 1
Init Mode: Active
IPv6 Session Working Under Ctrl Mode:
Local Discr: 513
Remote Discr: 33
Source IP: FE80::1:1B49 (link-local address of Loopback1 on Switch A)
Destination IP: FE80::1:1B49 (link-local address of Loopback1 on Switch B)
Session State: Up
Interface: Loop1
Hold Time: 2012ms
The output shows that the BFD session has been created.
# Display the IPv6 static routes on Switch A.
<SwitchA> display ipv6 routing-table protocol static
Summary Count : 1
Static Routing table Status : <Active>
Summary Count : 1
Destination: 120::/64
Protocol
NextHop
Preference: 60
: 2::9
280
: Static
Interface
: Vlan10
Cost
: 0
Static Routing table Status : <Inactive>
Summary Count : 0
The output shows that Switch A communicates Switch B through VLAN-interface 10. Then the link over
VLAN-interface 10 fails.
# Display IPv6 static routes on Switch A again.
<SwitchA> display ipv6 routing-table protocol static
Summary Count : 1
Static Routing table Status : <Active>
Summary Count : 1
Destination: 120::/64
Protocol
NextHop
: 10::100
Preference: 65
: Static
Interface
: Vlan11
Cost
: 0
Static Routing table Status : <Inactive>
Summary Count : 0
The output shows that Switch A communicates with Switch B through VLAN-interface 11.
281
Configuring an IPv6 default route
A default IPv6 route is used to forward packets that match no entry in the routing table.
A default IPv6 route can be configured in either of the following ways:
•
The network administrator can configure a default route with a destination prefix of ::/0. For more
information, see "Configuring an IPv6 static route."
•
Some dynamic routing protocols, such as OSPFv3, IPv6 IS-IS, and RIPng, can generate a default
IPv6 route. For example, an upstream router running OSPFv3 can generate a default IPv6 route and
advertise it to other routers, which install the default IPv6 route with the next hop being the upstream
router. For more information, see the respective chapters on those routing protocols in this
configuration guide.
282
Configuring RIPng
RIP next generation (RIPng) is an extension of RIP-2 for support of IPv6. Most RIP concepts are applicable
to RIPng.
Overview
RIPng is a distance vector routing protocol. It employs UDP to exchange route information through port
521. RIPng uses a hop count to measure the distance to a destination. The hop count is the metric or cost.
The hop count from a router to a directly connected network is 0. The hop count between two directly
connected routers is 1. When the hop count is greater than or equal to 16, the destination network or host
is unreachable.
By default, the routing update is sent every 30 seconds. If the router receives no routing updates from a
neighbor within 180 seconds, the routes learned from the neighbor are considered unreachable. If no
routing update is received within another 240 seconds, the router removes these routes from the routing
table.
RIPng for IPv6 has the following differences from RIP:
•
UDP port number—RIPng uses UDP port 521 to send and receive routing information.
•
Multicast address—RIPng uses FF02:9 as the link-local-router multicast address.
•
Destination Prefix—128-bit destination address prefix.
•
Next hop—128-bit IPv6 address.
•
Source address—RIPng uses FE80::/10 as the link-local source address.
RIPng route entries
RIP stores routing entries in a database. Each routing entry contains the following elements:
•
Destination address—IPv6 address of a destination host or a network.
•
Next hop address—IPv6 address of the next hop.
•
Egress interface—Egress interface of the route.
•
Metric—Cost from the local router to the destination.
•
Route time—Time elapsed since the last update. The time is reset to 0 every time the routing entry
is updated.
•
Route tag—Used for route control. For more information, see "Configuring routing policies."
RIPng packets
RIPng uses request and response packets to exchange routing information as follows:
1.
When RIPng starts or needs to update some routing entries, it sends a multicast request packet to
neighbors.
2.
When a RIPng neighbor receives the request packet, it sends back a response packet that contains
the local routing table. RIPng can also advertise route updates in response packets periodically or
advertise a triggered update caused by a route change.
283
3.
After RIPng receives a response, it checks the validity of the response before adding routes to its
routing table, such as whether the source IPv6 address is the link-local address and whether the
port number is correct. A response packet that fails the check is discarded.
Protocols and standards
•
RFC 2080, RIPng for IPv6
•
RFC 2081, RIPng Protocol Applicability Statement
RIPng configuration task list
Tasks at a glance
(Required.) Configuring basic RIPng
(Optional.) Configuring RIPng route control
•
•
•
•
•
•
Configuring an additional routing metric
Configuring RIPng route summarization
Advertising a default route
Configuring inbound/outbound route filtering
Configuring a preference for RIPng
Configuring RIPng route redistribution
(Optional.) Tuning and optimizing the RIPng network
•
•
•
•
Configuring RIPng timers
Configuring split horizon and poison reverse
Configuring zero field check on RIPng packets
Configuring the maximum number of ECMP routes
(Optional.) Configuring RIPng Graceful Restart
Configuring basic RIPng
Before you configure basic RIPng, configure IPv6 addresses for interfaces to ensure IPv6 connectivity
between neighboring nodes.
To configure basic RIPng:
Step
Command
Remarks
1.
Enter system view.
system-view
N/A
2.
Create a RIPng process and
enter its view.
ripng [ process-id ]
[ vpn-instance
vpn-instance-name ]
By default, the RIPng process is not
created.
3.
Return to system view.
quit
N/A
4.
Enter interface view.
interface interface-type
interface-number
N/A
284
Step
Command
Remarks
By default, RIPng is disabled.
Enable RIPng on the interface.
5.
ripng process-id enable
If RIPng is not enabled on an
interface, the interface does not send
or receive any RIPng route.
Configuring RIPng route control
Before you configure RIPng, complete the following tasks:
•
Configure IPv6 addresses for interfaces to ensure IPv6 connectivity between neighboring nodes.
•
Configure basic RIPng.
Configuring an additional routing metric
An additional routing metric (hop count) can be added to the metric of an inbound or outbound RIPng
route.
An outbound additional metric is added to the metric of a sent route, and it does not change the route's
metric in the routing table.
An inbound additional metric is added to the metric of a received route before the route is added into the
routing table, and the route's metric is changed.
To configure an inbound or outbound additional routing metric:
Step
Command
Remarks
1.
Enter system view.
system-view
N/A
2.
Enter interface view.
interface interface-type interface-number
N/A
3.
Specify an inbound
additional routing metric.
ripng metricin value
The default setting is 0.
4.
Specify an outbound
additional routing metric.
ripng metricout value
The default setting is 1.
Configuring RIPng route summarization
Configure route summarization on an interface, so RIPng advertises a summary route based on the
longest match.
RIPng route summarization improves network scalability, reduces routing table size, and increases
routing table lookup efficiency.
For example, RIPng has two specific routes to be advertised through an interface: 1:11:11::24 with a metric
of a 2 and 1:11:12::34 with a metric of 3. Configure route summarization on the interface, so RIPng
advertises a single route 11::0/16 with a metric of 2.
To configure RIPng route summarization:
Step
1.
Enter system view.
Command
Remarks
system-view
N/A
285
Step
Command
Remarks
2.
Enter interface view.
interface interface-type interface-number
N/A
3.
Advertise a summary IPv6
prefix.
ripng summary-address ipv6-address
prefix-length
By default, the
summary IPv6 prefix
is not configured.
Advertising a default route
Step
Command
Remarks
1.
Enter system view.
system-view
N/A
2.
Enter interface view.
interface interface-type
interface-number
N/A
By default, RIPng does not advertise a
default route.
3.
Configure RIPng to advertise a
default route.
ripng default-route { only |
originate } [ cost cost ]
This command advertises a default
route on the current interface
regardless of whether the default route
is available in the local IPv6 routing
table.
Configuring inbound/outbound route filtering
Perform this task to filter inbound or outbound routes by using an IPv6 prefix list. You can also configure
RIPng to filter routes redistributed from other routing protocols and routes from a specified neighbor.
To configure a RIPng route filtering policy:
Step
Command
Remarks
1.
Enter system view.
system-view
N/A
2.
Enter RIPng view.
ripng [ process-id ] [ vpn-instance
vpn-instance-name ]
N/A
3.
Configure a filter policy
to filter incoming routes.
filter-policy { acl6-number | prefix-list
prefix-list-name } import
By default, RIPng does not filter
incoming routing information.
4.
Configure a filter policy
to filter outgoing routes.
filter-policy { acl6-number | prefix-list
prefix-list-name } export [ protocol
[ process-id ] ]
By default, RIPng does not filter
outgoing routing information.
Configuring a preference for RIPng
Routing protocols each have a preference. When they find routes to the same destination, the route found
by the routing protocol with the highest preference is selected as the optimal route. You can manually set
a preference for RIPng. The smaller the value, the higher the preference.
To configure a preference for RIPng:
286
Step
Command
Remarks
1.
Enter system view.
system-view
N/A
2.
Enter RIPng view.
ripng [ process-id ] [ vpn-instance
vpn-instance-name ]
N/A
3.
Configure a preference for
RIPng.
preference [ route-policy
route-policy-name ] value
The default setting is 100.
Configuring RIPng route redistribution
Step
Command
Remarks
1.
Enter system view.
system-view
N/A
2.
Enter RIPng view.
ripng [ process-id ] [ vpn-instance
vpn-instance-name ]
N/A
3.
Redistribute routes from other
routing protocols.
import-route protocol [ process-id ]
[ allow-ibgp ] [ cost cost |
route-policy route-policy-name ] *
By default, RIPng does not
redistribute routes from other
routing protocols.
4.
(Optional.) Configure a
default routing metric for
redistributed routes.
default cost cost
The default metric of redistributed
routes is 0.
Tuning and optimizing the RIPng network
This section describes how to tune and optimize the performance of the RIPng network as well as
applications under special network environments.
Before you tune and optimize the RIPng network, complete the following tasks:
•
Configure IPv6 addresses for interfaces to ensure IPv6 connectivity between neighboring nodes.
•
Configure basic RIPng.
Configuring RIPng timers
You can adjust RIPng timers to optimize the performance of the RIPng network.
When you adjust RIPng timers, consider the network performance, and perform unified configurations on
routers running RIPng to avoid unnecessary network traffic or route oscillation.
To configure RIPng timers:
Step
Command
Remarks
1.
Enter system view.
system-view
N/A
2.
Enter RIPng view.
ripng [ process-id ] [ vpn-instance
vpn-instance-name ]
N/A
287
Step
3.
Command
Configure RIPng
timers.
Remarks
timers { garbage-collect
garbage-collect-value | suppress
suppress-value | timeout
timeout-value | update
update-value } *
By default:
•
•
•
•
The update timer is 30 seconds.
The timeout timer is 180 seconds.
The suppress timer is 120 seconds.
The garbage-collect timer is 120 seconds.
Configuring split horizon and poison reverse
If both split horizon and poison reverse are configured, only the poison reverse function takes effect.
Configuring split horizon
Split horizon disables RIP from sending routes through the interface where the routes were learned to
prevent routing loops between neighbors.
HP recommends enabling split horizon to prevent routing loops in normal cases.
To configure split horizon:
Step
Command
Remarks
1.
Enter system view.
system-view
N/A
2.
Enter interface view.
interface interface-type
interface-number
N/A
3.
Enable split horizon.
ripng split-horizon
By default, split horizon is enabled.
Configuring poison reverse
The poison reverse function enables a route learned from an interface to be advertised through the
interface. However, the metric of the route is set to 16, which means the route is unreachable.
To configure poison reverse:
Step
Command
Remarks
1.
Enter system view.
system-view
N/A
2.
Enter interface view.
interface interface-type
interface-number
N/A
3.
Enable poison reverse.
ripng poison-reverse
By default, poison reverse is
disabled.
Configuring zero field check on RIPng packets
Some fields in the RIPng packet header must be zero. These fields are called "zero fields." You can
enable zero field check on incoming RIPng packets. If a zero field of a packet contains a non-zero value,
RIPng does not process the packets. If you are certain that all packets are trustworthy, disable the zero
field check to save CPU resources.
To configure RIPng zero field check:
288
Step
Command
Remarks
1.
Enter system view.
system-view
N/A
2.
Enter RIPng view.
ripng [ process-id ] [ vpn-instance
vpn-instance-name ]
N/A
3.
Enable the zero field check on
incoming RIPng packets.
checkzero
By default, this feature is enabled.
Configuring the maximum number of ECMP routes
Step
Command
Remarks
1.
Enter system view.
system-view
N/A
2.
Enter RIPng view.
ripng [ process-id ] [ vpn-instance
vpn-instance-name ]
N/A
maximum load-balancing number
By default, the maximum number of
ECMP routes is the same as that
configured in the max-ecmp-num
command. For more information
about the max-ecmp-num
command, see IP Routing
Command Reference.
Configure the maximum
number of ECMP routes.
3.
Configuring RIPng Graceful Restart
Graceful Restart (GR) ensures the continuity of packet forwarding when a routing protocol restarts or an
active/standby switchover occurs.
•
GR Restarter—Graceful restarting router. It must have GR capability.
•
GR Helper—A neighbor of the GR Restarter. It helps the GR Restarter to complete the GR process.
After RIPng restarts on a router, the router must learn RIPng routes again and updates its FIB table, which
causes network disconnections and route reconvergence.
With the GR feature, the restarting router (known as the "GR Restarter") can notify the event to its GR
capable neighbors. GR capable neighbors (known as "GR Helpers") keep their adjacencies with the
router within a configurable GR interval. During this process, the FIB table of the router does not change.
After the restart, the router contacts its neighbors to retrieve its FIB.
By default, a RIPng-enabled device acts as the GR Helper. Perform this task on the GR Restarter.
To configure GR on the GR Restarter:
Step
Command
Remarks
1.
Enter system view.
system-view
N/A
2.
Enable RIPng and enter RIPng
view.
ripng [ process-id ] [ vpn-instance
vpn-instance-name ]
N/A
3.
Enable the GR capability for
RIPng.
graceful-restart
By default, RIP GR is disabled.
289
Displaying and maintaining RIPng
Execute display commands in any view and reset commands in user view.
Task
Command
Display configuration information of a RIPng
process.
display ripng [ process-id ]
Display routes in the RIPng database.
display ripng process-id database
Display the routing information of a specified
RIPng process.
display ripng process-id route
Display RIPng interface information.
display ripng process-id interface [ interface-type
interface-number ]
Reset a RIPng process.
reset ripng process-id process
Clear statistics of a RIPng process.
reset ripng process-id statistics
RIPng configuration examples
Basic RIPng configuration example
Network requirements
As shown in Figure 74, all switches run RIPng. Configure Switch B to filter the route 2::/64 learned from
Switch A and to forward only the route 4::/64 to Switch A.
Figure 74 Network diagram
Configuration procedure
1.
Configure IPv6 addresses for interfaces. (Details not shown.)
2.
Configure basic RIPng:
# Configure Switch A.
<SwitchA> system-view
[SwitchA] ripng 1
[SwitchA-ripng-1] quit
[SwitchA] interface vlan-interface 100
[SwitchA-Vlan-interface100] ripng 1 enable
[SwitchA-Vlan-interface100] quit
[SwitchA] interface vlan-interface 400
[SwitchA-Vlan-interface400] ripng 1 enable
[SwitchA-Vlan-interface400] quit
# Configure Switch B.
290
<SwitchA> system-view
[SwitchA] ripng 1
[SwitchA-ripng-1] quit
[SwitchA] interface vlan-interface 100
[SwitchA-Vlan-interface100] ripng 1 enable
[SwitchA-Vlan-interface100] quit
[SwitchA] interface vlan-interface 400
[SwitchA-Vlan-interface400] ripng 1 enable
[SwitchA-Vlan-interface400] quit
# Configure Switch C.
<SwitchC> system-view
[SwitchC] ripng 1
[SwitchC-ripng-1] quit
[SwitchC] interface vlan-interface 200
[SwitchC-Vlan-interface200] ripng 1 enable
[SwitchC-Vlan-interface200] quit
[SwitchC] interface vlan-interface 500
[SwitchC-Vlan-interface500] ripng 1 enable
[SwitchC-Vlan-interface500] quit
[SwitchC] interface vlan-interface 600
[SwitchC-Vlan-interface600] ripng 1 enable
[SwitchC-Vlan-interface600] quit
# Display the RIPng routing table on Switch B.
[SwitchB] display ripng 1 route
Route Flags: A - Aging, S - Suppressed, G - Garbage-collect
---------------------------------------------------------------Peer FE80::20F:E2FF:FE23:82F5
on Vlan-interface100
Dest 1::/64,
via FE80::20F:E2FF:FE23:82F5, cost
1, tag 0, A, 6 Sec
Dest 2::/64,
via FE80::20F:E2FF:FE23:82F5, cost
Peer FE80::20F:E2FF:FE00:100
1, tag 0, A, 6 Sec
on Vlan-interface200
Dest 3::/64,
via FE80::20F:E2FF:FE00:100, cost
1, tag 0, A, 11 Sec
Dest 4::/64,
via FE80::20F:E2FF:FE00:100, cost
1, tag 0, A, 11 Sec
Dest 5::/64,
via FE80::20F:E2FF:FE00:100, cost
1, tag 0, A, 11 Sec
# Display the RIPng routing table on Switch A.
[SwitchA] display ripng 1 route
Route Flags: A - Aging, S - Suppressed, G - Garbage-collect
----------------------------------------------------------------
Peer FE80::200:2FF:FE64:8904
on Vlan-interface100
Dest 1::/64,
via FE80::200:2FF:FE64:8904, cost
291
1, tag 0, A, 31 Sec
Dest 3::/64,
via FE80::200:2FF:FE64:8904, cost
1, tag 0, A, 31 Sec
Dest 4::/64,
via FE80::200:2FF:FE64:8904, cost
2, tag 0, A, 31 Sec
Dest 5::/64,
via FE80::200:2FF:FE64:8904, cost
3.
2, tag 0, A, 31 Sec
Configure route filtering:
# Use IPv6 prefix lists on Switch B to filter inbound and outbound routes.
[SwitchB] ipv6 prefix-list aaa permit 4:: 64
[SwitchB] ipv6 prefix-list bbb deny 2:: 64
[SwitchB] ipv6 prefix-list bbb permit :: 0 less-equal 128
[SwitchB] ripng 1
[SwitchB-ripng-1] filter-policy prefix-list aaa export
[SwitchB-ripng-1] filter-policy prefix-list bbb import
[SwitchB-ripng-1] quit
# Display RIPng routing tables on Switch B and Switch A.
[SwitchB] display ripng 1 route
Route Flags: A - Aging, S - Suppressed, G - Garbage-collect
----------------------------------------------------------------
Peer FE80::1:100 on Vlan-interface100
Destination 1::/64,
via FE80::2:100, cost 1, tag 0, A, 6 secs
Peer FE80::3:200 on Vlan-interface200
Destination 3::/64,
via FE80::2:200, cost 1, tag 0, A, 11 secs
Destination 4::/64,
via FE80::2:200, cost 1, tag 0, A, 11 secs
Destination 5::/64,
via FE80::2:200, cost 1, tag 0, A, 11 secs
[SwitchA] display ripng 1 route
Route Flags: A - Aging, S - Suppressed, G - Garbage-collect
----------------------------------------------------------------
Peer FE80::2:100
on Ethernet1/1
Destination 4::/64,
via FE80::1:100, cost 2, tag 0, A, 2 secs
Configuring RIPng route redistribution
Network requirements
As shown in Figure 75, Switch B communicates with Switch A through RIPng 100 and with Switch C
through RIPng 200.
Configure route redistribution on Switch B, so the two RIPng processes can redistribute routes from each
other.
292
Figure 75 Network diagram
Configuration procedure
1.
Configure IPv6 addresses for interfaces. (Details not shown.)
2.
Configure basic RIPng:
# Enable RIPng 100 on Switch A.
<SwitchA> system-view
[SwitchA] ripng 100
[SwitchA-ripng-100] quit
[SwitchA] interface vlan-interface 100
[SwitchA-Vlan-interface100] ripng 100 enable
[SwitchA-Vlan-interface100] quit
[SwitchA] interface vlan-interface 200
[SwitchA-Vlan-interface200] ripng 100 enable
[SwitchA-Vlan-interface200] quit
# Enable RIP 100 and RIP 200 on Switch B.
<SwitchB> system-view
[SwitchB] ripng 100
[SwitchB-ripng-100] quit
[SwitchB] interface vlan-interface 100
[SwitchB-Vlan-interface100] ripng 100 enable
[SwitchB-Vlan-interface100] quit
[SwitchB] ripng 200
[SwitchB-ripng-200] quit
[SwitchB] interface vlan-interface 300
[SwitchB-Vlan-interface300] ripng 200 enable
[SwitchB-Vlan-interface300] quit
# Enable RIPng 200 on Switch C.
<SwitchC> system-view
[SwitchC] ripng 200
[SwitchC] interface vlan-interface 300
[SwitchC-Vlan-interface300] ripng 200 enable
[SwitchC-Vlan-interface300] quit
[SwitchC] interface vlan-interface 400
[SwitchC-Vlan-interface400] ripng 200 enable
[SwitchC-Vlan-interface400] quit
# Display the routing table on Switch A.
[SwitchA] display ipv6 routing-table
Destinations : 7 Routes : 7
293
3.
Destination: ::1/128
Protocol
: Direct
NextHop
: ::1
Preference: 0
Interface
: InLoop0
Cost
: 0
Destination: 1::/64
Protocol
: Direct
NextHop
: 1::1
Preference: 0
Interface
: Vlan100
Cost
: 0
Destination: 1::1/128
Protocol
: Direct
NextHop
: ::1
Preference: 0
Interface
: InLoop0
Cost
: 0
Destination: 2::/64
Protocol
: Direct
NextHop
: 2::1
Preference: 0
Interface
: Vlan200
Cost
: 0
Destination: 2::1/128
Protocol
: Direct
NextHop
: ::1
Preference: 0
Interface
: InLoop0
Cost
: 0
Destination: FE80::/10
Protocol
: Direct
NextHop
: ::
Preference: 0
Interface
: NULL0
Cost
: 0
Destination: FF00::/8
Protocol
: Direct
NextHop
: ::
Preference: 0
Interface
: NULL0
Cost
: 0
Configure RIPng route redistribution:
# Configure route redistribution between the two RIPng processes on Switch B.
[SwitchB] ripng 100
[SwitchB-ripng-100] import-route ripng 200
[SwitchB-ripng-100] quit
[SwitchB] ripng 200
[SwitchB-ripng-200] import-route ripng 100
[SwitchB-ripng-200] quit
# Display the routing table on Switch A.
[SwitchA] display ipv6 routing-table
Destinations : 8 Routes : 8
Destination: ::1/128
Protocol
NextHop
: ::1
Preference: 0
Interface
: InLoop0
Cost
: 0
Destination: 1::/64
Protocol
: Direct
NextHop
: 1::1
Preference: 0
Interface
: Vlan100
Cost
294
: Direct
: 0
Destination: 1::1/128
Protocol
NextHop
: ::1
Preference: 0
Interface
: InLoop0
Cost
: 0
Destination: 2::/64
Protocol
: Direct
NextHop
: 2::1
Preference: 0
Interface
: Vlan200
Cost
: 0
Destination: 2::1/128
Protocol
: Direct
NextHop
: ::1
Preference: 0
Interface
: InLoop0
Cost
: 0
Destination: 4::/64
Protocol
: RIPng
NextHop
: FE80::200:BFF:FE01:1C02
Preference: 100
Interface
: Vlan100
Cost
: 1
Destination: FE80::/10
Protocol
: Direct
NextHop
: ::
Preference: 0
Interface
: NULL0
Cost
: 0d
Destination: FF00::/8
Protocol
: Direct
NextHop
: ::
Preference: 0
Interface
: NULL0
Cost
295
: Direct
: 0
Configuring OSPFv3
This chapter describes how to configure RFC 2740-compliant Open Shortest Path First version 3 (OSPFv3)
for an IPv6 network. For more information about OSPFv2, see "Configuring OSPF".
OSPFv3 overview
OSPFv3 and OSPFv2 have the following in common:
•
32-bit router ID and area ID
•
Hello, Database Description (DD), Link State Request (LSR), Link State Update (LSU), Link State
Acknowledgment (LSAck)
•
Mechanisms for finding neighbors and establishing adjacencies
•
Mechanisms for advertising and aging LSAs
OSPFv3 and OSPFv2 have the following differences:
•
OSPFv3 runs on a per-link basis. OSPFv2 runs on a per-IP-subnet basis.
•
OSPFv3 supports running multiple processes on an interface, but OSPFv2 does not support.
•
OSPFv3 identifies neighbors by router ID. OSPFv2 identifies neighbors by IP address.
OSPFv3 packets
OSPFv3 uses the following packet types:
•
Hello—Periodically sent to find and maintain neighbors, containing timer values, information about
the DR, BDR, and known neighbors.
•
DD—Describes the digest of each LSA in the LSDB, exchanged between two routers for data
synchronization.
•
LSR—Requests needed LSAs from the neighbor. After exchanging the DD packets, the two routers
know which LSAs of the neighbor are missing from their LSDBs. They then send an LSR packet to
each other, requesting the missing LSAs. The LSA packet contains the digest of the missing LSAs.
•
LSU—Transmits the requested LSAs to the neighbor
•
LSAck—Acknowledges received LSU packets.
OSPFv3 LSA types
OSPFv3 sends routing information in the following types of LSAs as defined in RFC 5340:
•
Router-LSA—Originated by all routers. This LSA describes the collected states of the router's
interfaces to an area, and is flooded throughout a single area only.
•
Network-LSA—Originated for broadcast and NBMA networks by the DR. This LSA contains the list
of routers connected to the network, and is flooded throughout a single area only.
•
Inter-Area-Prefix-LSA—Originated by ABRs and flooded throughout the LSA's associated area.
Each Inter-Area-Prefix-LSA describes a route with IPv6 address prefix to a destination outside the
area, yet still inside the AS.
296
•
Inter-Area-Router-LSA—Originated by ABRs and flooded throughout the LSA's associated area.
Each Inter-Area-Router-LSA describes a route to ASBR.
•
AS-external-LSA—Originated by ASBRs, and flooded throughout the AS, except stub and NSSA
areas. Each AS-external-LSA describes a route to another AS. A default route can be described by
an AS external LSA.
•
Link-LSA—A router originates a separate Link-LSA for each attached link. Link-LSAs have link-local
flooding scope. Each Link-LSA describes the IPv6 address prefix of the link and Link-local address of
the router.
•
Intra-Area-Prefix-LSA—Each Intra-Area-Prefix-LSA contains IPv6 prefix information on a router, stub
area, or transit area information, and has area flooding scope. It was introduced because
Router-LSAs and Network-LSAs contain no address information.
RFC 5187 defines the Grace-LSA. A Grace-LSA is generated by a GR (Graceful Restart) Restarter at
reboot and transmitted on the local link. The restarter describes the cause and interval of the reboot in the
Grace-LSA to tell its neighbors that it performs a GR operation.
Protocols and standards
•
RFC 5340, OSPF for IPv6
•
RFC 2328, OSPF Version 2
•
RFC 5187, OSPFv3 Graceful Restart
OSPFv3 configuration task list
Tasks at a glance
(Required.) Enabling OSPFv3
(Optional.) Configuring OSPFv3 area parameters:
• Configuring a stub area
• Configuring an OSPFv3 virtual link
(Optional.) Configuring OSPFv3 network types:
• Configuring the OSPFv3 network type for an interface
• Configuring an NBMA or P2MP neighbor
(Optional.) Configuring OSPFv3 route control:
•
•
•
•
•
•
•
Configuring OSPFv3 route summarization
Configuring OSPFv3 inbound route filtering
Configuring Inter-Area-Prefix-LSA filtering
Configuring an OSPFv3 cost for an interface
Configuring the maximum number of OSPFv3 ECMP routes
Configuring a preference for OSPFv3
Configuring OSPFv3 route redistribution
297
Tasks at a glance
(Optional.) Tuning and optimizing OSPFv3 networks
•
•
•
•
•
•
•
•
Configuring OSPFv3 timers
Specifying LSA transmission delay
Configuring a DR priority for an interface
Specifying SPF calculation interval
Specifying the LSA generation interval
Ignoring MTU check for DD packets
Disabling interfaces from receiving and sending OSPFv3 packets
Enabling the logging of neighbor state changes
(Optional.) Configuring OSPFv3 GR
• Configuring GR Restarter
• Configuring GR Helper
(Optional.) Configuring BFD for OSPFv3
Enabling OSPFv3
Before you enable OSPFv3, configure IPv6 addresses for interfaces to ensure IPv6 connectivity between
neighboring nodes.
To enable an OSPFv3 process on a router:
•
Enable the OSPFv3 process globally.
•
Assign the OSPFv3 process a router ID.
•
Enable the OSPFv3 process on related interfaces.
The router ID uniquely identifies the router within an AS. If a router runs multiple OSPFv3 processes, you
must specify a unique router ID for each process.
An OSPFv3 process ID has only local significance. Process 1 on a router can exchange packets with
process 2 on another router.
To enable OSPFv3:
Step
Command
Remarks
1.
Enter system view.
system-view
N/A
2.
Enable an OSPFv3 process
and enter its view.
ospfv3 [ process-id | vpn-instance
vpn-instance-name ] *
By default, no OSPFv3 process is
enabled.
3.
Specify a router ID.
router-id router-id
By default, no router ID is
configured.
4.
Enter interface view.
interface interface-type
interface-number
N/A
5.
Enable an OSPFv3 process on
the interface.
ospfv3 process-id area area-id
[ instance instance-id ]
No OSPFv3 process is enabled on
an interface by default.
298
Configuring OSPFv3 area parameters
OSPFv3 has the same stub area and virtual link features as OSPFv2.
After you split an OSPFv3 AS into multiple areas, the LSA number is reduced and OSPFv3 applications
are extended. To further reduce the size of routing tables and the number of LSAs, configure the
non-backbone areas at an AS edge as stub areas.
Non-backbone areas exchange routing information through the backbone area, so the backbone and
non-backbone areas (including the backbone itself) must be fully meshed. If no connectivity can be
achieved, configure virtual links.
Configuration prerequisites
Before you configure OSPFv3 area parameters, enable OSPFv3.
Configuring a stub area
All the routers attached to a stub area must be configured with the stub command. The keyword
no-summary is only available on the ABR of the stub area.
If you use the stub command with the keyword no-summary on an ABR, the ABR advertises a default
route in an Inter-Area-Prefix-LSA into the stub area. No AS-external-LSA, Inter-Area-Prefix-LSA, or other
Inter-Area-Router-LSA is advertised in the area. The stub area of this kind is also known as a "totally stub
area."
To configure an OSPFv3 stub area:
Step
Command
Remarks
1.
Enter system view.
system-view
N/A
2.
Enter OSPFv3 view.
ospfv3 [ process-id | vpn-instance
vpn-instance-name ] *
N/A
3.
Enter OSPFv3 area view.
area area-id
N/A
4.
Configure the area as a stub
area.
stub
[ default-route-advertise-always |
no-summary ] *
By default, no stub area is
configured as a stub area.
5.
(Optional.) Specify a cost for
the default route advertised to
the stub area.
default-cost value
The default setting is 1.
Configuring an OSPFv3 virtual link
You can configure a virtual link to maintain connectivity between a non-backbone area and the
backbone, or in the backbone itself.
IMPORTANT:
• Both ends of a virtual link are ABRs that must be configured with the vlink-peer command.
• Do not configure virtual links in the areas of a GR-capable process.
To configure a virtual link:
299
Step
Command
Remarks
1.
Enter system view.
system-view
N/A
2.
Enter OSPFv3 view.
ospfv3 [ process-id | vpn-instance
vpn-instance-name ] *
N/A
3.
Enter OSPFv3 area view.
area area-id
N/A
Configure a virtual link.
vlink-peer router-id [ dead seconds |
hello seconds | instance instance-id |
retransmit seconds | trans-delay
seconds ] *
By default, no virtual link is
configured.
4.
Configuring OSPFv3 network types
OSPFv3 classifies networks into the following types by the link layer protocol:
•
Broadcast—When the link layer protocol is Ethernet or FDDI, OSPFv3 considers the network type
as broadcast by default.
•
NBMA—When the link layer protocol is ATM, Frame Relay, or X.25, OSPFv3 considers the network
type as NBMA by default.
•
P2P—When the link layer protocol is PPP, LAPB, HDLC, or POS, OSPFv3 considers the network type
as P2P by default.
Follow these guidelines when you change the network type of an OSPFv3 interface:
•
An NBMA network must be fully connected. Any two routers in the network must be directly
reachable to each other through a virtual circuit. If no such direct link is available, you must change
the network type through a command.
•
If direct connections are not available between some routers in an NBMA network, the type of
interfaces associated must be configured as P2MP, or as P2P for interfaces with only one neighbor.
Configuration prerequisites
Before you configure OSPFv3 network types, enable OSPFv3.
Configuring the OSPFv3 network type for an interface
Step
Command
Remarks
1.
Enter system view.
system-view
N/A
2.
Enter interface view.
interface interface-type
interface-number
N/A
3.
Configure a network type for
the OSPFv3 interface.
ospfv3 network-type { broadcast |
nbma | p2mp [ unicast ] | p2p }
[ instance instance-id ]
By default, the network type of an
interface depends on the media type
of the interface.
300
Configuring an NBMA or P2MP neighbor
For NBMA and P2MP interfaces (only when in unicast mode), you must specify the link-local IP addresses
of their neighbors because these interfaces cannot find neighbors through broadcasting hello packets.
For NBMA interfaces, you can also specify DR priorities for neighbors.
To configure an NBMA or P2MP (unicast) neighbor and its DR priority:
Step
Command
Remarks
1.
Enter system view.
system-view
N/A
2.
Enter interface view.
interface interface-type
interface-number
N/A
3.
Specify an NBMA or P2MP
(unicast) neighbor and its DR
priority.
ospfv3 peer ipv6-address [ cost
value | dr-priority dr-priority ]
[ instance instance-id ]
By default, no link-local
address is specified for the
neighbor interface.
Configuring OSPFv3 route control
Configuration prerequisites
Before you configure OSPFv3 route control, complete the following tasks:
•
Configure IPv6 addresses for interfaces to ensure IPv6 connectivity between neighboring nodes.
•
Enable OSPFv3.
Configuring OSPFv3 route summarization
If contiguous network segments exist in an area, you can use the abr-summary command to summarize
them into one network segment on the ABR. The ABR will advertise only the summary route. Any LSA
falling into the specified network segment will not be advertised, reducing the LSDB size in other areas.
To configure route summarization:
Step
Command
Remarks
1.
Enter system view.
system-view
N/A
2.
Enter OSPFv3 view.
ospfv3 [ process-id | vpn-instance
vpn-instance-name ] *
N/A
3.
Enter OSPFv3 area view.
area area-id
N/A
4.
Configure route
summarization.
abr-summary ipv6-address prefix-length
[ not-advertise ] [ cost value ]
By default, route summarization is
not configured.
The abr-summary command takes
effect only on ABRs.
Configuring OSPFv3 inbound route filtering
According to some rules, you can configure OSPFv3 to filter routes calculated using received LSAs.
To configure OSPFv3 to filter routes calculated using received LSAs:
301
Step
Command
Remarks
1.
Enter system view.
system-view
N/A
2.
Enter OSPFv3 view.
ospfv3 [ process-id | vpn-instance
vpn-instance-name ] *
N/A
Configure OSPFv3 to
filter routes calculated
using received LSAs.
filter-policy { acl6-number [ gateway
prefix-list-name ] | prefix-list
prefix-list-name [ gateway
prefix-list-name ] | gateway
prefix-list-name | route-policy
route-policy-name } import
3.
By default, OSPFv3 accepts all
routes calculated using received
LSAs.
This command can only filter routes
computed by OSPFv3. Only routes
not filtered out can be added into
the local routing table.
Configuring Inter-Area-Prefix-LSA filtering
Step
Command
Remarks
1.
Enter system view.
system-view
N/A
2.
Enter OSPFv3 view.
ospfv3 [ process-id | vpn-instance
vpn-instance-name ] *
N/A
3.
Configure OSPFv3 to filter
Inter-Area-Prefix-LSAs.
filter { acl6-number | prefix-list
prefix-list-name | route-policy
route-policy-name } { export | import }
By default, OSPFv3 accepts all
Inter-Area-Prefix-LSAs.
This command takes effect only on
ABRs.
Configuring an OSPFv3 cost for an interface
You can configure an OSPFv3 cost for an interface with one of the following methods:
•
Configure the cost value in interface view.
•
Configure a bandwidth reference value for the interface, and OSPFv3 computes the cost
automatically based on the bandwidth reference value: Interface OSPFv3 cost = Bandwidth
reference value (100 Mbps)/Interface bandwidth (Mbps). If the calculated cost is greater than
65535, the value of 65535 is used; if the calculated cost is smaller than 1, the value of 1 is used.
If no cost is configured for an interface, OSPFv3 automatically computes the cost for the interface.
To configure an OSPFv3 cost for an interface:
Step
Command
Remarks
1.
Enter system view.
system-view
N/A
2.
Enter interface view.
interface interface-type
interface-number
N/A
3.
Configure an OSPFv3
cost for the interface.
ospfv3 cost value [ instance
instance-id ]
By default, the OSPF cost is 1 for a VLAN
interface, is 0 for a loopback interface, and is
automatically computed according to the
interface bandwidth for other interfaces.
To configure a bandwidth reference value:
302
Step
Command
Remarks
1.
Enter system view.
system-view
N/A
2.
Enter OSPFv3 view.
ospfv3 [ process-id | vpn-instance
vpn-instance-name ] *
N/A
3.
Configure a bandwidth
reference value.
bandwidth-reference value
The default setting is100 Mbps.
Configuring the maximum number of OSPFv3 ECMP routes
Perform this task to implement load sharing over ECMP routes.
To configure the maximum number of ECMP routes:
Step
Command
Remarks
1.
Enter system view.
system-view
N/A
2.
Enter OSPFv3 view.
ospfv3 [ process-id | vpn-instance
vpn-instance-name ] *
N/A
maximum load-balancing
maximum
By default, the maximum number
of ECMP routes is the same as that
configured in the max-ecmp-num
command. For more information
about the max-ecmp-num
command, see IP Routing
Command Reference.
3.
Specify the maximum number
of ECMP routes.
Configuring a preference for OSPFv3
A router can run multiple routing protocols. The system assigns a priority for each protocol. When these
routing protocols find the same route, the route found by the protocol with the highest priority is selected.
To configure a preference for OSPFv3:
Step
Command
Remarks
1.
Enter system view.
system-view
N/A
2.
Enter OSPFv3 view.
ospfv3 [ process-id |
vpn-instance
vpn-instance-name ] *
N/A
3.
Configure a preference
for OSPFv3.
preference [ ase ] [ route-policy
route-policy-name ] preference
By default, the preference of OSPFv3
internal routes is 10, and the priority of
OSPFv3 external routes is 150.
Configuring OSPFv3 route redistribution
Because OSPFv3 is a link state routing protocol, it cannot directly filter LSAs to be advertised. OSPFv3
filters only redistributed routes. Only routes that are not filtered out can be advertised in LSAs.
Executing the import-route or default-route-advertise command on a router makes it become an ASBR.
303
To configure OSPFv3 route redistribution:
Step
Command
Remarks
1.
Enter system view.
system-view
N/A
2.
Enter OSPFv3 view.
ospfv3 [ process-id | vpn-instance
vpn-instance-name ] *
N/A
3.
(Optional.) Specify a default
cost for redistributed routes.
default cost value
The default setting is 1.
4.
Configure OSPFv3 to
redistribute routes from other
routing protocols.
import-route protocol [ process-id |
all-processes | allow-ibgp ] [ cost cost |
route-policy route-policy-name | type
type ] *
By default, route redistribution
is disabled.
5.
(Optional.) Configure
OSPFv3 to redistribute a
default route.
default-route-advertise [ [ always |
permit-calculate-other ] | cost cost |
route-policy route-policy-name | type
type ] *
By default, no default route is
redistributed.
This command can only inject
and advertise a default route.
By default, OSPFv3 accepts
all redistributed routes.
(Optional.) Configure
OSPFv3 to filter redistributed
routes.
6.
filter-policy { acl6-number | prefix-list
prefix-list-name } export [ protocol
[ process-id ] ]
This command filters only
routes redistributed with the
import-route command. If the
import-route command is not
configured, executing this
command does not take
effect.
Tuning and optimizing OSPFv3 networks
This section describes configurations of OSPFv3 timers, interface DR priority, and the logging of
neighbor state changes.
Configuration prerequisites
Before you tune and optimize OSPFv3 networks, complete the following tasks:
•
Configure IPv6 addresses for interfaces to ensure IPv6 connectivity between neighboring nodes.
•
Enable OSPFv3.
Configuring OSPFv3 timers
Step
Command
Remarks
1.
Enter system view.
system-view
N/A
2.
Enter interface view.
interface interface-type
interface-number
N/A
3.
Configure the hello interval.
ospfv3 timer hello seconds
[ instance instance-id ]
By default, the hello interval on P2P and
broadcast interfaces is 10 seconds.
304
Step
Command
Remarks
By default, the dead interval on P2P and
broadcast interfaces is 40 seconds.
4.
Configure the dead interval.
ospfv3 timer dead seconds
[ instance instance-id ]
The dead interval set on neighboring
interfaces cannot be too short.
Otherwise, a neighbor is easily
considered down.
5.
Configure the poll interval.
ospfv3 timer poll seconds
[ instance instance-id ]
By default, the poll interval is 120
seconds.
The default setting is 5 seconds.
6.
Configure the LSA
retransmission interval.
ospfv3 timer retransmit
interval [ instance instance-id ]
The LSA retransmission interval cannot
be too short. Otherwise, unnecessary
retransmissions will occur.
Specifying LSA transmission delay
Each LSA in the LSDB has an age that is incremented by 1 every second, but the age does not change
during transmission. Therefore, it is necessary to add a transmission delay into the age time, especially
for low-speed links.
To specify the LSA transmission delay on an interface:
Step
Command
Remarks
1.
Enter system view.
system-view
N/A
2.
Enter interface view.
interface interface-type
interface-number
N/A
3.
Specify the LSA transmission
delay.
ospf trans-delay seconds [ instance
instance-id ]
By default, the LSA transmission
delay is 1 second.
Specifying SPF calculation interval
LSDB changes result in SPF calculations. When the topology changes frequently, a large amount of
network and router resources are occupied by SPF calculation. You can adjust the SPF calculation
interval to reduce the impact.
When network changes are not frequent, the minimum-interval is adopted. If network changes become
frequent, the SPF calculation interval is incremented by incremental-interval × 2n-2 (n is the number of
generation times) each time an SPF calculation occurs until the maximum-interval is reached.
To configure SPF calculation interval:
Step
Command
Remarks
1.
Enter system view.
system-view
N/A
2.
Enter OSPFv3 view.
ospfv3 [ process-id | vpn-instance
vpn-instance-name ] *
N/A
305
Step
Command
Remarks
By default:
• The maximum interval is 5
3.
Specify the SPF
calculation interval.
seconds.
spf-schedule-interval maximum-interval
[ minimum-interval
[ incremental-interval ] ]
• The minimum interval is 50
milliseconds.
• The incremental interval is 200
milliseconds.
Specifying the LSA generation interval
You can adjust the LSA generation interval to protect network resources and routers from being over
consumed by frequent network changes.
When network changes are not frequent, LSAs are generated at the minimum-interval. If network
changes become frequent, the LSA generation interval is incremented by incremental-interval × 2n-2 (n is
the number of generation times) each time an LSA generation occurs until the maximum-interval is
reached.
To configure the LSA generation interval:
Step
Command
Remarks
1.
Enter system view.
system-view
N/A
2.
Enter OSPFv3 view.
ospf [ process-id | vpn-instance
vpn-instance-name ] *
N/A
3.
Configure the LSA
generation interval.
lsa-generation-interval
maximum-interval [ minimum-interval
[ incremental-interval ] ]
By default, the maximum interval is 5
seconds, the minimum interval is 0
milliseconds, and the incremental
interval is 0 milliseconds.
Configuring a DR priority for an interface
The router priority is used for DR election. Interfaces having the priority 0 cannot become a DR or BDR.
To configure a DR priority for an interface:
Step
Command
Remarks
1.
Enter system view.
system-view
N/A
2.
Enter interface view.
interface interface-type interface-number
N/A
3.
Configure a router priority.
ospfv3 dr-priority priority [ instance
instance-id ]
The default router priority
is 1.
Ignoring MTU check for DD packets
When LSAs are few in DD packets, it is unnecessary to check the MTU in DD packets to improve
efficiency.
To ignore MTU check for DD packets:
306
Step
Command
Remarks
1.
Enter system view.
system-view
N/A
2.
Enter interface view.
interface interface-type
interface-number
N/A
3.
Ignore MTU check for DD
packets.
ospfv3 mtu-ignore [ instance
instance-id ]
By default, OSPFv3 does not
ignore MTU check for DD packets.
Disabling interfaces from receiving and sending OSPFv3
packets
After an OSPF interface is set to silent, direct routes of the interface can still be advertised in
Intra-Area-Prefix-LSAs through other interfaces, but other OSPFv3 packets cannot be advertised. No
neighboring relationship can be established on the interface. This feature can enhance the adaptability
of OSPFv3 networking.
To disable interfaces from receiving and sending OSPFv3 packets:
Step
Command
Remarks
1.
Enter system view.
system-view
N/A
2.
Enter OSPFv3 view.
ospfv3 [ process-id | vpn-instance
vpn-instance-name ] *
N/A
By default, the interfaces are able
to receive and send OSPFv3
packets.
3.
Disable interfaces from
receiving and sending
OSPFv3 packets.
silent-interface { interface-type
interface-number | all }
This command disables only the
interfaces associated with the
current process, though multiple
OSPFv3 processes can disable the
same interface from receiving and
sending OSPFv3 packets.
Enabling the logging of neighbor state changes
Step
Command
Remarks
1.
Enter system view.
system-view
N/A
2.
Enter OSPFv3 view.
ospfv3 [ process-id | vpn-instance
vpn-instance-name ] *
N/A
3.
Enable the logging of
neighbor state changes.
log-peer-change
By default, this feature is enabled.
Configuring OSPFv3 GR
Graceful Restart ensures the continuity of packet forwarding when a routing protocol restarts or an
active/standby switchover occurs:
307
•
GR Restarter—Graceful restarting router. It must be Graceful Restart capable.
•
GR Helper—The neighbor of the GR Restarter. It helps the GR Restarter to complete the GR process.
To prevent service interruption after a master/backup switchover, a GR Restarter running OSPFv3 must
complete the following tasks:
•
Keep the GR Restarter forwarding entries stable during reboot.
•
Establish all adjacencies and obtain complete topology information after reboot.
After the active/standby switchover, the GR Restarter sends a Grace-LSA to tell its neighbors that it
performs a GR. Upon receiving the Grace-LSA, the neighbors with the GR Helper capability enter the
helper mode (and are called "GR Helpers"). Then, the GR Restarter retrieves its adjacencies and LSDB
with the help of the GR Helpers.
Configuring GR Restarter
You can configure the GR Restarter capability on a GR Restarter.
To configure GR Restarter:
Step
Command
Remarks
1.
Enter system view.
system-view
N/A
2.
Enter OSPFv3 view.
ospfv3 [ process-id | vpn-instance
vpn-instance-name ] *
N/A
3.
Enable the GR
capability.
graceful-restart enable
By default, OSPFv3 GR Restarter
capability is disabled.
4.
(Optional.) Configure
the GR interval.
graceful-restart interval
interval-value
By default, the GR interval is 120
seconds.
Configuring GR Helper
You can configure the GR Helper capability on a GR Helper.
To configure GR Helper
Step
Command
Remarks
1.
Enter system view.
system-view
N/A
2.
Enter OSPFv3 view.
ospfv3 [ process-id | vpn-instance
vpn-instance-name ] *
N/A
3.
Enable the GR Helper
capability.
graceful-restart helper enable
By default, the GR Helper capability is
enabled.
4.
Enable strict LSA
checking.
graceful-restart helper
strict-lsa-checking
By default, strict LSA checking is
disabled.
Configuring BFD for OSPFv3
Bidirectional forwarding detection (BFD) provides a mechanism to quickly detect the connectivity of links
between OSPFv3 neighbors, improving the convergence speed of OSPFv3. For more information about
BFD, see High Availability Configuration Guide.
308
After discovering neighbors by sending hello packets, OSPFv3 notifies BFD of the neighbor addresses,
and BFD uses these addresses to establish sessions. Before a BFD session is established, it is in the down
state. In this state, BFD control packets are sent at an interval of no less than 1 second to reduce BFD
control packet traffic. After the BFD session is established, BFD control packets are sent at the negotiated
interval, thereby implementing fast fault detection.
To configure BFD for OSPFv3, you need to configure OSPFv3 first.
To configure BFD for OSPFv3:
Step
Command
Remarks
1.
Enter system view.
system-view
N/A
2.
Enter OSPFv3 view.
ospfv3 [ process-id | vpn-instance
vpn-instance-name ] *
N/A
3.
Specify a router ID.
router-id router-id
N/A
4.
Quit the OSPFv3 view.
quit
N/A
5.
Enter interface view.
interface interface-type
interface-number
N/A
6.
Enable an OSPFv3 process
on the interface.
ospfv3 process-id area area-id
[ instance instance-id ]
N/A
7.
Enable BFD on the interface.
ospfv3 bfd enable [ instance
instance-id ]
By default, BFD on the interface is
disabled.
Displaying and maintaining OSPFv3
Execute display commands in any view.
Purpose
Command
Display information about the routes to
OSPFv3 ABR and ASBR.
display ospfv3 [ process-id ] abr-asbr
Display brief OSPFv3 process
information.
display ospfv3 [ process-id ] brief
Display GR status of the specified
OSPFv3 process.
display ospfv3 [ process-id ] graceful-restart status
Display OSPFv3 interface information.
display ospfv3 [ process-id ] interface [ interface-type
interface-number | verbose ]
Display OSPFv3 LSDB information.
display ospfv3 [ process-id ] lsdb [ { external | grace | inter-prefix |
inter-router | intra-prefix | link | network | router | unknown
[ type ] } [ link-state-id ] [ originate-router router-id | self-originate ] |
statistics | total ]
Display OSPFv3 neighbor information.
display ospfv3 [ process-id ] [ area area-id ] peer [ [ interface-type
interface-number ] [ verbose ] | peer-router-id | statistics ]
Display OSPFv3 request list
information.
display ospfv3 [ process-id ] [ area area-id ] request-queue
[ interface-type interface-number ] [ neighbor-id ]
Display OSPFv3 retransmission list
information.
display ospfv3 [ process-id ] [ area area-id ] retrans-queue
[ interface-type interface-number ] [ neighbor-id ]
309
Purpose
Command
Display OSPFv3 routing information.
display ospfv3 [ process-id ] routing [ ipv6-address prefix-length ]
Display OSPFv3 statistics.
display ospfv3 [ process-id ] statistics
Display OSPFv3 virtual link
information.
display ospfv3 [ process-id ] vlink
OSPFv3 configuration examples
Configuring OSPFv3 areas
Network requirements
As shown in Figure 76:
•
Enable OSPFv3 on all switches.
•
Split the AS into three areas.
•
Configure Switch B and Switch C as ABRs to forward routing information between areas.
•
Configure Area 2 as a stub area to reduce LSAs in the area without affecting route reachability.
Figure 76 Network diagram
Configuration procedure
1.
Configure IPv6 addresses for interfaces. (Details not shown.)
2.
Configure basic OSPFv3:
# Configure Switch A: enable OSPFv3 and specify the router ID as 1.1.1.1.
<SwitchA> system-view
[SwitchA] ospfv3
[SwitchA-ospfv3-1] router-id 1.1.1.1
[SwitchA-ospfv3-1] quit
[SwitchA] interface vlan-interface 300
[SwitchA-Vlan-interface300] ospfv3 1 area 1
[SwitchA-Vlan-interface300] quit
[SwitchA] interface vlan-interface 200
[SwitchA-Vlan-interface200] ospfv3 1 area 1
[SwitchA-Vlan-interface200] quit
310
# Configure Switch B: enable OSPFv3 and specify the router ID as 2.2.2.2.
<SwitchB> system-view
[SwitchB] ospfv3
[SwitchB-ospf-1] router-id 2.2.2.2
[SwitchB-ospf-1] quit
[SwitchB] interface vlan-interface 100
[SwitchB-Vlan-interface100] ospfv3 1 area 0
[SwitchB-Vlan-interface100] quit
[SwitchB] interface vlan-interface 200
[SwitchB-Vlan-interface200] ospfv3 1 area 1
[SwitchB-Vlan-interface200] quit
# Configure Switch C: enable OSPFv3 and specify the router ID as 3.3.3.3.
<SwitchC> system-view
[SwitchC] ospfv3
[SwitchC-ospfv3-1] router-id 3.3.3.3
[SwitchC-ospfv3-1] quit
[SwitchC] interface vlan-interface 100
[SwitchC-Vlan-interface100] ospfv3 1 area 0
[SwitchC-Vlan-interface100] quit
[SwitchC] interface vlan-interface 400
[SwitchC-Vlan-interface400] ospfv3 1 area 2
[SwitchC-Vlan-interface400] quit
# Configure Switch D: enable OSPFv3 and specify the router ID as 4.4.4.4.
<SwitchD> system-view
[SwitchD] ospfv3
[SwitchD-ospfv3-1] router-id 4.4.4.4
[SwitchD-ospfv3-1] quit
[SwitchD] interface vlan-interface 400
[SwitchD-Vlan-interface400] ospfv3 1 area 2
[SwitchD-Vlan-interface400] quit
# Display OSPFv3 neighbors on Switch B.
[SwitchB] display ospfv3 peer
OSPFv3 Process 1 with Router ID 2.2.2.2
Area: 0.0.0.0
------------------------------------------------------------------------Router ID
Pri State
Dead-Time Interface
Inst ID
3.3.3.3
1
00:00:40
0
Full/Backup
Vlan100
Area: 0.0.0.1
------------------------------------------------------------------------Router ID
Pri State
Dead-Time Interface
Inst ID
1.1.1.1
1
00:00:40
0
Full/DR
# Display OSPFv3 neighbors on Switch C.
[SwitchC] display ospfv3 peer
311
Vlan200
OSPFv3 Process 1 with Router ID 3.3.3.3
Area: 0.0.0.0
------------------------------------------------------------------------Router ID
Pri State
Dead-Time Interface
Inst ID
2.2.2.2
1
00:00:40
0
Full/DR
Vlan100
Area: 0.0.0.2
------------------------------------------------------------------------Router ID
Pri State
Dead-Time Interface
Inst ID
4.4.4.4
1
00:00:40
0
Full/Backup
Vlan400
# Display OSPFv3 routing table information on Switch D.
[SwitchD] display ospfv3 routing
OSPFv3 Process 1 with Router ID 4.4.4.4
------------------------------------------------------------------------E1 - Type 1 external route,
IA - Inter area route,
E2 - Type 2 external route,
*
I - Intra area route
- Selected route
*Destination: 2001::/64
Type
: IA
Cost
: 2
NextHop
: FE80::F40D:0:93D0:1
Interface: Vlan400
*Destination: 2001:1::/64
Type
: IA
Cost
: 3
NextHop
: FE80::F40D:0:93D0:1
Interface: Vlan400
*Destination: 2001:2::/64
Type
: I
Cost
: 1
NextHop
: directly-connected
Interface: Vlan400
*Destination: 2001:3::/64
Type
: IA
Cost
: 4
NextHop
: FE80::F40D:0:93D0:1
Interface: Vlan400
Total: 4
Intra area: 1
3.
Inter area: 3
ASE: 0
Configure Area 2 as a stub area:
# Configure Switch D
[SwitchD] ospfv3
[SwitchD-ospfv3-1] area 2
[SwitchD-ospfv3-1-area-0.0.0.2] stub
# Configure Switch C, and specify the cost of the default route sent to the stub area as 10.
[SwitchC] ospfv3
[SwitchC-ospfv3-1] area 2
[SwitchC-ospfv3-1-area-0.0.0.2] stub
[SwitchC-ospfv3-1-area-0.0.0.2] default-cost 10
312
# Display OSPFv3 routing table information on Switch D.
[SwitchD] display ospfv3 routing
OSPFv3 Process 1 with Router ID 4.4.4.4
------------------------------------------------------------------------E1 - Type 1 external route,
IA - Inter area route,
E2 - Type 2 external route,
*
I - Intra area route
- Selected route
*Destination: ::/0
Type
: IA
Cost
: 11
NextHop
: FE80::F40D:0:93D0:1
Interface: Vlan400
*Destination: 2001::/64
Type
: IA
Cost
: 2
NextHop
: FE80::F40D:0:93D0:1
Interface: Vlan400
*Destination: 2001:1::/64
Type
: IA
Cost
: 3
NextHop
: FE80::F40D:0:93D0:1
Interface: Vlan400
*Destination: 2001:2::/64
Type
: I
Cost
: 1
NextHop
: directly-connected
Interface: Vlan400
*Destination: 2001:3::/64
Type
: IA
Cost
: 4
NextHop
: FE80::F40D:0:93D0:1
Interface: Vlan400
Total: 5
Intra area: 1
Inter area: 4
ASE: 0
The output shows that a default route is added, and its cost is the cost of a direct route plus the
configured cost.
4.
Configure Area 2 as a totally stub area:
# Configure Area 2 as a totally stub area on Switch C.
[SwitchC-ospfv3-1-area-0.0.0.2] stub no-summary
# Display OSPFv3 routing table information on Switch D.
[SwitchD] display ospfv3 routing
OSPFv3 Process 1 with Router ID 4.4.4.4
------------------------------------------------------------------------E1 - Type 1 external route,
IA - Inter area route,
E2 - Type 2 external route,
*
I - Intra area route
- Selected route
*Destination: ::/0
Type
: IA
Cost
NextHop
: FE80::F40D:0:93D0:1
Interface: Vlan400
*Destination: 2001:2::/64
313
: 11
Type
: I
Cost
NextHop
: directly-connected
Interface: Vlan400
: 1
Total: 2
Intra area: 1
Inter area: 1
ASE: 0
The output shows that route entries are reduced. All indirect routes are removed, except the default
route.
Configuring OSPFv3 DR election
Network requirements
•
Configure router priority 100 for Switch A, the highest priority on the network, so it will become the
DR.
•
Configure router priority 2 for Switch C, the second highest priority on the network, so it will
become the BDR.
•
Configure router priority 0 for Switch B, so it cannot become a DR or BDR.
•
Switch D uses the default router priority 1.
Figure 77 Network diagram
Configuration procedure
1.
Configure IPv6 addresses for interfaces. (Details not shown.)
2.
Configure basic OSPFv3:
# Configure Switch A: enable OSPFv3 and specify the router ID as 1.1.1.1.
<SwitchA> system-view
[SwitchA] ospfv3
[SwitchA-ospfv3-1] router-id 1.1.1.1
[SwitchA-ospfv3-1] quit
[SwitchA] interface vlan-interface 100
[SwitchA-Vlan-interface100] ospfv3 1 area 0
[SwitchA-Vlan-interface100] quit
# Configure Switch B: enable OSPFv3 and specify the router ID as 2.2.2.2.
<SwitchB> system-view
[SwitchB] ospfv3
[SwitchB-ospfv3-1] router-id 2.2.2.2
314
[SwitchB-ospfv3-1] quit
[SwitchB] interface vlan-interface 200
[SwitchB-Vlan-interface200] ospfv3 1 area 0
[SwitchB-Vlan-interface200] quit
# Configure Switch C: enable OSPFv3 and specify the router ID as 3.3.3.3.
<SwitchC> system-view
[SwitchC] ospfv3
[SwitchC-ospfv3-1] router-id 3.3.3.3
[SwitchC-ospfv3-1] quit
[SwitchC] interface vlan-interface 100
[SwitchC-Vlan-interface100] ospfv3 1 area 0
[SwitchC-Vlan-interface100] quit
# Configure Switch D: enable OSPFv3 and specify the router ID as 4.4.4.4.
<SwitchD> system-view
[SwitchD] ospfv3
[SwitchD-ospfv3-1] router-id 4.4.4.4
[SwitchD-ospfv3-1] quit
[SwitchD] interface vlan-interface 200
[SwitchD-Vlan-interface200] ospfv3 1 area 0
[SwitchD-Vlan-interface200] quit
# Display neighbor information on Switch A. The switches have the same default DR priority 1, so
Switch D (the switch with the highest Router ID) is elected as the DR, and Switch C is the BDR.
[SwitchA] display ospfv3 peer
OSPFv3 Process 1 with Router ID 1.1.1.1
Area: 0.0.0.0
------------------------------------------------------------------------Router ID
Pri State
Dead-Time Interface
Inst ID
2.2.2.2
1
2-Way/DROther
00:00:36
Vlan200
0
3.3.3.3
1
Full/Backup
00:00:35
Vlan100
0
4.4.4.4
1
Full/DR
00:00:33
Vlan200
0
# Display neighbor information on Switch D. The neighbor states are all full.
[SwitchD] display ospfv3 peer
OSPFv3 Process 1 with Router ID 4.4.4.4
Area: 0.0.0.0
-------------------------------------------------------------------------
3.
Router ID
Pri State
Dead-Time Interface
Inst ID
1.1.1.1
1
Full/DROther
00:00:30
Vlan100
0
2.2.2.2
1
Full/DROther
00:00:37
Vlan200
0
3.3.3.3
1
Full/Backup
00:00:31
Vlan100
0
Configure router priorities for interfaces:
# Configure the router priority of VLAN-interface 100 as 100 on Switch A.
[SwitchA] interface Vlan-interface 100
[SwitchA-Vlan-interface100] ospfv3 dr-priority 100
315
[SwitchA-Vlan-interface100] quit
# Configure the router priority of VLAN-interface 200 as 0 on Switch B.
[SwitchB] interface vlan-interface 200
[SwitchB-Vlan-interface200] ospfv3 dr-priority 0
[SwitchB-Vlan-interface200] quit
# Configure the router priority of VLAN-interface 100 of Switch C as 2.
[SwitchC] interface Vlan-interface 100
[SwitchC-Vlan-interface100] ospfv3 dr-priority 2
[SwitchC-Vlan-interface100] quit
# Display neighbor information on Switch A. Router priorities have been updated, but the DR and
BDR are not changed.
[SwitchA] display ospfv3 peer
OSPFv3 Process 1 with Router ID 1.1.1.1
Area: 0.0.0.0
------------------------------------------------------------------------Router ID
Pri State
Dead-Time Interface
Inst ID
2.2.2.2
0
2-Way/DROther
00:00:36
Vlan200
0
3.3.3.3
2
Full/Backup
00:00:35
Vlan200
0
4.4.4.4
1
Full/DR
00:00:33
Vlan200
0
# Display neighbor information on Switch D. Switch D is still the DR.
[SwitchD] display ospfv3 peer
OSPFv3 Process 1 with Router ID 4.4.4.4
Area: 0.0.0.0
-------------------------------------------------------------------------
4.
Router ID
Pri State
Dead-Time Interface
Inst ID
1.1.1.1
100 Full/DROther
00:00:30
Vlan100
0
2.2.2.2
0
Full/DROther
00:00:37
Vlan200
0
3.3.3.3
2
Full/Backup
00:00:31
Vlan100
0
Restart DR and BDR election:
# Use the shutdown and undo shutdown commands on interfaces to restart DR and BDR election.
(Details not shown.)
# Display neighbor information on Switch A. The output shows that Switch C becomes the BDR.
[SwitchA] display ospfv3 peer
OSPFv3 Process 1 with Router ID 1.1.1.1
Area: 0.0.0.0
------------------------------------------------------------------------Router ID
Pri State
Dead-Time Interface
Inst ID
2.2.2.2
0
Full/DROther
00:00:36
Vlan200
0
3.3.3.3
2
Full/Backup
00:00:35
Vlan100
0
4.4.4.4
1
Full/DROther
00:00:33
Vlan200
0
# Display neighbor information on Switch D.
316
[SwitchD] display ospfv3 peer
OSPFv3 Process 1 with Router ID 4.4.4.4
Area: 0.0.0.0
------------------------------------------------------------------------Router ID
Pri State
Dead-Time Interface
Inst ID
1.1.1.1
100 Full/DR
00:00:30
Vlan100
0
2.2.2.2
0
2-Way/DROther
00:00:37
Vlan200
0
3.3.3.3
2
Full/Backup
00:00:31
Vlan100
0
The output shows that Switch A becomes the DR.
Configuring OSPFv3 route redistribution
Network requirements
As shown in Figure 78:
•
Switch A, Switch B, and Switch C are in Area 2.
•
OSPFv3 process 1 and OSPFv3 process 2 run on Switch B. Switch B communicates with Switch A
and Switch C through OSPFv3 process 1 and OSPFv3 process 2.
•
Configure OSPFv3 process 2 to redistribute direct routes and the routes from OSPFv3 process 1 on
Switch B, and set the default metric for redistributed routes to 3. Switch C can then learn the routes
destined for 1::0/64 and 2::0/64, and Switch A cannot learn the routes destined for 3::0/64 or
4::0/64.
Figure 78 Network diagram
Configuration procedure
1.
Configure IPv6 addresses for interfaces. (Details not shown.)
2.
Configure basic OSPFv3:
# Enable OSPFv3 process 1 on Switch A.
<SwitchA> system-view
[SwitchA] ospfv3 1
[SwitchA-ospfv3-1] router-id 1.1.1.1
[SwitchA-ospfv3-1] quit
[SwitchA] interface vlan-interface 100
[SwitchA-Vlan-interface100] ospfv3 1 area 2
[SwitchA-Vlan-interface100] quit
[SwitchA] interface vlan-interface 200
317
[SwitchA-Vlan-interface200] ospfv3 1 area 2
[SwitchA-Vlan-interface200] quit
# Enable OSPFv3 process 1 and OSPFv3 process 2 on Switch B.
<SwitchB> system-view
[SwitchB] ospfv3 1
[SwitchB-ospfv3-1] router-id 2.2.2.2
[SwitchB-ospfv3-1] quit
[SwitchB] interface vlan-interface 100
[SwitchB-Vlan-interface100] ospfv3 1 area 2
[SwitchB-Vlan-interface100] quit
[SwitchB] ospfv3 2
[SwitchB-ospfv3-2] router-id 3.3.3.3
[SwitchB-ospfv3-2] quit
[SwitchB] interface vlan-interface 300
[SwitchB-Vlan-interface300] ospfv3 2 area 2
[SwitchB-Vlan-interface300] quit
# Enable OSPFv3 process 2 on Switch C.
<SwitchC> system-view
[SwitchC] ospfv3 2
[SwitchC-ospfv3-2] router-id 4.4.4.4
[SwitchC-ospfv3-2] quit
[SwitchC] interface vlan-interface 300
[SwitchC-Vlan-interface300] ospfv3 2 area 2
[SwitchC-Vlan-interface300] quit
[SwitchC] interface vlan-interface 400
[SwitchC-Vlan-interface400] ospfv3 2 area 2
[SwitchC-Vlan-interface400] quit
# Display the routing table on Switch C.
[SwitchC] display ipv6 routing-table
Destinations : 7 Routes : 7
Destination: ::1/128
Protocol
NextHop
: ::1
Preference: 0
Interface
: InLoop0
Cost
: 0
Destination: 3::/64
Protocol
: Direct
NextHop
: 3::2
Preference: 0
Interface
: Vlan300
Cost
: 0
Destination: 3::2/128
Protocol
: Direct
NextHop
: ::1
Preference: 0
Interface
: InLoop0
Cost
: 0
Destination: 4::/64
Protocol
: Direct
NextHop
: 4::1
Preference: 0
Interface
: Vlan400
Cost
318
: Direct
: 0
3.
Destination: 4::1/128
Protocol
NextHop
: ::1
Preference: 0
: Direct
Interface
: InLoop0
Cost
: 0
Destination: FE80::/10
Protocol
: Direct
NextHop
: ::
Preference: 0
Interface
: NULL0
Cost
: 0
Destination: FF00::/8
Protocol
: Direct
NextHop
: ::
Preference: 0
Interface
: NULL0
Configure OSPFv3 route redistribution:
# Configure OSPFv3 process 2 to redistribute direct routes and the routes from OSPFv3 process 1
on Switch B.
[SwitchB] ospfv3 2
[SwitchB-ospfv3-2] default cost 3
[SwitchB-ospfv3-2] import-route ospfv3 1
[SwitchB-ospfv3-2] import-route direct
[SwitchB-ospfv3-2] quit
# Display the routing table on Switch C.
[SwitchC] display ipv6 routing-table
Destinations : 9 Routes : 9
Destination: ::1/128
Protocol
NextHop
: ::1
Preference: 0
Interface
: InLoop0
Cost
: 0
Destination: 1::/64
Protocol
: OSPFv3
NextHop
: FE80::200:CFF:FE01:1C03
Preference: 150
Interface
: Vlan300
Cost
: 3
Destination: 2::/64
Protocol
: OSPFv3
NextHop
: FE80::200:CFF:FE01:1C03
Preference: 150
Interface
: Vlan300
Cost
: 3
Destination: 3::/64
Protocol
: Direct
NextHop
: 3::2
Preference: 0
Interface
: Vlan300
Cost
: 0
Destination: 3::2/128
Protocol
: Direct
NextHop
: ::1
Preference: 0
Interface
: InLoop0
Cost
: 0
Destination: 4::/64
Protocol
: Direct
NextHop
: 4::1
Preference: 0
Interface
: Vlan400
Cost
319
: Direct
: 0
Destination: 4::1/128
Protocol
NextHop
: ::1
Preference: 0
: Direct
Interface
: InLoop0
Cost
: 0
Destination: FE80::/10
Protocol
: Direct
NextHop
: ::
Preference: 0
Interface
: NULL0
Cost
: 0
Destination: FF00::/8
Protocol
: Direct
NextHop
: ::
Preference: 0
Interface
: NULL0
Configuring OSPFv3 GR
Network requirements
•
As shown in Figure 79, Switch A, Switch B, and Switch C that reside in the same AS and the same
OSPFv3 routing domain are GR capable.
•
Switch A acts as the GR Restarter. Switch B and Switch C act as the GR Helpers, and synchronize
their LSDBs with Switch A through out-of-band (OOB) communication of GR.
Figure 79 Network diagram
Configuration procedure
1.
Configure IPv6 addresses for interfaces. (Details not shown.)
2.
Configure basic OSPFv3:
# On Switch A, enable OSPFv3 process 1, enable GR, and set the router ID to 1.1.1.1.
<SwitchA> system-view
[SwitchA] ospfv3 1
[SwitchA-ospfv3-1] router-id 1.1.1.1
[SwitchA-ospfv3-1] graceful-restart enable
[SwitchA-ospfv3-1] quit
[SwitchA] interface vlan-interface 100
[SwitchA-Vlan-interface100] ospfv3 1 area 1
[SwitchA-Vlan-interface100] quit
# On Switch B, enable OSPFv3 and set the router ID to 2.2.2.2. (By default, GR helper is enabled
on Switch B.)
<SwitchB> system-view
[SwitchB] ospfv3 1
320
[SwitchB-ospfv3-1] router-id 2.2.2.2
[SwitchB-ospfv3-1] quit
[SwitchB] interface vlan-interface 100
[SwitchB-Vlan-interface100] ospfv3 1 area 1
[SwitchB-Vlan-interface100] quit
# On Switch C, enable OSPFv3 and set the router ID to 3.3.3.3. (By default, GR helper is enabled
on Switch C.)
<SwitchC> system-view
[SwitchC] ospfv3 1
[SwitchC-ospfv3-1] router-id 3.3.3.3
[SwitchC-ospfv3-1] quit
[SwitchC] interface vlan-interface 100
[SwitchC-Vlan-interface100] ospfv3 1 area 1
[SwitchC-Vlan-interface100] quit
Verifying the configuration
After all switches function properly, perform a master/backup switchover on Switch A to trigger an
OSPFv3 GR operation.
Configuring BFD for OSPFv3
Network requirements
As shown in Figure 80:
•
Configure OSPFv3 on Switch A, Switch B and Switch C and configure BFD over the link Switch
A<—>L2 Switch<—>Switch B.
•
After the link Switch A<—>L2 Switch<—>Switch B fails, BFD can quickly detect the failure and
notify OSPFv3 of the failure. Then Switch A and Switch B communicate through Switch C.
Figure 80 Network diagram
Device
Interface
IPv6 address
Device
Interface
IPv6 address
Switch A
Vlan-int10
2001::1/64
Switch B
Vlan-int10
2001::2/64
Vlan-int11
2001:2::1/64
Vlan-int13
2001:3::2/64
Switch C
Vlan-int11
2001:2::2/64
Vlan-int13
2001:3::1/64
Configuration procedure
1.
Configure IP addresses for the interfaces. (Details not shown.)
321
2.
Configure basic OSPF:
# On Switch A, enable OSPFv3 and specify the router ID as 1.1.1.1.
<SwitchA> system-view
[SwitchA] ospfv3
[SwitchA-ospfv3-1] router-id 1.1.1.1
[SwitchA-ospfv3-1] quit
[SwitchA] interface vlan-interface 10
[SwitchA-Vlan-interface10] ospfv3 1 area 0
[SwitchA-Vlan-interface10] quit
[SwitchA] interface vlan-interface 11
[SwitchA-Vlan-interface11] ospfv3 1 area 0
[SwitchA-Vlan-interface11] quit
# On Switch B, enable OSPFv3 and specify the router ID as 2.2.2.2.
<SwitchB> system-view
[SwitchB] ospfv3
[SwitchB-ospf-1] router-id 2.2.2.2
[SwitchB-ospf-1] quit
[SwitchB] interface vlan-interface 10
[SwitchB-Vlan-interface10] ospfv3 1 area 0
[SwitchB-Vlan-interface10] quit
[SwitchB] interface vlan-interface 13
[SwitchB-Vlan-interface13] ospfv3 1 area 0
[SwitchB-Vlan-interface13] quit
# On Switch C, enable OSPFv3 and configure the router ID as 3.3.3.3.
<SwitchC> system-view
[SwitchC] ospfv3
[SwitchC-ospfv3-1] router-id 3.3.3.3
[SwitchC-ospfv3-1] quit
[SwitchC] interface vlan-interface 11
[SwitchC-Vlan-interface11] ospfv3 1 area 0
[SwitchC-Vlan-interface11] quit
[SwitchC] interface vlan-interface 13
[SwitchC-Vlan-interface13] ospfv3 1 area 0
[SwitchC-Vlan-interface13] quit
3.
Configure BFD:
# Enable BFD and configure BFD parameters on Switch A.
[SwitchA] bfd session init-mode active
[SwitchA] interface vlan-interface 10
[SwitchA-Vlan-interface10] ospfv3 bfd enable
[SwitchA-Vlan-interface10] bfd min-transmit-interval 500
[SwitchA-Vlan-interface10] bfd min-receive-interval 500
[SwitchA-Vlan-interface10] bfd detect-multiplier 7
[SwitchA-Vlan-interface10] return
# Enable BFD and configure BFD parameters on Switch B.
[SwitchB] bfd session init-mode active
[SwitchB] interface vlan-interface 10
[SwitchB-Vlan-interface10] ospfv3 bfd enable
322
[SwitchB-Vlan-interface10] bfd min-transmit-interval 500
[SwitchB-Vlan-interface10] bfd min-receive-interval 500
[SwitchB-Vlan-interface10] bfd detect-multiplier 6
Verifying the configuration
# Display the BFD information of Switch A.
<SwitchA> display bfd session
Total Session Num: 1
Init Mode: Active
IPv6 Session Working Under Ctrl Mode:
Local Discr: 1441
Remote Discr: 1450
Source IP: FE80::20F:FF:FE00:1202 (link-local address of VLAN-interface 10 on
Switch A)
Destination IP: FE80::20F:FF:FE00:1200 (link-local address of VLAN-interface 10 on
Switch B)
Session State: Up
Interface: Vlan10
Hold Time: 2319ms
# Display routes destined for 2001:4::0/64 on Switch A.
<SwitchA> display ipv6 routing-table 2001:4::0 64
Summary Count : 1
Destination: 2001:4::/64
Protocol
: OSPFv3
NextHop
: FE80::20F:FF:FE00:1200
Preference: 10
Interface
: Vlan10
Cost
: 1
The output information shows that Switch A communicates with Switch B through VLAN-interface 10. The
the link over VLAN-interface 10 fails.
# Display routes to 2001:4::0/64 on Switch A.
<SwitchA> display ipv6 routing-table 2001:4::0 64
Summary Count : 1
Destination: 2001:4::/64
Protocol
NextHop
: FE80::BAAF:67FF:FE27:DCD0
Preference: 10
: OSPFv3
Interface
: Vlan11
Cost
: 2
The output shows that Switch A communicates with Switch B through VLAN-interface 11.
323
Configuring IPv6 IS-IS
IPv6 IS-IS supports all IPv4 IS-IS features except that it advertises IPv6 routing information. This chapter
describes only IPv6 IS-IS specific configuration tasks. For information about IS-IS, see "Configuring IS-IS."
Overview
Intermediate System-to-Intermediate System (IS-IS) supports multiple network protocols, including IPv6. To
support IPv6, the IETF added two type-length-values (TLVs) and a new network layer protocol identifier
(NLPID).
The TLVs are as follows:
•
IPv6 Reachability—Contains routing prefix and metric information to describe network reachability
and has a type value of 236 (0xEC).
•
IPv6 Interface Address—Same as the "IP Interface Address" TLV in IPv4 ISIS, except that the 32-bit
IPv4 address is translated to the 128-bit IPv6 address.
The new NLPID is an 8-bit field that identifies which network layer protocol is supported. For IPv6, the
NLPID is 142 (0x8E), which must be carried in hello packets sent by IPv6 IS-IS.
Configuring basic IPv6 IS-IS
Before you configure basic IPv6 IS-IS, complete the following tasks:
•
Configure IPv6 addresses for interfaces to ensure IPv6 connectivity between neighboring nodes.
•
Enable IS-IS.
Basic IPv6 IS-IS configuration can implement the interconnection of IPv6 networks.
To configure basic IPv6 IS-IS:
Step
Command
Remarks
1.
Enter system view.
system-view
N/A
2.
Enable an IS-IS process and
enter IS-IS view.
isis [ process-id ] [ vpn-instance
vpn-instance-name ]
By default, no IS-IS process is
enabled.
3.
Configure the network entity
title (NET) for the IS-IS
process.
network-entity net
By default, no NET is configured.
4.
Enable IPv6 for the IS-IS
process.
ipv6 enable
The default setting is disabled.
5.
Return to system view.
quit
N/A
6.
Enter interface view.
interface interface-type
interface-number
N/A
7.
Enable IPv6 for an IS-IS
process on the interface.
isis ipv6 enable [ process-id ]
The default setting is disabled.
324
Configuring IPv6 IS-IS route control
Before you configure IPv6 IS-IS route control, complete basic IPv6 IS-IS configuration.
To configure IPv6 IS-IS route control:
Step
Command
Remarks
1.
Enter system view.
system-view
N/A
2.
Enter IS-IS view.
isis [ process-id ] [ vpn-instance
vpn-instance-name ]
N/A
3.
Specify a preference for
IPv6 IS-IS routes.
ipv6 preference { route-policy
route-policy-name | preference } *
By default, the default
setting is 15.
4.
Configure an IPv6 IS-IS
summary route.
ipv6 summary ipv6-prefix prefix-length
[ avoid-feedback | generate_null0_route |
[ level-1 | level-1-2 | level-2 ] | tag tag ] *
By default, no IPv6 IS-IS
summary route is
configured.
5.
Generate an IPv6 IS-IS
default route.
ipv6 default-route-advertise [ [ level-1 |
level-1-2 | level-2 ] | route-policy
route-policy-name ] *
By default, no IPv6 default
route is generated.
By default, IPv6 IS-IS does
not filter redistributed
routes.
Configure IPv6 IS-IS to
filter redistributed routes.
ipv6 filter-policy { acl6-number | prefix-list
prefix-list-name | route-policy
route-policy-name } export [ protocol
[ process-id ] ]
7.
Configure IPv6 IS-IS to
filter inbound routes.
ipv6 filter-policy { acl6-number | prefix-list
prefix-list-name | route-policy
route-policy-name } import
By default, IPv6 IS-IS does
not filter inbound routes.
8.
Configure IPv6 IS-IS to
redistribute routes from
another routing protocol.
ipv6 import-route protocol [ process-id ]
[ allow-ibgp ] [ cost cost | [ level-1 | level-1-2
| level-2 ] | route-policy route-policy-name |
tag tag ] *
By default, IPv6 IS-IS does
not redistribute routes from
any other routing protocol.
9.
Configure the maximum
number of redistributed
Level 1/Level 2 IPv6
routes.
ipv6 import-route limit number
By default, the maximum
number of redistributed
Level 1/Level 2 IPv6 routes
is 8192.
10. Configure route
advertisement from Level-2
to Level-1.
ipv6 import-route isisv6 level-2 into level-1
[ filter-policy { acl6-number | prefix-list
prefix-list-name | route-policy
route-policy-name } | tag tag ] *
By default, IPv6 IS-IS does
not advertise routes from
Level-2 to Level-1.
11. Configure route
advertisement from Level-1
to Level-2.
ipv6 import-route isisv6 level-1 into level-2
[ filter-policy { acl6-number | prefix-list
prefix-list-name | route-policy
route-policy-name } | tag tag ] *
By default, IPv6 IS-IS
advertises routes from
Level-1 to Level-2.
6.
325
This command is usually
used together with the ipv6
import-route command.
Step
12. Specify the maximum
number of ECMP routes for
load balancing.
Command
Remarks
ipv6 maximum load-balancing number
By default, the maximum
number of ECMP routes is
the same as that configured
in the max-ecmp-num
command. For more
information about the
max-ecmp-num command,
see IP Routing Command
Reference.
Configuring BFD for IPv6 IS-IS
Bidirectional forwarding detection (BFD) can quickly detect faults between IPv6 IS-IS neighbors to
improve the convergence speed of IPv6 IS-IS. For more information about BFD, see High Availability
Configuration Guide.
To configure BFD for IPv6 IS-IS:
Step
Command
Remarks
1.
Enter system view.
system-view
N/A
2.
Enable an IS-IS process and
enter IS-IS view.
isis [ process-id ] [ vpn-instance
vpn-instance-name ]
N/A
3.
Configure the NET for the IS-IS
process.
network-entity net
By default, no NET is configured.
4.
Enable IPv6 for the IS-IS
process.
ipv6 enable
By default, IPv6 for the IS-IS
process is disabled.
5.
Return to system view.
quit
N/A
6.
Enter interface view.
interface interface-type
interface-number
N/A
7.
Enable IPv6 for an IS-IS
process.
isis ipv6 enable [ process-id ]
By default, IPv6 is disabled for an
IS-IS process.
8.
Enable BFD for IPv6 IS-IS.
isis ipv6 bfd enable
By default, BFD for IPv6 IS-IS is
disabled.
Displaying and maintaining IPv6 IS-IS
Execute display commands in any view. For other display and reset commands, see "Configuring IS-IS."
Task
Command
Display information about routes
redistributed by IPv6 IS-IS.
display isis redistribute ipv6 [ ipv6-address mask-length ]
[ level-1 | level-2 ] [ process-id ]
Display IPv6 IS-IS routing information.
display isis route ipv6 [ ipv6-address ] [ [ level-1 | level-2 ] |
verbose ] * [ process-id ]
326
IPv6 IS-IS configuration examples
IPv6 IS-IS basic configuration example
Network requirements
As shown in Figure 81, Switch A, Switch B, Switch C, and Switch D, all enabled with IPv6, reside in the
same AS. Configure IPv6 IS-IS on the switches so that they can reach each other.
Switch A and Switch B are Level-1 switches, Switch D is a Level-2 switch, and Switch C is a Level-1-2 switch.
Figure 81 Network diagram
Configuration procedure
1.
Configure IPv6 addresses for interfaces. (Details not shown.)
2.
Configure IPv6 IS-IS:
# Configure Switch A.
<SwitchA> system-view
[SwitchA] isis 1
[SwitchA-isis-1] is-level level-1
[SwitchA-isis-1] network-entity 10.0000.0000.0001.00
[SwitchA-isis-1] ipv6 enable
[SwitchA-isis-1] quit
[SwitchA] interface vlan-interface 100
[SwitchA-Vlan-interface100] isis ipv6 enable 1
[SwitchA-Vlan-interface100] quit
# Configure Switch B.
<SwitchB> system-view
[SwitchB] isis 1
[SwitchB-isis-1] is-level level-1
[SwitchB-isis-1] network-entity 10.0000.0000.0002.00
[SwitchB-isis-1] ipv6 enable
[SwitchB-isis-1] quit
[SwitchB] interface vlan-interface 200
[SwitchB-Vlan-interface200] isis ipv6 enable 1
[SwitchB-Vlan-interface200] quit
327
# Configure Switch C.
<SwitchC> system-view
[SwitchC] isis 1
[SwitchC-isis-1] network-entity 10.0000.0000.0003.00
[SwitchC-isis-1] ipv6 enable
[SwitchC-isis-1] quit
[SwitchC] interface vlan-interface 100
[SwitchC-Vlan-interface100] isis ipv6 enable 1
[SwitchC-Vlan-interface100] quit
[SwitchC] interface vlan-interface 200
[SwitchC-Vlan-interface200] isis ipv6 enable 1
[SwitchC-Vlan-interface200] quit
[SwitchC] interface vlan-interface 300
[SwitchC-Vlan-interface300] isis ipv6 enable 1
[SwitchC-Vlan-interface300] quit
# Configure Switch D.
<SwitchD> system-view
[SwitchD] isis 1
[SwitchD-isis-1] is-level level-2
[SwitchD-isis-1] network-entity 20.0000.0000.0004.00
[SwitchD-isis-1] ipv6 enable
[SwitchD-isis-1] quit
[SwitchD] interface vlan-interface 300
[SwitchD-Vlan-interface300] isis ipv6 enable 1
[SwitchD-Vlan-interface300] quit
[SwitchD] interface vlan-interface 301
[SwitchD-Vlan-interface301] isis ipv6 enable 1
[SwitchD-Vlan-interface301] quit
Verifying the configuration
# Display the IPv6 IS-IS routing table on Switch A.
[SwitchA] display isis route ipv6
Route information for IS-IS(1)
-----------------------------Level-1 IPv6 Forwarding Table
----------------------------Destination : ::
PrefixLen: 0
Flag
: R/-/-
Cost
Next Hop
: FE80::200:FF:FE0F:4
Interface: Vlan100
: 10
Destination : 2001:1::
PrefixLen: 64
Flag
: D/L/-
Cost
Next Hop
: Direct
Interface: Vlan100
Destination : 2001:2::
: 10
PrefixLen: 64
328
Flag
: R/-/-
Cost
Next Hop
: FE80::200:FF:FE0F:4
Interface: Vlan100
: 20
Destination : 2001:3::
PrefixLen: 64
Flag
: R/-/-
Cost
Next Hop
: FE80::200:FF:FE0F:4
Interface: Vlan100
: 20
Flags: D-Direct, R-Added to Rib, L-Advertised in LSPs, U-Up/Down Bit Set
# Display the IPv6 IS-IS routing table on Switch B.
[SwitchB] display isis route ipv6
Route information for IS-IS(1)
------------------------------
Level-1 IPv6 Forwarding Table
-----------------------------
Destination : ::
PrefixLen: 0
Flag
: R/-/-
Cost
Next Hop
: FE80::200:FF:FE0F:4
Interface: Vlan200
: 10
Destination : 2001:1::
PrefixLen: 64
Flag
: D/L/-
Cost
Next Hop
: FE80::200:FF:FE0F:4
Interface: Vlan200
: 10
Destination : 2001:2::
PrefixLen: 64
Flag
: R/-/-
Cost
Next Hop
: Direct
Interface: Vlan200
: 20
Destination : 2001:3::
PrefixLen: 64
Flag
: R/-/-
Cost
Next Hop
: FE80::200:FF:FE0F:4
Interface: Vlan200
: 20
Flags: D-Direct, R-Added to Rib, L-Advertised in LSPs, U-Up/Down Bit Set
# Display the IPv6 IS-IS routing table on Switch C.
[SwitchC] display isis route ipv6
Route information for IS-IS(1)
-----------------------------Level-1 IPv6 Forwarding Table
----------------------------Destination : 2001:1::
PrefixLen: 64
Flag
: D/L/-
Cost
Next Hop
: Direct
Interface: Vlan100
Destination : 2001:2::
: 10
PrefixLen: 64
329
Flag
: D/L/-
Cost
Next Hop
: Direct
Interface: Vlan200
: 10
Destination : 2001:3::
PrefixLen: 64
Flag
: D/L/-
Cost
Next Hop
: Direct
Interface: Vlan300
: 10
Flags: D-Direct, R-Added to Rib, L-Advertised in LSPs, U-Up/Down Bit Set
Level-2 IPv6 Forwarding Table
----------------------------Destination : 2001:1::
PrefixLen: 64
Flag
: D/L/-
Cost
Next Hop
: Direct
Interface: Vlan100
: 10
Destination : 2001:2::
PrefixLen: 64
Flag
: D/L/-
Cost
Next Hop
: Direct
Interface: Vlan200
: 10
Destination : 2001:3::
PrefixLen: 64
Flag
: D/L/-
Cost
Next Hop
: Direct
Interface: Vlan300
: 10
Destination : 2001:4::1
PrefixLen: 128
Flag
: R/-/-
Cost
Next Hop
: FE80::20F:E2FF:FE3E:FA3D
Interface: Vlan300
: 10
Flags: D-Direct, R-Added to Rib, L-Advertised in LSPs, U-Up/Down Bit Set
# Display the IPv6 IS-IS routing table on Switch D.
[SwitchD] display isis route ipv6
Route information for IS-IS(1)
------------------------------
Level-2 IPv6 Forwarding Table
-----------------------------
Destination : 2001:1::
PrefixLen: 64
Flag
: R/-/-
Cost
Next Hop
: FE80::200:FF:FE0F:4
Interface: Vlan300
: 20
Destination : 2001:2::
PrefixLen: 64
Flag
: R/-/-
Cost
Next Hop
: FE80::200:FF:FE0F:4
Interface: Vlan300
: 20
Destination : 2001:3::
PrefixLen: 64
Flag
Cost
: D/L/-
330
: 10
Next Hop
: Direct
Interface: Vlan300
Destination : 2001:4::1
PrefixLen: 128
Flag
: D/L/-
Cost
Next Hop
: Direct
Interface: Loop1
: 0
Flags: D-Direct, R-Added to Rib, L-Advertised in LSPs, U-Up/Down Bit Set
BFD for IPv6 IS-IS configuration example
Network requirements
•
As shown in Figure 82, configure IPv6 IS-IS on Switch A and Switch B so that they can reach other.
•
Enable BFD on VLAN-interface 10 of Switch A and Switch B. After the link between Switch B and
the Layer-2 switch fails, BFD can quickly detect the failure and notify IPv6 IS-IS of the failure. Then
Switch A and Switch B communicate through Switch C.
Figure 82 Network diagram
Device
Interface
IPv6 address
Device
Interface
IPv6 address
Switch A
Vlan-int10
2001::1/64
Switch B
Vlan-int10
2001::2/64
Vlan-int11
2001:2::1/64
Vlan-int13
2001:3::2/64
Switch C
Vlan-int11
2001:2::2/64
Vlan-int13
2001:3::1/64
Configuration procedure
1.
Configure IP addresses for interfaces. (Details not shown.)
2.
Configure IPv6 IS-IS:
# Configure Switch A.
<SwitchA> system-view
[SwitchA] isis 1
[SwitchA-isis-1] is-level level-1
[SwitchA-isis-1] network-entity 10.0000.0000.0001.00
[SwitchA-isis-1] ipv6 enable
[SwitchA-isis-1] quit
[SwitchA] interface vlan-interface 10
[SwitchA-Vlan-interface10] isis ipv6 enable 1
[SwitchA-Vlan-interface10] quit
331
[SwitchA] interface vlan-interface 11
[SwitchA-Vlan-interface11] isis ipv6 enable 1
[SwitchA-Vlan-interface11] quit
# Configure Switch B.
<SwitchB> system-view
[SwitchB] isis 1
[SwitchB-isis-1] is-level level-1
[SwitchB-isis-1] network-entity 10.0000.0000.0002.00
[SwitchB-isis-1] ipv6 enable
[SwitchB-isis-1] quit
[SwitchB] interface vlan-interface 10
[SwitchB-Vlan-interface10] isis ipv6 enable 1
[SwitchB-Vlan-interface10] quit
[SwitchB] interface vlan-interface 13
[SwitchB-Vlan-interface13] isis ipv6 enable 1
[SwitchB-Vlan-interface13] quit
# Configure Switch C.
<SwitchC> system-view
[SwitchC] isis 1
[SwitchC-isis-1] network-entity 10.0000.0000.0003.00
[SwitchC-isis-1] ipv6 enable
[SwitchC-isis-1] quit
[SwitchC] interface vlan-interface 11
[SwitchC-Vlan-interface11] isis ipv6 enable 1
[SwitchC-Vlan-interface11] quit
[SwitchC] interface vlan-interface 13
[SwitchC-Vlan-interface13] isis ipv6 enable 1
[SwitchC-Vlan-interface13] quit
3.
Configure BFD functions:
# Enable BFD and configure BFD parameters on Switch A.
[SwitchA] bfd session init-mode active
[SwitchA] interface vlan-interface 10
[SwitchA-Vlan-interface10] isis ipv6 bfd enable
[SwitchA-Vlan-interface10] bfd min-transmit-interval 500
[SwitchA-Vlan-interface10] bfd min-receive-interval 500
[SwitchA-Vlan-interface10] bfd detect-multiplier 7
[SwitchA-Vlan-interface10] return
# Enable BFD and configure BFD parameters on Switch B.
[SwitchB] bfd session init-mode active
[SwitchB] interface vlan-interface 10
[SwitchB-Vlan-interface10] isis ipv6 bfd enable
[SwitchB-Vlan-interface10] bfd min-transmit-interval 500
[SwitchB-Vlan-interface10] bfd min-receive-interval 500
[SwitchB-Vlan-interface10] bfd detect-multiplier 6
Verifying the configuration
# Display BFD session information on Switch A.
332
<SwitchA> display bfd session
Total Session Num: 1
Init Mode: Active
IPv6 Session Working Under Ctrl Mode:
Local Discr: 1441
Remote Discr: 1450
Source IP: FE80::20F:FF:FE00:1202 (link-local address of VLAN-interface 10 on
Switch A)
Destination IP: FE80::20F:FF:FE00:1200 (link-local address of VLAN-interface 10 on
Switch B)
Session State: Up
Interface: Vlan10
Hold Time: 2319ms
# Display routes destined for 2001:4::0/64 on Switch A.
<SwitchA> display ipv6 routing-table 2001:4::0 64
Summary Count : 1
Destination: 2001:4::/64
Protocol
NextHop
: FE80::20F:FF:FE00:1200
Preference: 15
: ISISv6
Interface
: Vlan10
Cost
: 10
The output shows that Switch A and Switch B communicate through VLAN-interface 10. Then the link over
VLAN-interface 10 fails.
# Display routes destined for 2001:4::0/64 on Switch A.
<SwitchA> display ipv6 routing-table 2001:4::0 64
Summary Count : 1
Destination: 2001:4::/64
Protocol
: ISISv6
NextHop
: FE80::BAAF:67FF:FE27:DCD0
Preference: 15
Interface
: Vlan11
Cost
: 20
The output shows that Switch A and Switch B communicate through VLAN-interface 11.
333
Configuring IPv6 PBR
Introduction to IPv6 PBR
Policy-based routing (PBR) uses user-defined policies to route packets. A policy can specify the next hop
and other parameters for packets that match specific criteria such as ACLs.
A device uses PBR to forward matching packets and uses the routing table to forward non-matching
packets. If PBR is not configured, the device uses the routing table to forward packets.
The device supports only interface PBR, which guides the forwarding of packets received on an interface
only.
Policy
An IPv6 policy includes match criteria and actions to be taken on the matching packets. A policy can
have one or multiple nodes as follows:
•
Each node is identified by a node number. A smaller node number has a higher priority.
•
A node comprises if-match and apply clauses. An if-match clause specifies a match criterion, and
an apply clause specifies an action.
•
A node has a match mode of permit or deny.
An IPv6 policy matches nodes in priority order against packets. If a packet satisfies the match criteria on
a node, it is processed by the action on the node. Otherwise, it goes to the next node for a match. If the
packet does not match the criteria on any node, it is forwarded according to the routing table.
if-match clause
IPv6 PBR supports only the if-match acl clause, which sets an ACL match criterion.
You can specify only one if-match clause of each type for a node.
apply clause
IPv6 PBR supports only the apply next-hop clause, which sets the next hop for packets.
Relationship between the match mode and clauses on the node
Does a packet match all the
if-match clauses on the
node?
Match mode
In permit mode
In deny mode
• If the node is configured with an
apply clause, IPv6 PBR executes
the apply clause on the node.
Yes
• If the node is configured with no
The packet is forwarded according
to the routing table.
IPv6 PBR matches the packet against
the next node.
IPv6 PBR matches the packet against
the next node.
apply clause, the packet is
forwarded according to the
routing table.
No
334
A node that has no if-match clauses matches any packet.
PBR and track
PBR can work with the Track feature to dynamically adapt the availability status of a node configured
with an apply clause to the link status of a tracked next hop.
When the track entry associated with the node changes to negative because the next hop is detected to
be unavailable, the node cannot be used for forwarding. When the track entry changes to positive or
NotReady because the next hop is detected to be available, the node can be used for forwarding.
For more information about track-PBR collaboration, see High Availability Configuration Guide.
IPv6 PBR configuration task list
Tasks at a glance
(Required.) Configuring an IPv6 policy:
• Creating an IPv6 node
• Configuring match criteria for an IPv6 node
• Configuring actions for an IPv6 node
(Required.) Configuring IPv6 PBR
Configuring an IPv6 policy
Creating an IPv6 node
Step
Command
Remarks
1.
Enter system view.
system-view
N/A
2.
Create an IPv6 policy
or policy node, and
enter IPv6 policy
node view.
ipv6 policy-based-route policy-name [ deny |
permit ] node node-number
By default, no IPv6 policy
node is created.
Configuring match criteria for an IPv6 node
Step
Command
Remarks
1.
Enter system view.
system-view
N/A
2.
Enter IPv6 policy
node view.
ipv6 policy-based-route policy-name [ deny | permit ]
node node-number
N