Huawei AR150&200 Enterprise Router Configuration Guide

, the mask length of all the IPv6 addresses is 64 bits. It is required that

Figure 2-2

every two hosts or routers be interconnected.

NOTE

AR150/200 can be used as RouterA, or RouterC.

Figure 2-2 Networking diagram for configuring IPv6 static routes

Eth0/0/1

VLANIF10

1::1/64

PC2

2::2/64

GE0/0/0

2::1/24

GE2/0/0

GE1/0/0

RouterB

RouterA

Eth0/0/8 Eth0/0/8

RouterC

Eth0/0/1

VLANIF20

3::1/64

PC1

1::2/64

PC3

3::2/64

Figure 2-2

, PC1, PC2, and PC3 use static routes because they cannot be configured with dynamic routing protocols. The interface of the router connected to the PC uses the IPv6 linklocal address.

Configuration Roadmap

The configuration roadmap is as follows:

Configure an IPv6 address for each interface on each router for interworking.

Configure an IPv6 static route and a default route to the destination address on each router.

Configure an IPv6 default gateway on each host to make any two hosts communicate.

Data Preparation

To complete the configuration, you need the following data:

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Configuration Guide - IP Routing

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2 IP Static Route Configuration l Link-local addresses of interfaces, as shown in the following table.

Device Interface Link-local address

RouterA Eth0/0/8

RouterB GE1/0/0

FE80::A19:A6FF:FECD:A

897

FE80::E0:FCD5:A2BF:

401

RouterB

RouterC

GE2/0/0

Eth0/0/8

FE80::A19:A6FF:FECD:A

896

FE80::A19:A6FF:FECD:A

895 l Default route on RouterA: its outbound interface Eth0/0/8 and next hop address

FE80::E0:FCD5:A2BF:401 l Static route of RouterB: destination address 1:: 64, outbound interface GE1/0/0, and next hop address FE80::A19:A6FF:FECD:A897 l Static route of RouterB: destination address 3:: 64, outbound interface GE2/0/0 and next hop addressFE80::A19:A6FF:FECD:A895 l Default route of RouterC: outbound interface Eth0/0/8 and next hop address

FE80::A19:A6FF:FECD:A896 l Default gateway addresses of PC1, PC2, and PC3 being 1::1, 2::1, and 3::1 respectively

Procedure

Step 1 Configure an IPv6 address for each interface.

The configuration details are not described here.

Step 2 Configure IPv6 static routes.

# Configure an IPv6 default route on Router A.

[RouterA] ipv6 route-static :: 0 ethernet 0/0/8 FE80::E0:FCD5:A2BF:401

# Configure two IPv6 static routes on Router B.

[RouterB] ipv6 route-static 1:: 64 gigabitethernet 1/0/0 FE80::A19:A6FF:FECD:A897

[RouterB] ipv6 route-static 3:: 64 gigabitethernet 2/0/0 FE80::A19:A6FF:FECD:A895

# Configure an IPv6 default route on Router C.

[RouterC] ipv6 route-static :: 0 ethernet 0/0/8 FE80::A19:A6FF:FECD:A896

Step 3 Configure host addresses and gateways.

Configure IPv6 addresses for hosts according to the networking diagram, and set default gateway addresses of PC1, PC2, and PC3 to 1::1, 2::1, and 3::1 respectively.

Step 4 Verify the configuration.

# Check the IPv6 routing table of Router A.

[RouterA] display ipv6 routing-table

Routing Table : Public

Destinations : 5 Routes : 5

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Configuration Guide - IP Routing 2 IP Static Route Configuration

Destination : :: PrefixLength : 0

NextHop : FE80::E0:FCD5:A2BF:401 Preference : 60

Cost : 0 Protocol : Static

RelayNextHop : :: TunnelID : 0x0

Interface : Ethernet0/0/8 Flags : D

Destination : ::1 PrefixLength : 128

NextHop : ::1 Preference : 0

Cost : 0 Protocol : Direct

RelayNextHop : :: TunnelID : 0x0

Interface : InLoopBack0 Flags : D

Destination : 1:: PrefixLength : 64

NextHop : 1::1 Preference : 0

Cost : 0 Protocol : Direct

RelayNextHop : :: TunnelID : 0x0

Interface : Vlanif10 Flags : D

Destination : 1::1 PrefixLength : 128

NextHop : ::1 Preference : 0

Cost : 0 Protocol : Direct

RelayNextHop : :: TunnelID : 0x0

Interface : Vlanif10 Flags : D

Destination : FE80:: PrefixLength : 10

NextHop : :: Preference : 0

Cost : 0 Protocol : Direct

RelayNextHop : :: TunnelID : 0x0

Interface : NULL0 Flags : D

# Run the ping command to verify the connectivity.

[RouterA] ping ipv6 3::1

PING 3::1 : 56 data bytes, press CTRL_C to break

Reply from 3::1

bytes=56 Sequence=1 hop limit=254 time = 63 ms

Reply from 3::1

bytes=56 Sequence=2 hop limit=254 time = 62 ms

Reply from 3::1

bytes=56 Sequence=3 hop limit=254 time = 62 ms

Reply from 3::1

bytes=56 Sequence=4 hop limit=254 time = 63 ms

Reply from 3::1

bytes=56 Sequence=5 hop limit=254 time = 63 ms

--- 3::1 ping statistics ---

5 packet(s) transmitted

5 packet(s) received

0.00% packet loss

round-trip min/avg/max = 62/62/63 ms

# Run the tracert command to verify the connectivity.

[RouterA] tracert ipv6 3::1 traceroute to 3::1 30 hops max,60 bytes packet

1 FE80::E0:FCD5:86D4:401 11 ms 3 ms 4 ms

2 3::1 4 ms 3 ms 3 ms

----End

Configuration Files

l Configuration file of Router A

sysname RouterA

ipv6

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Configuration Guide - IP Routing 2 IP Static Route Configuration vlan batch 10

# interface Vlanif10

ipv6 enable

ipv6 address 1::1/64

# interface Ethernet0/0/1

port link-type access

port default vlan 10

# interface Ethernet0/0/8

ipv6 enable

ipv6 address auto link-local

# ipv6 route-static :: 0 Ethernet 0/0/8 FE80::E0:FCD5:A2BF:401

# return l Configuration file of Router B

sysname RouterB

ipv6

# interface GigabitEthernet0/0/0

ipv6 address 2::1/64

# interface GigabitEthernet1/0/0

ipv6 address auto link-local

# interface GigabitEthernet2/0/0

ipv6 address auto link-local

# ipv6 route-static 1:: 64 GigabitEthernet 1/0/0 FE80::A19:A6FF:FECD:A897 ipv6 route-static 3:: 64 GigabitEthernet 2/0/0 FE80::A19:A6FF:FECD:A895

# return l Configuration file of Router C

sysname RouterC

ipv6

# vlan batch 20

# interface Vlanif20

ipv6 enable

ipv6 address 3::1/64

# interface Ethernet0/0/1

port link-type access

port default vlan 20

# interface Ethernet0/0/8

ipv6 enable

ipv6 address auto link-local

# ipv6 route-static :: 0 Ethernet 0/0/8 FE80::A19:A6FF:FECD:A896

# return

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Configuration Guide - IP Routing 3 RIP Configuration

RIP Configuration

About This Chapter

Issue 02 (2012-03-30)

RIP can advertise and receive routes to affect the selection of data forwarding paths, and can provide the network management function. RIP is commonly used on small-scale networks.

3.1 Overview of RIP

RIP is widely used on small-scale network because it is simple to deploy and easier to configure and maintain than OSPF and IS-IS.

3.2 RIP Features Supported by the AR150/200

The RIP features supported by the AR150/200 include RIPv1, RIPv2, split horizon, poison reverse, and multi-instance.

3.3 Configuring Basic RIP Functions

To implement RIP features, configure basic RIP functions including enabling RIP, specifying the network segment in which RIP runs, and setting the RIP version.

3.4 Configuring RIP Route Attributes

By setting RIP route attributes, you can change RIP routing policies to meet the requirements of complex networks.

3.5 Controlling the Advertising of RIP Routing Information

To meet the requirements of complex networks, accurately controlling the advertising of RIP routing information is essential.

3.6 Controlling the Receiving of RIP Routing Information

To meet the requirements of complex networks, accurately controlling the receiving of RIP routing information is essential.

3.7 Configuring RIP-2 Features

Different from RIP-1, RIP-2 supports VLSM, CIDR, and authentication to ensure higher security.

3.8 Optimizing a RIP Network

You can adjust and optimize the RIP network performance by configuring RIP functions in special network environments, such as configuring RIP timers, setting the interval for sending packets, and setting the maximum number of packets to be sent.

3.9 Configuring RIP GR

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Configuration Guide - IP Routing 3 RIP Configuration

This section describes how to configure RIP GR to avoid incorrect route calculation and packet loss after a RIP router restarts.

3.10 Configuring BFD for RIP

On a network that runs high-rate data services, BFD for RIP can be configured to quickly detect and respond to network faults.

3.11 Configuring Static BFD for RIP

BFD provides link failure detection featuring light load and high speed. Static BFD for RIP is a mode to implement the BFD function.

3.12 Configuring the Network Management Function in RIP

By binding RIP to MIBs, you can view and configure RIP through the NMS.

3.13 Maintaining RIP

This section describes how to reset RIP connections and clear RIP information.

3.14 Configuration Examples

In actual networking, RIP versions and whether to import external routes will affect which routes can be learned.

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Configuration Guide - IP Routing 3 RIP Configuration

3.1 Overview of RIP

RIP is widely used on small-scale network because it is simple to deploy and easier to configure and maintain than OSPF and IS-IS.

The Routing Information Protocol (RIP) is a simple Interior Gateway Protocol (IGP). RIP is mainly used on small-scale networks such as campus networks and simple regional networks.

RIP uses the distance-vector routing algorithm and exchanges routing information by using User

Datagram Protocol (UDP) packets through port 520.

RIP uses the hop count to measure the distance to the destination. The distance is called the routing metric. In RIP, the hop count from a router to its directly connected network is 0, and the hop count from a router to a network, which can be reached through another router, is 1. To speed up route convergence, RIP defines the cost as an integer that ranges from 0 to 15. If the hop count is equal to or exceeds 16, the destination network or host is unreachable because the path is considered to have an infinite metric. It is this limitation to the hop count that makes RIP inapplicable to large-scale networks.

To improve network performance and prevent routing loops, RIP supports both split horizon and poison reverse.

l Split horizon is a method of preventing routing loops in a network and reducing bandwidth consumption. The basic principle is simple: Information about the routing for a particular packet is never sent back in the direction from which it was received.

l Poison reverse is that RIP sets the cost of the route learnt from an interface of a neighbor to 16 (specifying the route as unreachable) and then sends the route from the interface back to the neighbor. In this way, RIP can delete useless routes from the routing table of the neighbor.

RIP has two versions: l RIPv1 l RIPv2

RIPv1 is a classful routing protocol, whereas RIPv2 is a classless routing protocol. In RIPv2, address 224.0.0.9 is the multicast address of a RIP router.

Compared with RIPv1, RIPv2 has the following advantages: l Supports route tag and can flexibly control routes on the basis of the tag in the routing policy.

l Provides packets that contain mask information and supports route aggregation and

Classless Inter-domain Routing (CIDR).

l Supports the next hop address and can select the optimal next hop address in the broadcast network.

Uses multicast routes to send update packets. Only RIPv2 routers can receive protocol packets. This reduces the resource consumption.

l To enhance the security, Provides two authentication modes to enhance security: plain-text authentication and MD5 authentication.

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Configuration Guide - IP Routing 3 RIP Configuration

3.2 RIP Features Supported by the AR150/200

The RIP features supported by the AR150/200 include RIPv1, RIPv2, split horizon, poison reverse, and multi-instance.

The AR150/200 supports the following RIP features: l RIPv1 and RIPv2 l RIP multi-instance

3.3 Configuring Basic RIP Functions

To implement RIP features, configure basic RIP functions including enabling RIP, specifying the network segment in which RIP runs, and setting the RIP version.

3.3.1 Establishing the Configuration Task

Before configuring basic RIP functions, familiarize yourself with the applicable environment, complete the pre-configuration tasks, and obtain the required data. This can help you complete the configuration task quickly and accurately.

Applicable Environment

Configuring basic RIP functions allows you to enjoy certain RIP features.

Pre-configuration Tasks

Before configuring basic RIP functions, complete the following tasks: l Configuring the link layer protocol l Configuring IP addresses for interfaces to ensure that neighboring nodes are reachable at the network layer

Data Preparation

To configure basic RIP functions, you need the following data.

No.

Data

1 RIP process ID

Network segment in which the RIP interface resides

RIP version number

3.3.2 Enabling RIP

Creating RIP processes is the prerequisite to performing RIP configurations.

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3 RIP Configuration

Context

If you run RIP-related commands in the interface view before enabling RIP, the configurations take effect only after RIP is enabled.

Do as follows on the router to be enabled with RIP:

Procedure

Step 1 Run:

system-view

The system view is displayed.

Step 2 Run:

rip [ process-id ]

The RIP is enabled and the RIP view is displayed.

RIP supports multi-instance. To associate RIP processes with VPN instances, you can run the

rip [ process-id ] vpn-instance vpn-instance-name command.

NOTE

For easy management and effective control, RIP supports multi-process and multi-instance. The multiprocess feature allows a set of interfaces to be associated with a specific RIP process and an interface can be associated with only one RIP process. This ensures that the specific RIP process performs all the protocol operations only on this set of interfaces. Thus, multiple RIP processes can work on a single router and each process is responsible for a unique set of interfaces. In addition, the routing data is independent between

RIP processes; however, routes can be imported between processes.

For the routers that support the VPN, each RIP process is associated with a specific VPN instance. In this case, all the interfaces attached to the RIP process should be associated with the RIP-process-related VPN instance.

----End

3.3.3 Enabling RIP on the Specified Network Segment

After enabling RIP, you need to specify the network segment in which RIP runs. RIP runs only on the interfaces on the specified network segment. RIP does not receive, send, or forward routes on the interfaces that do not reside on the specified network segment.

Context

By default, after RIP is enabled, it is disabled on all interfaces.

Do as follows on the router to be enabled with RIP.

Procedure

Step 1 Run:

system-view

The system view is displayed.

Step 2 Run:

rip [ process-id ]

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The RIP process is enabled and the RIP view is displayed.

Step 3 Run:

network network-address

RIP is enabled in the specified network segment.

network-address specifies the address of a natural network segment.

NOTE

An interface can be associated with only one RIP process.

If any network segment in which an interface configured with multiple sub-interface IP addresses resides is associated with a RIP process, the interface cannot be associated with any other RIP processes.

----End

3.3.4 Configuring RIP Version Number

RIP versions include RIPv1 and RIPv2. The two versions have different functions.

Context

3 RIP Configuration

Do as follows on the RIP router.

Procedure

Configuring the Global RIP Version Number

Run:

system-view

The system view is displayed.

Run:

rip [ process-id ]

The RIP process is enabled and the RIP view is displayed.

Run:

version { 1 | 2 }

The global RIP version number is specified.

l Configuring the RIP Version Number for an Interface

Run:

system-view

The system view is displayed.

Run:

interface interface-type interface-number

The interface view is displayed.

Run:

rip version { 1 | 2 [ broadcast | multicast ] }

The RIP version number of the packets received by the interface is specified.

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Configuration Guide - IP Routing 3 RIP Configuration

NOTE

By default, an interface receives both RIPv1 and RIPv2 packets but sends only RIPv1 packets.

When configuring RIPv2 on an interface, you can specify the mode in which the interface sends packets. If no RIP version number is configured in the interface view, the global RIP version is used. The RIP version set on an interface takes precedence over the global RIP version.

----End

3.3.5 Checking the Configuration

After basic RIP functions are successfully configured, you can view the current running status, configuration, and routing information of RIP.

Prerequisites

The configurations of basic RIP functions are complete.

Procedure

l Run display rip [ process-id | vpn-instance vpn-instance-name ] command to check the running status and configuration of RIP.

l Run display rip process-id route command to check all the RIP routes that are learned from other routers.

l Run display default-parameter rip command to check the default RIP configuration.

l Run the display rip process-id statistics interface { all | interface-type interface-

number [ verbose | neighbor neighbor-ip-address ] } command to check statistics about

RIP interfaces.

----End

3.4 Configuring RIP Route Attributes

By setting RIP route attributes, you can change RIP routing policies to meet the requirements of complex networks.

3.4.1 Establishing the Configuration Task

RIP route attributes include the RIP preference, additional metrics of an interface, and maximum number of equal-cost routes.

Applicable Environment

For complex networks, you can set RIP route attributes to change RIP routing policies. After performing the configuration procedures in this section, you can: l Affect route selection by changing the additional metric of a RIP interface.

l Change the matching order by configuring the RIP preference when multiple routing protocols discover routes to the same destination.

l Implement load balancing among multiple equal-cost routes.

Pre-configuration Tasks

Before configuring RIP route attributes, complete the following tasks:

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Configuration Guide - IP Routing 3 RIP Configuration l Configuring IP addresses for interfaces to ensure that neighboring nodes are reachable at the network layer l

Data Preparation

To configure RIP route attributes, you need the following data.

No.

Data

1 Additional metric of the interface

RIP preference

Maximum number of equal-cost routes

3.4.2 Configuring Additional Metrics of an Interface

The additional metric is the metric (hop count) to be added to the original metric of a RIP route.

You can specify commands to set additional metrics for incoming and outgoing RIP routes.

Context

The additional metric is added to the original metric of the RIP route.

The rip metricin command is used to add an additional metric to an incoming route. After this route is added to the routing table, its metric in the routing table changes.Running this command affects route selection on the local device and other devices on the network.

l The rip metricout command is used to add an additional metric to an outgoing route. When this route is advertised, an additional metric is added to this route, but the metric of the route in the routing table does not change.Running this command does not affect route selection on the local device or other devices on the network.

Do as follows on the RIP router:

Procedure

Step 1 Run:

system-view

The system view is displayed.

Step 2 Run:

interface interface-type interface-number

The interface view is displayed.

Step 3 Run:

rip metricin value

The metric added to an incoming route is set.

Step 4 Run:

rip metricout { value | { acl-number | acl-name acl-name | ip-prefix ip-prefix-

name } value1 }

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3 RIP Configuration

The metric added to an outgoing route is set.

NOTE

You can specify the value of the metric to be added to the RIP route that passes the filtering policy by specifying value1 through an ACL or an IP prefix list. If a RIP route does not pass the filtering, its metric is increased by 1.

----End

3.4.3 Configuring RIP Preference

When there are routes discovered by multiple routing protocols on the same Router, you can set

RIP preferences to instruct the Router to prefer certain RIP routes over others.

Context

Do as follows on the RIP router:

Procedure

Step 1 Run:

system-view

The system view is displayed.

Step 2 Run:

rip [ process-id ]

The RIP process is enabled and the RIP view is displayed.

Step 3 Run:

preference { preference | route-policy route-policy-name } *

The RIP preference is set.

By default, the RIP preference is 100.

----End

3.4.4 Setting the Maximum Number of Equal-Cost Routes

By setting the maximum number of equal-cost RIP routes, you can change the number of routes for load balancing.

Context

Do as follows on the RIP router:

Procedure

Step 1 Run:

system-view

The system view is displayed.

Step 2 Run:

rip [ process-id ]

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Configuration Guide - IP Routing 3 RIP Configuration

The RIP process is enabled and the RIP view is displayed.

Step 3 Run:

maximum load-balancing number

The maximum number of equal-cost routes is set.

----End

3.4.5 Checking the Configuration

After RIP route attributes are successfully set, you can view the current running status, configuration, and routing information about RIP.

Prerequisites

The configurations for RIP route attributes are complete.

Procedure

l Run display rip [ process-id | vpn-instance vpn-instance-name ] command to check the running status and configuration of RIP.

l Run display rip process-id database command to check all activated routes in the RIP database.

l Run display rip process-id route command to check all the RIP routes that are learned from other routers.

----End

3.5 Controlling the Advertising of RIP Routing Information

To meet the requirements of complex networks, accurately controlling the advertising of RIP routing information is essential.

3.5.1 Establishing the Configuration Task

RIP routing information can be advertised through default routes, Update packets, and imported external routes.

Applicable Environment

To meet the requirements of a network, you need to control the advertising of RIP routing information accurately. After performing the configuration procedures in this section, you can: l Advertise default routes to neighbors.

l Suppress interfaces from sending RIP Update packets.

l Import external routes from various routing protocols and filter the routes to be advertised.

Pre-configuration Tasks

Before configuring the router to control the advertising of RIP routing information, complete the following tasks:

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Configuration Guide - IP Routing 3 RIP Configuration l Configuring IP addresses for interfaces to ensure that neighboring nodes are reachable at the network layer l

Data Preparation

To control the advertising of RIP routing information, you need the following data.

No.

Data

1 Metric of the default route to be advertised

Number of the interface that is suppressed from sending RIP Update packets

Protocol name and process ID of the external route to be imported

3.5.2 Configuring RIP to Advertise Default Routes

A default route is a route destined for 0.0.0.0. By default, RIP does not advertise default routes to its neighbors.

Context

Do as follows on the RIP router:

Procedure

Step 1 Run:

system-view

The system view is displayed.

Step 2 Run:

rip [ process-id ]

The RIP process is enabled and the RIP view is displayed.

Step 3 Run:

default-route originate [ match default [ avoid-learning ] ] [ cost cost ]

RIP is configured to advertise a default route.

You can configure a router to advertise a default route or set the default routes in routing table with the specified metric to its RIP neighbors.

----End

3.5.3 Disabling an Interface from Sending Update Packets

Disabling interfaces from sending Update packets is a method of preventing routing loops and can be implemented in two ways.

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Configuration Guide - IP Routing 3 RIP Configuration

Context

Do as follows on the RIP router:

Procedure

l Configuration in a RIP Process (with a High Priority)

Run:

system-view

The system view is displayed.

Run:

rip [ process-id ]

The RIP process is enabled and the RIP view is displayed.

Run one of the following commands depending on the site requirements.

Run:

silent-interface all

All interfaces are disabled from sending Update packets.

Run:

silent-interface interface-type interface-number

An interface is disabled from sending Update packets.

You can set an interface to silent so that it only receives Update packets to update its routing table. The silent-interface command takes precedence over the rip output command in the interface view.

By default, an interface can receive and send Update packets.

l Configuration in the Interface View (with a Low Priority)

Run:

system-view

The system view is displayed.

Run:

interface interface-type interface-number

The interface view is displayed.

Run:

undo rip output

The interface is disabled from sending RIP Update packets.

By running this command, you can specify whether to send RIP Update packets on an interface. The silent-interface command takes precedence over the undo rip

output command. By default, an interface is allowed to send RIP Update packets.

----End

3.5.4 Configuring RIP to Import External Routes

To enrich its routing information, RIP can import the routes learned by other processes or other routing protocols.

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Configuration Guide - IP Routing 3 RIP Configuration

Context

Do as follows on the RIP router:

Procedure

Step 1 Run:

system-view

The system view is displayed.

Step 2 Run:

rip [ process-id ]

The RIP process is enabled and the RIP view is displayed.

Step 3 (Optional) Run:

default-cost cost

The default cost of imported routes is set.

If no cost is specified when external routes are imported, the default cost is used.

Step 4 Run:

import-route bgp [ cost { cost | transparent } | route-policy route-policy-name ]

or import-route { { static | direct } | { { rip | ospf | isis } [ process-id ] } }

[ cost cost | route-policy route-policy-name ]

Step 5 (Optional) Run:

filter-policy { acl-number | acl-name acl-name | ip-prefix ip-prefix-name } export

[ protocol [ process-id ] | interface-type interface-number ]

The imported routes are filtered when being advertised.

If the routing information to be advertised by RIP contains the routes imported from other routing protocols, you can specify protocol to filter the specified routes. If protocol is not specified, all the routing information to be advertised will be filtered, including the imported routes and local

RIP routes (directly connected routes).

NOTE

The Tag field in RIP is 16 bits in length, whereas the Tag field in other routing protocols is 32 bits in length.

If the routes of other routing protocols are imported and the tag is used in the routing policy, ensure that the tag value does not exceed 65535. Otherwise, the routing policy becomes invalid or the matching result is incorrect.

----End

3.5.5 Checking the Configuration

After the function of controlling the advertising of RIP routing information is successfully configured, you can view the current running status, configuration, and routing information about RIP.

Prerequisites

The configurations for controlling the advertising of RIP routing information are complete.

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Configuration Guide - IP Routing

Procedure

3 RIP Configuration l Run the display rip [ process-id | vpn-instance vpn-instance-name ] command to check the running status and configuration of RIP.

l Run the display rip process-id database command to check all activated routes in the RIP database.

l Run the display rip process-id route command to check all the RIP routes that are learned from other routers..

----End

3.6 Controlling the Receiving of RIP Routing Information

To meet the requirements of complex networks, accurately controlling the receiving of RIP routing information is essential.

3.6.1 Establishing the Configuration Task

You can obtain RIP routing information by receiving Update packets and host routes.

Applicable Environment

In practice, to meet the requirements of a complex network, it is required to control the receiving of RIP routing information accurately. After performing configuration procedures in this section, you can: l Disable an interface from receiving RIP Update packets.

l Filter the received routing information.

Import external routes from various routing protocols and filter the imported routes.

Pre-configuration Tasks

Before configuring a router to control the receiving of RIP routing information, complete the following tasks: l Configuring IP addresses for interfaces to ensure that neighboring nodes are reachable at the network layer l

Data Preparation

To control the receiving of RIP routing information, you need the following data.

No.

Data

1 ACL used to filter the routing information

3.6.2 Disabling an Interface from Receiving RIP Update Packets

Disabling interfaces from receiving Update packets is a method of preventing routing loops.

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Configuration Guide - IP Routing 3 RIP Configuration

Context

By default, an interface is allowed to receive RIP Update packets.

Do as follows on the RIP router:

Procedure

Step 1 Run:

system-view

The system view is displayed.

Step 2 Run:

interface interface-type interface-number

The interface view is displayed.

Step 3 Run:

undo rip input

The interface is disabled from receiving RIP Update packets.

----End

3.6.3 Disabling RIP from Receiving Host Routes

When you disable RIP from receiving host routes on a router, the router rejects to receive host routes. This prevents the router from receiving a large number of unnecessary routes and thus avoiding wasting network resources.

Context

In certain situations, a router may receive a large number of host routes from the same network segment. These routes are not required in route addressing, but consume many network resources. You can configure the router to refuse to accept host routes by disabling RIP from accepting host routes.

By default, host routes are added to the routing table.

Do as follows on the RIP router:

Procedure

Step 1 Run:

system-view

The system view is displayed.

Step 2 Run:

rip [ process-id ]

The RIP process is enabled and the RIP view is displayed.

Step 3 Run:

undo host-route

RIP is disabled from adding host routes to the routing table.

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NOTE

undo host-route command will not be effective in RIP version 2. By default, RIP version 2 always supports host-route.

----End

3.6.4 Configuring RIP to Filter the Received Routes

By specifying ACLs and IP prefix lists, you can configure the inbound policy to filter the routes to be received. You can also configure a router to receive only RIP packets from a specified neighbor.

Context

The router can filter routing information. To filter the imported and advertised routes, you can configure inbound and outbound routing policies by specifying ACLs and IP prefix lists.

You can also configure the router to receive RIP packets only from a specified neighbor.

Do as follows on the RIP router:

Procedure

Step 1 Run:

system-view

The system view is displayed.

Step 2 Run:

rip [ process-id ]

The RIP process is enabled and the RIP view is displayed.

Step 3 Depending on type of desired filtering, run one of following commands to configure RIP to filter the received routes: l Run:

filter-policy { acl-number | acl-name acl-name } import

The learned routing information is filtered based on an ACL.

l Run:

filter-policy gateway ip-prefix-name import

The routing information advertised by neighbors is filtered based on the IP prefix list.

l Run:

filter-policy ip-prefix ip-prefix-name [ gateway ip-prefix-name ] import

[ interface-type interface-number ]

The routes learned by the specified interface are filtered based on the IP prefix list and neighbors.

NOTE

To filter routes to be advertised, run the filter-policy { acl-number | acl-name acl-name | ip-prefix ip-

prefix-name } export [ protocol [ process-id ] | interface-type interface-number ] command.

----End

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3.6.5 Checking the Configuration

After the receiving of RIP routing information is successfully controlled, you can view the current running status, configuration, and routing information about RIP.

Procedure

l Run the display rip [ process-id | vpn-instance vpn-instance-name ] command to check the running status and configuration of RIP.

l Run the display rip process-id database [ verbose ] command to check all activated RIP routes in the database.

l Run the display rip process-id interface [ interface-type interface-number ] [ verbose ] command to check information about the RIP interface.

l Run the display rip process-id neighbor [ verbose ] command to check information about

RIP neighbors.

Run the display rip process-id route command to check all the RIP routes that are learned from other routers.

----End

3.7 Configuring RIP-2 Features

Different from RIP-1, RIP-2 supports VLSM, CIDR, and authentication to ensure higher security.

3.7.1 Establishing the Configuration Task

Before configuring RIP-2 features, familiarize yourself with the applicable environment, complete the pre-configuration tasks, and obtain the data required for the configuration. This will help you complete the configuration task quickly and accurately.

Applicable Environment

RIP-2 is a type of classless routing protocol. A RIP-2 packet carries subnet mask information.

Deploying a RIP-2 network saves IP addresses. For a network on which the IP addresses of devices are not consecutive, only RIP-2 can be deployed, whereas RIP-1 cannot be deployed.

RIP-2 features include: l RIP-2 route summarization l

RIP-2 authentication mode

Pre-configuration Tasks

Before configuring RIP-2 features, complete the following tasks: l Configuring the link layer protocol l Configuring IP addresses for interfaces to ensure that neighboring nodes are reachable at the network layer

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Data Preparation

To configure RIP-2 features, you need the following data.

No.

Data

1 RIP-2 process ID

2 Network segment where the RIP-2 interface resides

3 RIP Configuration

3.7.2 Configuring RIP-2 Route Summarization

Route summarization is enabled in RIP-1 by default, and no need to be configured. RIP-2 supports VLSM and CIDR. You can configure route summarization in RIP-2 to improve the flexibility of RIP-2. To broadcast all subnet routes, you can disable route summarization in

RIP-2.

Context

Route summarization indicates that multiple subnet routes on the same natural network segment are summarized into one route with the natural mask when being advertised to other network segments. Therefore, route summarization reduces the network traffic and the size of the routing table.

Route summarization does not take effect in RIP-1. RIP-2 supports Variable Length Subnet

Mask (VLSM) and Classless Interdomain Routing (CIDR). To broadcast all subnet routes, you can disable automatic route summarization of RIP-2.

Do as follows on the RIP router:

NOTE

Route summarization is invalid when split horizon or poison reverse is configured. When the summarized routes are sent outside the natural network boundary, split horizon or poison reverse in related views needs to be disabled.

Procedure

l Enabling RIP-2 Automatic Route Summarization

Run:

system-view

The system view is displayed.

Run:

rip [ process-id ]

The RIP process is enabled and the RIP view is displayed.

Run:

version 2

RIP-2 is configured.

Run:

summary [ always ]

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– Enable the RIP-2 automatic route summarization when split horizon is disabled, there is no need to configure always.

– Enable the RIP-2 automatic route summarization irrespective of split horizon configuration, always must be configured.

NOTE

The summary command is used in the RIP view to enable classful network-based route summarization.

l Configuring RIP-2 to Advertise the Summary Address

Run:

system-view

The system view is displayed.

Run:

interface interface-type interface-number

The interface view is displayed.

Run:

rip summary-address ip-address mask [ avoid-feedback ]

The local summary address of RIP-2 is advertised.

NOTE

The rip summary-address ip-address mask [ avoid-feedback ] command is run in the interface view to enable classless network-based route summarization.

----End

3.7.3 Configuring Packet Authentication of RIP-2

RIP-2 supports the ability to authenticate protocol packets and provides two authentication modes, Simple authentication and Message Digest 5 (MD5) authentication, to enhance security.

Context

RIP-2 supports two authentication modes: l Simple authentication l MD5 authentication

In simple authentication mode, the unencrypted authentication key is sent in every RIP-2 packet.

Therefore, simple authentication does not guarantee security, and cannot meet the requirements for high security.

Do as follows on the RIP router:

Procedure

Step 1 Run:

system-view

The system view is displayed.

Step 2 Run:

interface interface-type interface-number

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The interface view is displayed.

Step 3 Run the following command as required: l Run:

rip authentication-mode simple { [ plain ] plain-text | cipher password-key }

Simple authentication is configured for RIP-2 packets.

l Run:

rip authentication-mode usual { plain plain-text | [ cipher ] password-key }

MD5 usual authentication is configured for RIP-2 packets.

l Run:

rip authentication-mode nonstandard { keychain keychain-name | { { plain plain-

text | [ cipher ] password-key } key-id } }

MD5 nonstandard authentication is configured for RIP-2 packets.

NOTE

The MD5 type must be specified if MD5 authentication is configured. The usual type supports private standard authentication packets, and the nonstandard type supports IETF standard authentication packets.

The MD5 authentication password that starts and ends with $@$@ is invalid, because $@$@ is used to distinguish old and new passwords.

----End

3.7.4 Checking the Configuration

After RIP-2 features are successfully configured, you can view the current running status, configuration, and routing information of RIP.

Prerequisites

The configurations of RIP-2 features are complete.

Procedure

l Run the display rip [ process-id | vpn-instance vpn-instance-name ] command to check the running status and configuration of RIP.

l Run the display rip process-id database [ verbose ] command to check all activated RIP routes in the database.

Run the display rip process-id route command to check all the RIP routes that are learned from other routers.

----End

3.8 Optimizing a RIP Network

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3.8.1 Establishing the Configuration Task

Before adjusting and optimizing the RIP network performance, familiarize yourself with the applicable environment, complete the pre-configuration tasks, and obtain the data required for the configuration. This will help you complete the configuration task quickly and accurately.

Applicable Environment

On certain networks, you need to configure RIP features and optimize the performance of a RIP network. After performing configuration procedures in this section, you can: l Change the convergence speed of the RIP network by adjusting the values of RIP timers.

l Reduce the consumption of device resources and network bandwidth by adjusting the number of packets to be sent by interfaces and the interval at which packets are sent.

l Configure split horizon or poison reverse to prevent routing loops.

l After the replay-protect function is enabled, neighbors can communicate after a RIP process is restarted.

l Check the validity of packets and authenticate packets on a network demanding high security.

l Run RIP on a link that does not support broadcast or multicast packets.

Pre-configuration Tasks

Before optimizing a RIP network, complete the following tasks: l Configuring IP addresses for interfaces to ensure that neighboring nodes are reachable at the network layer l

, establish the neighbor relationship successfully

Data Preparation

To optimize a RIP network, you need the following data.

No.

Data

1 Values of timers

2 Number of Update packets that an interface sends each time and interval for sending an Update packet

Maximum number of equal-cost routes

Packet authentication mode and password

IP addresses of RIP neighbors

3.8.2 Configuring RIP Timers

RIP has three timers: Update timer, Age timer and Garbage-collect timer. Changing the values of the three timers affects the RIP convergence speed.

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Context

RIP has three timers: Update timer, Age timer and Garbage-collect timer. Changing the values of the three timers affects the RIP convergence speed. For details on timers, see corresponding description in the chapter "RIP" in the Huawei AR150&200 Series Enterprise Routers Feature

Description - IP Routing.

Do as follows on the RIP router:

Procedure

Step 1 Run:

system-view

The system view is displayed.

Step 2 Run:

rip [ process-id ]

The RIP process is enabled and the RIP view is displayed.

Step 3 Run:

timers rip update age garbage-collect

RIP timers are configured.

NOTE

l RIP timers take effect immediately after being changed.

l Route flapping occurs if the values of the times are set improperly. The relationship between the values is as follows: update must be smaller than age and update must be smaller than garbage-collect. For example, if the update time is longer than the aging time, and a RIP route changes within the update time, the router cannot inform its neighbors of the change on time.

l You must configure RIP timers based on the network performance and uniformly on all the routers running RIP. This avoids unnecessary network traffic or route flapping.

By default, the Update timer is 30s; the Age timer is 180s; the Garbage-collect timer is four times the Update timer, namely, 120s.

In practice, the Garbage-collect timer is not fixed. If the Update timer is set to 30s, the Garbagecollect timer may range from 90s to 120s.

Before permanently deleting an unreachable route from the routing table, RIP advertises this route (with the metric being set to 16) by periodically sending Update packets four times.

Subsequently, all the neighbors know that this route is unreachable. Because a route may not always become unreachable at the beginning of an Update period, the Garbage-collect timer is actually three or four times the Update timer.

----End

3.8.3 Setting the Interval for Sending Packets and the Maximum

Number of the Sent Packets

By setting the interval for sending RIP Update packets and the maximum number of Update packets to be sent each time, you can effectively control the memory used by a Router to process

RIP Update packets.

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3 RIP Configuration

Context

Do as follows on the RIP router:

Procedure

Step 1 Run:

system-view

The system view is displayed.

Step 2 Run:

interface interface-type interface-number

The interface view is displayed.

Step 3 Run:

rip pkt-transmit { interval interval | number pkt-count }

The interval for sending Update packets and the maximum number of packets sent each time are set on the interface.

----End

3.8.4 Configuring Split Horizon and Poison Reverse

You can configure split horizon and poison reverse to prevent routing loops.

Context

If both split horizon and poison reverse are configured, only poison reverse takes effect.

On Non-Broadcast Multi-Access (NBMA) networks such as frame relay (FR) and X.25

networks, split horizon is disabled by default.

Do as follows on the RIP router:

Procedure

Step 1 Run:

system-view

The system view is displayed.

Step 2 Run:

interface interface-type interface-number

The interface view is displayed.

Step 3 Run the following command as required: l Run:

rip split-horizon

Split horizon is enabled.

l Run:

rip poison-reverse

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Poison reverse is enabled.

----End

3.8.5 Enabling replay-protect Function

By enabling the replay-protect function, you can obtain the Identification field in the last RIP packet sent by a RIP interface before it goes Down. This prevents RIP routing information on both ends from being unsynchronized or lost.

Context

If the Identification field in the last RIP packet sent before a RIP interface goes Down is X, after the interface goes Up, the Identification field in the subsequent RIP packet sent by this interface becomes 0. If the remote end does not receive the RIP packet with the Identification field being

0, subsequent RIP packets will be discarded until the remote end receives the RIP packet with the Identification field being X+1. This leads to the unsynchronization and loss of RIP routing information of both ends.

To solve this problem, you need to enable the replay-protect function so that RIP can obtain the

Identification field in the last RIP packet sent before the RIP interface goes Down and increase the Identification field in the subsequent RIP packet by one.

Do as follows on the RIP router:

Procedure

Step 1 Run:

system-view

The system view is displayed.

Step 2 Run:

interface interface-type interface-number

The interface view is displayed.

Step 3 Run:

rip authentication-mode md5 nonstandard password-key key-id

RIPv2 is configured to use MD5 authentication, and authentication packets use the nonstandard packet format.

NOTE

Before running the rip replay-protect command, run the rip authentication-mode md5 nonstandard command in the RIP interface view to configure MD5 authentication packets to use the nonstandard packet format (private standard).

Step 4 Run:

rip replay-protect

The replay-protect function is enabled.

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NOTE

l For details of the Identification field in an IP packet, see Feature Description - IP Services.

l If you run the rip replay-protect command in the same view multiple times, only the last configuration takes effect.

----End

3.8.6 Configuring RIP to Check the Validity of Update Packets

The check on RIP Update packets includes the check on zero fields in RIPv1 packets and the check on source addresses of RIP Update packets. The two types of check have different functions and applications.

Context

Do as follows on the RIP router:

Procedure

l Configuring the Zero Field Check for RIPv1 Packets

Run:

system-view

The system view is displayed.

Run:

rip [ process-id ]

The RIP process is enabled and the RIP view is displayed.

Run:

checkzero

The zero field check is configured for RIPv1 packets.

Certain fields in a RIPv1 packet must be 0s, and these fields are called zero fields.

RIPv1 checks the zero fields on receiving a packet. If the value of any zero field in a

RIPv1 packet is not 0, this packet is not processed.

As a RIPv2 packet does not contain any zero field, configuring the zero field check is invalid in RIPv2.

l Configuring the Source Address Check for RIP Update Packets

Run:

system-view

The system view is displayed.

Run:

rip [ process-id ]

The RIP process is enabled and the RIP view is displayed.

Run:

verify-source

The source address check is configured for RIP Update packets.

When receiving a packet, RIP checks the source address of the packet. If the packet fails in the check, it is not processed.

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By default, the source address check is enabled.

----End

3.8.7 Configuring RIP Neighbors

Generally, RIP sends packets by using broadcast or multicast addresses. To run RIP on the links that do not support the forwarding of broadcast or multicast packets, you need to specify RIP neighbors.

Context

Generally, RIP sends packets by using broadcast or multicast addresses. If RIP needs to run on the links that do not support the forwarding of broadcast or multicast packets, you need to configure the devices at both ends of the link as each other's neighbor.

Do as follows on the RIP router:

Procedure

Step 1 Run:

system-view

The system view is displayed.

Step 2 Run:

rip [ process-id ]

The RIP process is enabled and the RIP view is displayed.

Step 3 Run:

peer ip-address

The RIP neighbor is configured.

----End

3.8.8 Checking the Configuration

After the function of adjusting and optimizing the RIP network performance is successfully configured, you can view the current running status, routing information, neighbor information, and interface information of RIP.

Prerequisites

The configurations of optimizing a RIP network are complete.

Procedure

l Run the display rip [ process-id | vpn-instance vpn-instance-name ] command to check the running status and configuration of RIP.

l Run the display rip process-id database [ verbose ] command to check all activated RIP routes in the database.

l Run the display rip process-id interface [ interface-type interface-number ] [ verbose ] command to check information about the RIP interface.

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Configuration Guide - IP Routing 3 RIP Configuration l Run the display rip process-id neighbor [ verbose ] command to check information about

RIP neighbors.

l Run the display rip process-id route command to check all the RIP routes that are learned from other routers.

----End

3.9 Configuring RIP GR

This section describes how to configure RIP GR to avoid incorrect route calculation and packet loss after a RIP router restarts.

3.9.1 Establishing the Configuration Task

In practice, you can configure RIP GR on the device with two main control boards to prevent service forwarding from being affected by the fault on one main control board.

Applicable Environment

To avoid traffic interruption and route flapping caused by master/slave switchover, you can enable RIP graceful restart (GR). GR is a technology used to ensure normal traffic forwarding and non-stop forwarding of key services during the restart of routing protocols.

After a RIP process is restarted through GR, the Restarter and the Helper re-establish the neighbor relationship and update the routing table and forwarding table. This ensures non-stop traffic forwarding and stabilizes the network topology. During RIP GR, except the neighbor of the device where master/slave switchover occurs, other routers do not detect the route change.

NOTE

In practice, you can configure RIP GR on the device with two main control boards to prevent service forwarding from being affected by the fault on one main control board.

The AR150/200 can function as only the Helper router, but cannot function as the Restarter router.

Pre-configuration Tasks

Before configuring RIP GR, complete the following tasks: l Configuring IP addresses for interfaces to ensure that neighboring nodes are reachable at the network layer l

Configuring basic RIP functions

Data Preparation

To configure RIP GR, you need the following data

No.

Data

1 RIP process ID

2 Parameters for establishing a GR session

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3.9.2 Enabling RIP GR

To avoid traffic interruption and route flapping caused by master/slave switchover, you can enable RIP GR.

Context

Do as follows on the router to be enabled with GR:

Procedure

Step 1 Run:

system-view

The system view is displayed.

Step 2 Run:

rip [ process-id ]

The RIP view is displayed.

Step 3 Run:

graceful-restart [ period period | wait-time time | planned-only time ]

RIP GR is enabled.

When most routers on a network do not support RIP GR, setting wait-time time to a greater value is recommended. This ensures that the Restarter has enough time to learn correct routes.

----End

Follow-up Procedure

If the Restarter finishes GR within the GR period specified by period period, the Restarter automatically exits from GR. Otherwise, the Restarter is forced to exit from GR.

3.9.3 Checking the Configuration

After RIP GR is configured, you can check the RIP GR status.

Prerequisites

The configurations of RIP GR are complete.

Procedure

l Run the display rip process-id graceful-restart [ verbose ] command to check the status of RIP GR.

----End

3.10 Configuring BFD for RIP

On a network that runs high-rate data services, BFD for RIP can be configured to quickly detect and respond to network faults.

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Applicable Environment

Generally, RIP uses timers to receive and send Update messages to maintain neighbor relationships. If a RIP device does not receive an Update message from a neighbor after the Age timer expires, the RIP device will announce that this neighbor goes Down. The default value of the Age timer is 180s. If a link fault occurs, RIP can detect this fault after 180s. If high-rate data services are deployed on a network, a great deal of data will be lost during the aging time.

BFD provides millisecond-level fault detection. It can rapidly detect faults in protected links or nodes and report them to RIP. This speeds up RIP processes's response to network topology changes and achieves rapid RIP route convergence.

In BFD for RIP, BFD session establishment is triggered by RIP. When establishing a neighbor relationship, RIP will send detection parameters of the neighbor to BFD. Then, a BFD session will be established based on these detection parameters. If a link fault occurs, the local RIP process will receive a neighbor unreachable message within seconds. Then, the local RIP device will delete routing entries in which the neighbor relationship is Down and use the backup path to transmit messages.

Either of the following methods can be used to configure BFD for RIP: l

Enable BFD in a RIP process

: This method is recommended when BFD for RIP needs to be enabled on most RIP interfaces.

Enable BFD on RIP interfaces

: This method is recommended when BFD for RIP needs to be enabled on a small number of RIP interfaces.

NOTE

Pre-configuration Tasks

Before configuring BFD for RIP, complete the following tasks: l Assigning an IP address to each interface to ensure reachability between neighboring nodes at the network layer l

Data Preparation

To complete the configuration, you need the following data.

No.

Data

ID of a RIP process to be enabled with BFD

Type and number of an interface to be enabled with BFD

(Optional) BFD session parameter values

NOTE

Default BFD session parameter values are recommended.

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Procedure

Issue 02 (2012-03-30) l Enable BFD in a RIP process.

Run:

system-view

The system view is displayed.

Run:

bfd

BFD is enabled globally.

Run:

quit

Return to the system view.

Run:

rip process-id

The RIP view is displayed.

Run:

bfd all-interfaces enable

BFD is enabled in the RIP process to establish a BFD session.

If BFD is enabled globally, RIP will use default BFD parameters to establish BFD sessions on all the interfaces where RIP neighbor relationships are in the Up state.

(Optional) Run:

bfd all-interfaces { min-rx-interval min-receive-value | min-tx-interval

min-transmit-value | detect-multiplier detect-multiplier-value }

The values of BFD parameters used to establish the BFD session are set.

BFD parameter values are determined by the actual network situation and network reliability requirement.

–

If links have a high reliability requirement, reduce the interval at which BFD packets are sent.

– If links have a low reliability requirement, increase the interval at which BFD packets are sent.

Running the bfd all-interfaces command changes BFD session parameters on all RIP interfaces. The default detection multiplier and interval at which BFD packets are sent are recommended.

(Optional) Perform the following operations to prevent an interface in the RIP process from establishing a BFD session:

–

Run the quit command to return to the system view.

–

Run the interface interface-type interface-number command to enter the view of a specified interface.

–

Run the rip bfd block command to prevent the interface from establishing a BFD session.

l Enable BFD on RIP interfaces.

Run:

system-view

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The system view is displayed.

Run:

bfd

BFD is enabled globally.

Run:

quit

Return to the system view.

Run:

interface interface-type interface-number

The view of the specified interface is displayed.

Run:

rip bfd enable

BFD is enabled on the interface to establish a BFD session.

(Optional) Run:

rip bfd { min-rx-interval min-receive-value | min-tx-interval min-

transmit-value | detect-multiplier detect-multiplier-value }

The values of BFD parameters used to establish the BFD session are set.

----End

Checking the Configuration

After enabling BFD for RIP at both ends of a link, run the display rip bfd session { interface

interface-type interface-number | neighbor-id | all } command. You can see that the BFDState field value on the local router is displayed Up.

3.11 Configuring Static BFD for RIP

BFD provides link failure detection featuring light load and high speed. Static BFD for RIP is a mode to implement the BFD function.

Context

Establishing BFD sessions between RIP neighbors can rapidly detect faults on links and speed up response of RIP to network topology changes. Static BFD implements the following functions: l One-arm BFD: If some devices on a network support BFD but some do not, configure onearm BFD to implement fault detection.

Two-arm BFD: If all the devices on a network support BFD, configure two-arm BFD to implement fault detection.

Static BFD must be enabled using a command and session parameters are also set using commands.

Pre-configuration Tasks

Before configuring static BFD for RIP, complete the following tasks:

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Configuration Guide - IP Routing l Assigning an IP address to each interface to ensure IP connectivity l

Configuring basic RIP functions

Data Preparation

To complete the configuration, you need the following data:

No.

Data

1 ID of a RIP process

2 Type and number of the interface to be enabled with BFD

3 RIP Configuration

Procedure

Step 1 Enable BFD globally.

Run:

system-view

The system view is displayed.

Run:

bfd

BFD is enabled globally.

Run:

quit

Return to the system view.

NOTE

To configure one-arm BFD, go to Step 2. To configure two-arm BFD, go to Step 3.

Step 2 Configure one-arm BFD.

Run:

bfd cfg-name bind peer-ip peer-ip interface interface-type interface-number

one-arm-echo

BFD is enabled between the specified interface and peer router.

If a peer IP address and a local interface are specified, BFD detects only a single-hop link, that is, a route with the interface specified in the bfd command as the outbound interface and with the peer IP address specified in the peer-ip command as the next-hop address.

Run:

discriminator local discr-value

The local discriminator is set.

(Optional) Run:

min-echo-rx-interval interval

The minimum interval at which BFD packets are received is configured.

Run:

commit

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3 RIP Configuration

The configuration is committed.

Run:

quit

Return to the system view.

Step 3 Configure two-arm BFD.

Run:

bfd cfg-name bind peer-ip ip-address [ interface interface-type interface-

number ]

BFD binding is created.

Set discriminators.

l Run:

discriminator local discr-value

The local discriminator is set.

l Run:

discriminator remote discr-value

The remote discriminator is set.

The local discriminator must be the remote discriminator of the device on the other end; otherwise, a BFD session cannot be established. The local and remote discriminators cannot be modified after being configured.

NOTE

local discr-value set on the local device is the same as that of remote discr-value set on the remote device.remote discr-value set on the local device is the same as that of local discr-value set on the remote device.

Run:

commit

The configuration is committed.

Run:

quit

Return to the system view.

Step 4 Enable static BFD on an interface.

Run:

interface interface-type interface-number

The view of the specified interface is displayed.

Run:

rip bfd static

Static BFD is enabled on the interface.

Run:

quit

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Return to the system view.

----End

Checking the Configuration

After configuring static BFD for RIP, run the display rip process-id command to check BFD for RIP configurations on the specified interface. interface [ interface-type interface-number ]

verbose

<Huawei> display rip 1 interface ethernet1/0/0 verbose

Ethernet1/0/0 (81.1.1.1)

State : UP MTU : 500

Metricin : 0

Metricout : 1

Input : Enabled Output : Enabled

Protocol : RIPv1 Compatible (Non-Standard)

Send : RIPv1 Packets

Receive : RIPv1 Packets, RIPv2 Multicast and Broadcast Packets

Poison-reverse : Disabled

Split-Horizon : Enabled

Authentication type : None

Replay Protection : Disabled

BFD : Enabled (Static)

Summary Address (es):

1.1.0.0/16

3.12 Configuring the Network Management Function in RIP

By binding RIP to MIBs, you can view and configure RIP through the NMS.

3.12.1 Establishing the Configuration Task

Before binding RIP to MIBs, familiarize yourself with the applicable environment, complete the pre-configuration tasks, and obtain the data required for the configuration. This will help you complete the configuration task quickly and accurately.

Applicable Environment

After performing configuration procedures in this section, you can bind RIP to a MIB.

Pre-configuration Tasks

Before configuring the network management function in RIP, complete the following tasks: l Configuring IP addresses for interfaces to ensure that neighboring nodes are reachable at the network layer l

Data Preparation

None.

3.12.2 Binding RIP to MIBs

Before binding RIP to MIBs, you need to specify the RIP process ID.

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Context

Do as follows on the RIP router:

Procedure

Step 1 Run:

system-view

The system view is displayed.

Step 2 Run:

rip mib-binding process-id

RIP is bound to MIBs.

This command is used to bind a RIP process ID to MIBs and specify the ID of the RIP process that accepts Simple Network Management Protocol (SNMP) requests.

----End

3.12.3 Checking the Configuration

After RIP and MIBs are successfully bound, you can view binding information in the current

RIP configuration.

Prerequisites

The configurations of the network management function in RIP are complete.

Procedure

Step 1 Run the display current-configuration command to check the parameters that take effect on the router.

----End

3.13 Maintaining RIP

This section describes how to reset RIP connections and clear RIP information.

3.13.1 Resetting RIP

Restarting RIP can reset RIP.

Context

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CAUTION

The RIP neighbor relationship is deleted after you reset RIP connections with the reset rip command. Exercise caution when running this command.

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Configuration Guide - IP Routing 3 RIP Configuration

To reset RIP connections, run the following reset commands in the user view.

Procedure

l Run the reset rip process-id configuration command in the user view to reset the parameters of the specified RIP process. When the RIP process starts, all parameters use default values.

----End

3.13.2 Clearing RIP

This section describes how to clear statistics about RIP counters.

Context

CAUTION

RIP information cannot be restored after it is cleared. Exercise caution when running the commands.

To clear RIP information, run the following reset command in the user view.

Procedure

l Run the reset rip process-id statistics [ interface { all | interface-type interface-number

[ neighbor neighbor-ip-address ] } ] command in the user view to clear statistics about the counter that is maintained by a specified RIP process.

----End

3.14 Configuration Examples

In actual networking, RIP versions and whether to import external routes will affect which routes can be learned.

3.14.1 Example for Configuring RIP Version

Before using RIP, you need to configure basic RIP functions and specify a RIP version. You can run commands to view the configuration results.

Networking Requirements

RIPng is a distance-vector routing protocol, which measures the distance to the destination host by the hop count.

Figure 3-1

, it is required that RIP be enabled on all interfaces of Router A, Router

B, Router C, and Router D and the routers interconnect with each other by using RIPv2.

NOTE

AR150/200 is RouterA, RouterC, or RouterD.

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Configuration Guide - IP Routing

Figure 3-1 Networking diagram for configuring the RIP version number

RouterC

3 RIP Configuration

Eth2/0/0

172.16.1.2/24

Eth1/0/0

192.168.1.1/24

RouterA

RouterB

Eth1/0/0

192.168.1.2/24

Eth2/0/0

172.16.1.1/24

Eth1/0/1

10.1.1.1/24

Eth1/0/0

10.1.1.2/24

RouterD

Configuration Roadmap

The configuration roadmap is as follows:

Configure an IP address for each interface to ensure that neighboring nodes are reachable at the network layer.

Enable RIP on each router and configure basic RIP functions.

Configure RIPv2 on each router and check information about subnet masks.

Data Preparation

To complete the configuration, you need the following data: l Network segment (192.168.1.0) to be enabled with RIP on Router A l Network segments (192.168.1.0, 172.16.0.0, and 10.0.0.0) to be enabled with RIP on Router

B l Network segment (172.16.0.0) to be enabled with RIP on Router C l Network segment (10.0.0.0) to be enabled with RIP on Router D l RIPv2 on Router A, Router B, Router C, and Router D

Procedure

Step 1 Configure an IP address for each interface.

The configuration details are not described here.

Step 2 Configure basic RIP functions.

# Configure Router A.

[RouterA] rip

[RouterA-rip-1] network 192.168.1.0

[RouterA-rip-1] quit

# Configure Router B.

[RouterB] rip

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3 RIP Configuration

[RouterB-rip-1] network 192.168.1.0

[RouterB-rip-1] network 172.16.0.0

[RouterB-rip-1] network 10.0.0.0

[RouterB-rip-1] quit

# Configure Router C.

[RouterC] rip

[RouterC-rip-1] network 172.16.0.0

[RouterC-rip-1] quit

# Configure Router D.

[RouterD] rip

[RouterD-rip-1] network 10.0.0.0

[RouterD-rip-1] quit

# Check the RIP routing table of Router A.

[RouterA] display rip 1 route

Route Flags: R - RIP, T - TRIP

P - Permanent, A - Aging, S - Suppressed, G - Garbage-collect

-------------------------------------------------------------------------

Peer 192.168.1.2 on Ethernet1/0/0

Destination/Mask Nexthop Cost Tag Flags Sec

10.0.0.0/8 192.168.1.2 1 0 RA 14

172.16.0.0/16 192.168.1.2 1 0 RA 14

The preceding display shows that the routes advertised by RIPv1 carry natural masks.

Step 3 Configure the RIP version number.

# Configure RIPv2 on Router A.

[RouterA] rip

[RouterA-rip-1] version 2

[RouterA-rip-1] quit

# Configure RIPv2 on Router B.

[RouterB] rip

[RouterB-rip-1] version 2

[RouterB-rip-1] quit

# Configure RIPv2 on Router C.

[RouterC] rip

[RouterC-rip-1] version 2

[RouterC-rip-1] quit

# Configure RIPv2 on Router D.

[RouterD] rip

[RouterD-rip-1] version 2

[RouterD-rip-1] quit

Step 4 Verify the configuration.

# Check the RIP routing table of Router A.

[RouterA] display rip 1 route

Route Flags: R - RIP

A - Aging, S - Suppressed, G - Garbage-collect

-------------------------------------------------------------------------

Peer 192.168.1.2 on Ethernet1/0/0

Destination/Mask Nexthop Cost Tag Flags Sec

10.1.1.0/24 192.168.1.2 1 0 RA 32

172.16.1.0/24 192.168.1.2 1 0 RA 32

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Configuration Guide - IP Routing 3 RIP Configuration

The preceding display shows that the routes advertised by RIPv2 carry subnet masks.

----End

Configuration Files

Configuration file of Router A

sysname RouterA

# interface Ethernet1/0/0

ip address 192.168.1.1 255.255.255.0

# rip 1

version 2

network 192.168.1.0

# return l Configuration file of Router B

sysname RouterB

# interface Ethernet1/0/0

ip address 192.168.1.2 255.255.255.0

# interface Ethernet1/0/1

ip address 10.1.1.1 255.255.255.0

# interface Ethernet2/0/0

ip address 172.16.1.1 255.255.255.0

# rip 1

version 2

network 192.168.1.0

network 172.16.0.0

network 10.0.0.0

# return l

Configuration file of Router C

sysname RouterC

# interface Ethernet2/0/0

ip address 172.16.1.2 255.255.255.0

# rip 1

version 2

network 172.16.0.0

# return l Configuration file of Router D

sysname RouterD

# interface Ethernet1/0/0

ip address 10.1.1.2 255.255.255.0

# rip 1

version 2

network 10.0.0.0

# return

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Configuration Guide - IP Routing 4 RIPng Configuration

RIPng Configuration

About This Chapter

RIPng is an extension of RIP for support of IPv6.

4.1 RIPng Overview

4.2 RIPng Features Supported by the AR150/200

The RIPng features supported by the AR150/200 include split horizon and poison reverse.

4.3 Configuring Basic RIPng Functions

To implement RIPng features, you need to configure basic RIPng functions, including creating

RIPng processes and enabling RIPng on interfaces.

4.4 Configuring RIPng Route Attributes

By setting RIPng route attributes, you can change RIPng routing policies.

4.5 Controlling the Advertising of RIPng Routing Information

To meet the requirements of complex networks, it is required to accurately control the advertising of RIPng routing information.

4.6 Controlling the Receiving of RIPng Routing Information

To meet the requirements of complex networks, it is required to accurately control the receiving of RIPng routing information.

4.7 Optimizing a RIPng Network

You can adjust and optimize the RIPng network performance by configuring RIPng timers, split horizon, poison reverse, and zero field check.

4.8 Maintaining RIPng

This section describes how to clear statistics of a specified RIPng process.

4.9 Configuration Examples

In actual networking, different RIPng features have different applications.

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4.1 RIPng Overview

RIPng is a distance-vector routing protocol, which measures the distance to the destination host by the hop count.

The Routing Information Protocol Next Generation (RIPng) protocol is an extension of RIPv2 that is applied to IPv4 networks. Most RIP-related concepts are applicable to RIPng.

Extension of RIP

For IPv6 applications, RIPng extends RIP as follows: l

UDP port number: In RIPng, UDP port number 521 is used to send and receive routing information.

Multicast group address: In RIPng, FF02::9 is used as the multicast group address of RIPng routers.

Prefix length: In RIPng, the prefix length of a destination address is 128 bits (the mask length).

Next-hop address: In RIPng, a next-hop address is a 128-bit IPv6 address.

l Source address: In RIPng, link-local address is used as the source address to send RIPng

Update packets.

Operation Principle of RIPng

RIPng is a distance-vector routing protocol. It exchanges routing information by using User

Datagram Protocol (UDP) packets through the port 521.

RIPng employs the hop count to measure the distance to the destination. The distance is called the routing metric. In RIPng, the hop count from the router to its directly connected network is

0, and the hop count from the router to a network, which can be reached through another router, is 1. The hop count that is equal to or exceeds 16 is defined as infinity, indicating that the destination network or host is unreachable.

By default, RIPng sends an Update packet every 30 seconds. If no Update packet is received from a neighbor in 180 seconds, RIPng marks all the routes learned from the neighbor as unreachable. If no Update packet is received from a neighbor in 300 seconds, RIPng deletes the routes of the neighbor from the routing table.

To prevent routing loops, RIPng supports split horizon and poison reverse. In addition, RIPng can import routes from other routing protocols.

Each router running RIPng manages a routing database, which contains routing entries to all accessible destinations on a network. These routing entries contain the following information: l Destination address: indicates the IPv6 address of a host or network.

l Next-hop address: indicates the address of the next router to the destination.

l Interface: indicates the interface through which an IP packet is forwarded.

l Cost: indicates the hop count to the destination. The value is an integer that ranges from 0 to 16. If the value is 16, it indicates that the destination host or network is unreachable.

l Timer: indicates the time since a routing entry is last updated. The timer is reset to 0 when a routing entry is updated.

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Configuration Guide - IP Routing 4 RIPng Configuration l Route tag: indicates a label that differentiates routes of interior routing protocols and those of exterior routing protocols.

4.2 RIPng Features Supported by the AR150/200

The RIPng features supported by the AR150/200 include split horizon and poison reverse.

In the AR150/200, you can modify the routing policy of RIPng by configuring RIPng route attributes. You can also control the advertising and receiving of RIPng routing information to meet the requirements of a complex network. On certain networks, you can configure RIPng features to optimize the RIPng network performance.

NOTE

The RIPng function is used with a license. To use the RIPng function, apply for and purchase the following license from the Huawei local office: l AR150&200 Value-Added Data Package

4.3 Configuring Basic RIPng Functions

To implement RIPng features, you need to configure basic RIPng functions, including creating

RIPng processes and enabling RIPng on interfaces.

4.3.1 Establishing the Configuration Task

To make a Router learn the routes to the network segment of an interface, ensure that the link status of the interface is Up.

Applicable Environment

The configuration of basic RIPng functions involves the configuration of basic RIPng features.

After the configuration, the RIPng features are available.

During the RIPng configuration, you must enable RIPng in the system view first. If you run

RIPng-related commands in the interface view, these commands take effect only after RIPng is enabled in the system view.

Pre-configuration Tasks

Before configuring basic RIPng functions, complete the following tasks: l Enabling IPv6 on the router l Configuring IPv6 addresses for interfaces to ensure that neighboring nodes are reachable at the network layer

Data Preparation

To configure basic RIPng functions, you need the following data.

No.

Data

1 RIPng process ID

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No.

Data

2 Interface to be enabled with RIPng

4.3.2 Enabling RIPng and Entering the RIPng View

Creating RIPng processes is the prerequisite to performing RIPng configurations. When creating

RIPng processes, you can also enter the RIPng view to perform configurations.

Context

Do as follows on the router to be enabled with RIPng:

Procedure

Step 1 Run:

system-view

The system view is displayed.

Step 2 Run:

ripng [ process-id ]

The RIPng process is enabled and the RIPng view is displayed.

When only one RIPng process runs, process-id does not need to be specified. That is, process-

id defaults to 1.

After the RIPng process is cancelled, the ripng process-id enable command needs to be reconfigured on an interface.

----End

4.3.3 Enabling RIPng in the Interface View

After an interface is associated with a RIPng process, routing information on this interface can be exchanged through RIPng.

Context

Do as follows on the router to be enabled with RIPng:

Procedure

Step 1 Run:

system-view

The system view is displayed.

Step 2 Run:

interface interface-type interface-number

The interface view is displayed.

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The interface is at the network side of the router. That is, the router is connected to other devices through this interface. To enable the router to learn routes to the network segment where the interface resides, ensure that the link status of the interface is Up.

Step 3 Run:

ripng process-id enable

RIPng is enabled on the specified interface.

NOTE

In the interface view, this command cannot be executed if IPv6 is not enabled.

This command is inapplicable to ATM interfaces.

If the router connects to other devices through multiple interfaces, repeatedly perform Step 2 and Step 3.

----End

4.3.4 Checking the Configuration

After basic RIPng functions are successfully configured, you can view the configuration and routing information of RIPng.

Prerequisites

The configurations of basic RIPng functions are complete.

Procedure

l Run the display ripng [ process-id ] command to check the configuration of the RIPng process.

l Run the display ripng process-id route command to check all the RIPng routes that are learned from other routers.

l Run the display default-parameter ripng command to check the default RIPng configuration.

Run the display ripng process-id statistics interface { all | interface-type interface-

number [ verbose | neighbor neighbor-ipv6-address ] } command to check statistics about

RIPng interfaces.

----End

4.4 Configuring RIPng Route Attributes

By setting RIPng route attributes, you can change RIPng routing policies.

4.4.1 Establishing the Configuration Task

RIPng route attributes include the RIPng preference and interface metric.

Applicable Environment

To meet the requirements of a complex network, you can change RIPng routing policies by configuring RIPng route attributes. After performing configuration procedures in this section, you can:

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Configuration Guide - IP Routing 4 RIPng Configuration l Affect route selection by changing the additional metric of a RIPng interface.

l Change the matching order of routing protocols by configuring the RIPng preference when multiple routing protocols discover routes to the same destination.

l Implement load balancing among multiple equal-cost routes.

Pre-configuration Tasks

Before configuring RIPng route attributes, complete the following tasks: l Configuring IPv6 addresses for interfaces to ensure that neighboring nodes are reachable at the network layer l

3.3 Configuring Basic RIP Functions

Data Preparation

To configure RIPng route attributes, you need the following data.

No.

Data

1 Additional metric of the interface

RIPng preference

Maximum number of equal-cost routes

4.4.2 Configuring the RIPng Preference

When there are routes discovered by multiple routing protocols on the same router, you can make the router prefer RIPng routes by setting the RIPng preference.

Context

Each routing protocol has its preference, according to which a routing policy selects the optimal route. The RIPng preference can be set manually. The greater the value is, the lower the preference is.

Do as follows on the RIPng router:

Procedure

Step 1 Run:

system-view

The system view is displayed.

Step 2 Run:

ripng [ process-id ]

The RIPng process is enabled and the RIPng view is displayed.

Step 3 Run:

preference { preference | route-policy route-policy-name } *

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The RIPng preference is set.

----End

4.4.3 Configuring Additional Metrics of an Interface

You can set additional metrics for received and sent RIPng routes by using different commands.

Context

The additional route metric is the metric (hop count) to be added to the original metric of a RIPng route.

l The ripng metricin command is used to configure a device to add an additional metric to a received route before the device adds the route to its routing table, causing the metric of the route in the routing table to change. Running this command affects route selection on the device and other devices.

l The ripng metricout command is used to configure a device to add an additional metric to a route before the device advertises the route, keeping the metric of the route in the routing table unchanged. Running this command does not affect route selection on the local device but will affect route selection of other devices.

You can specify the value of the metric to be added to the RIPng route that passes the filtering policy by specifying value1 through an IPv6 prefix list. If a RIPng route does not pass the filtering, its metric is increased by 1.

Do as follows on the RIPng router:

Procedure

Step 1 Run:

system-view

The system view is displayed.

Step 2 Run:

interface interface-type interface-number

The interface view is displayed.

Step 3 Run:

ripng metricin value

The metric added to a received route is set.

Step 4 Run:

ripng metricout { value | ipv6-prefix ipv6-prefix-name value1 }

The metric added to a sent route is set.

NOTE

If the router connects to other RIPng routers through multiple interfaces, repeatedly perform Step 2 to Step

4 until metrics of all links are set.

----End

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4.4.4 Configuring the Maximum Number of Equal-Cost Routes

By setting the maximum number of equal-cost RIPng routes, you can change the number of routes for load balancing.

Context

Do as follows on the RIPng router:

Procedure

Step 1 Run:

system-view

The system view is displayed.

Step 2 Run:

ripng [ process-id ]

The RIPng view is displayed.

Step 3 Run:

maximum load-balancing number

The maximum number of equal-cost routes is set.

----End

4.4.5 Checking the Configuration

After RIPng route attributes are successfully set, you can view the configuration and routing information of RIPng.

Prerequisites

The configurations of RIPng route attributes are complete.

Procedure

l Run the display ripng [ process-id ] command to check the running status and configuration of RIPng.

l Run the display ripng process-id database command to check all activated routes in the

RIPng database.

l Run the display ripng process-id route command to check all the RIPng routes that are learned from other routers.

----End

4.5 Controlling the Advertising of RIPng Routing

Information

To meet the requirements of complex networks, it is required to accurately control the advertising of RIPng routing information.

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Configuration Guide - IP Routing 4 RIPng Configuration

4.5.1 Establishing the Configuration Task

RIPng routing information can be advertised through route summarization, default routes, and imported external routes.

Applicable Environment

To meet the requirements of a complex network, you need to control the advertising of RIPng routing information accurately. After performing configuration procedures in this section, you can: l Advertise default routes to neighbors.

l Suppress interfaces from sending RIPng Update packets.

l Import external routes from various routing protocols and filter routes to be advertised.

Pre-configuration Tasks

Before configuring the router to control the advertising of RIPng routing information, complete the following tasks: l Configuring IPv6 addresses for interfaces to ensure that neighboring nodes are reachable at the network layer l

3.3 Configuring Basic RIP Functions

Data Preparation

To control the advertising of RIPng routing information, you need the following data.

No.

Data

1 Metric of the default route to be advertised

2 Protocol name and process ID of the external route to be imported

4.5.2 Configuring RIPng Route Summarization

By configuring a RIPng router to advertise the summarized IPv6 address on an interface, you can save the space used by RIPng routes in the routing table. You can also set parameters to prevent an interface from learning the same summarized route.

Context

This configuration is to configure the RIPng router to advertise the summarized IPv6 prefix rather than specific routes on an interface.

Do as follows on the RIPng router:

Procedure

Step 1 Run:

system-view

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The system view is displayed.

Step 2 Run:

interface interface-type interface-number

The interface view is displayed.

Step 3 Run:

ripng summary-address ipv6-address prefix-length [ avoid-feedback ]

RIPng route summarization is configured.

----End

4.5.3 Configuring RIPng to Advertise the Default Routes

There are two methods of advertising RIPng default routes. You can configure a router to advertise RIPng default routes according to the actual networking. Additionally, you can specify the cost of the default routes to be advertised.

Context

Do as follows on the RIPng router:

Procedure

Step 1 Run:

system-view

The system view is displayed.

Step 2 Run:

interface interface-type interface-number

The interface view is displayed.

Step 3 Run:

ripng default-route { only | originate } [ cost cost ]

RIPng is configured to advertise a default route.

You can configure RIPng to advertise default routes as required: l only: advertises only IPv6 default routes (::/0) and suppresses the advertising of other routes.

l originate: advertises IPv6 default routes (::/0) and does not affect the advertising of other routes.

A RIPng default route is forcibly advertised by using an Update packet through a specified interface, regardless of whether this route exists in the IPv6 routing table.

----End

4.5.4 Configuring the Default Cost for External Routes Imported by

RIPng

If RIPng imports routes from other routing protocols, but no metric is specified, you can set the default metric for imported external routes.

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Configuration Guide - IP Routing 4 RIPng Configuration

Context

Do as follows on the RIPng router:

Procedure

Step 1 Run:

system-view

The system view is displayed.

Step 2 Run:

ripng [ process-id ]

The RIPng view is displayed.

Step 3 Run:

default-cost cost

The default cost is set for the external routes imported by RIPng.

If no metric is specified, this command can be used to set the default cost for the external routes imported by RIPng from other routing protocols.

----End

4.5.5 Configuring RIPng to Import External Routes

Similar to RIP, RIPng can import external routes to enrich routing information.

Context

Do as follows on the RIPng router:

Procedure

Step 1 Run:

system-view

The system view is displayed.

Step 2 Run:

ripng [ process-id ]

The RIPng view is displayed.

Step 3 (Optional) Run:

default-cost cost

The default cost is set for imported external routes.

Step 4 Run:

import-route protocol [ process-id ] [ cost cost | route-policy route-policy-name ]

External routes are imported.

If no cost is specified for imported routes, the default cost is used.

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Step 5 (Optional) Run:

filter-policy ipv6-prefix ipv6-prefix-name export [ protocol [ process-id ] ]

RIPng is configured to filter the imported routing information.

RIPng can filter the imported routes based on an IPv6 prefix list. Only the routes that meet the match conditions are advertised to neighbors. If protocol is not specified in the command, all the routing information to be advertised will be filtered, including the imported routes and local

RIPng routes (directly connected routes).

----End

4.5.6 Checking the Configuration

After the function of controlling the advertising of RIPng routing information is successfully configured, you can view RIPng routing information.

Prerequisites

The configurations of controlling the advertising of RIPng routing information are complete.

Procedure

l Run the display ripng process-id database command to check all activated routes in the

RIPng database.

l Run the display ripng process-id route command to check all the RIPng routes that are learned from other routers.

----End

4.6 Controlling the Receiving of RIPng Routing Information

To meet the requirements of complex networks, it is required to accurately control the receiving of RIPng routing information.

4.6.1 Establishing the Configuration Task

Before controlling the receiving of RIPng routes, familiarize yourself with the applicable environment, complete the pre-configuration tasks, and obtain the data required for the configuration. This will help you complete the configuration task quickly and accurately.

Applicable Environment

To meet the requirements of a complicated networking environment, you need to control the receiving of RIPng routing information accurately. After performing configuration procedures in this section, you can: l Disable an interface from receiving RIPng Update packets.

l Filter the received routing information.

l Import external routes from various routing protocols and filter the imported routes.

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Configuration Guide - IP Routing 4 RIPng Configuration

Pre-configuration Tasks

Before configuring the router to control the receiving of RIPng routing information, complete the following tasks: l Configuring IPv6 addresses for interfaces to ensure that neighboring nodes are reachable at the network layer l

Configuring Basic RIPng Functions

Data Preparation

To control the receiving of RIPng routing information, you need the following data.

No.

Data

1 Name of the IP prefix list used to filter routes

4.6.2 Configuring RIPng to Filter the Received Routes

By configure an IPv6 prefix list to filter received routes, you can configure a router to selectively receive routes.

Context

Do as follows on the RIPng router:

Procedure

Step 1 Run:

system-view

The system view is displayed.

Step 2 Run:

ripng [ process-id ]

The RIPng view is displayed.

Step 3 Run:

filter-policy ipv6-prefix ipv6-prefix-name import

The imported routes are filtered.

You can specify an IPv6 prefix list to filter the imported routes. Only the routes that pass the filtering can be added to the RIPng routing table.

----End

4.6.3 Checking the Configuration

After the function of controlling the receiving of RIPng routing information is successfully configured, you can view RIPng routing information.

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Prerequisites

The configurations of controlling the receiving of RIPng routing information are complete.

Procedure

Run the display ripng process-id database command to check all activated routes in the

RIPng database.

l Run the display ripng process-id route command to check all the RIPng routes that are learned from other routers.

----End

4.7 Optimizing a RIPng Network

You can adjust and optimize the RIPng network performance by configuring RIPng timers, split horizon, poison reverse, and zero field check.

4.7.1 Establishing the Configuration Task

Before adjusting and optimizing the RIPng network performance, familiarize yourself with the applicable environment, complete the pre-configuration tasks, and obtain the data required for the configuration. This will help you complete the configuration task quickly and accurately.

Applicable Environment

On certain networks, you need to configure RIPng features and optimize the performance of a

RIPng network. After performing configuration procedures in this section, you can: l Change the convergence speed of the RIPng network by adjusting RIPng timers.

l Configure split horizon and poison reverse to prevent routing loops.

Pre-configuration Tasks

Before optimizing a RIPng network, complete the following tasks: l

Configuring IPv6 addresses for interfaces to ensure that neighboring nodes are reachable at the network layer l

Configuring Basic RIPng Functions

Data Preparation

To optimize a RIPng network, you need the following data.

No.

Data

1 Values of timers

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4 RIPng Configuration

4.7.2 Configuring RIPng Timers

RIPng has three timers: Update timer, Age timer and Garbage-collect timer. If the three RIPng timers are configured improperly, routes become unstable.

Context

NOTE

Route flapping occurs if the values of the four RIPng timers are set improperly. The relationship between the values is as follows: update < age, update < garbage-collect. For example, if the update time is longer than the aging time, and a RIPng route changes within the update time, the router cannot inform its neighbors of the change on time.

By default, the Update timer is 30s; the Age timer is 180s; the Garbage-collect timer is 120s.

Do as follows on the RIPng router:

Procedure

Step 1 Run:

system-view

The system view is displayed.

Step 2 Run:

ripng [ process-id ]

The RIPng view is displayed.

Step 3 Run:

timers ripng update age garbage-collect

RIPng timers are configured.

----End

4.7.3 Setting the Interval for Sending Update Packets and the

Maximum Number of Packets Sent Each Time

By setting the interval for sending packets and the maximum number of packets to be sent each time, you can optimize the RIPng performance.

Context

Do as follows on the RIPng router:

Procedure

Step 1 Run:

system-view

The system view is displayed.

Step 2 Run:

interface interface-type interface-number

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The interface view is displayed.

Step 3 Run:

ripng pkt-transmit { interval interval | number pkt-count }

The interval for sending RIPng Update packets and the maximum number of packets sent each time are set on the specified interface.

----End

4.7.4 Configuring Split Horizon and Poison Reverse

You can configure split horizon and poison reverse to prevent routing loops.

Context

Split horizon is a method of preventing routing loops by preventing the router from advertising a route back onto the interface from which the route is learned. On NBMA networks such as FR networks and X.25 networks, split horizon is disabled by default.

Poison reverse is another method of preventing routing loops by enabling the router to advertise a route as unreachable back through the interface from which the route is learned.

If both split horizon and poison reverse are configured, only poison reverse takes effect.

Do as follows on the RIPng router:

Procedure

Step 1 Run:

system-view

The system view is displayed.

Step 2 Run:

interface interface-type vlan-id

The interface view is displayed.

Step 3 Run the following command as required: l Run:

ripng split-horizon

Split horizon is enabled.

l Run:

ripng poison-reverse

Poison reverse is enabled.

----End

4.7.5 Enabling the Zero Field Check for RIPng Packets

In a RIPng packet, there are certain fields whose values must be 0. These fields are called zero fields. If the values of these zero fields in some RIPng packets are not 0s, these RIPng packets are ignored.

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Configuration Guide - IP Routing

Context

Do as follows on the RIPng router:

4 RIPng Configuration

Procedure

Step 1 Run:

system-view

The system view is displayed.

Step 2 Run:

ripng [ process-id ]

The RIPng view is displayed.

Step 3 Run:

checkzero

The zero field check is configured for RIPng packets.

----End

4.7.6 Checking the Configuration

After the function of adjusting and optimizing the RIPng network performance is successfully configured, you can view routing information, neighbor information, and interface information of RIPng.

Prerequisites

The configurations of adjusting and optimizing the RIPng network performance are complete.

Procedure

Run the display ripng [ process-id ] command to check the configuration of the RIPng process.

l Run the display ripng process-id database [ verbose ] command to check all activated routes in the RIPng database.

l Run the display ripng process-id interface [ interface-type interface-number ]

[ verbose ] command to check information about the RIPng interface.

l Run the display ripng process-id neighbor [ verbose ] command to check information about RIPng neighbors.

l Run the display ripng process-id route command to check all the RIPng routes that are learned from other routers.

----End

4.8 Maintaining RIPng

This section describes how to clear statistics of a specified RIPng process.

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4.8.1 Clearing RIPng

This section describes how to clear statistics about RIPng counters.

Context

4 RIPng Configuration

CAUTION

RIPng information cannot be restored after it is cleared. Exercise caution when running the commands.

To clear RIPng information, run the following reset command in the user view.

Procedure

l Run the reset ripng process-id statistics [ interface { all | interface-type interface-

number [ neighbor neighbor-ip-address ] } ] command in the user view to clear statistics about the counter that is maintained by a specified RIPng process.

----End

4.9 Configuration Examples

In actual networking, different RIPng features have different applications.

4.9.1 Example for Configuring Basic RIPng Functions

Before using RIP, you need to configure basic RIP functions.

Networking requirements

, the prefix length of all the IPv6 addresses is 64 bits and the neighboring

Figure 4-1

routers are assigned IPv6 link-local addresses. All the routers must learn IPv6 routing information using RIPng.

NOTE

Only RouterC can use the AR150/200.

Figure 4-1 Networking diagram of configuring basic RIPng functions

Eth2/0/0

1::1/64

Eth1/0/0

RouterA

Eth2/0/0

Eth1/0/0

RouterB RouterC

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4 RIPng Configuration

Configuration Roadmap

The configuration roadmap is as follows:

Configure IPv6 addresses for interfaces.

Enable RIPng on each router so that the routers can communicate with each other.

Data Preparation

To complete the configuration, you need the following data: l RIPng1 enabled on each router

Procedure

Step 1 Configure an IPv6 address for each interface. The configuration details are not mentioned here.

Step 2 Configure basic RIPng functions.

# Configure RouterA.

[RouterA] ripng 1

[RouterA-ripng-1] quit

[RouterA] interface ethernet 2/0/0

[RouterA-Ethernet2/0/0] ripng 1 enable

[RouterA-Ethernet2/0/0] quit

[RouterA] interface ethernet 1/0/0

[RouterA-Ethernet1/0/0] ripng 1 enable

[RouterA-Ethernet1/0/0] quit

# Configure RouterB.

[RouterB] ripng 1

[RouterB-ripng-1] quit

[RouterB] interface ethernet 1/0/0

[RouterB-Ethernet1/0/0] ripng 1 enable

[RouterB-Ethernet1/0/0] quit

[RouterB] interface ethernet 2/0/0

[RouterB-Ethernet2/0/0] ripng 1 enable

[RouterB-Ethernet2/0/0] quit

# Configure RouterC.

[RouterC] ripng 1

[RouterC-ripng-1] quit

[RouterC] interface ethernet 1/0/0

[RouterC-Ethernet1/0/0] ripng 1 enable

[RouterC-Ethernet1/0/0] quit

# View the RIPng routing table of RouterB.

[RouterB] display ripng 1 route

Route Flags: A - Aging, G - Garbage-collect

----------------------------------------------------------------

Peer FE80::A19:A6FF:FECE:7D4C on Ethernet1/0/0

Dest 1::/64,

via FE80::A19:A6FF:FECE:7D4C, cost 1, tag 0, A, 25 Sec

# View the RIPng routing table of RouterC.

[RouterC] display ripng 1 route

Route Flags: A - Aging, G - Garbage-collect

----------------------------------------------------------------

Peer FE80::2E0:FCFF:FE01:9 on Ethernet1/0/0

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Dest 1::/64,

via FE80::2E0:FCFF:FE01:9, cost 2, tag 0, A, 4 Sec

----End

Configuration Files

l Configuration file of RouterA

sysname RouterA

ipv6

# interface Ethernet1/0/0

ipv6 enable

ipv6 address auto link-local

ripng 1 enable

# interface Ethernet2/0/0

ipv6 enable

ipv6 address 1::1/64

ripng 1 enable

# ripng 1

# return l Configuration file of RouterB

sysname RouterB

ipv6

# interface Ethernet1/0/0

ipv6 enable

ipv6 address auto link-local

ripng 1 enable

# interface Ethernet2/0/0

ipv6 enable

ipv6 address auto link-local

ripng 1 enable

# ripng 1

# return l Configuration file of RouterC

sysname RouterC

ipv6

# interface Ethernet1/0/0

ipv6 enable

ipv6 address auto link-local

ripng 1 enable

# ripng 1

# return

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Configuration Guide - IP Routing 5 OSPF Configuration

OSPF Configuration

About This Chapter

OSPF, which is developed by the IETF, is a link-state IGP. OSPF is widely used in access networks and MANs.

5.1 OSPF Overview

OSPF is a link-state IGP. At present, OSPFv2 is intended for IPv4.

5.2 OSPF Features Supported by the AR150/200

The AR150/200 supports various OSPF features, including multi-process, authentication,

Smart-discover, GR, VPN multi-instance, sham link,BFD, OSPF-BGP association, and

GTSM.

5.3 Configuring Basic OSPF Functions

This section describes how to configure basic OSPF functions.

5.4 Configuring OSPF on the NBMA or P2MP Network

This section describes how to configure OSPF and modify attributes on the NBMA or point-tomultipoint (P2MP) network to flexibly construct the OSPF network.

5.5 Configuring an OSPF Route Selection Rule

You can configure an OSPF route selection rule to meet requirements of complex networks.

5.6 Controlling OSPF Routing Information

You can control the advertising and receiving of OSPF routing information and import routes of other protocols.

5.7 Configuring an OSPF Stub Area

Configuring a non-backbone area as a stub area can reduce routing entries in the area in an AS does not transmit routes learned from other areas in the AS or AS external routes. This reduces bandwidth and storage resource consumption.

5.8 Configuring an NSSA

Configuring a non-backbone area on the border of an AS as an NSSA does not transmit routes learned from other areas in the AS but imports AS external routes. This reduces bandwidth and storage resource consumption on the router.

5.9 Configuring BFD for OSPF

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After BFD for OSPF is enabled, when a link fails, the router rapidly detects the failure, notifies the OSPF process or interface of the fault, and instructs OSPF to recalculate routes. This speeds up OSPF network convergence.

5.10 Configuring OSPF GR

Configuring OSPF GR to avoid traffic interruption and route flapping caused by the active/ standby switchover.

5.11 Improving Security of an OSPF Network

On a network demanding high security, you can adopt the GTSM mechanism and configure

OSPF authentication to improve the security of the OSPF network.

5.12 Configuring the Network Management Function of OSPF

OSPF supports the network management function. You can bind the OSPF MIB to a certain

OSPF process, and configure the trap function and log function.

5.13 Maintaining OSPF

Maintaining OSPF involves resetting OSPF and clearing OSPF statistics.

5.14 Configuration Examples

This section provides several configuration examples of OSPF together with the configuration flowchart. The configuration examples explain networking requirements, configuration notes, and configuration roadmap.

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5.1 OSPF Overview

OSPF is a link-state IGP. At present, OSPFv2 is intended for IPv4.

Defined by the Internet Engineering Task Force (IETF), the Open Shortest Path First (OSPF) protocol is an Interior Gateway Protocol (IGP) implemented on the basis of the link status.

NOTE

In this chapter, OSPF refers to OSPFv2, unless otherwise specified.

OSPF Features

OSPF has the following features: l Wide applications

OSPF is applicable to networks of various sizes and even to the network consisting of hundreds of routers.

Fast convergence

Once the network topology changes, Update packets are transmitted to synchronize the link state databases (LSDBs) of all the routers within the Autonomous System (AS).

l Loop-free

According to the collected link status, OSPF calculates routes with the shortest path tree algorithm. This algorithm ensures the generation of loop-free routes.

l Area division

An AS can be divided into different areas to facilitate AS management. After the area partition, an LSDB stores routing information only of the local area. The reduce of LSDB size dramatically reduces memory and CPU usage. In addition, less bandwidth is consumed because of the decrease in routing information transmitted within the AS.

l Equal-cost routes

OSPF supports multiple equal-cost routes to the same destination.

l Routing hierarchy

Four types of routing are available. They are listed in the descending order of priority: intraarea routes, inter-area routes, Type 1 external routes, and Type 2 external routes.

l Authentication

Area-based and interface-based packet authentication guarantees the security of packet interaction.

Multicast

Multicast packets are transmitted only on certain types of links to reduce the interference for some devices.

Process of OSPF Route Calculation

The process of calculating OSPF routes is as follows:

Based on the surrounding network topology, each OSPF device originates a Link State

Advertisement (LSA). The router then transmits Update packets containing the LSAs to other OSPF devices.

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Each OSPF device collects the LSAs from other devices, and all these LSAs compose the

LSDB. An LSA describes the network topology around a router, whereas an LSDB describes the network topology of the whole AS.

OSPF devices transform the LSDB into a weighted directed map. The weighted directed map reflects the topology of the entire network. All routers in the same area have the same map.

According to the directed map, each router uses the Shortest Path First (SPF) algorithm to calculate the shortest path tree, regarding itself as the root. The tree displays the routes to each node in the AS.

Area Division

The number of routers increases with the unceasing expansion of the network scale. This leads to a large LSDB on each router. As a result, the load of each router is very heavy. OSPF solves this problem by dividing an AS into different areas. An area is regarded as a device group logically. Each group is identified by an area ID. On the border of an area resides a router rather than a link. A network segment (or a link) belongs to only one area. That is, the area to which

each OSPF interface belongs must be specified, as shown in

Figure 5-1

Figure 5-1 OSPF area division

Area1

Area0

Area4

Area2 Area3

After area division, route aggregation can be performed on border routers to reduce the number of LSAs advertised to other areas. Route aggregation also minimizes the influence caused by changes in the topology.

Router Type

OSPF routers are classified into the following types according to their locations in the AS: l Internal routers

All interfaces of the routers of this type belong to the same OSPF area.

l Area border routers (ABRs)

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The routers of this type can belong to more than two areas, but one of the areas must be a backbone area. An ABR is used to connect the backbone area to the non-backbone areas.

An ABR can be physically or logically connected to the backbone area.

l Backbone routers

A minimum of one interface on the router of this type belongs to the backbone area.

Therefore, all ABRs and the internal nodes in Area 0 are backbone routers.

l AS boundary routers (ASBRs)

The router that exchanges routing information with other ASs is called an ASBR. The

ASBR may not be located on the boundary of an AS. It can be an internal router or an ABR.

When an OSPF device imports the external routing information, the device becomes an

ASBR.

Figure 5-2 Types of OSPF routers

ASBR

Area1

Internal

Router

Area0

Area4

Backbone

Router

Area2

ABR

Area3

OSPF Network Types

OSPF classifies networks into four types according to the link layer protocol: l Broadcast: If the link layer protocol is Ethernet or FDDI, OSPF defaults the network type to broadcast. In this type of networks, the following situations occur.

–

Hello packets and packets from the Designated Router (DR) are sent in multicast mode

(224.0.0.5: indicates the reserved IP multicast addresses for OSPF routers).

–

Link State Update (LSU) packets are sent to the DR in multicast mode (224.0.0.6: indicates the reserved IP multicast address for the OSPF DR), and the DR forwards the

LSU packets to destination 224.0.0.5.

– Database Description (DD) packets, Link State Request (LSR) packets, and all retransmission packets are sent in unicast mode.

– Link State Acknowledgement (LSAck) packets are usually sent in multicast mode

(224.0.0.5). When a router receives repeated LSAs, or the LSAs are deleted due to the timeout of the maximum lifetime, LSAck packets are sent in unicast mode.

l Non-Broadcast Multi-Access (NBMA): If the link layer protocol is Frame Relay, ATM, or

X.25, OSPF defaults the network type to NBMA. In this type of networks, protocol packets, such as Hello packets, DD packets, LSR packets, LSU packets, and LSAck packet, are transmitted in unicast mode.

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Configuration Guide - IP Routing 5 OSPF Configuration l Point-to-Multipoint (P2MP): A P2MP network must be forcibly changed from other network types. In this type of networks, Hello packets are transmitted in multicast mode

(224.0.0.5); DD packets, LSR packets, LSU packets, and LSAck packets are transmitted in unicast mode.

l Point-to-Point (P2P): If the link layer protocol is PPP, HDLC, or LAPB, OSPF defaults the network type to P2P. In this type of networks, protocol packets, such as Hello packets, DD packets, LSR packets, LSU packets, and LSAck packets, are transmitted in multicast mode

(224.0.0.5).

5.2 OSPF Features Supported by the AR150/200

The AR150/200 supports various OSPF features, including multi-process, authentication,

Smart-discover, GR, VPN multi-instance, sham link,BFD, OSPF-BGP association, and

GTSM.

Multi-process

OSPF supports multi-process. More than one OSPF process can run on the same router because processes are mutually independent. Route interaction between different OSPF processes is similar to the interaction between different routing protocols.

An interface of a router belongs to only a certain OSPF process.

A typical application of OSPF multi-process is to run OSPF between PEs and CEs in the VPN where OSPF is also adopted in the backbone network. On the PEs, the two OSPF processes are independent of each other.

Authentication

OSPF supports packet authentication. Only the OSPF packets that pass the authentication can be received. If the packets fail to pass the authentication, the neighbor relationship cannot be established.

The AR150/200 supports two authentication modes: l Area authentication mode l Interface authentication mode

If both modes are available, the latter is preferred.

Smart-discover

Generally, routers periodically send Hello packets through interfaces that run OSPF, routers set up and maintain the neighbor relationship, and elect the DR and the Backup Designated Router

(BDR) on the multi-access network (broadcast or NBMA) by exchanging Hello packets. When establishing the neighbor relationship or electing the DR and the BDR on the multi-access network, interfaces can send Hello packets only when the Hello timer expires. This affects the speed for establishing the neighbor relationship and electing the DR and the BDR.

NOTE

l The interval for sending Hello packets on an interface depends on the interval for sending Hello packets set on the interface.

l The default value of the interval for sending Hello packets varies with the network type.

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The Smart-discover function can solve the preceding problem.

l In broadcast and NBMA networks, the neighbor relationship can be established rapidly and a DR and a BDR on the networks can be elected rapidly.

When the neighbor status becomes 2-way for the first time, or it returns to Init from the 2way or higher state as shown in

Figure 5-3

, the interface enabled with the Smart-discover

function sends Hello packets to the neighbor without waiting for the timeout of the Hello timer when the interface finds that the status of the neighbor changes.

When the interface status of the DR and the BDR in the multi-access network changes, the interface enabled with the Smart-discover function sends Hello packets to the network segment and takes part in the DR or BDR election.

Figure 5-3 Changes of the neighbor state machine

Down Init 2-way Exstart Exchange Loading Full

Attempt

(NBMA) l On P2P and P2MP networks, the adjacency relationship can be established rapidly. The principle is the same as that in broadcast and NBMA networks.

OSPF GR

When a router restarts or performs the active/standby switchover, it directly ages all routing entries in the Forward Information Base (FIB) table. This results in route interruption. In addition, neighboring routers remove this router from the neighbor list, and notify other routers. This causes the re-calculation of SPF. If this router recovers within a few seconds, the neighbor relationship becomes unstable. This results in route flapping.

After being enabled with OSPF Graceful Restart (GR), a router can ensure continuous packet forwarding if it restarts just for abnormities. In such a case, route flapping is avoided during the short restart of the router.

NOTE

Unless otherwise specified, "protocol restart" in this document refers to restarting OSPF in GR mode.

When a router restarts OSPF, the GR Restarter does not age the forwarding information. At the same time, the GR Helper keeps the topology information or routes obtained from the GR

Restarter for a period. This ensures that traffic forwarding is not interrupted when protocol restart occurs.

OSPF VPN Multi-instance

OSPF supports multi-instance, which can run between PEs and CEs in VPN networks.

In BGP MPLS VPN, many sites of one VPN can use OSPF as the internal routing protocol. The sites, however, are handled as being from different ASs. In this way, the OSPF routes learned on one site are transmitted as external routes to another site. This causes a heavy OSPF traffic and some avoidable network management problems.

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In the AR150/200 implementation, you can configure domain IDs on a PE to differentiate the

VPNs where different sites reside. Different sites in one VPN consider each other as if they were connected directly. Thus, PEs exchange OSPF routing information as if they were directly connected through a leased line. This improves network management and enhances the validity of the OSPF application.

NOTE

For detailed configuration of this feature, refer to the Huawei AR150&200 Series Enterprise Routers

Configuration Guide - VPN.

OSPF Sham Links

OSPF sham links are unnumbered P2P links between two PEs over an MPLS VPN backbone network.

Generally, BGP extended community attributes carry routing information over the MPLS VPN backbone between BGP peers. OSPF running on the remote PE uses this information to generate

Type3 summary LSAs from PE to CE. These routes are considered as inter-area routes.

If a router, however, connects to PEs in its own area and establishes an intra-area route (backdoor route) to a particular destination, the VPN traffic always traverses the backdoor route rather than the backbone route. This is because OSPF intra-area routes in the routing table have relatively higher priorities. To prevent this, an unnumbered P2P sham link is configured between the PEs.

This provides an intra-area path with a lower cost to the PE.

NOTE

For configurations of OSPF sham links, refer to the Huawei AR150&200 Series Enterprise Routers

Configuration Guide - VPN.

BFD for OSPF

By default, in broadcast networks, the interval for OSPF to send Hello packets is 10 seconds; in

NBMA networks, the interval for sending Hello packets is 30 seconds, and the period for advertising that the neighbor is Down is four times the interval for sending Hello packets. If the router does not receive the Hello packet from the neighbor before the neighboring router becomes invalid, it deletes the neighbor. That is, the router detects the neighbor faults in seconds. This leads to the loss of a large number of packets in a high-speed network.

To solve the preceding problem in the current detection mechanism, Bidirectional Forwarding

Detection (BFD) is developed. BFD can implement detection at the millisecond level. Instead of replacing the Hello mechanism of OSPF, BFD works with OSPF to fast detect the adjacency fault. BFD is used to notify OSPF of recalculating routes. This can correctly guide the packet forwarding.

Routing Management (RM) module exchanges routing information with the BFD module.

Through RM, OSPF notifies BFD of dynamically setting up or deleting BFD sessions. The Event message of BFD is delivered to OSPF through RM.

The process of establishing and deleting a BFD session is as follows: l Process of establishing a BFD session: If BFD feature is globally configured, BFD is enabled on an interface or a process, and the status of the OSPF neighbor is Full, OSPF uses RM to notify the BFD module of establishing the BFD session and negotiate related parameters of BFD.

l Process of deleting a BFD session: When BFD detects a link fault, BFD generates a Down event and notifies the upper protocol of the fault through RM. OSPF then responds to the

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Configuration Guide - IP Routing 5 OSPF Configuration event and immediately deletes the adjacency relationship on the link. At this time, the status of the neighbor is not Full. This does not meet the requirements of establishing a BFD session. OSPF then uses RM to notify the BFD module of deleting the BFD session.

OSPF supports dynamically establishing or deleting a BFD session on broadcast, P2P, P2MP, and NBMA links.

Configure BFD according to the actual network environment. If time parameters are set incorrectly, network flapping occurs.

OSPF-BGP

When a new router is connected to the network, or a router restarts, the network traffic may be lost during BGP convergence. This is because the IGP route convergence is quicker than the

BGP route convergence.

If the backup link exists, OSPF-BGP linkage makes a router that restarts or a router that is connected to the network start the stub router timer during the OSPF-BGP linkage. During the set linkage period, the router acts as the stub router by increasing the metrics of the links in the

LSA generated by the router to 65535. Other OSPF routers are notified of not using the stub router to forward data. This ensures that the router is not used as the spanned router. This avoids traffic loss during traffic switchback because route convergence speed is slower than that of

OSPF.

GTSM

The Generalized TTL Security Mechanism (GTSM) refers to the generic TTL security protection mechanism. GTSM protects services of the upper layer over the IP layer by checking whether the TTL value in the IP header is in a pre-defined range. In applications, GTSM is designed to protect the TCP/IP-based control plane (like routing protocols) from CPU-utilization attacks, such as CPU overload attacks.

5.3 Configuring Basic OSPF Functions

This section describes how to configure basic OSPF functions.

5.3.1 Establishing the Configuration Task

Before configuring basic OSPF functions, enable OSPF, specify the OSPF process and area, and establish OSPF neighbor relationships.

Applicable Environment

When OSPF is configured on multiple routers in the same area, most configuration data, such as the timer, filter, and aggregation, must be planned uniformly in the area. Incorrect configurations may cause neighboring routers to fail to send messages to each other or even causing routing information congestion and self-loops.

The OSPF-relevant commands that are configured in the interface view take effect regardless of whether OSPF is enabled. After OSPF is disabled, the OSPF-relevant commands also exist on interfaces.

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Pre-configuration Tasks

Before configuring basic OSPF functions, complete the following tasks: l Configuring a link layer protocol l Configuring IP addresses for interfaces to ensure that neighboring routers are reachable at the network layer

Data Preparation

To configure basic OSPF functions, you need the following data.

No.

Data

1 Router ID

OSPF process ID

VPN instance name (if OSPF multi-instance is configured)

ID of the area to which an interface belongs

IP address of the network segment where an interface resides

5.3.2 Enabling OSPF

Create an OSPF process and specify a router ID to enable OSPF. After enabling OSPF, specify an interface on which the OSPF protocol is running and the area to which the interface belongs.

After that, routes can be discovered and calculated in the AS.

Context

Before running OSPF on the router, specify a router ID for the router. The router ID is a 32-bit unsigned integer, which identifies the router in the AS. To ensure OSPF stability, manually set the router ID of each router during network planning.

This causes the link state database (LSDB) to unexpectedly grow. OSPF resolves this problem by partitioning an AS into different areas. The area is regarded as a logical group and each group is identified by an area ID. At the border of an area resides the router instead of a link. A network segment (or a link) belongs to only one area. The area to which each OSPF interface belongs must be specified.

Procedure

Step 1 Run:

system-view

The system view is displayed.

Step 2 Run:

ospf [ process-id | router-id router-id | vpn-instance vpn-instance-name ]

The OSPF process is started, and the OSPF view is displayed.

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Configuration Guide - IP Routing 5 OSPF Configuration l process-id specifies the process ID and the process-id value is 1 by default. The

AR150/200 supports OSPF multi-process. Processes can be classified by service type. The

AR150/200s exchange packets regardless of process IDs. Packets can be exchanged between

AR150/200s with different process IDs.

l Each router ID in an OSPF process must be unique. Otherwise, the OSPF neighbor relationship cannot be established and the routing information is incorrect. By default, the system automatically selects the IP address of an interface as the router ID. Ensure that each router ID is unique in the AS when manually configuring router IDs. The IP address of an interface on the AR150/200 is generally configured as the router ID of the AR150/200.

l If a VPN instance is specified, the OSPF process belongs to the VPN instance; if a VPN instance is not specified, the OSPF process belongs to a public network instance.

Step 3 Run:

area area-id

The OSPF area view is displayed.

The OSPF areas can be classified into a backbone area with the area ID of 0 and non-backbone areas. The backbone area is responsible for forwarding inter-area routing information. The routing information between the non-backbone areas must be forwarded through the backbone area.

Step 4 Run:

network ip-address wildcard-mask [ description text ]

The network segments are configured to belong to the area. description is used to configure a description for the specified OSPF network segment.

OSPF can run on an interface properly only when the following conditions are met: l The mask length of the IP address of an interface is greater than or equal to that specified by the network command.

l The primary IP address of an interface is on the network segment specified by the

network command.

By default, OSPF uses a 32-bit host route to advertise the IP address of a loopback interface. To advertise routes to the network segment of the loopback interface, configure the network type

as NBMA or broadcast in the interface view. For details, see

Configuring Network Types for

OSPF Interfaces

----End

5.3.3 (Optional) Creating OSPF Virtual Links

This section describes how to create logical links between backbone areas to ensure the OSPF network connectivity.

Context

After OSPF areas are defined, OSPF route updates between non-backbone areas are transmitted through a backbone area. Therefore, OSPF requires that all non-backbone areas maintain the connectivity with the backbone area and the backbone areas in different OSPF areas maintain the connectivity with each other. In real world situations, this requirement may not be met because of some restrictions. To resolve this problem, you can configure OSPF virtual links.

Perform the following steps on the router running OSPF.

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Procedure

Step 1 Run:

system-view

The system view is displayed.

Step 2 Run:

ospf [ process-id ]

The OSPF process view is displayed.

Step 3 Run:

area area-id

The OSPF area view is displayed.

Step 4 Run:

vlink-peer router-id [ smart-discover | hello hello-interval | retransmit

retransmit-interval | trans-delay trans-delay-interval | dead dead-interval |

[ simple [ plain plain-text | cipher cipher-text ] | { md5 | hmac-md5 } [ key-id

{ plain plain-text | cipher cipher-text } ] | authentication-null | keychain

keychain-name ] ]

A virtual link is created.

This command must also be configured on the neighboring router.

----End

Follow-up Procedure

After virtual links are created, different default MTUs may be used on devices provided by different vendors. To ensure consistency, the MTU is set to 0 by default when the interface sends

DD packets. For details, see

Configuring an Interface to Fill in the DD Packet with the Actual

MTU

5.3.4 (Optional) Configuring a Route Selection Rule on the router

You can configure the router to comply with the route selection rule defined in RFC 1583 or

RFC 2328.

Context

RFC 2328 and RFC 1583 define the route selection rule differently. After OSPF is enabled on the router, specify a route selection rule based on the router configuration. The router complies with the route selection rule defined in RFC 1583 by default. If the neighboring router complies with the route selection rule defined in RFC 2328, configure the local router to comply with that defined in RFC 2328. This allows all routers in the OSPF area to comply with the same route selection rule.

Perform the following steps on the router running OSPF.

Procedure

Step 1 Run:

system-view

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The system view is displayed.

Step 2 Run:

ospf [ process-id ]

The OSPF process view is displayed.

Step 3 Run:

undo rfc1583 compatible

The router is configured to comply with the route selection rule defined in RFC 2328, not RFC

1583.

By default, the router complies with route selection rule defined in RFC 1583.

----End

5.3.5 (Optional) Setting the OSPF Priority

When multiple routing protocols are used to select routes, you can set the OSPF priority to maneuver route selection.

Context

The routing protocols may share and select the routing information because the router may run multiple dynamic routing protocols at the same time. The system sets a priority for each routing protocol. When multiple routing protocols are used to select routes, the route selected by the routing protocol with a higher priority takes effect.

Perform the following steps on the router running OSPF.

Procedure

Step 1 Run:

system-view

The system view is displayed.

Step 2 Run:

ospf [ process-id ]

The OSPF process view is displayed.

Step 3 Run:

preference [ ase ] { preference | route-policy route-policy-name }

The OSPF priority is set.

l ase: sets the priority of the AS-External route.

l preference: sets the priority for OSPF. The smaller the value, the higher the priority.

l route-policy-name: sets the priority for specified routes in the routing policy.

The default OSPF priority value is 10. When an ASE is specified, the default OSPF priority value is 150.

----End

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5.3.6 (Optional) Restricting the Flooding of LSA Update Packets

When a large number of LSA update packets are flooded, the neighboring router may be busy processing LSA update packets and has to discard the Hello packets that are used to maintain neighbor relationships. This causes neighbor relationships to be interrupted. To resolve this problem, you can restrict the flooding of LSA update packets to maintain neighbor relationships.

Context

When multiple neighboring routers are configured or a large number of LSA update packets are flooded, the neighboring router may receive a large number of LSA update packets in a short period. This keeps the neighboring router busy processing a burst of LSA update packets and causes the neighboring router to unexpectedly discard Hello packets that are used to maintain the OSPF neighbor relationships. As a result, the neighbor relationships are interrupted. After the neighbor relationships are reestablished, more packets are to be exchanged. This intensifies neighbor relationship interruption. To resolve this problem, you can restrict the flooding of LSA update packets to maintain neighbor relationships.

Perform the following steps on the router running OSPF.

Procedure

Step 1 Run:

system-view

The system view is displayed.

Step 2 Run:

ospf [ process-id ]

The OSPF process view is displayed.

Step 3 Run:

flooding-control [ number transmit-number | timer-interval transmit-interval ]

The flooding of LSA update packets is restricted.

By default, the number of LSA update packets to be flooded each time is 50, and the interval at which LSA update packets are flooded is 30s.

After the flooding-control command is run, the flooding of LSA update packets is immediately restricted.

If the flooding-control command is not run, the function of restricting the flooding of LSA update packets automatically takes effect when the number of neighboring routers exceeds 256.

----End

5.3.7 (Optional) Configuring the Maximum Number of Packet

Retransmission Attempts

When no response to DD packets, LSU packets, or LSR packets is received, the retransmission mechanism is used and the maximum number of packet retransmission attempts is set.

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Context

If no response is received when the maximum number of packet retransmission attempts is reached, the neighbor relationship will be interrupted.

By default, the retransmission mechanism is disabled.

Perform the following steps on the router running OSPF.

Procedure

Step 1 Run:

system-view

The system view is displayed.

Step 2 Run:

ospf [ process-id ]

The OSPF process view is displayed.

Step 3 Run:

retransmission-limit [ max-number ]

The maximum number of OSPF packet retransmission attempts is set.

max-number specifies the maximum number of packet retransmission attempts and is 30 by default.

----End

5.3.8 (Optional) Setting an Interval at Which an LSA Packet Is

Retransmitted to the Neighboring router

You can control packet retransmission and improve the convergence rate by setting an interval at which an LSA packet is retransmitted to the neighboring router.

Context

After sending an LSA packet to the neighboring router, the router waits for a response. If no response is received within the set interval, the router retransmits the LSA packet to the neighboring router.

Perform the following steps on the router running OSPF.

Procedure

Step 1 Run:

system-view

The system view is displayed.

Step 2 Run:

interface interface-type interface-number

The interface view is displayed.

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Step 3 Run:

ospf timer retransmit interval

An interval at which an LSA packet is retransmitted to the neighboring router is set.

Setting the interval to a proper value is recommended. A rather small interval will cause unnecessary retransmission. The interval is generally longer than a round trip of one packet transmitted between two routers.

The default retransmission interval is 5s and is widely used.

----End

5.3.9 (Optional) Configuring an Interface to Fill in a DD Packet with the Interface MTU

You can configure an interface to fill in the Interface MTU field of a DD packet with the interface

MTU.

Context

The default MTU is 0.

After virtual links are created, different default MTUs may be used on devices provided by different vendors. To ensure consistency, the MTU is set to 0 by default when the interface sends

DD packets.

CAUTION

Setting the MTU in a DD packet will have the neighbor relationship reestablished.

Perform the following steps on the router running OSPF.

Procedure

Step 1 Run:

system-view

The system view is displayed.

Step 2 Run:

interface interface-type interface-number

The interface view is displayed.

Step 3 Run:

ospf mtu-enable

The interface is configured to fill in a DD packet with the interface MTU and check whether the

MTU in the DD packet from the neighboring router exceeds the MTU of the local router.

----End

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5.3.10 Checking the Configuration

After basic OSPF functions are successfully configured, you can check information about the

LSDB, neighbors in each area, and routing table.

Prerequisites

All configurations of basic OSPF functions are complete.

Procedure

l Run the display ospf [ process-id ] peer command to check OSPF neighbor information.

l Run the display ospf [ process-id ] routing command to check OSPF routing table information.

Run the display ospf [ process-id ] lsdb command to check OSPF LSDB information.

----End

5.4 Configuring OSPF on the NBMA or P2MP Network

This section describes how to configure OSPF and modify attributes on the NBMA or point-tomultipoint (P2MP) network to flexibly construct the OSPF network.

5.4.1 Establishing the Configuration Task

To implement OSPF functions, configure OSPF on the NBMA or P2MP network.

Applicable Environment

, OSPF classifies networks into four types based on the types of link layer

Table 5-1

protocols.

NOTE

Differentiated OSPF configurations that are applicable to the NBMA network and P2MP network are provided in this section.The OSPF configurations not provided here are applicable to the four types of networks.

Table 5-1 Network types supported by OSPF

Network Type Characteristic

Broadcast On the broadcast network, Hello packets, LSU packets, and LSAck packets are multicasted; DD packets and LSR packets are unicasted.

Default Configuration

If the link layer protocol is

Ethernet or Fiber Distributed Data

Interface (FDDI), OSPF regards the network as a broadcast network by default.

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Network Type

Non-broadcast multiple access

(NBMA)

Point-to-point

(P2P)

Point-tomultipoint (P2MP)

Characteristic

On an NBMA network, Hello packets, DD packets, LSR packets, LSU packets, and LSAck packets are unicasted.

The NBMA network must be fully meshed. Any two routers on the

NBMA network must be directly reachable.

On a P2P network, Hello packets,

DD packets, LSR packets, LSU packets, and LSAck packets are multicasted.

On a P2MP network, Hello packets are multicasted; DD packets, LSR packets, LSU packets, and LSAck packets are unicasted.

The mask lengths of the routers on the P2MP network must be the same.

Default Configuration

If the link layer protocol is ATM,

OSPF regards the network as an

NBMA network by default.

If the link layer protocol is PPP,

HDLC, or Link Access Procedure

Balanced (LAPB), OSPF regards the network as a P2P network by default.

OSPF does not regard a network as a P2MP network by default regardless of any link layer protocol. A P2MP network is forcibly changed from the network of another type.

, OSPF sends packets in different manners on networks of different types.

Table 5-1

Therefore, the difference between OSPF configurations on the networks lies in the packet sending configurations.

Pre-configuration Tasks

Before configuring OSPF on the NBMA or P2MP network, complete the following tasks: l Configuring IP addresses for interfaces to ensure that neighboring routers are reachable at the network layer l

Configuring Network Types for OSPF Interfaces

Data Preparation

To configure OSPF on the NBMA or P2MP network, you need the following data.

No.

Data

1 Number of the interface running OSPF

2 Network type

DR priority of an interface

IP address of a neighbor on an NBMA network

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No.

Data

5 Interval at which Hello packets are sent on an NBMA network

5.4.2 Configuring Network Types for OSPF Interfaces

OSPF classifies networks into four types based on the types of link layer protocols. You can configure the network type for an OSPF interface to forcibly change its original network type.

Context

By default, the physical interface type determines the network type.

l The network type of an Ethernet interface is Broadcast.

l The network type of a Frame Relay (FR) interface is NBMA.

NOTE

A P2MP network is forcibly changed from another other type of network.

The network types of the interfaces on both ends of a link must be the same; otherwise, the OSPF neighbor relationship cannot be established. Only when the network type of one OSPF interface is broadcast and the network type of the other OSPF interface is P2P, the two interfaces can still set up the neighbor relationship. but cannot learn the OSPF routing information each other.

Perform the following steps on the router running OSPF.

Procedure

Step 1 Run:

system-view

The system view is displayed.

Step 2 Run:

interface interface-type interface-number

The interface view is displayed.

Step 3 Run:

ospf network-type { broadcast | nbma | p2mp | p2p }

The network type of the OSPF interface is configured.

When the network type is configured for an interface, the original network type of the interface is replaced.

The network type can be configured based on the real world situations.

l On an interface with the broadcast network type, if a router that does not support the multicast address exists, change the network type of the interface to NBMA.

l On an interface with the NBMA network type, if the network is fully meshed or any two routers are directly connected, change the network type of the interface to broadcast and do not configure neighboring router information on the interface.

l On an interface with the NBMA network type, if the network is not fully meshed, change the network type of the interface to P2MP. After that, two indirectly connected routers can

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5 OSPF Configuration communicate through one router that can directly reach both the two routers. After the network type of the interface is changed to P2MP, configuring neighboring router information on the interface is unnecessary.

l If only two routers run OSPF on the same network segment, changing the network type of the interface to P2P is recommended.

NOTE

OSPF cannot be configured on a null interface.

----End

5.4.3 Configuring NBMA Network Attributes

To implement OSPF functions, configure NBMA network attributes.

Procedure

Step 1 (Optional) Set the network type to NBMA.

The NBMA network must be fully meshed. Any two routers on the NBMA network must be directly reachable. In most cases, however, this requirement cannot be met. To resolve this problem, run specific commands to forcibly change the network type to NBMA. For details, see

Run:

system-view

The system view is displayed.

Run:

interface interface-type interface-number

The interface view is displayed.

Run:

ospf network-type nbma

The network type of the OSPF interface is set to NBMA.

Step 2 (Optional) Set the interval at which Hello packets for polling are sent on the NBMA network.

On the NBMA network, after the neighbor relationship becomes invalid, the router sends Hello packets at an interval defined in the polling mechanism.

Run:

ospf timer poll interval

The interval at which Hello packets for polling are sent by an NBMA interface is set.

The default value is 120, in seconds.

Step 3 Configure a neighboring router on the NBMA network.

The interface with the network type of NBMA cannot broadcast Hello packets to discover neighboring routers. Therefore, the IP address of a neighboring router must be configured on the interface and whether the neighboring router can participate in DR election must be determined on the interface.

Run:

quit

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Exit from the interface view.

Run:

ospf [ process-id ]

The OSPF process view is displayed.

Run:

peer ip-address [ dr-priority priority ]

A neighboring router is configured.

----End

5.4.4 Configuring P2MP Network Attributes

To implement OSPF functions, configure P2MP network attributes.

Context

Perform the following steps on the router running OSPF.

Procedure

Step 1 Disable OSPF from checking the network mask.

The OSPF neighbor relationship cannot be established between the routers with different mask lengths on the P2MP network. After OSPF is disabled from checking the network mask, the

OSPF neighbor relationship can be properly established.

Run:

system-view

The system view is displayed.

Run:

interface interface-type interface-number

The interface view is displayed.

Run:

ospf network-type p2mp

The network type of the OSPF interface is configured.

A P2MP network is forcibly changed from another other type of network. For details, see

Configuring Network Types for OSPF Interfaces

Run:

ospf p2mp-mask-ignore

OSPF is disabled from checking the network mask on the P2MP network.

Step 2 (Optional) Configure the router to filter the LSA packets to be sent.

When multiple links exist between two routers, you can configure the local router to filter the

LSA packets to be sent. This can reduce unnecessary LSA retransmission attempts and save bandwidth resources.

Run:

quit

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Exit from the interface view.

Run:

ospf [ process-id ]

The OSPF process view is displayed.

Run:

filter-lsa-out peer ip-address { all | { summary [ acl{ acl-number | acl-

name } ] | ase [ acl{ acl-number | acl-name } ] | nssa [ acl{ acl-number | acl-

name } ] }

}

The local router is configured to filter the LSA packets to be sent on the P2MP network.

By default, the LSA packets to be sent are not filtered.

----End

5.4.5 Checking the Configuration

After OSPF attributes on the NBMA network and P2MP network are set, you can check OSPF statistics, LSDB information, neighbor information, and interface information.

Prerequisites

The configurations for OSPF attributes on the NBMA network and P2MP network are complete.

Procedure

l Run the either of the following command to check LSDB information.

– display ospf [ process-id ] lsdb [ brief ]

–

opaque-link | opaque-area | opaque-as ] [ link-state-id ] [ originate-router

[ advertising-router-id ] | self-originate ] [ age { min-value min-age-value | max-

value max-age-value }

] l Run the display ospf [ process-id ] peer [ [ interface-type interface-number ] neighbor-

id | brief | last-nbr-down ] command to view neighbor information.

l Run the display ospf [ process-id ] nexthop command to check next hop information.

l Run the either of the following command to check routing table information.

–

display ospf [ process-id ] routing [ ip-address [ mask | mask-length ] ] [ interface

interface-type interface-number ] [ nexthop nexthop-address ]

– display ospf [ process-id ] routing router-id [ router-id ] l Run the display ospf [ process-id ] interface [ all | interface-typeinterface-number ]

[ verbose ] command to check interface information.

----End

5.5 Configuring an OSPF Route Selection Rule

You can configure an OSPF route selection rule to meet requirements of complex networks.

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5.5.1 Establishing the Configuration Task

Before configuring an OSPF route selection rule, familiarize yourself with the applicable environment, complete the pre-configuration tasks, and obtain the data required for the configuration. This will help you complete the configuration task quickly and efficiently.

Applicable Environment

In real world situations, you can configure an OSPF route selection rule by setting OSPF route attributes to meet the requirements of complex networks.

Set the cost of an interface. The link connected to the interface with a smaller cost value preferentially transmits routing information.

l Configure equal-cost routes to implement load balancing.

l Configure a stub router during the maintenance operations such as upgrade to ensure stable data transmission through key routes.

l Suppress interfaces from sending or receiving packets to help select the optimal route.

Pre-configuration Tasks

Before configuring an OSPF route selection rule, complete the following tasks: l Configuring IP addresses for interfaces to ensure that neighboring routers are reachable at the network layer l

Data Preparation

To configure an OSPF route selection rule, you need the following data.

No.

Data

1 Interface cost

Maximum number of equal-cost routes

Equal-cost route preference

5.5.2 Setting the Interface Cost

You can adjust and optimize route selection by setting the OSPF interface cost.

Context

After the OSPF interface costs are set, the interface with a smaller cost value preferentially transmits routing information. This helps select the optimal route.

The OSPF interface cost can be set manually or calculated based on the interface bandwidth.

Perform the following steps on the router running OSPF.

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Procedure

Step 1 Run:

system-view

The system view is displayed.

Step 2 Run:

interface interface-type interface-number

The interface view is displayed.

Step 3 Run:

ospf cost cost

The OSPF interface cost is set.

The router generally transmits routing information using the link connected to the interface with a smaller cost value.

If no interface cost is configured, the system automatically calculates the interface cost based on the interface bandwidth. The calculation formula is as follows: Cost of the interface =

Bandwidth reference value/Interface bandwidth. The integer of the calculated result is the cost of the interface. If the calculated result is smaller than 1, the cost value is 1. By default, the bandwidth reference value is 100, in Mbit/s. Changing the bandwidth reference value can change the cost of an interface.

Perform the following steps to change the bandwidth reference value:

Run:

system-view

The system view is displayed.

Run:

ospf [ process-id ]

The OSPF process view is displayed.

Run:

bandwidth-reference value

The bandwidth reference value is set.

Ensure that the bandwidth reference values of routers in an OSPF process are the same.

----End

5.5.3 Configuring Equal-Cost Routes

You can set the number of OSPF equal-cost routes and route preference to implement load balancing and adjust route selection.

Context

If the destinations and costs of the multiple routes discovered by one routing protocol are the same, load balancing can be implemented among the routes.

, three routes between router A and router B that run OSPF have the

Figure 5-4

same costs. The three routes are equal-cost routes for load balancing.

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Figure 5-4 Networking diagram of equal-cost routes

RouterA cos t=5 cost=10 cost=

IP Network cost=

IP Network cost=5

RouterB cos t=7

IP Network

5 OSPF Configuration

Perform the following steps on the router running OSPF.

Procedure

Step 1 Run:

system-view

The system view is displayed.

Step 2 Run:

ospf [ process-id ]

The OSPF process view is displayed.

Step 3 Run:

maximum load-balancing number

The maximum number of equal-cost routes is set.

NOTE

The maximum number of equal-cost routes is 4, by default, it is 4.

Step 4 (Optional) Run:

nexthop ip-address weight value

The route preferences are configured for load balancing.

When the number of equal-cost routes on the live network is greater than that specified in the

maximum load-balancing command, valid routes are randomly selected for load balancing. To specify valid routes for load balancing, run the nexthop command to set the route preference.

Ensure that the preferences of valid routes to be used must be high.

The smaller the weight value, the higher the preference of the route. The default weight value is 255, which indicates that load balancing is implemented regardless of the route preferences.

----End

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5.5.4 Configuring a Stub Router

To ensure that a route is not interrupted during flapping-triggering maintenance operations such as upgrade, you can configure a router as a stub router to allow traffic to bypass the route on the stub router.

Context

Procedure

Step 1 Run:

system-view

The system view is displayed.

Step 2 Run:

ospf [ process-id ]

The OSPF process view is displayed.

Step 3 Run:

stub-router [ on-startup [ interval ] ]

A stub router is configured.

By default, no router is configured as a stub router.

If a router is configured as a stub router, the router keeps functioning as a stub router for 500s.

NOTE

The stub router configured in this manner is irrelevant to the router in the stub area.

----End

5.5.5 Suppressing an Interface from Receiving and Sending OSPF

Packets

After an interface is suppressed from receiving and sending OSPF packets, routing information can bypass a specific router and the local router can reject routing information advertised by another router.

Context

After a stub router is configured, the route on the stub router will not be preferentially selected.

After the route cost is set to the maximum value 65535, traffic generally bypasses the router.

This ensures an uninterrupted route on the router during maintenance operations such as upgrade.

Perform the following steps on the router running OSPF.

Suppressing an interface from receiving and sending OSPF packets helps routing information to bypass a specific router and enables the local router to reject routing information advertised by another router. This ensures that an optimal route is provided.

Perform the following steps on the router running OSPF.

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Procedure

Step 1 Run:

system-view

The system view is displayed.

Step 2 Run:

ospf [ process-id ]

The OSPF process view is displayed.

Step 3 Run:

silent-interface { all | interface-typeinterface-number }

An interface is suppressed from receiving and sending OSPF packets.

The same interface in different processes can be suppressed from sending and receiving OSPF packets, but the silent-interface command is valid only for the OSPF interface in the local process.

After an OSPF interface is configured to be in the silent state, the interface can still advertise its direct routes. Hello packets on the interface, however, cannot be forwarded. Therefore, no neighbor relationship can be established on the interface. This can enhance the networking adaptability of OSPF and reduce system resource consumption.

----End

5.5.6 Checking the Configuration

After an OSPF route selection rule is configured, you can check information about the OSPF routing table, interface, and next hop.

Prerequisites

All OSPF route selection configurations are complete.

Procedure

l Run the display ospf [ process-id ] routing [ ip-address [ mask | mask-length ] ]

[ interface interface-type interface-number ] [ nexthop nexthop-address ] command to check the OSPF routing table information.

l Run the display ospf [ process-id ] interface [ all | interface-type interface-number ]

[ verbose ] command to check OSPF interface information.

----End

5.6 Controlling OSPF Routing Information

You can control the advertising and receiving of OSPF routing information and import routes of other protocols.

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5.6.1 Establishing the Configuration Task

Before controlling OSPF routing information, familiarize yourself with the applicable environment, complete the pre-configuration tasks, and obtain the data required for the configuration. This will help you complete the configuration task quickly and efficiently.

Applicable Environment

You can control the advertising and receiving of OSPF routing information and import routes of other protocols.

Pre-configuration Tasks

Before controlling OSPF routing information, complete the following tasks: l Configuring IP addresses for interfaces to ensure that neighboring routers are reachable at the network layer l

can be advertised only when meeting filtering conditions.

Data Preparation

To control OSPF routing information, you need the following data.

No.

Data

1 Link cost

ACL for route filtering

Name of the imported routing protocol, OSPF process ID, and default parameters

5.6.2 Configuring OSPF to Import External Routes

Importing the routes discovered by other routing protocols can enrich OSPF routing information.

Context

To access a router running a non-OSPF protocol, an OSPF-capable router needs to import routes of the non-OSPF protocol into the OSPF network.

OSPF provides loop-free intra-area routes and inter-area routes; however, OSPF cannot prevent external routing loops. Therefore, exercise caution when configuring OSPF to import external routes. For details, see "OSPF VPN Extension" in the Huawei AR150&200 Series Enterprise

Routers Feature Description - VPN.

Perform the following steps on the ASBR running OSPF.

Procedure

Step 1 Run:

system-view

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The system view is displayed.

Step 2 Run:

ospf [ process-id ]

The OSPF process view is displayed.

Step 3 Run:

import-route { limit limit-number | { bgp [ permit-ibgp ] | direct | unr | rip

[ process-id-rip ] | static | isis [ process-id-isis ] | ospf [ process-id-ospf ] }

[ cost cost | type type | tag tag | route-policy route-policy-name ]

}

Routes are imported from another protocol.

Step 4 (Optional) Run:

default { cost { cost | inherit-metric } | limit limit | tag tag | type type }

The default values of parameters (the cost, number of routes, tag, and type) are set for imported routes.

When OSPF imports external routes, you can set default values for some additional parameters, such as the cost, number of routes to be imported, route tag, and route type. The route tag is used to identify the protocol-related information. For example, it can be used to differentiate AS numbers carried in BGP routes imported by OSPF.

By default, the cost of the external routes imported by OSPF is 1; a maximum of 2147483647 routes can be imported each time; the type of the imported external routes is Type 2; the default tag value of the imported routes is 1.

NOTE

You can run one of the following commands to set the cost of the imported route. The following commands are listed in descending order of priorities.

l Run the apply cost command to set the cost of a route.

l Run the import-route command to set the cost of the imported route.

l Run the default command to set the default cost of the imported route.

Step 5 (Optional) Run:

filter-policy { acl-number | acl-nameacl-name | ip-prefixip-prefix-name } export

[ protocol [ process-id ] ]

Routes imported using

Step 3

OSPF filters the imported routes. OSPF uses Type 5 LSAs to carry routes that meet the filtering conditions and advertises these Type 5 LSAs.

You can specify the parameter protocol [ process-id ] to filter the routes of a certain routing protocol or a certain OSPF process. If protocol [ process-id ] is not specified, OSPF filters all imported routes.

The import-route command cannot be used to import the default route from another AS.

----End

5.6.3 Configuring OSPF to Import a Default Route

The default route is widely applied on the OSPF network to reduce routing entries in the routing table and filter specific routing information.

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Context

5 OSPF Configuration

On the area border and AS border of an OSPF network generally reside multiple routers for nexthop backup or traffic load balancing. A default route can be configured to reduce routing entries and improve resource usage on the OSPF network.

The default route is generally applied to the following scenarios:

An ABR in an area advertises Type 3 LSAs carrying the default route within the area.

routers in the area use the received default route to forward inter-area packets.

An ASBR in an AS advertises Type 5 or Type 7 LSAs carrying the default route within the

AS. routers in the AS use the received default route to forward AS external packets.

When no exactly matched route is discovered, the router can forward packets through the default route.

The preference of the default route in Type 3 LSAs is higher than that of the route in Type 5 or

Type 7 LSAs.

The advertising mode of the default route is determined by the type of the area to which the

default route is imported, as shown in

Table 5-2

Table 5-2 Default route advertising mode

Area

Type

Generated By

Commo n area

Stub area

The default-route-advertise command

Automatically

NSSA The nssa[ default-route-advertise ] command

Totally

NSSA

Automatically

ASBR

ABR

ASBR

ABR

Advertise d By

LSA Type Floodi ng

Area

Type 5 LSA Comm on area

Type 3 LSA Stub area

Type 7 LSA NSSA

Type 3 LSA NSSA

Perform the following steps on the ASBR running OSPF.

Procedure

Step 1 Run:

system-view

The system view is displayed.

Step 2 Run:

ospf [ process-id ]

The OSPF process view is displayed.

Step 3 Run:

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default-route-advertise [ [ always | permit-calculate-other ] | cost cost | type

type | route-policy route-policy-name ]

The default route is imported into the OSPF process.

To configure the parameter cost to specify the default cost of Type-3 summary LSAs, enable

VPN first.

Before advertising a default route, OSPF compares the preferences of default routes. Therefore, if a static default route is configured on an OSPF device, to add the default route advertised by

OSPF to the current routing table, ensure that the preference of the configured static default route is lower than that of the default route advertised by OSPF.

For details about how to configure the default route in the NSSA, see

Configuring an NSSA

----End

5.6.4 Configuring Route Summarization

When a large-scale OSPF network is deployed, you can configure route summarization to reduce routing entries. Otherwise, a large number of routing entries are generated and consume system resources unexpectedly.

Context

Route summarization on a large-scale OSPF network efficiently reduces routing entries. This minimizes system resource consumption and maintains the system performance. In addition, if a specific link frequently alternates between Up and Down, the links not involved in the route summarization will not be affected. This prevents route flapping and improves the network stability.

Perform the following steps on the router running OSPF.

Procedure

l Configure ABR route summarization.

Run:

system-view

The system view is displayed.

Run:

ospf [ process-id ]

The OSPF process view is displayed.

Run:

area area-id

The OSPF area view is displayed.

Run:

abr-summary ip-address mask [ [ advertise | not-advertise ] | cost cost ]

ABR route summarization is configured.

Configure ASBR route summarization.

Run:

system-view

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The system view is displayed.

Run:

ospf [ process-id ]

The OSPF process view is displayed.

Run:

asbr-summary ip-address mask [ not-advertise | tag tag | cost cost |

distribute-delay interval ]

ASBR route summarization is configured.

NOTE

After route summarization is configured, the routing table on the local OSPF router remains the same.

The routing table on another OSPF router, however, contains only one summarized route, no specific route. This summarized route is not removed until all specific routes are interrupted.

----End

5.6.5 Configuring OSPF to Filter Routes Received by OSPF

By configuring filtering conditions for the received routes, you can allow only the routes that meet the filtering conditions to be added to the routing table.

Context

Perform the following steps on the router running OSPF.

Procedure

Step 1 Run:

system-view

The system view is displayed.

Step 2 Run:

ospf [ process-id ]

The OSPF process view is displayed.

Step 3 Run:

filter-policy { acl-number | acl-name acl-name | ip-prefix ip-prefix-name } import

Routes received by OSPF are filtered.

OSPF is a dynamic routing protocol based on the link state, and routing information is carried in LSAs. The filter-policy import command cannot be used to filter the advertised and received

LSAs. Actually, this command is used to filter the routes calculated by OSPF. Only the routes that meet the filtering conditions are added to the routing table. Therefore, the LSDB is not affected regardless of whether the received routes meet the filtering conditions.

----End

5.6.6 Configuring the router to Filter LSAs to Be Sent

Filtering the LSAs to be sent on the local router can prevent unnecessary LSA transmission.

This reduces the size of the LSDB on the neighboring router and speeds up network convergence.

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Context

When multiple links exist between two routers, you can configure the local router to filter the

LSAs to be sent. This prevents unnecessary LSA transmission and saves bandwidth resources.

Perform the following steps on the router running OSPF.

Procedure

Step 1 Run:

system-view

The system view is displayed.

Step 2 Run:

interface interface-type interface-number

The interface view is displayed.

Step 3 Run:

ospf filter-lsa-out { all | { summary [ acl { acl-number | acl-name } ] | ase

[ acl { acl-number | acl-name } ] | nssa [ acl { acl-number | acl-name } ] }

}

The LSAs to be sent are filtered.

By default, the LSAs to be sent are not filtered.

----End

5.6.7 (Optional) Configuring OSPF to Filter LSAs in an Area

Filtering LSAs in an area can prevent unnecessary LSA transmission. This reduces the size of the LSDB on the neighboring router and speeds up network convergence.

Context

After filtering conditions are set for the incoming or outgoing Type 3 LSAs (Summary LSAs) in an area, only the Type 3 LSAs that meet the filtering conditions can be received or advertised.

This function is applicable only to the ABR.

Perform the following steps on the router running OSPF.

Procedure

Step 1 Run:

system-view

The system view is displayed.

Step 2 Run:

ospf [ process-id ]

The OSPF process view is displayed.

Step 3 Run:

area area-id

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The OSPF area view is displayed.

Step 4 Filter incoming or outgoing Type 3 LSAs in the area.

l Filter incoming Type 3 LSAs in the area.

Run the filter { acl-number | acl-name acl-name | ip-prefix ip-prefix-name | route-policy

route-policy-name } export command to filter incoming Type 3 LSAs in the area.

l Filter outgoing Type 3 LSAs in the area.

Run the filter { acl-number | acl-name acl-name | ip-prefix ip-prefix-name | route-policy

route-policy-name } import command to filter outgoing Type 3 LSAs in the area.

----End

5.6.8 (Optional) Enabling the Mesh-Group Function

The mesh-group function is used to prevent repeated flooding and save system resources.

Context

When concurrent links exist between two routers, you can enable the mesh-group function to reduce the load on the links.

The neighboring router ID identifies each mesh group. Several concurrent links are added to a mesh group. Flooding is implemented once in the group. You can add interfaces that meet the following conditions to the same mesh group.

l The interfaces belong to the same area and OSPF process.

l The interfaces begin to exchange DD packets.

l The interfaces are connected to the same neighboring router.

Perform the following steps on the router running OSPF.

Procedure

Step 1 Run:

system-view

The system view is displayed.

Step 2 Run:

ospf [ process-id ]

The OSPF process view is displayed.

Step 3 Run:

mesh-group enable

The mesh-group function is enabled.

By default, the mesh-group function is disabled.

----End

5.6.9 Setting the Maximum Number of External LSAs in the LSDB

You can set the maximum number of external LSAs in the LDSB to keep a proper number of external LSAs.

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Procedure

Step 1 Run:

system-view

The system view is displayed.

Step 2 Run:

ospf [ process-id ]

The OSPF process view is displayed.

Step 3 Run:

lsdb-overflow-limit number

The maximum number of external LSAs in the LSDB is set.

----End

5.6.10 Checking the Configuration

After controlling OSPF routing information, you can check information about the OSPF routing table, interface, and ASBR summarization.

Prerequisites

The configurations of controlling OSPF routing information are complete.

Procedure

l Run either of the following commands to check routing table information.

–

display ospf [ process-id ] routing [ ip-address [ mask | mask-length ] ] [ interface

interface-type interface-number ] [ nexthop nexthop-address ]

–

display ospf [ process-id ] routing router-id [ router-id ] l Run the display ospf [ process-id ] interface [ all | interface-type interface-number ]

[ verbose ] command to check OSPF interface information.

l Run the display ospf [ process-id ] asbr-summary [ ip-address mask ] command to check

OSPF ASBR summarization information.

----End

5.7 Configuring an OSPF Stub Area

Applicable Environment

The number of LSAs can be reduced by partitioning an AS into different areas. To reduce the number of entries in the routing table and the number of LSAs to be transmitted in a nonbackbone area, configure the non-backbone area on the border of the AS as a stub area.

Configuring a stub area is optional. A stub area generally resides on the border of an AS. For example, a non-backbone area with only one ABR can be configured as a stub area. In a stub

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Note the following points when configuring a stub area: l The backbone area (Area 0) cannot be configured as a stub area.

If an area needs to be configured as a stub area, all the routers in this area must be configured with stub attributes using the stub command.

l An ASBR cannot exist in a stub area. External routes are not transmitted in the stub area.

Virtual links cannot exist in the stub area.

Pre-configuration Tasks

Before configuring a stub area, complete the following tasks: l Configuring IP addresses for interfaces to ensure that neighboring routers are reachable at the network layer l

Data Preparation

To configure a stub area, you need the following data.

No.

Data

1 (Optional) Cost of the default route to the stub area

NOTE

By default, the cost of the default route to the stub area is 1.

Procedure

Step 1 Run:

system-view

The system view is displayed.

Step 2 Run:

ospf [ process-id ]

The OSPF process view is displayed.

Step 3 Run:

area area-id

The OSPF area view is displayed.

Step 4 Run:

stub

The specified area is configured as a stub area.

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NOTE

l All routers in a stub area must be configured with stub attributes using the stub command.

l Configuring or deleting stub attributes will update routing information in the area. Stub attributes can be deleted or configured again only after the routing update is complete.

Step 5 (Optional) Run:

stub [ no-summary ]

The ABR is prevented from sending Type 3 LSAs to the stub area.

Step 6 (Optional) Run:

default-cost cost

The cost of the default route to the stub area is set.

To ensure the reachability of AS external routes, the ABR in the stub area generates a default route and advertises the route to the non-ABR routers in the stub area.

By default, the cost of the default route to the stub area is 1.

----End

Checking the Configuration

Run either of the following commands to check LSDB information.

link | opaque-area | opaque-as ] [ link-state-id ] [ originate-router [ advertising-router-

id ] | self-originate ] [ age { min-value min-age-value | max-value max-age-value }

]

Run either of the following commands to check routing table information.

l display ospf [ process-id ] routing [ ip-address [ mask | mask-length ] ] [ interface

interface-type interface-number ] [ nexthop nexthop-address ] l display ospf [ process-id ] routing router-id [ router-id ]

Run the display ospf [ process-id ] abr-asbr [ router-id ] command to check ASBR and ABR information.

5.8 Configuring an NSSA

Applicable Environment

An NSSA is configured in the scenario where AS external routes are to be imported but not forwarded to save system resources.

The NSSA is a new type of OSPF area. Neither the NSSA nor the stub area transmits routes learned from other areas in the AS it resides. The stub area does not allow AS external routes to be imported, whereas the NSSA allows AS external routes to be imported and forwarded in the entire AS.

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Type 7 LSAs are used to carry imported AS external routing information in the NSSA. Type 7

LSAs are generated by the ASBRs of NSSAs and flooded only in the NSSAs where ASBRs reside. The ABR in an NSSA selects certain Type 7 LSAs from the received ones and translates them into Type 5 LSAs to advertise AS external routing information to the other areas over the

OSPF network.

To configure an area as an NSSA, configure NSSA attributes on all the routers in this area.

Pre-configuration Tasks

Before configuring an NSSA, complete the following tasks: l Configuring IP addresses for interfaces to ensure that neighboring routers are reachable at the network layer l

Data Preparation

To configure an NSSA, you need the following data.

No.

Data

1 (Optional) Cost of the default route to the NSSA

NOTE

By default, the cost of the default route to the NSSA is 1.

Procedure

Step 1 Run:

system-view

The system view is displayed.

Step 2 Run:

ospf [ process-id ]

The OSPF process view is displayed.

Step 3 Run:

area area-id

The OSPF area view is displayed.

Step 4 Run:

nssa [ default-route-advertise | flush-waiting-timer interval-value | no-import-

translator-interval interval-value | zero-address-forwarding ]

The specified area is configured as an NSSA.

NOTE

l All routers in the NSSA must be configured with NSSA attributes using the nssa command.

l Configuring or deleting NSSA attributes may trigger routing update in the area. A second configuration of NSSA attributes can be implemented or canceled only after routing update is complete.

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The nssa command is applicable to the following scenarios: l The parameter default-route-advertise is used to advertise Type 7 LSAs carrying the default route on the ABR or ASBR to the NSSA.

Type 7 LSAs carrying the default route will be generated regardless of whether the default route 0.0.0.0 exists in the routing table on the ABR. On the ASBR, however, the default Type

7 LSA is generated only when the default route 0.0.0.0 exists in the routing table.

l When the area to which the ASBR belongs is configured as an NSSA, invalid Type 5 LSAs from other routers in the area where LSAs are flooded will be reserved. These LSAs will be deleted only when the aging time reaches 3600s. The router performance is affected because the forwarding of a large number of LSAs consumes the memory resources. To resolve such a problem, you can set the parameter flush-waiting-timer to the maximum value 3600s for

Type 5 LSAs so that the invalid Type 5 LSAs from other routers can be deleted in time.

NOTE

l When the LS age field value (aging time) in the header of an LSA reaches 3600s, the LSA is deleted.

l If an ASBR also functions as an ABR, flush-waiting-timer does not take effect. This prevents

Type 5 LSAs in the non-NSSAs from being deleted.

l If an ASBR also functions as an ABR, set the parameter no-import-route to prevent external routes imported using the import-route command from being advertised to the NSSA.

l To reduce the number of LSAs that are transmitted to the NSSA, set the parameter no-

summary on an ABR. This prevents the ABR from transmitting Type 3 LSAs to the NSSA.

l After the parameter set-n-bit is configured, the router re-establishes neighbor relationships with the neighboring routers in the NSSA.

l If multiple ABRs are deployed in the NSSA, the system automatically selects an ABR

(generally the router with the largest router ID) as a translator to translate Type 7 LSAs into

Type 5 LSAs. You can also configure the parameter translator-always on an ABR to specify the ABR as an all-the-time translator. To specify two ABRs for load balancing, configure the parameter translator-always on two ABRs to specify the ABRs as all-the-time translators. This prevents LSA flooding caused by translator role changes.

l The parameter translator-interval is used to ensure uninterrupted services when translator roles change. The interval-value value must be greater than the flooding period.

Step 5 (Optional)Run:

default-cost cost

The cost of the default route to the NSSA is set.

To ensure the reachability of AS external routes, the ABR in the NSSA generates a default route and advertises the route to the other routers in the NSSA.

Type 7 LSAs can be used to carry default route information to guide traffic to other ASs.

Multiple ABRs may be deployed in an NSSA. To prevent routing loops, ABRs do not calculate the default routes advertised by each other.

By default, the cost of the default route to the NSSA is 1.

----End

Checking the Configuration

Run either of the following commands to check LSDB information.

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link | opaque-area | opaque-as ] [ link-state-id ] [ originate-router [ advertising-router-

id ] | self-originate ]

Run either of the following commands to check routing table information.

l display ospf [ process-id ] routing [ ip-address [ mask | mask-length ] ] [ interface

interface-type interface-number ] [ nexthop nexthop-address ] l display ospf [ process-id ] routing router-id [ router-id ]

Run the display ospf [ process-id ] interface [ all | interface-type interface-number ]

[ verbose ] command to check OSPF interface information.

5.9 Configuring BFD for OSPF

5.9.1 Establishing the Configuration Task

Before configuring BFD for OSPF, familiarize yourself with the applicable environment, complete the pre-configuration tasks, and obtain the data required for the configuration. This will help you complete the configuration task quickly and efficiently.

Applicable Environment

OSPF enables the router to periodically send Hello packets to a neighboring router for fault detection. Detecting a fault takes more than 1s. As technologies develop, voice, video, and other

VOD services are widely used. These services are quite sensitive to packet loss and delays. When traffic is transmitted at gigabit rates, long-time fault detection will cause packet loss. This cannot meet high reliability requirements of the carrier-class network.

BFD for OSPF is introduced to resolve this problem. After BFD for OSPF is configured in a specified process or on a specified interface, the link status can be rapidly detected and fault detection can be completed in milliseconds. This speeds up OSPF convergence when the link status changes.

NOTE

Pre-configuration Tasks

Before configuring BFD for OSPF, complete the following task: l Configuring IP addresses for interfaces to ensure that neighboring routers are reachable at the network layer l

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Data Preparation

To configure BFD for OSPF, you need the following data.

No.

Data

1 Number of the OSPF process to be enabled with BFD for OSPF

2 Type and number of the interface to be enabled with BFD for OSPF

3 (Optional) Values of BFD session parameters

NOTE

The default parameter values are recommended.

5.9.2 Configuring BFD for OSPF in a Specified Process

Configuring BFD for OSPF in a specified process helps the system to rapidly detect the link status and speeds up OSPF convergence in the case of a link failure.

Context

After BFD for OSPF is configured, when detecting a link fault, BFD rapidly notifies the routers on both ends of the link of the fault, triggering rapid OSPF convergence. When the OSPF neighbor relationship goes Down, the BFD session will be dynamically deleted.

Before configuring BFD for OSPF, enable BFD globally.

Perform the following steps on the routers between which a BFD session is to be created.

Procedure

Step 1 Run:

system-view

The system view is displayed.

Step 2 Run:

bfd

BFD is globally configured.

Step 3 Run:

quit

Return to the system view.

Step 4 Run:

ospf [ process-id ]

The OSPF process view is displayed.

Step 5 Run:

bfd all-interfaces enable

BFD for OSPF is configured. The default parameter values are used to create a BFD session.

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If all the interfaces in a certain process are configured with BFD and their neighbor relationships are in the Full state, OSPF creates BFD sessions with default parameter values on all the interfaces in the process.

Step 6 (Optional) Run:

bfd all-interfaces { min-rx-interval receive-interval | min-tx-interval transmit-

interval | detect-multiplier multiplier-value }

BFD session parameters are modified.

You can skip this step. The default interval at which BFD packets are transmitted and the default detection multiplier are recommended.

The parameters are configured based on the network status and network reliability requirements.

A short interval at which BFD packets are transmitted can be configured for a link that has a higher requirement for reliability. A long interval at which BFD packets are transmitted can be configured for a link that has a lower requirement for reliability.

NOTE

l Actual interval at which BFD packets are transmitted on the local router = Max { configured interval

transmit-interval at which BFD packets are transmitted on the local router, configured interval receive-

interval at which BFD packets are received on the peer router } l Actual interval at which BFD packets are received on the local router = Max { configured interval transmit-

interval at which BFD packets are transmitted on the peer router, configured interval receive-interval at which BFD packets are received on the local router } l Actual time for detecting BFD packets = Actual interval at which BFD packets are received on the local router x Configured detection multiplier multiplier-value on the peer router

For example: l On the local router, the configured interval at which BFD packets are transmitted is 200 ms; the configured interval at which BFD packets are received is 300 ms; the detection multiplier is 4.

l On the peer router, the configured interval at which BFD packets are transmitted is 100 ms; the interval at which BFD packets are received is 600 ms; the detection multiplier is 5.

Then: l On the local router, the actual interval at which BFD packets are transmitted is 600 ms calculated by using the formula max {200 ms, 600 ms}; the interval at which BFD packets are received is 300 ms calculated by using the formula max {100 ms, 300 ms}; the detection period is 1500 ms calculated by multiplying 300 ms by 5.

l On the peer router, the actual interval at which BFD packets are transmitted is 300 ms calculated by using the formula max {100 ms, 300 ms}, the actual interval at which BFD packets are received is 600 ms calculated by using the formula max {200 ms, 600 ms}, and the detection period is 2400 ms calculated by multiplying

600 ms by 4.

Step 7 (Optional) Prevent an interface from dynamically creating a BFD session.

After BFD for OSPF is configured, all interfaces on which neighbor relationships are Full in the

OSPF process will create BFD sessions. To prevent specific interfaces from being enabled with

BFD, disable these interfaces from dynamically creating BFD sessions.

Run:

quit

Return to the system view.

Run:

interface interface-type interface-number

The interface view is displayed.

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Run:

ospf bfd block

An interface is prevented from dynamically creating a BFD session.

----End

5.9.3 Configuring BFD for OSPF on a Specified Interface

Configuring BFD for OSPF on a specified interface helps speed up OSPF convergence in the case of an interface failure.

Context

After BFD for OSPF is configured on a specified interface and the interface becomes faulty, the router rapidly detects the fault and instructs OSPF to recalculate routes. This speeds up OSPF convergence. When the OSPF neighbor relationship goes Down, the BFD session between OSPF neighbors is dynamically deleted.

Before configuring BFD for OSPF, enable BFD globally.

Perform the following steps on the router:

Procedure

Step 1 Run:

system-view

The system view is displayed.

Step 2 Run:

bfd

BFD is globally configured.

Step 3 Run:

quit

Return to the system view.

Step 4 Run:

interface interface-type interface-number

The interface view is displayed.

Step 5 Run:

ospf bfd enable

BFD for OSPF is configured. The default parameter values are used to create a BFD session.

NOTE

The priority of BFD for OSPF configured on an interface is higher than that of BFD for OSPF configured for a process.

Step 6 (Optional) Run:

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ospf bfd { min-rx-interval receive-interval | min-tx-interval transmit-interval |

detect-multiplier multiplier-value }

BFD session parameters are modified.

You can skip this step. The default interval at which BFD packets are transmitted and the default detection multiplier are recommended.

The parameters are configured based on the network status and network reliability requirements.

NOTE

l Actual interval at which BFD packets are transmitted on the local router = Max { configured interval

transmit-interval at which BFD packets are transmitted on the local router, configured interval receive-

interval at which BFD packets are received on the peer router } l Actual interval at which BFD packets are received on the local router = Max { configured interval transmit-

For example: l On the local router, the configured interval at which BFD packets are transmitted is 200 ms; the interval at which BFD packets are received is set to 300 ms; the detection multiplier is 4.

l On the peer router, the configured interval at which BFD packets are transmitted is 100 ms; the interval at which BFD packets are received is 600 ms; the detection multiplier is 5.

600 ms by 4.

----End

5.9.4 Checking the Configuration

After configuring BFD for OSPF, you can view information about the BFD session between two OSPF neighbors.

Prerequisites

All BFD for OSPF configurations are complete.

Procedure

l Run the display ospf [process-id ] bfd session interface-type interface-number [ router-

id ] or display ospf [process-id ] bfd session { router-id | all } command to check information about the BFD session between two OSPF neighbors.

----End

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5.10 Configuring OSPF GR

Configuring OSPF GR to avoid traffic interruption and route flapping caused by the active/ standby switchover.

5.10.1 Establishing the Configuration Task

Before configuring OSPF GR, familiarize yourself with the applicable environment, complete the pre-configuration tasks, and obtain the data required for the configuration. This will help you complete the configuration task quickly and efficiently.

Applicable Environment

To avoid traffic interruption and route flapping caused by the active/standby switchover, you can enable OSPF GR.

After the OSPF process is restarted through GR, the Restarter and the Helper reestablish the neighbor relationship, exchange routing information, synchronize the LSDB, and update the routing table and forwarding table. These operations ensure the fast convergence of OSPF and the stability the network topology.

NOTE

In practical applications, you can configure OSPF GR on the dual main control boards to avoid service forwarding from being affected by the fault occurred on the main control board.

The AR150/200 can function as only the Helper router, but cannot function as the Restarter router.

Pre-configuration Tasks

Before configuring OSPF GR, complete the following tasks: l Configuring IP addresses for interfaces to ensure that neighboring routers are reachable at the network layer l

Data Preparation

To configure OSPF GR, you need the following data.

No.

Data

1 OSPF process number

2 (Optional) Parameters for establishing GR sessions

NOTE

The default parameter values are recommended.

5.10.2 Enabling OSPF GR

Enabling OSPF GR to ensure the fast convergence of OSPF and the stability the network topology.

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Procedure

Step 1 Run:

system-view

The system view is displayed.

Step 2 Run:

ospf [ process-id ]

The OSPF view is displayed.

Step 3 Run:

opaque-capability enable

The opaque-LSA function is enabled.

The opaque-LSA feature of OSPF needs to be enabled first because OSPF supports GR through

Type 9 LSAs.

Step 4 Run:

graceful-restart

The OSPF GR feature is enabled.

----End

5.10.3 (Optional) Configuring the GR Session Parameters on the

Restarter

This part describes how to set GR session parameters (including GR period, planned GR, and totally GR) on the Restarter.

Procedure

Step 1 Run:

system-view

The system view is displayed.

Step 2 Run:

ospf [ process-id ]

The OSPF view is displayed.

Step 3 Run:

graceful-restart [ period period | planned-only | partial ]

The GR session parameters is set.

l Set period, the GR period on the Restarter is set. By default, the restart time is 120 seconds.

l Set planned-only, the Restarter supports only the planned GR. By default, the Restarter supports both the planned GR and unplanned GR.

l Set partial, the Restarter supports the partial GR. By default, the Restarter supports the totally

GR.

----End

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5.10.4 (Optional) Configuring GR Session Parameters on the Helper

This part describes how to set GR session parameters (including the filtering policies, checks the LSAs outside the AS, and Planned GR) on the Helper.

Procedure

Step 1 Run:

system-view

The system view is displayed.

Step 2 Run:

ospf [ process-id ]

The OSPF view is displayed.

Step 3 Run:

graceful-restart helper-role { [ { ip-prefix ip-prefix-name | acl-number acl-

number | acl-name acl-name } | ignore-external-lsa | planned-only ]

| never }

The GR session parameters is set.

l Set ACL parameters, the local router can enter the Helper mode only after neighbors pass the filtering policies of ip-prefix or acl.

l Set ignore-external-lsa, the Helper does not check the LSAs outside the AS (AS-external

LSA). By default, the Helper checks the LSAs outside the AS.

l Set planned-only, the Helper supports only the planned GR. By default, the Helper supports both the planned GR and unplanned GR.

l Set never, the router does not support the Helper mode.

----End

5.10.5 Checking the Configuration

After OSPF GR is configured, you can check the OSPF GR status.

Prerequisites

The configurations for the OSPF GR are complete.

Procedure

l Run the display ospf [ process-id ] graceful-restart [ verbose ] command to check the restart status of OSPF GR.

----End

5.11 Improving Security of an OSPF Network

On a network demanding high security, you can adopt the GTSM mechanism and configure

OSPF authentication to improve the security of the OSPF network.

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5.11.1 Establishing the Configuration Task

Before improving the security of an OSPF network, familiarize yourself with the applicable environment, complete pre-configuration tasks, and obtain the required data. This can help you complete the configuration task quickly and accurately.

Applicable Environment

In a network demanding high security, you can configure OSPF authentication and adopt the

GTSM mechanism to improve the security of the OSPF network.

The GTSM mechanism defends against attacks by checking the TTL value. If an attacker keeps sending packets to a router by simulating real OSPF unicast packets, the router finds itself is the destination of the packets after the interface board receives these packets. The router directly sends the packets to the control plane for OSPF processing without checking the validity of the packets. The router busies itself with processing these "valid" packets. As a result, the system is busy, and the CPU is highly occupied.

The GTSM mechanism protects a router by checking whether the TTL value in the IP packet header is in a pre-defined range to enhance the system security.

NOTE

GTSM supports only unicast addresses; therefore, in OSPF, GTSM takes effect on the virtual link and the sham link.

Pre-configuration Tasks

Before improving the security of an OSPF network, complete the following tasks: l

Configuring IP addresses for interfaces to make neighboring nodes reachable l

Data Preparation

To improve the security of an OSPF network, you need the following data.

No.

Data

1 OSPF process ID

(Optional) Names of VPN instances of OSPF

(Optional) TTL value to be checked

ID of an OSPF area that needs to be configured with authentication

Number of an OSPF interface that needs to be configured with authentication

Authentication mode and password

5.11.2 Configuring the OSPF GTSM Functions

The GTSM defends against attacks by checking the TTL value.

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Context

5 OSPF Configuration

To apply GTSM functions, enable GTSM on the two ends of the OSPF connection.

The valid TTL range of the detected packets is [255 -hops + 1, 255].

GTSM checks the TTL value of only the packet that matches the GTSM policy. For the packets that do not match the GTSM policy, you can set them as "pass" or "drop". If the GTSM default action performed on the packet is set as "drop", you need to configure all the router connections for GTSM. If the packets sent from a router do not match the GTSM policy, they are dropped.

The connection thus cannot be established. This ensures security but reduces the ease of use.

You can enable the log function to record the information that the packets are dropped. This is convenient for fault location.

Procedure

Step 1 Run:

system-view

The system view is displayed.

Step 2 Run:

ospf valid-ttl-hops hops [ vpn-instance vpn-instance-name ]

OSPF GTSM functions are configured.

NOTE

The ospf valid-ttl-hops command has two functions: l Enabling OSPF GTSM l Configuring the TTL value to be detected

The parameter vpn-instance is valid only for the latter function.

Thus, if the private network policy or the public network policy is configured only, it is recommended to set the default action performed on the packets that do not match the GTSM policy as pass. This prevents the OSPF packets of other processes from being discarded incorrectly.

Step 3 (Optional) Run:

gtsm default-action { drop | pass }

The default action performed on the packets that do not match the GTSM policy is set.

By default, the packets that do not match the GTSM policy can pass the filtering.

NOTE

If the default action is configured but the GTSM policy is not configured, GTSM does not take effect.

Step 4 (Optional) Run:

gtsm log drop-packet all

The log function is enabled on the specified board in the system view. The information that

GTSM drops packets is recorded in the log.

----End

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5.11.3 Configuring the Authentication Mode

OSPF supports packet authentication. Only the packets that pass the authentication can be received. If packets fail to pass the authentication, the neighbor relationship cannot be established.

Context

5 OSPF Configuration

In area authentication, all the routers in an area must use the same area authentication mode and password. For example, the authentication mode of all devices in Area 0 is simple authentication and the password is abc.

The interface authentication mode is used among neighbor routers to set the authentication mode and password. Its priority is higher than that of the area authentication mode.

Procedure

l Configuring the Area Authentication Mode

Run:

system-view

The system view is displayed.

Run:

ospf [ process-id ]

The OSPF process view is displayed.

Run:

area area-id

The OSPF area view is displayed.

Run the following commands to configure the authentication mode of the OSPF area as required:

–

Run:

authentication-mode simple [ [ plain ] plain-text | cipher cipher-

text ]

The simple authentication is configured for the OSPF area.

– Run:

authentication-mode { md5 | hmac-md5 } [ key-id { plain plain-text |

[ cipher ] cipher-text } ]

The MD5 authentication is configured for the OSPF area.

OSPF supports packet authentication. Only the OSPF packets passing the authentication can be received; otherwise, the neighbor relationship cannot be established normally.

All the routers in an area must agree on the same area authentication mode and password. For example, the authentication mode of all routers in area 0 is simple authentication, and the password is abc.

– Run:

authentication-mode keychain keychain-name

The Keychain authentication is configured for the OSPF area.

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NOTE

Before using the Keychain authentication, you need to configure Keychain information in the system view. To establish the OSPF neighbor relationship, you need to ensure that the

key-id, algorithm, and key-string of the local ActiveSendKey are the same as those of the remote ActiveRecvKey.

l Configuring the Interface Authentication Mode

Run:

system-view

The system view is displayed.

Run:

interface interface-type interface-number

The interface view is displayed.

Run the following commands to configure the interface authentication mode as required:

–

Run:

ospf authentication-mode simple [ [ plain ] plain-text | cipher cipher-

text ]

The simple authentication is configured for the OSPF interface.

–

Run:

ospf authentication-mode { md5 | hmac-md5 } [ key-id { plain plain-

text | [ cipher ] cipher-text } ]

The MD5 authentication is configured for the OSPF interface.

– Run:

ospf authentication-mode null

The non-authentication mode is configured for the OSPF interface.

–

Run:

ospf authentication-mode keychain keychain-name

The Keychain authentication is configured for the OSPF area.

NOTE

Before using the Keychain authentication, you need to configure Keychain information in the system view. To establish the OSPF neighbor relationship, you need to ensure that the

key-id, algorithm, and key-string of the local ActiveSendKey are the same as those of the remote ActiveRecvKey.

The authentication mode and password of interfaces in the same network segment must be consistent except the Keychain authentication mode. If the interfaces are in different network segments, the authentication mode and password of the interfaces can be different.

----End

5.11.4 Checking the Configuration

After OSPF features are configured to improve the stability of an OSPF network, you can check

GTSM statistics and brief statistics.

Prerequisites

The configurations for Improving Security of an OSPF Network are complete.

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Procedure

5 OSPF Configuration l Run the display gtsm statistics all command to check the GTSM statistics.

l Run the display ospf [ process-id ] request-queue [ interface-type interface-number ]

[neighbor-id ] command to check the OSPF request queue.

l Run the display ospf [ process-id ] retrans-queue [ interface-type interface-number ]

[ neighbor-id ] command to check the OSPF retransmission queue.

Run the display ospf [ process-id ] error [ lsa ] or display ospf error [ packet

[ number ] ] command to check the OSPF error information.

----End

5.12 Configuring the Network Management Function of

OSPF

OSPF supports the network management function. You can bind the OSPF MIB to a certain

OSPF process, and configure the trap function and log function.

5.12.1 Establishing the Configuration Task

Before configuring the network management function for OSPF, familiarize yourself with the applicable environment, complete pre-configuration tasks, and obtain the required data. This can help you complete the configuration task quickly and accurately.

Applicable Environment

OSPF supports the network management function. You can bind OSPF MIB and a certain OSPF process. In addition, OSPF also supports the trap function and the log function.

Pre-configuration Tasks

Before configuring the network management function of OSPF, complete the following tasks: l Configuring IP addresses for interfaces to make neighboring nodes reachable l

Data Preparation

To configuring the network management function of OSPF, you need the following data.

No.

Data

1 OSPF process ID

5.12.2 Configuring OSPF MIB Binding

The MIB is a virtual database of the device status maintained by the managed devices.

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Context

When multiple OSPF processes are enabled, you can configure OSPF MIB to select the process to be processed, that is, configure OSPF MIB to select the process to which it is bound.

Do as follows on the OSPF router:

Procedure

Step 1 Run:

system-view

The system view is displayed.

Step 2 Run:

ospf mib-binding process-id

OSPF MIB binding is configured.

----End

5.12.3 Configuring OSPF Trap

Traps are the notifications sent from a router to inform the NMS of the fault detected by the system.

Context

Do as follows on the OSPF router.

Procedure

Step 1 Run:

system-view

The system view is displayed.

Step 2 Run:

snmp-agent trap enable feature-name ospf [ trap-name { ospfifauthfailure |

ospfifconfigerror | ospfifrxbadpacket | ospfifstatechange |

ospflsdbapproachingoverflow | ospflsdboverflow | ospfmaxagelsa |

ospfnbrrestarthelperstatuschange | ospfnbrstatechange |

ospfnssatranslatorstatuschange | ospforiginatelsa | ospfrestartstatuschange |

ospftxretransmit | ospfvirtifauthfailure | ospfvirtifconfigerror |

ospfvirtifrxbadpacket | ospfvirtifstatechange | ospfvirtiftxretransmit |

ospfvirtnbrrestarthelperstatuschange | ospfvirtnbrstatechange } ]

The trap function for the OSPF module is enabled.

To enable the traps of one or more events, you can specify type-name.

----End

5.12.4 Configuring OSPF Log

Logs record the operations (such as configuring commands) and specific events (such as the network connection failure) on routers.

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Context

Do as follows on the OSPF router:

5 OSPF Configuration

Procedure

Step 1 Run:

system-view

The system view is displayed.

Step 2 Run:

ospf [ process-id ]

The OSPF process view is displayed.

Step 3 Run:

enable log [ config | error | state | snmp-trap ]

The log function is enabled.

----End

5.12.5 Checking the Configuration

After the network management function is configured for OSPF, you can check the contents of the information channel, information recorded in the information center, log buffer, and trap buffer.

Prerequisites

The configurations for the network management function of OSPF are complete.

Procedure

l Run the display ospf [ process-id ] brief command to view information about the binding of OSPF MIBs and OSPF processes.

l Run the display snmp-agent trap feature-name ospf all command to view all trap messages of the OSPF module.

----End

5.13 Maintaining OSPF

Maintaining OSPF involves resetting OSPF and clearing OSPF statistics.

5.13.1 Resetting OSPF

Restarting OSPF can reset OSPF. In addition, you can reset OSPF through GR.

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Context

5 OSPF Configuration

CAUTION

The OSPF neighbor relationship is deleted after you reset OSPF connections with the reset

ospf command. Exercise caution when running this command.

To reset OSPF connections, run the following reset ospf commands in the user view.

Procedure

l Run the reset ospf [ process-id ] process [ flush-waiting-timer time ] command in the user view to Restart the OSPF process.

l Run the reset ospf [ process-id ] process [ graceful-restart ] command in the user view to Restart the OSPF process in GR mode.

----End

5.13.2 Clearing OSPF

This section describes how to clear OSPF statistics, including OSPF counters, imported routes, and GTSM statistics on the board.

Context

CAUTION

OSPF information cannot be restored after being cleared. Exercise caution when running this command.

To clear the OSPF information, run the following reset ospf commands in the user view.

Procedure

l Run the reset ospf [ process-id ] counters [ neighbor [ interface-type interface-number ]

[ router-id ] ] command in the user view to clear OSPF counters.

l Run the reset ospf [ process-id ] redistribution command in the user view to clear the routes imported by OSPF.

l Run the reset gtsm statistics all command in the user view to clear the GTSM statistics on the board.

----End

5.14 Configuration Examples

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5.14.1 Example for Configuring Basic OSPF Functions

This part provides an example for configuring basic OSPF functions. Detailed operations include enabling OSPF on each router and specifying network segments in different areas.

Networking Requirements

, all routers run OSPF, and the entire AS is divided into three areas.

Figure 5-5

Router A and Router B serve as ABRs to forward routes between areas.

After the configuration, each router should learn the routes from the AS to all network segments.

NOTE

AR150/200 is RouterE or RouterF.

Figure 5-5 Networking diagram of configuring basic OSPF functions

RouterA

Area0

Eth1/0/0

192.168.0.1/24

Eth1/0/0

192.168.0.2/24

Eth2/0/0

192.168.1.1/24

Eth1/0/0

192.168.1.2/24

ASBR

RouterC

Eth2/0/0

172.16.1.1/24

Eth2/0/0

172.16.1.2/24

RouterE

Area1

Stub

RouterB

Eth2/0/0

192.168.2.1/24

Eth1/0/0

192.168.2.2/24

ASBR

RouterD

Eth2/0/0

172.17.1.1/24

Eth2/0/0

172.17.1.2/24

RouterF

Area2

Configuration Roadmap

The configuration roadmap is as follows:

Enable OSPF on each router.

Specify network segments in different areas.

Data Preparation

To complete the configuration, you need the following data: l The router ID of Router A is 1.1.1.1, the OSPF process number is 1, the network segment of Area 0 is 192.168.0.0/24, and the network segment of Area 1 is 192.168.1.0/24.

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5 OSPF Configuration l The router ID of Router B is 2.2.2.2, the OSPF process number is 1, the network segment of Area 0 is 192.168.0.0/24, and the network segment of Area 2 is 192.168.2.0/24.

l The router ID of Router C is 3.3.3.3, the OSPF process number is 1, and the network segments of Area 1 are 192.168.1.0/24 and 172.16.1.0/24.

l The router ID of Router D is 4.4.4.4, the OSPF process number is 1, and the network segments of Area 2 are 192.168.2.0/24 and 172.17.1.0/24.

l The router ID of Router E is 5.5.5.5, the OSPF process number is 1, and the network segment of Area 1 is 172.16.1.0/24.

l The router ID of Router F is 6.6.6.6, the OSPF process number is 1, and the network segment of Area 2 is 172.17.1.0/24.

Procedure

Step 1 Configure an IP address for each interface.

The configuration details are not mentioned here.

Step 2 Configure basic OSPF functions.

# Configure Router A.

[RouterA] router id 1.1.1.1

[RouterA] ospf

[RouterA-ospf-1] area 0

[RouterA-ospf-1-area-0.0.0.0] network 192.168.0.0 0.0.0.255

[RouterA-ospf-1-area-0.0.0.0] quit

[RouterA-ospf-1] area 1

[RouterA-ospf-1-area-0.0.0.1] network 192.168.1.0 0.0.0.255

[RouterA-ospf-1-area-0.0.0.1] quit

# Configure Router B.

[RouterB] router id 2.2.2.2

[RouterB] ospf

[RouterB-ospf-1] area 0

[RouterB-ospf-1-area-0.0.0.0] network 192.168.0.0 0.0.0.255

[RouterB-ospf-1-area-0.0.0.0] quit

[RouterB-ospf-1] area 2

[RouterB-ospf-1-area-0.0.0.2] network 192.168.2.0 0.0.0.255

[RouterB-ospf-1-area-0.0.0.2] quit

# Configure Router C.

[RouterC] router id 3.3.3.3

[RouterC] ospf

[RouterC-ospf-1] area 1

[RouterC-ospf-1-area-0.0.0.1] network 192.168.1.0 0.0.0.255

[RouterC-ospf-1-area-0.0.0.1] network 172.16.1.0 0.0.0.255

[RouterC-ospf-1-area-0.0.0.1] quit

# Configure Router D.

[RouterD] router id 4.4.4.4

[RouterD] ospf

[RouterD-ospf-1] area 2

[RouterD-ospf-1-area-0.0.0.2] network 192.168.2.0 0.0.0.255

[RouterD-ospf-1-area-0.0.0.2] network 172.17.1.0 0.0.0.255

[RouterD-ospf-1-area-0.0.0.2] quit

# Configure Router E.

[RouterE] router id 5.5.5.5

[RouterE] ospf

[RouterE-ospf-1] area 1

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[RouterE-ospf-1-area-0.0.0.1] network 172.16.1.0 0.0.0.255

[RouterE-ospf-1-area-0.0.0.1] quit

# Configure Router F.

[RouterF] router id 6.6.6.6

[RouterF] ospf

[RouterF-ospf-1] area 2

[RouterF-ospf-1-area-0.0.0.2] network 172.17.1.0 0.0.0.255

[RouterF-ospf-1-area-0.0.0.2] quit

Step 3 Verify the configuration.

# View OSPF neighbors of Router A.

[RouterA] display ospf peer

OSPF Process 1 with Router ID 1.1.1.1

Neighbors

Area 0.0.0.0 interface 192.168.0.1(Ethernet1/0/0)'s neighbors

Router ID: 2.2.2.2 Address: 192.168.0.2

State: Full Mode:Nbr is Master Priority: 1

DR: 192.168.0.2 BDR: 192.168.0.1 MTU: 0

Dead timer due in 36 sec

Retrans timer interval: 5

Neighbor is up for 00:15:04

Authentication Sequence: [ 0 ]

Neighbors

Area 0.0.0.1 interface 192.168.1.1(Ethernet2/0/0)'s neighbors

Router ID: 3.3.3.3 Address: 192.168.1.2

State: Full Mode:Nbr is Master Priority: 1

DR: 192.168.1.2 BDR: 192.168.1.1 MTU: 0

Dead timer due in 39 sec

Retrans timer interval: 5

Neighbor is up for 00:07:32

Authentication Sequence: [ 0 ]

# View the OSPF routing information of Router A.

[RouterA] display ospf routing

OSPF Process 1 with Router ID 1.1.1.1

Routing Tables

Routing for Network

Destination Cost Type NextHop AdvRouter Area

172.16.1.0/24 2 Transit 192.168.1.2 3.3.3.3 0.0.0.1

172.17.1.0/24 3 Inter-area 192.168.0.2 2.2.2.2 0.0.0.0

192.168.0.0/24 1 Stub 192.168.0.1 1.1.1.1 0.0.0.0

192.168.1.0/24 1 Stub 192.168.1.1 1.1.1.1 0.0.0.1

192.168.2.0/24 2 Inter-area 192.168.0.2 2.2.2.2 0.0.0.0

Total Nets: 5

Intra Area: 3 Inter Area: 2 ASE: 0 NSSA: 0

# View the LSDB of Router A.

[RouterA] display ospf lsdb

OSPF Process 1 with Router ID 1.1.1.1

Link State Database

Area: 0.0.0.0

Type LinkState ID AdvRouter Age Len Sequence Metric

Router 2.2.2.2 2.2.2.2 317 48 80000003 1

Router 1.1.1.1 1.1.1.1 316 48 80000002 1

Sum-Net 172.16.1.0 1.1.1.1 250 28 80000001 2

Sum-Net 172.17.1.0 2.2.2.2 203 28 80000001 2

Sum-Net 192.168.2.0 2.2.2.2 237 28 80000002 1

Sum-Net 192.168.1.0 1.1.1.1 295 28 80000002 1

Area: 0.0.0.1

Type LinkState ID AdvRouter Age Len Sequence Metric

Router 5.5.5.5 5.5.5.5 214 36 80000004 1

Router 3.3.3.3 3.3.3.3 217 60 80000008 1

Router 1.1.1.1 1.1.1.1 289 48 80000002 1

Network 172.16.1.1 3.3.3.3 670 32 80000001 0

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Sum-Net 172.17.1.0 1.1.1.1 202 28 80000001 3

Sum-Net 192.168.2.0 1.1.1.1 242 28 80000001 2

Sum-Net 192.168.0.0 1.1.1.1 300 28 80000001 1

# View the routing table of Router D and test connectivity by using the ping command.

[RouterD] display ospf routing

OSPF Process 1 with Router ID 4.4.4.4

Routing Tables

Routing for Network

Destination Cost Type NextHop AdvRouter Area

172.16.1.0/24 4 Inter-area 192.168.2.1 2.2.2.2 0.0.0.2

172.17.1.0/24 1 Transit 172.17.1.1 4.4.4.4 0.0.0.2

192.168.0.0/24 2 Inter-area 192.168.2.1 2.2.2.2 0.0.0.2

192.168.1.0/24 3 Inter-area 192.168.2.1 2.2.2.2 0.0.0.2

192.168.2.0/24 1 Stub 192.168.2.2 4.4.4.4 0.0.0.2

Total Nets: 5

Intra Area: 2 Inter Area: 3 ASE: 0 NSSA: 0

[RouterD] ping 172.16.1.1

PING 172.16.1.1: 56 data bytes, press CTRL_C to break

Reply from 172.16.1.1: bytes=56 Sequence=1 ttl=253 time=62 ms

Reply from 172.16.1.1: bytes=56 Sequence=2 ttl=253 time=16 ms

Reply from 172.16.1.1: bytes=56 Sequence=3 ttl=253 time=62 ms

Reply from 172.16.1.1: bytes=56 Sequence=4 ttl=253 time=94 ms

Reply from 172.16.1.1: bytes=56 Sequence=5 ttl=253 time=63 ms

--- 172.16.1.1 ping statistics ---

5 packet(s) transmitted

5 packet(s) received

0.00% packet loss

round-trip min/avg/max = 16/59/94 ms

----End

Configuration Files

l Configuration file of Router A

sysname RouterA

# interface Ethernet1/0/0

ip address 192.168.0.1 255.255.255.0

# interface Ethernet2/0/0

ip address 192.168.1.1 255.255.255.0

# ospf 1

area 0.0.0.0

network 192.168.0.0 0.0.0.255

area 0.0.0.1

network 192.168.1.0 0.0.0.255

# return l Configuration file of Router B

sysname RouterB

# router id 2.2.2.2

# interface Ethernet1/0/0

ip address 192.168.0.2 255.255.255.0

# interface Ethernet2/0/0

ip address 192.168.2.1 255.255.255.0

# ospf 1

area 0.0.0.0

network 192.168.0.0 0.0.0.255

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area 0.0.0.2

network 192.168.2.0 0.0.0.255

# return l Configuration file of Router C

sysname RouterC

# router id 3.3.3.3

# interface Ethernet1/0/0

ip address 192.168.1.2 255.255.255.0

# interface Ethernet2/0/0

ip address 172.16.1.1 255.255.255.0

# ospf 1

area 0.0.0.1

network 192.168.1.0 0.0.0.255

network 172.16.1.0 0.0.0.255

# return l Configuration file of Router D

sysname RouterD

# router id 4.4.4.4

# interface Ethernet1/0/0

ip address 192.168.2.2 255.255.255.0

# interface Ethernet2/0/0

ip address 172.17.1.1 255.255.255.0

# ospf 1

area 0.0.0.2

network 192.168.2.0 0.0.0.255

network 172.17.1.0 0.0.0.255

# return l Configuration file of Router E

sysname RouterE

# router id 5.5.5.5

# interface Ethernet2/0/0

ip address 172.16.1.2 255.255.255.0

# ospf 1

area 0.0.0.1

network 172.16.1.0 0.0.0.255

# return l Configuration file of Router F

sysname RouterF

# router id 6.6.6.6

# interface Ethernet2/0/0

ip address 172.17.1.2 255.255.255.0

# ospf 1

area 0.0.0.2

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network 172.17.1.0 0.0.0.255

# return

5.14.2 Example for Configuring DR Election of OSPF

This part provides an example for setting the DR priority on an interface for DR election on a broadcast network.

Networking Requirements

, Router A has the highest priority (100) in the network and is elected

Figure 5-6

as the DR. Router C has the second highest priority, and is elected as the BDR. The priority of

Router B is 0, and Router B cannot be elected as the DR or BDR. The priority of Router D is not configured and its default value is 1.

Figure 5-6 Configuring DR election of OSPF

RouterA RouterB

Eth1/0/0

192.168.1.1/24

Eth1/0/0

192.168.1.3/24

Eth1/0/0

192.168.1.2/24

Eth1/0/0

192.168.1.4/24

RouterC RouterD

Configuration Roadmap

The configuration roadmap is as follows:

Configure the router ID on each router, enable OSPF, and specify the network segment.

Check the DR/BDR status of each router with the default priority.

Configure the DR priority of the interface and check the DR/BDR status.

Data Preparation

To complete the configuration, you need the following data: l The router ID of Router A is 1.1.1.1 and the DR priority is 100.

l The router ID of Router B is 2.2.2.2 and the DR priority is 0.

l The router ID of Router C is 3.3.3.3 and the DR priority is 2.

l The router ID of Router D is 4.4.4.4 and the DR priority is 1.

Procedure

Step 1 Configure an IP address for each interface.

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The configuration details are not mentioned here.

Step 2 Configure basic OSPF functions.

# Configure Router A.

[RouterA] router id 1.1.1.1

[RouterA] ospf

[RouterA-ospf-1] area 0

[RouterA-ospf-1-area-0.0.0.0] network 192.168.1.0 0.0.0.255

[RouterA-ospf-1-area-0.0.0.0] quit

# Configure Router B.

[RouterB] router id 2.2.2.2

[RouterB] ospf

[RouterB-ospf-1] area 0

[RouterB-ospf-1-area-0.0.0.0] network 192.168.1.0 0.0.0.255

[RouterB-ospf-1-area-0.0.0.0] quit

# Configure Router C.

[RouterC] router id 3.3.3.3

[RouterC] ospf

[RouterC-ospf-1] area 0

[RouterC-ospf-1-area-0.0.0.0] network 192.168.1.0 0.0.0.255

[RouterC-ospf-1-area-0.0.0.0] quit

# Configure Router D.

[RouterD] router id 4.4.4.4

[RouterD] ospf

[RouterD-ospf-1] area 0

[RouterD-ospf-1-area-0.0.0.0] network 192.168.1.0 0.0.0.255

[RouterD-ospf-1-area-0.0.0.0] quit

# View the DR/BDR status.

[RouterA] display ospf peer

OSPF Process 1 with Router ID 1.1.1.1

Neighbors

Area 0.0.0.0 interface 192.168.1.1(Ethernet1/0/0)'s neighbors

Router ID: 2.2.2.2 Address: 192.168.1.2

State: Full Mode:Nbr is Master Priority: 1

DR: 192.168.1.4 BDR: 192.168.1.3 MTU: 0

Dead timer due in 32 sec

Retrans timer interval: 5

Neighbor is up for 00:04:21

Authentication Sequence: [ 0 ]

Router ID: 3.3.3.3 Address: 192.168.1.3

State: Full Mode:Nbr is Master Priority: 1

DR: 192.168.1.4 BDR: 192.168.1.3 MTU: 0

Dead timer due in 37 sec

Retrans timer interval: 5

Neighbor is up for 00:04:06

Authentication Sequence: [ 0 ]

Router ID: 4.4.4.4 Address: 192.168.1.4

State: Full Mode:Nbr is Master Priority: 1

DR: 192.168.1.4 BDR: 192.168.1.3 MTU: 0

Dead timer due in 37 sec

Retrans timer interval: 5

Neighbor is up for 00:03:53

Authentication Sequence: [ 0 ]

# View the neighbor information of Router A. You can see the priority of DR and the neighbor status. The Router D is the DR, and Router C is the BDR.

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NOTE

When the priority is the same, the router with a higher router ID is elected as the DR. If a new router is added after the DR/BDR election is complete, the new router cannot become the DR even if it has the highest priority.

Step 3 Configure DR priorities on interfaces.

# Configure Router A.

[RouterA] interface Ethernet 1/0/0

[RouterA-Ethernet1/0/0] ospf dr-priority 100

[RouterA-Ethernet1/0/0] quit

# Configure Router B.

[RouterB] interface Ethernet 1/0/0

[RouterB-Ethernet1/0/0] ospf dr-priority 0

[RouterB-Ethernet1/0/0] quit

# Configure Router C.

[RouterC] interface Ethernet 1/0/0

[RouterC-Ethernet1/0/0] ospf dr-priority 2

[RouterC-Ethernet1/0/0] quit

# View the DR/BDR status.

[RouterD] display ospf peer

OSPF Process 1 with Router ID 4.4.4.4

Neighbors

Area 0.0.0.0 interface 192.168.1.4(Ethernet1/0/0)'s neighbors

Router ID: 1.1.1.1 Address: 192.168.1.1

State: Full Mode:Nbr is Slave Priority: 100

DR: 192.168.1.4 BDR: 192.168.1.3 MTU: 0

Dead timer due in 31 sec

Retrans timer interval: 5

Neighbor is up for 00:11:17

Authentication Sequence: [ 0 ]

Router ID: 2.2.2.2 Address: 192.168.1.2

State: Full Mode:Nbr is Slave Priority: 0

DR: 192.168.1.4 BDR: 192.168.1.3 MTU: 0

Dead timer due in 35 sec

Retrans timer interval: 5

Neighbor is up for 00:11:19

Authentication Sequence: [ 0 ]

Router ID: 3.3.3.3 Address: 192.168.1.3

State: Full Mode:Nbr is Slave Priority: 2

DR: 192.168.1.4 BDR: 192.168.1.3 MTU: 0

Dead timer due in 33 sec

Retrans timer interval: 5

Neighbor is up for 00:11:15

Authentication Sequence: [ 0 ]

Step 4 Restart OSPF processes.

In the user view of each router, run the reset ospf 1 process command to restart the OSPF process.

Step 5 View the configuration.

# View the status of OSPF neighbors.

[RouterD] display ospf peer

OSPF Process 1 with Router ID 4.4.4.4

Neighbors

Area 0.0.0.0 interface 192.168.1.4(Ethernet1/0/0)'s neighbors

Router ID: 1.1.1.1 Address: 192.168.1.1

State: Full Mode:Nbr is Slave Priority: 100

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DR: 192.168.1.1 BDR: 192.168.1.3 MTU: 0

Dead timer due in 35 sec

Retrans timer interval: 5

Neighbor is up for 00:07:19

Authentication Sequence: [ 0 ]

Router ID: 2.2.2.2 Address: 192.168.1.2

State: Full Mode:Nbr is Master Priority: 0

DR: 192.168.1.1 BDR: 192.168.1.3 MTU: 0

Dead timer due in 35 sec

Retrans timer interval: 5

Neighbor is up for 00:07:19

Authentication Sequence: [ 0 ]

Router ID: 3.3.3.3 Address: 192.168.1.3

State: Full Mode:Nbr is Slave Priority: 2

DR: 192.168.1.1 BDR: 192.168.1.3 MTU: 0

Dead timer due in 37 sec

Retrans timer interval: 5

Neighbor is up for 00:07:17

Authentication Sequence: [ 0 ]

# View the status of the OSPF interface.

[RouterA] display ospf interface

OSPF Process 1 with Router ID 1.1.1.1

Interfaces

Area: 0.0.0.0

IP Address Type State Cost Pri DR BDR

192.168.1.1 Broadcast DR 1 100 192.168.1.1 192.168.1.3

[RouterB] display ospf interface

OSPF Process 1 with Router ID 2.2.2.2

Interfaces

Area: 0.0.0.0

IP Address Type State Cost Pri DR BDR

192.168.1.2 Broadcast DROther 1 0 192.168.1.1 192.168.1.3

If all neighbors are in the Full state, it indicates that Router A establishes the neighbor relationship with its neighbor. If the neighbor stays "2-Way", it indicates both of them are not the DR or BDR. They need not exchange LSAs.

If the status of the OSPF interface is DROther, it indicates that it is neither DR nor BDR.

----End

Configuration Files

l Configuration file of Router A

sysname RouterA

# router id 1.1.1.1

# interface Ethernet1/0/0

ip address 192.168.1.1 255.255.255.0

ospf dr-priority 100

# ospf 1

area 0.0.0.0

network 192.168.1.0 0.0.0.255

# return l Configuration file of Router B

sysname RouterB

# router id 2.2.2.2

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ip address 192.168.1.2 255.255.255.0

ospf dr-priority 0

# ospf 1

area 0.0.0.0

network 192.168.1.0 0.0.0.255

# return l Configuration file of Router C

sysname RouterC

# router id 3.3.3.3

# interface Ethernet1/0/0

ip address 192.168.1.3 255.255.255.0

ospf dr-priority 2

# ospf 1

area 0.0.0.0

network 192.168.1.0 0.0.0.255

# return l

Configuration file of Router D

sysname RouterD

# router id 4.4.4.4

# interface Ethernet1/0/0

ip address 192.168.1.4 255.255.255.0

# ospf 1

area 0.0.0.0

network 192.168.1.0 0.0.0.255

# return

5.14.3 Example for Configuring OSPF Stub Areas

This part provides an example for configuring a stub area that imports static routes to reduce the number of LSAs advertised in this area without affecting the route reachability.

Networking Requirements

, all routers run OSPF, and the entire AS is divided into three areas.

Figure 5-7

Router A and Router B serve as ABRs to forward routes between areas. Router D serves as an

ASBR to import external routes (static routes).

It is required to configure Area 1 as a stub area to reduce the LSAs advertised to this area without affecting the route reachability.

NOTE

AR150/200 is RouterE or RouterF.

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Figure 5-7 Configuring OSPF stub areas

RouterA

Area1

Area0

Eth1/0/0

192.168.0.1/24 Eth1/0/0

192.168.0.2/24

Eth2/0/0

192.168.1.1/24

Eth1/0/0

192.168.1.2/24

RouterC

ASBR

Eth2/0/0

172.16.1.1/24

Eth2/0/0

172.16.1.2/24

RouterE

Stub

5 OSPF Configuration

RouterB

Area2

Eth2/0/0

192.168.2.1/24

Eth1/0/0

192.168.2.2/24

RouterD

ASBR

Eth2/0/0

172.17.1.1/24

Eth2/0/0

172.17.1.2/24

RouterF

Configuration Roadmap

The configuration roadmap is as follows:

Enable OSPF on each router, and configure basic OSPF functions.

Configure static routes on Router D, and import them into OSPF.

Configure Area 1 as a stub area, and check the OSPF routing information on Router C.

Stop Router A from advertising Type 3 LSAs to the stub area, and check the OSPF routing information on Router C.

Data Preparation

To complete the configuration, you need the following data: l The router ID of Router A is1.1.1.1, the OSPF process number is 1, the network segment of Area 0 is 192.168.0.0/24, and the network segment of Area 1 is 192.168.1.0/24.

l The router ID of Router B is 2.2.2.2, the OSPF process number is 1, the network segment of Area 0 is 192.168.0.0/24, and the network segment of Area 2 is 192.168.2.0/24.

l The router ID of Router C is 3.3.3.3, the OSPF process number is 1, and the network segments of Area 1 are 192.168.1.0/24 and 172.16.1.0/24.

l The router ID of Router D is 4.4.4.4, the OSPF process number is 1, and the network segments of Area 2 are 192.168.2.0/24 and 172.17.1.0/24.

l The router ID of Router E is 5.5.5.5, the OSPF process number is 1, and the network segment of Area 1 is 172.16.1.0/24.

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5 OSPF Configuration l The router ID of Router F is 6.6.6.6, the OSPF process number is 1, and the network segment of Area 2 is 172.17.1.0/24.

Procedure

Step 1 Configure an IP address for each interface.

The configuration details are not mentioned here.

Step 2 Configure basic OSPF functions (see

Example for Configuring Basic OSPF Functions

Step 3 Configure Router D to import static routes.

[RouterD] ip route-static 200.0.0.0 8 null 0

[RouterD] ospf

[RouterD-ospf-1] import-route static type 1

[RouterD-ospf-1] quit

# View ABR/ASBR information on Router C.

[RouterC] display ospf abr-asbr

OSPF Process 1 with Router ID 3.3.3.3

Routing Table to ABR and ASBR

RtType Destination Area Cost Nexthop Type

Intra-area 1.1.1.1 0.0.0.1 1 192.168.1.1 ABR

Inter-area 4.4.4.4 0.0.0.1 3 192.168.1.1 ASBR

# View the OSPF routing table of Router C.

NOTE

When Router C is in a common area, there are AS external routes in the routing table.

[RouterC] display ospf routing

OSPF Process 1 with Router ID 3.3.3.3

Routing Tables

Routing for Network

Destination Cost Type NextHop AdvRouter Area

172.16.1.0/24 1 Transit 172.16.1.1 3.3.3.3 0.0.0.1

172.17.1.0/24 4 Inter-area 192.168.1.1 1.1.1.1 0.0.0.1

192.168.0.0/24 2 Inter-area 192.168.1.1 1.1.1.1 0.0.0.1

192.168.1.0/24 1 Stub 192.168.1.2 3.3.3.3 0.0.0.1

192.168.2.0/24 3 Inter-area 192.168.1.1 1.1.1.1 0.0.0.1

Routing for ASEs

Destination Cost Type Tag NextHop AdvRouter

200.0.0.0/8 4 Type1 1 192.168.1.1 4.4.4.4

Total Nets: 6

Intra Area: 2 Inter Area: 3 ASE: 1 NSSA: 0

Step 4 Configure Area 1 as a stub area.

# Configure Router A.

[RouterA] ospf

[RouterA-ospf-1] area 1

[RouterA-ospf-1-area-0.0.0.1] stub

[RouterA-ospf-1-area-0.0.0.1] quit

# Configure Router C.

[RouterC] ospf

[RouterC-ospf-1] area 1

[RouterC-ospf-1-area-0.0.0.1] stub

[RouterC-ospf-1-area-0.0.0.1] quit

# Configure Router E.

[RouterE] ospf

[RouterE-ospf-1] area 1

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[RouterE-ospf-1-area-0.0.0.1] stub

[RouterE-ospf-1-area-0.0.0.1] quit

# View the routing table of Router C.

NOTE

After the area where Router C resides is configured as a stub area, AS external routes are invisible. Instead, there is a default route.

[RouterC] display ospf routing

OSPF Process 1 with Router ID 3.3.3.3

Routing Tables

Routing for Network

Destination Cost Type NextHop AdvRouter Area

0.0.0.0/0 2 Inter-area 192.168.1.1 1.1.1.1 0.0.0.1

172.16.1.0/24 1 Transit 172.16.1.1 3.3.3.3 0.0.0.1

172.17.1.0/24 4 Inter-area 192.168.1.1 1.1.1.1 0.0.0.1

192.168.0.0/24 2 Inter-area 192.168.1.1 1.1.1.1 0.0.0.1

192.168.1.0/24 1 Stub 192.168.1.2 3.3.3.3 0.0.0.1

192.168.2.0/24 3 Inter-area 192.168.1.1 1.1.1.1 0.0.0.1

Total Nets: 6

Intra Area: 2 Inter Area: 4 ASE: 0 NSSA: 0

Step 5 # Stop Router A from advertising Type 3 LSAs to the stub area.

[RouterA] ospf

[RouterA-ospf-1] area 1

[RouterA-ospf-1-area-0.0.0.1] stub no-summary

[RouterA-ospf-1-area-0.0.0.1] quit

Step 6 Verify the configuration.

# View the OSPF routing table of Router C.

[RouterC] display ospf routing

OSPF Process 1 with Router ID 3.3.3.3

Routing Tables

Routing for Network

Destination Cost Type NextHop AdvRouter Area

0.0.0.0/0 2 Inter-area 192.168.1.1 1.1.1.1 0.0.0.1

172.16.1.0/24 1 Transit 172.16.1.1 3.3.3.3 0.0.0.1

192.168.1.0/24 1 Stub 192.168.1.2 3.3.3.3 0.0.0.1

Total Nets: 3

Intra Area: 2 Inter Area: 1 ASE: 0 NSSA: 0

NOTE

After the advertisement of summary LSAs to a stub area is disabled, the routing entries of the stub router are further reduced, and only the default route to a destination outside the AS is reserved.

----End

Configuration Files

NOTE

The configuration files of Router B and Router F are the same as those in the preceding example, and are not mentioned here.

Configuration file of Router A

sysname RouterA

# router id 1.1.1.1

# interface Ethernet1/0/0

ip address 192.168.0.1 255.255.255.0

# interface Ethernet2/0/0

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ip address 192.168.1.1 255.255.255.0

# ospf 1

area 0.0.0.0

network 192.168.0.0 0.0.0.255

area 0.0.0.1

network 192.168.1.0 0.0.0.255

stub no-summary

# return l Configuration file of Router C

sysname RouterC

# router id 3.3.3.3

# interface Ethernet1/0/0

ip address 192.168.1.2 255.255.255.0

# interface Ethernet2/0/0

ip address 172.16.1.1 255.255.255.0

# ospf 1

area 0.0.0.1

network 192.168.1.0 0.0.0.255

network 172.16.1.0 0.0.0.255

stub

# return l

Configuration file of Router D

sysname RouterD

# router id 4.4.4.4

# interface Ethernet1/0/0

ip address 192.168.2.2 255.255.255.0

# interface Ethernet2/0/0

ip address 172.17.1.1 255.255.255.0

# ospf 1

import-route static type 1

area 0.0.0.2

network 192.168.2.0 0.0.0.255

network 172.17.1.0 0.0.0.255

# ip route-static 200.0.0.0 255.0.0.0 NULL0

# return l

Configuration file of Router E

sysname RouterE

# router id 5.5.5.5

# interface Ethernet2/0/0

ip address 172.16.1.2 255.255.255.0

# ospf 1

area 0.0.0.1

network 172.16.1.0 0.0.0.255

stub

# return

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OSPFv3 Configuration

About This Chapter

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By building Open Shortest Path First Version 3 (OSPFv3) networks, you can enable OSPFv3 to discover and calculate routes in ASs. OSPFv3 is applicable to a large-scale network that consists of hundreds of routers.

6.1 OSPFv3 Overview

OSPFv3 uses the same implementation mechanism as OSPFv2 but is not compatible with

OSPFv2.

6.2 OSPFv3 Features Supported by AR150/200

The AR150/200 supports various OSPFv3 features, including multi-process and GR.

6.3 Configuring Basic OSPFv3 Functions

Before building OSPFv3 networks, you need to configure basic OSPFv3 functions.

6.4 Establishing or Maintaining OSPFv3 Neighbor Relationship

By establishing and maintaining OSPFv3 neighbor relationships or adjacencies, you can build

OSPFv3 networks.

6.5 Configuring OSPFv3 Areas

OSPFv3 supports stub areas and virtual links, the principle and applicable environment of which are similar to those in OSPFv2.

6.6 Configuring OSPFv3 NSSA Areas

By configuring areas as NSSA areas, external routes can be imported, and a new type of LSA, namely, Type 7 NSSA LSA is introduced.

6.7 Configuring OSPFv3 Route Attributes

By setting OSPFv3 route attributes, you can change OSPFv3 routing policies to meet the requirements of complex networks.

6.8 Controlling OSPFv3 Routing Information

This section describes how to control OSPFv3 routing information. Detailed operations include configuring route aggregation, filtering the received routes, and importing external routes.

6.9 Optimizing an OSPFv3 Network

By configuring OSPFv3 functions in special network environments, you can adjust and optimize the OSPFv3 network performance.

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6.10 Configuration OSPFv3 GR

By configuring OSPFv3 GR, you can avoid inaccurate route calculation and packet loss after an OSPFv3 router restarts.

6.11 Configuring the Network Management Function of OSPFv3

OSPFv3 supports the network management function. You can bind the OSPFv3 MIB to a certain

OSPFv3 process.

6.12 Maintaining OSPFv3

Maintaining OSPFv3 and Debugging OSPFv3 involve resetting OSPFv3.

6.13 Configuration Examples

This section provides several configuration examples of OSPFv3 together with the configuration flowchart. The configuration examples explain networking requirements, configuration notes, and configuration roadmap.

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6.1 OSPFv3 Overview

OSPFv3 uses the same implementation mechanism as OSPFv2 but is not compatible with

OSPFv2.

The Open Shortest Path First Version 3.0 (OSPFv3) supports the version 6 of the Internet

Protocol (IPv6). OSPFv3 conforms to RFC 2740 (OSPF for IPv6).

OSPFv3 and OSPFv2 have the following in common: l 32-bit Router ID, Area ID, and Link State Advertisement (LSA) link-state ID l Five types of packets such as Hello, Database Description (DD), Link State Request (LSR),

Link State Update (LSU), and Link State Acknowledgement (LSAck) packets l Neighbor discovery and adjacency establishment mechanisms l Flooding and aging mechanisms of LSAs l LSA types

OSPFv3 and OSPFv2 differ as follows: l OSPFv3 runs based on a link; OSPFv2 runs based on a network segment.

OSPFv3 can run multiple instances on the same link.

l The topology of OSPFv3 is independent of IPv6 address prefixes.

OSPFv3 identifies its neighbors with the IPv6 link-local addresses.

l OSPFv3 has three new types of LSA flooding scopes.

6.2 OSPFv3 Features Supported by AR150/200

The AR150/200 supports various OSPFv3 features, including multi-process and GR.

The AR150/200 supports the following OSPFv3 features: l Basic features stipulated in RFC 2740 l OSPFv3 stub areas l OSPFv3 multi-process l Multiple OSPFv3 processes can run on a router.

l OSPFv3 GR

–

If a router restarts or performs the active/standby switchover, it directly ages all the entries in the Forward Information Base (FIB). This interrupts the routing. The neighboring routers remove the router from the neighbor list and inform other routers of the router failure. Then, SPF needs to be calculated again. If the router recovers after a short period of time, the neighbor relationship becomes unstable. This results in route flapping.

–

If a router restarts because of abnormalities, you can enable OSPFv3 Graceful Restart

(GR) to avoid service interruption during the restart of the router.

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NOTE

The OSPFv3 function is used with a license. To use the OSPFv3 function, apply for and purchase the following license from the Huawei local office: l AR150&200 Value-Added Data Package

6.3 Configuring Basic OSPFv3 Functions

Before building OSPFv3 networks, you need to configure basic OSPFv3 functions.

6.3.1 Establishing the Configuration Task

You need to enable OSPFv3 and specify interfaces and area IDs before configuring other functions.

Applicable Environment

Enable the OSPFv3 process and specify its router ID before configuring OSPFv3; otherwise, other functions cannot take effect.

You must enable OSPFv3 and specify the interface and area ID before configuring other functions. OSPFv3 configurations, however, are independent of interface-related features.

Pre-configuration Tasks

Before configuring basic OSPFv3 functions, complete the following tasks: l Making the network layers of the adjacent nodes accessible l Enabling IPv6 capabilities

Data Preparation

To configure basic OSPFv3 functions, you need the following data.

No.

Data

1 Router ID

OSPFv3 process ID

Interfaces on which OSPFv3 needs to be enabled and their areas

6.3.2 Enabling OSPFv3

Creating an OSPFv3 process is a prerequisite for configuring all OSPFv3 features. By creating an OSPFv3 process, you can manually specify the router ID for a router.

Context

OSPFv3 supports multiple processes. Multiple OSPFv3 processes running on one router are differentiated by process IDs. OSPFv3 process ID is set when OSPFv3 is enabled and is only locally valid. It does not affect the packet exchange with other routers.

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In the format of an IPv4 address, a router ID is a 32-bit unsigned integer that uniquely identifies a router within an AS. The router ID of OSPFv3 must be manually set. If no router ID is set,

OSPFv3 fails to run normally.

When manually setting the router ID, ensure that the router IDs of any two routers in an AS are different. When multiple processes are enabled on a router, it is necessary to specify a unique route ID for each process.

To ensure the stable running of OSPFv3, you need to allocate router IDs and set them in network planning.

Do as follows on the router that runs OSPFv3.

Procedure

Step 1 Run:

system-view

The system view is displayed.

Step 2 Run:

ospfv3 [ process-id ]

OSPFv3 is enabled and the OSPFv3 view is displayed.

Step 3 Run:

router-id router-id

A Router ID is set.

----End

6.3.3 Enabling OSPFv3 on an Interface

For an interface with multiple instances, you need to specify which instance of the interface is enabled in the OSPFv3 process when enabling OSPFv3 on the interface.

Context

After enabling OSPFv3 in the system view, you need to enable OSPFv3 on the interface.

Because an interface has multiple instances, you need to specify which instance of the interface is enabled in the OSPFv3 process when OSPFv3 is enabled on the interface. If no instance ID is specified, the value defaults to 0. The same instance must be enabled on the interfaces between which the neighbor relationship is set up.

Do as follows on the router that runs OSPFv3.

Procedure

Step 1 Run:

system-view

The system view is displayed.

Step 2 Run:

interface interface-type interface-number

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The interface view is displayed.

Step 3 Run:

ospfv3 process-id area area-id [ instance instance-id ]

OSPFv3 is enabled on the interface.

The area ID can be a decimal integer or in the IPv4 address format, but it is displayed in the IPv4 address format.

Step 4 (Optional) Run the ospfv3 network-type { broadcast | nbma | p2mp [ non-broadcast ] |

p2p } [ instance instance-id ] command to configure the network type of an interface.

When an interface supports multi-instances, you must specify the value of instance-id when enabling OSPFv3 on the interface. If the value of instance-id is not specified, the default value

0 is adopted. In this case, the configured network type of an interface mismatches the actual network type of the interface. This step is mandatory in such a case.

----End

6.3.4 Entering the OSPFv3 Area View

By dividing an AS into different areas, specifying OSPFv3 interfaces, and specifying areas to which these interfaces belong, OSPFv3 can discover and calculate routes in an AS.

Context

You must configure the routers in the same area based on the area. Otherwise, the neighbor routers cannot exchange information with each other. The congestion of routing information or routing loop is thus caused.

Do as follows on the router that runs OSPFv3.

Procedure

Step 1 Run:

system-view

The system view is displayed.

Step 2 Run:

ospfv3 [ process-id ]

The OSPFv3 view is displayed.

Step 3 Run:

area area-id

The OSPFv3 area view is displayed.

The area ID can be a decimal integer or in the IPv4 address format, but it is displayed in the IPv4 address format.

An OSPFv3 area cannot be deleted directly. Only after all the configurations in the area view are removed and the status of the related interfaces in this area become Down, this area is automatically removed.

----End

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6.3.5 Checking the Configuration

After basic OSPFv3 functions are configured, you can check OSPFv3 brief information, LSDB information, neighbor information, and OSPFv3 routing table.

Prerequisites

The configurations for the Basic OSPFv3 Functions are complete.

Procedure

l Run the display ospfv3 [ process-id ] command to check the summary information about the OSPFv3 process.

l Run the display ospfv3 [ process-id ] interface [ area area-id ] [ interface-type interface-

number ] command to check the OSPFv3 interface information.

Run the commands as follow to check the LSDB information about OSPFv3:

–

display ospfv3 [ process-id ] lsdb [ area area-id ] [ originate-router advertising-

router-id | self-originate ] [ { router | network | inter-router [ asbr-router asbr-

router-id ] | { inter-prefix | nssa } [ ipv6-address prefix-length ] | link | intra-prefix |

grace } [ link-state-id ] ]

– display ospfv3 [ process-id ] lsdb [ originate-router advertising-router-id | self-

originate ] external [ ipv6-address prefix-length ] [ link-state-id ] l Run the display ospfv3 [ process-id ] [ area area-id ] peer [ interface-type interface-

number ] [ verbose ] command or display ospfv3 [ process-id ] [ area area-id ] peer

neighbor-id [ verbose ] command to check the information about the OSPFv3 neighbor.

l Run the commands as follow to check the OSPFv3 routing table:

–

display ospfv3 [ process-id ] routing

– display ospfv3 [ process-id ] routing [ abr-routes | asbr-routes | statistics | ipv6-

address prefix-length | intra-routes | inter-routes | ase-routes | nssa-routes ] l Run the display ospfv3 [ process-id ] path command to check the paths to a destination address.

l Run the display default-parameter ospfv3 command to check the default OSPFv3 configuration.

----End

6.4 Establishing or Maintaining OSPFv3 Neighbor

Relationship

By establishing and maintaining OSPFv3 neighbor relationships or adjacencies, you can build

OSPFv3 networks.

6.4.1 Establishing the Configuration Task

When setting parameters on an interface, ensure that these parameters are consistent with those on the adjacent router.

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Applicable Environment

In applications, establishing or maintaining the OSPFv3 neighbor relationship is a premise for the construction of an OSPFv3 network. After the configuration in this section, you can: l

Adjust the convergence speed of the OSPFv3 network and network load posed by protocol packets by modifying OSPFv3 timers.

l Enable OSPFv3 to be disconnected from its neighbor when the number of OSPFv3 packet retransmissions exceeds the threshold by configuring Retransmission Limitation for

OSPFv3. This prevents non-stop packet retransmissions if the neighbor does not receive packets.

l Speed up the convergence of an OSPFv3 network by adjusting the intervals for updating and receiving LSAs.

Pre-configuration Tasks

Before establishing or maintaining the OSPFv3 neighbor relationship, complete the following tasks: l Enabling IPv6 capability l

Data Preparation

To establish or maintain the OSPFv3 neighbor relationship, you need the following data.

No.

Data

1 Interval for sending Hello packets

Dead time of the neighbor relationship

Interval for retransmitting LSAs to adjacent routers

Delay in sending LSAs

6.4.2 Configuring the Interval for Sending Hello Packets

By adjusting the Hello interval set on OSPFv3 neighbors, you can change the speed of establishing the neighbor relationship, thus changing the speed of network convergence.

Context

Hello packets are periodically sent to the neighbor router to detect and maintain the neighbor relationship and to elect the DR and the BDR. RFC 2328 requires that the Hello timer values of neighbors be consistent. The value of the Hello timer is inversely proportional to the route convergence speed and network load.

Do as follows on the router that runs OSPFv3.

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Procedure

Step 1 Run:

system-view

The system view is displayed.

Step 2 Run:

interface interface-type interface-number

The interface view is displayed.

Step 3 Run:

ospfv3 timer hello interval [ instance instance-id ]

The interval for sending Hello packets is set on the interface.

----End

6.4.3 Configuring Dead Time of Neighbor Relationship

If a router does not receive a Hello packet from its neighbor within the Holddown time, the router considers the neighbor relationship invalid.

Context

If a router does not receive any Hello packet from its neighbor during a specified period, the neighbor router is considered invalid. The specified period is called the dead time of the neighbor relationship. The dead time must be at least four times the Hello interval on an interface.

Do as follows on the router that runs OSPFv3.

Procedure

Step 1 Run:

system-view

The system view is displayed.

Step 2 Run:

interface interface-type interface-number

The interface view is displayed.

Step 3 Run:

ospfv3 timer dead interval [ instance instance-id ]

The dead time of the neighbor relationship is specified.

----End

6.4.4 Configuring the Interval for Retransmitting LSAs to

Neighboring

After a router sends an LSA to its neighbor, the router expects to receive an LSAck packet from its neighbor. If the router does not receive an LSAck packet within the LSA retransmission interval, it retransmits the LSA to the neighbor.

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Context

Do as follows on the router that runs OSPFv3.

Procedure

Step 1 Run:

system-view

The system view is displayed.

Step 2 Run:

interface interface-type interface-number

The interface view is displayed.

Step 3 Run:

ospfv3 timer retransmit interval [ instance instance-id ]

The interval for retransmitting LSAs to the adjacent routers is set.

The value of seconds must be greater than the time taken to transmit a packet between two routers.

NOTE

Do not set a value which is too small, for the interval between LSA retransmissions. Otherwise, unnecessary retransmissions may occur.

----End

6.4.5 Configuring the Delay for Transmitting LSAs on the Interface

It takes time to transmit OSPFv3 packets on a link. Therefore, a certain delay is added to the aging time of an LSA before the LSA is sent.

Context

The LSA ages out in the LSDB of a local router instead of in the transmission process. You need to set the delay for an LSA before sending it. For a low-speed network, this configuration is necessary.

Do as follows on the router that runs OSPFv3.

Procedure

Step 1 Run:

system-view

The system view is displayed.

Step 2 Run:

interface interface-type interface-number

The interface view is displayed.

Step 3 Run:

ospfv3 trans-delay interval [ instance instance-id ]

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The delay in transmitting LSAs on the interface is set.

----End

6.4.6 Checking the Configuration

After OSPFv3 neighbor relationships or adjacencies are stable, you can check OSPFv3 interface information and neighbor information.

Prerequisites

The configurations for the Establishing or Maintaining OSPFv3 Neighbor Relationship are complete.

Procedure

l Run the display ospfv3 [ process-id ] interface [ area area-id ] [ interface-type interface-

number ] command to check the OSPFv3 interface information.

----End

6.5 Configuring OSPFv3 Areas

OSPFv3 supports stub areas and virtual links, the principle and applicable environment of which are similar to those in OSPFv2.

6.5.1 Establishing the Configuration Task

Configuring a stub area is optional. Not all areas can be configured as stub areas. Generally, a stub area, which is located at the AS boundary, is a non-backbone area with only one ABR.

Applicable Environment

To reduce the number of LSAs in the network and enhance OSPFv3 extensibility, define OSPFv3 areas. For some non-backbone areas at the edge of ASs, you can define them as stub areas for further reducing the size of the routing table and the number of LSAs.

Pre-configuration Tasks

Before configuring OSPFv3 area attributes, complete the following tasks: l

Enabling IPv6 capability l

Data Preparation

To configure OSPFv3 area attributes, you need the following data.

No.

Data

1 Areas to be defined as stub areas

2 Metrics of default routes sent to stub areas

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6.5.2 Configuring OSPFv3 Stub Areas

A stub area is a special area in which ABRs do not flood the received AS external routes. Thus, the number of LSAs is greatly reduced.

Context

Do as follows on each router that runs OSPFv3 in the stub area:

Procedure

Step 1 Run:

system-view

The system view is displayed.

Step 2 Run:

ospfv3 [ process-id ]

The OSPFv3 view is displayed.

Step 3 Run:

area area-id

The OSPFv3 area view is displayed.

Step 4 Run:

stub [ no-summary ]

The area is configured as a stub area.

Step 5 (Optional) Run:

default-cost cost

The cost of the default route sent to the stub area is set.

By default, the cost of the default route sent to the stub area is 1.

This command is configured on the ABR of the stub area only to set the cost of the default route to be sent to the stub area. This command does not need to be configured on other routers in the stub area.

The parameter no-summary takes effect only when the stub command is configured on the

ABR. If this parameter is configured, the ABR only sends the summary-LSA of a default route to the stub area without originating other summary-LSAs. The stub area without AS-external-

LSAs or Summary-LSAs is called a totally stub area.

----End

6.5.3 Configuring OSPFv3 Virtual Links

You can establish the logical connectivity between backbone areas and the non-backbone areas that are not physically connected to the backbone area.

Context

After OSPFv3 areas are defined, OSPFv3 route update between non-backbone areas is implemented through a backbone area. Then, OSPFv3 requires that all non-backbone areas

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Configuration Guide - IP Routing 6 OSPFv3 Configuration should maintain the connectivity with the backbone area and the backbone area should maintain its own connectivity. In actual applications, this requirement may not be met because of some restrictions. To solve this problem, you can configure OSPFv3 virtual links.

A virtual link must be configured at both ends of the link; otherwise, it does not take effect.

Do as follows on the router that runs OSPFv3.

Procedure

Step 1 Run:

system-view

The system view is displayed.

Step 2 Run:

ospfv3 [ process-id ]

The OSPFv3 view is displayed.

Step 3 Run:

area area-id

The OSPFv3 area view is displayed.

Step 4 Run:

vlink-peer router-id [ hello hello-interval | retransmit retransmit-interval |

trans-delay trans-delay-interval | dead dead-interval | instance instance-id ]

A virtual link is created and configured.

----End

6.5.4 Checking the Configuration

After OSPFv3 area attributes are configured, you can check the OSPFv3 LSDB, routing table, and virtual links.

Prerequisites

The configurations for the OSPFv3 Areas are complete.

Procedure

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Run the commands as follow to check the LSDB information about OSPFv3:

–

display ospfv3 [ process-id ] lsdb [ area area-id ] [ originate-router advertising-

router-id | self-originate ] [ { router | network | inter-router [ asbr-router asbr-

router-id ] | { inter-prefix | nssa } [ ipv6-address prefix-length ] | link | intra-prefix |

grace } [ link-state-id ] ]

–

display ospfv3 [ process-id ] lsdb [ originate-router advertising-router-id | self-

originate ] external [ ipv6-address prefix-length ] [ link-state-id ] l

Run the commands as follow to check the OSPFv3 routing table:

–

display ospfv3 [ process-id ] routing

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– display ospfv3 [ process-id ] routing [ abr-routes | asbr-routes | statistics

nssa-routes ] l Run the display ospfv3 [ process-id ] vlink command to check the information about

OSPFv3 virtual links.

----End

6.6 Configuring OSPFv3 NSSA Areas

By configuring areas as NSSA areas, external routes can be imported, and a new type of LSA, namely, Type 7 NSSA LSA is introduced.

6.6.1 Establishing the Configuration Task

NSSAs are introduced because stub areas cannot import external routes. An NSSA allows the transmission of Type 7 LSAs.

Applicable Environment

An NSSA allows the transmission of Type 7 LSAs, which are generated by ASBRs in an NSSA.

The Type 7 LSAs converting into Type 5 LSAs in the NSSA and advertised to other areas.

Pre-configuration Tasks

Before configuring an OSPFv3 NSSA, complete the following tasks: l Configuring IP addresses for interfaces to make neighboring nodes reachable l

Configuring basic OSPFv3 functions

Data Preparation

To configure an OSPFv3 NSSA, you need the following data.

No.

Data

1 Cost of the default route sent to an NSSA

6.6.2 Defining the Current Area to Be an NSSA Area

Derived from a stub area, an NSSA allows AS external routes to be imported; an ASBR advertises Type 7 NSSA LSAs in the local NSSA.

Context

Do as follows on the OSPFv3 router:

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Procedure

Step 1 Run:

system-view

The system view is displayed.

Step 2 Run:

ospfv3 [ process-id ]

The OSPFv3 process view is displayed.

Step 3 Run:

area area-id

The OSPFv3 area view is displayed.

Step 4 Run:

nssa [ default-route-advertise [ cost cost | type type | tag tag ]

| no-import-

route | no-summary | translator-always | translator-interval translator-interval |

set-n-bit ]

An area is configured as an NSSA.

----End

Follow-up Procedure

To connect routers to an NSSA, you need to run the nssa command to configure NSSA attributes for the area to which the routers belong.

The area may be updated after NSSA attributes are configured or deleted. Thus, the NSSA attributes can be re-configured or deleted only after the last update of NSSA attributes is complete.

6.6.3 Checking the Configuration

After OSPFv3 NSSAs are configured, you can check OSPFv3 routing table information.

Prerequisites

The configurations for OSPFv3 NSSAs are complete.

Procedure

l Run the display ospfv3 area command to check information about OSPFv3 areas.

l Run the commands as follow to check the OSPFv3 routing table.

– display ospfv3 [ process-id ] routing

–

display ospfv3 [ process-id ] routing [ abr-routes | asbr-routes | statistics | ipv6-

address prefix-length | intra-routes | inter-routes | ase-routes | nssa-routes ]

----End

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6.7 Configuring OSPFv3 Route Attributes

By setting OSPFv3 route attributes, you can change OSPFv3 routing policies to meet the requirements of complex networks.

6.7.1 Establishing the Configuration Task

Before configuring OSPFv3 route attributes, familiarize yourself with the applicable environment, complete pre-configuration tasks, and obtain the required data. This can help you complete the configuration task quickly and accurately.

Applicable Environment

In actual applications, to meet the requirements of a complicated networking environment, you can change OSPFv3 routing policies by configuring OSPFv3 route attributes. Through the following procedures, you can: l

Set the cost on the OSPFv3 interface.

l Configure load balancing among equal-cost routes.

Pre-configuration Tasks

Before configuring OSPFv3 route attributes, complete the following tasks: l Enabling IPv6 capability l

Data Preparation

To configure OSPFv3 route attributes, you need the following data.

No.

Data

1 Link cost

2 Maximum number of equal-cost routes

6.7.2 Setting the Cost of the OSPFv3 Interface

OSPFv3 can automatically calculate the link cost for an interface according to the interface bandwidth. You can also set the link cost for the interface by using the related command.

Context

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You can control route calculation by setting the link cost of OSPFv3 on different interfaces.

Do as follows on the router that runs OSPFv3.

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Procedure

Step 1 Run:

system-view

The system view is displayed.

Step 2 Run:

interface interface-type interface-number

The interface view is displayed.

Step 3 Run:

ospfv3 cost cost [ instance instance-id ]

The cost is set on the OSPFv3 interface.

By default, the link cost on an OSPFv3 interface is 1.

----End

6.7.3 Setting the Maximum Number of OSPFv3 Equal-Cost Routes

If the destinations and costs of the multiple routes discovered by one routing protocol are the same, load balancing can be performed among these routes.

Context

Do as follows on the router that runs OSPFv3:

Procedure

Step 1 Run:

system-view

The system view is displayed.

Step 2 Run:

ospfv3 [ process-id ]

The OSPFv3 view is displayed.

Step 3 Run:

maximum load-balancing number

The maximum number of equal-cost routes is set.

The value is an integer ranging from 1 to 32. The default value is 32.

----End

6.7.4 Checking the Configuration

After OSPFv3 route attributes are configured, you can check the OSPFv3 interface, LSDB, and routing table.

Prerequisites

The configurations for the OSPFv3 Route Attributes are complete.

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Procedure

6 OSPFv3 Configuration l

Run the display ospfv3[ process-id ] interface [ area area-id ] [ interface-type interface-

number ] command to check the OSPFv3 interface information.

l Run the commands as follow to check the LSDB information about OSPFv3:

–

display ospfv3 [ process-id ] lsdb [ area area-id ] [ originate-router advertising-

router-id | self-originate ] [ { router | network | inter-router [ asbr-router asbr-

router-id ] | { inter-prefix | nssa } [ ipv6-address prefix-length ] | link | intra-prefix |

grace } [ link-state-id ] ]

– display ospfv3 [ process-id ] lsdb [ originate-router advertising-router-id | self-

originate ] external [ ipv6-address prefix-length ] [ link-state-id ] l Run the commands as follow to check the OSPFv3 routing table:

–

display ospfv3 [ process-id ] routing

–

display ospfv3 [ process-id ] routing [ abr-routes | asbr-routes | statistics | ipv6-

address prefix-length | intra-routes | inter-routes | ase-routes | nssa-routes ]

----End

6.8 Controlling OSPFv3 Routing Information

This section describes how to control OSPFv3 routing information. Detailed operations include configuring route aggregation, filtering the received routes, and importing external routes.

6.8.1 Establishing the Configuration Task

Before controlling OSPFv3 routing information, familiarize yourself with the applicable environment, complete pre-configuration tasks, and obtain the required data. This can help you complete the configuration task quickly and accurately.

Applicable Environment

Through the configuration in this section, you can control the advertising and receiving of

OSPFv3 routing information and configure OSPFv3 to import external routes.

Pre-configuration Tasks

Before controlling OSPFv3 routing information, complete the following tasks: l Enabling IPv6 capability l

Data Preparation

To control OSPFv3 routing information, you need the following data.

No.

Data

1 Prefix of IPv6 routes after aggregation

2 Filtering list or name used to filter routing information

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No.

Data

3 Link cost on an OSPFv3 interface

Maximum number of equal-cost routes

Name, process ID, and metric of external routes to be imported

6.8.2 Configuring OSPFv3 Route Aggregation

An ABR can summarize routes with the same prefix into one LSA and advertise the summarized route in other areas. An ASBR can also summarize imported routes with the same prefix into one LSA and then advertise the summarized route to other areas. This can reduce the size of the

LSDB in other areas.

Context

If multiple continuous network segments exist in this area, use the abr-summary command to summarize them into one network segment. In this way, the ABR only sends an LSA after summarization. No LSA that belongs to the summarization network segment is separately transmitted, thus reducing the LSDB size of other areas.

When a large number of routes are imported, use the asbr-summary command to summarize the imported routes and set the delay for advertising the summarized route. In this manner, the summarized route advertised each time contains more valid routing information, and network flapping caused by incorrect routing information is avoided.

Procedure

l Configure route summarization on an ABR.

Do as follows on the ABR that runs OSPFv3:

Run:

system-view

The system view is displayed.

Run:

ospfv3 [ process-id ]

The OSPFv3 view is displayed.

Run:

area area-id

The OSPFv3 area view is displayed.

Run:

abr-summary ipv6-address prefix-length [ cost cost | not-advertise ]

Route summarization is configured in the OSPFv3 area.

cost cost set the cost of a summarized route. By default, the cost of a summarized route is the maximum cost among those of routes that are summarized. The value ranges from 1 to 16777214.

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If not-advertise is set, no routing information of the network segment is advertised.

l Configure route summarization on an ASBR.

Do as follows on the ASBR that runs OSPFv3:

Run:

system-view

The system view is displayed.

Run:

ospfv3 [ process-id ]

The OSPFv3 view is displayed.

Run:

asbr-summary ipv6-address prefix-length [ cost cost | tag tag | not-

advertise | distribute-delay interval ]

Route summarization is configured on the ASBR.

cost cost specifies the cost of a summarized route. By default, the cost of a summarized route is the maximum cost among those of routes that are summarized. The value ranges from 1 to 16777214.

tag tag specifies the tag used to control route advertisement. The value of this parameter ranges from 1 to 4294967295.

If not-advertise is specified in the command, the summarized IPv6 route that matches a specified IPv6 prefix or prefix length is not advertised.

distribute-delay interval specifies the delay for advertising a summarized route.

----End

6.8.3 Configuring OSPFv3 to Filter the Received Routes

By configuring filtering conditions for routing information, you can allow only the routes that pass the filtering to be received or advertised.

Context

After receiving LSAs, OSPFv3 determines whether to add the calculated routes to the local routing table according to the filtering policy.

Do as follows on the router that runs OSPFv3.

Procedure

Step 1 Run:

system-view

The system view is displayed.

Step 2 Run:

ospfv3 [ process-id ]

The OSPFv3 view is displayed.

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Step 3 Run:

filter-policy ipv6-prefix ipv6-prefix-name import

OSPFv3 is configured to filter the imported routes.

Using the filter-policy command, you can only filter the routes calculated by OSPFv3. Routes that do not pass the filtering are neither added to the OSPFv3 routing table nor advertised.

----End

6.8.4 Configuring OSPFv3 to Import External Routes

Importing the routes discovered by other routing protocols can enrich OSPFv3 routing information.

Context

Because OSPFv3 is a link state-based routing protocol and cannot directly filter the advertised

LSAs, OSPFv3 must filter the routes when importing them. Then, only the routes that pass the filtering can be advertised.

Do as follows on the router that runs OSPFv3.

Procedure

Step 1 Run:

system-view

The system view is displayed.

Step 2 Run:

ospfv3 [ process-id ]

The OSPFv3 view is displayed.

Step 3 Run:

default { cost cost | tag tag | type type }

The default cost of the imported route is set.

Step 4 Run:

import-route protocol [ process-id ] [ cost cost | type type | tag tag | route-

policy route-policy-name ]

External routes are imported.

Step 5 (Optional) Run:

default-route-advertise [ always | cost cost | type type | tag tag | route-policy

route-policy-name ]

Default routes are advertised to the OSPFv3 route area.

Step 6 (Optional) Run:

filter-policy ipv6-prefix ipv6-prefix-name export [ protocol [ process-id ] ]

The imported external routes are filtered.

After you run the import-route command on an OSPFv3 router to import external routes, the router becomes an ASBR.

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You can configure OSPFv3 to filter a certain type of routing information by specifying the

protocol. If protocol is not specified, OSPFv3 filters all the imported routes.

NOTE

The filter-policy command takes effect only on the routes imported through the import-route command by the ASBR, that is, filters the imported routes. The routes that are filtered out do not generate LSAs and cannot be advertised by OSPFv3. If the import-route command is not configured to import other external routes (including OSPFv3 routes in different processes), the filter-policy command does not takes effect.

----End

6.8.5 Checking the Configuration

After OSPFv3 route attributes are configured, you can check the OSPFv3 interface, LSDB, and routing table.

Prerequisites

The configurations for Controlling OSPFv3 Routing Information are complete.

Procedure

l Run the commands as follow to check the OSPFv3 route aggregation:

– display ospfv3 [ process-id ] abr-summary-list [ ipv6-address prefix-length ]

–

display ospfv3 [ process-id ] asbr-summary [ ipv6-address prefix-length ]

[ verbose ] l Run the commands as follow to check the LSDB information about OSPFv3:

– display ospfv3 [ process-id ] lsdb [ area area-id ] [ originate-router advertising-

router-id | self-originate ] [ { router | network | inter-router [ asbr-router asbr-

router-id ] | { inter-prefix | nssa } [ ipv6-address prefix-length ] | link | intra-prefix |

grace } [ link-state-id ] ]

–

display ospfv3 [ process-id ] lsdb [ originate-router advertising-router-id | self-

originate ] external [ ipv6-address prefix-length ] [ link-state-id ] l Run the commands as follow to check the OSPFv3 routing table:

–

display ospfv3 [ process-id ] routing

–

display ospfv3 [ process-id ] routing [ abr-routes | asbr-routes | statistics | ipv6-

address prefix-length | intra-routes | inter-routes | ase-routes | nssa-routes ]

----End

6.9 Optimizing an OSPFv3 Network

By configuring OSPFv3 functions in special network environments, you can adjust and optimize the OSPFv3 network performance.

6.9.1 Establishing the Configuration Task

Before optimizing an OSPFv3 network, familiarize yourself with the applicable environment, complete pre-configuration tasks, and obtain the required data. This can help you complete the configuration task quickly and accurately.

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Applicable Environment

By adjusting the OSPFv3 timer, you can change the convergence speed of an OSPFv3 network and the network overload caused by protocol packets. On low-speed links, you need to consider the delay in transmitting LSAs on the interface. By adjusting the SPF calculation interval, you can mitigate resource consumption due to frequent network changes.

You can specify the DR priority of an interface to affect the DR/BDR election in a broadcast network.

Pre-configuration Tasks

Before optimizing an OSPFv3 network, complete the configuration tasks: l

Enabling IPv6 capability l

Data Preparation

To optimize an OSPFv3 network, you need the following data.

No.

Data

1 Values of OSPFv3 timers

Values of SPF timers

DR priority of the interface

6.9.2 Configuring the SPF Timer

By setting the interval for SPF calculation, you can reduce resource consumption caused by frequent network changes.

Context

Whenever the LSDB of OSPFv3 changes, the shortest path should be recalculated. Calculating the shortest path each time the LSDB changes consumes enormous resources and lowers the efficiency of a router.

Adjusting the SPF delay and hold interval can suppress frequent network changes to avoid resource consumption.

Do as follows on the router that runs OSPFv3.

Procedure

l Configure an SPF normal timer.

Do as follows on the router that runs OSPFv3:

Run:

system-view

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The system view is displayed.

Run:

ospfv3 [ process-id ]

The OSPFv3 view is displayed.

Run:

spf timers delay-interval hold-interval

An SPF normal timer is configured.

Configure an SPF intelligent timer.

Do as follows on the router that runs OSPFv3:

Run:

system-view

The system view is displayed.

Run:

ospfv3 [ process-id ]

The OSPFv3 view is displayed.

Run:

spf-schedule-interval { delay-interval hold-interval | intelligent-timer

max-interval start-interval hold-interval-1 }

An SPF intelligent timer is configured.

NOTE

An SPF normal timer and an SPF intelligent timer are mutually exclusive.

----End

6.9.3 Setting the Interval for Receiving LSAs

Setting the interval for receiving LSAs prevents unnecessary LSA updates.

Context

When a network is instable, control the minimum interval for receiving the same LSA update.

To prevent unnecessary LSA updates caused by network changes, by default, set the interval for receiving the same LSA update to 1000ms.

Do as follows on the router that runs OSPFv3.

Procedure

Step 1 Run:

system-view

The system view is displayed.

Step 2 Run:

ospfv3 [ process-id ]

The OSPFv3 view is displayed.

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Step 3 Run:

lsa-arrival-interval arrival-interval

The interval for receiving LSAs is set.

arrival-interval is an integer ranging from 1 to 10000, in milliseconds. By default, the interval for receiving LSAs is 1000ms.

----End

6.9.4 Configuring an Intelligent Timer for Generating LSAs

Configuring an intelligent timer for generating LSAs speeds up network convergence.

Context

Setting the millisecond-level interval for generating the same LSA speeds up network convergence. When a network becomes instable, reduce the interval for generating the same

LSA by using an intelligent timer.

Do as follows on the router that runs OSPFv3.

Procedure

Step 1 Run:

system-view

The system view is displayed.

Step 2 Run:

ospfv3 [ process-id ]

The OSPFv3 view is displayed.

Step 3 Run:

lsa-originate-interval intelligent-timer max-interval start-interval hold-interval

The interval for generating the same LSA is set.

l max-interval specifies the maximum interval for updating LSAs. The value ranges from 1 to

10000, in milliseconds.

l start-interval specifies the initial interval for updating LSAs. The value ranges from 0 to

1000, in milliseconds.

l hold-interval specifies the hold interval for updating LSAs. The value ranges from 1 to 5000, in milliseconds.

By default, the maximum interval for updating LSAs is 5000ms, the initial interval for updating

LSAs is 500ms, the hold interval for updating LSAs is 1000ms.

----End

6.9.5 Suppressing an Interface from Sending and Receiving OSPFv3

Packets

By suppressing the OSPFv3 interface from receiving and sending OSPFv3 packets, you can prevent routers on a certain network from obtaining OSPFv3 routing information and prevent the local router from receiving routing information from other routers.

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Context

To prevent a router from advertising routes to the router on a certain network and from importing the routes of other routers, you can suppress the interface on which OSPFv3 is enabled from receiving and sending OSPFv3 packets.

Do as follows on the router that runs OSPFv3.

Procedure

Step 1 Run:

system-view

The system view is displayed.

Step 2 Run:

ospfv3 [ process-id ]

The OSPFv3 view is displayed.

Step 3 Run:

silent-interface interface-type interface-number

The interface is suppressed from sending and receiving OSPFv3 packets.

----End

Follow-up Procedure

Different processes can suppress the same interface from sending and receiving OSPFv3 packets, but the silent-interface command is valid only for the OSPFv3 interface on which the specified process is enabled, and does not take effect on the interface of other processes.

After an OSPFv3 interface is set to be silent, the interface can still advertise its direct routes through the Intra-Area-Prefix-LSA of the same router. No OSPFv3 neighbor relationship can be set up on the interface. Therefore, the OSPFv3 adaptability is enhanced.

6.9.6 Configuring DR Priority of an Interface

When configuring a broadcast network or an NBMA network, you can specify the DR priority for each interface to change the results of DR/BDR election on the network.

Context

The DR priority on a router interface qualifies the interface for the DR election. If the DR priority is 0, the router cannot be elected as a DR or BDR.

Do as follows on the router that runs OSPFv3.

Procedure

Step 1 Run:

system-view

The system view is displayed.

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Step 2 Run:

interface interface-type interface-number

The interface view is displayed.

Step 3 Run:

ospfv3 dr-priority priority [ instance instance-id ]

The DR priority of the interface is set.

----End

Follow-up Procedure

After the DR priority is changed, you can re-elect a DR or BDR through the following methods, which, however, will result in the interruption of the OSPFv3 neighbor relationship between routers and therefore are used only when necessary.

Restarting all routers.

Running the shutdown and undo shutdown commands on the interface on which the

OSPFv3 neighbor relationship is set up.

6.9.7 Configuring Stub Routers

When a router has a heavy load and cannot forward any other packets, you can configure it as a stub router. After the router is configured as a stub router, other OSPFv3 routers do not use this router to forward data but they can have a route to this stub router.

Context

A stub router is used to control traffic. It notifies OSPFv3 routers not to forward data by the stub router, but they can have a route to the stub router.

Do as follows on the router that runs OSPFv3:

Procedure

Step 1 Run:

system-view

The system view is displayed.

Step 2 Run:

ospfv3 [ process-id ]

The OSPFv3 process view is displayed.

Step 3 Run:

stub-router [ on-startup [ interval ] ]

The stub router is configured.

NOTE

There is no correlation between the stub router configured through this command and the router in the stub area.

----End

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6.9.8 Ignoring MTU Check on DD Packets

By disabling an interface from checking the MTU field in the received DD packet, you can enable an OSPFv3 router to receive the packet with the MTU field being 0.

Context

6 OSPFv3 Configuration

Do as follows on the router that runs OSPFv3:

Procedure

Step 1 Run:

system-view

The system view is displayed.

Step 2 Run:

interface interface-type interface-number

The interface view is displayed.

Step 3 Run:

ospfv3 mtu-ignore [ instance instance-id ]

The MTU check on DD packets is ignored.

After the command is used, the interface does not check the MTU field of a received DD packet.

----End

6.9.9 Checking the Configuration

After an OSPFv3 network is optimized, you can check the OSPFv3 interface, LSDB, and routing table.

Prerequisites

The configurations for Optimizing an OSPFv3 Network are complete.

Procedure

l Run the display ospfv3[ process-id ] interface [ area area-id ] [ interface-type interface-

number ] command to check the OSPFv3 interface information.

l Run the commands as follow to check the LSDB information about OSPFv3:

–

display ospfv3 [ process-id ] lsdb [ area area-id ] [ originate-router advertising-

router-id | self-originate ] [ { router | network | inter-router [ asbr-router asbr-

router-id ] | { inter-prefix | nssa } [ ipv6-address prefix-length ] | link | intra-prefix |

grace } [ link-state-id ] ]

–

display ospfv3 [ process-id ] lsdb [ originate-router advertising-router-id | self-

originate ] external [ ipv6-address prefix-length ] [ link-state-id ] l Run the commands as follow to check the OSPFv3 routing table:

–

display ospfv3 [ process-id ] routing

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– display ospfv3 [ process-id ] routing [ abr-routes | asbr-routes | statistics | ipv6-

address prefix-length | intra-routes | inter-routes | ase-routes | nssa-routes ]

----End

6.10 Configuration OSPFv3 GR

By configuring OSPFv3 GR, you can avoid inaccurate route calculation and packet loss after an OSPFv3 router restarts.

6.10.1 Establishing the Configuration Task

By default, the OSPFv3 GR capability and Helper capability are disabled.

Applicable Environment

To prevent route flapping and service interruption due to the restart of OSPFv3, you can enable

OSPFv3 GR.

After OSPFv3 restarts, the GR restarter and the GR helper keep the neighbor relationship, exchange routing information, synchronize the database, and update the routing table and the forwarding table. OSPFv3 fast convergence is thus realized.

NOTE

The AR150/200 can function as only the Helper router, but cannot function as the Restarter router.

Pre-configuration Tasks

Before configuring OSPFv3 GR, complete the following task: l

Data Preparation

To configure OSPFv3 GR, you need the following data.

No.

Data

1 OSPFv3 process ID

2 Filtering rule of the helper mode of OSPFv3 peers

6.10.2 Enabling OSPFv3 GR

After an OSPFv3 process restarts through GR, the Restarter and the Helper reestablish the neighbor relationship, exchange routing information, synchronize the LSDB, and update the routing table and forwarding table. These operations help ensure OSPFv3 fast convergence and stabilize the network topology.

Context

Do as follows on the router that runs OSPFv3:

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Procedure

Step 1 Run:

system-view

The system view is displayed.

Step 2 Run:

ospfv3 process-id

The OSPFv3 view is displayed.

Step 3 Run:

graceful-restart [ period period | ack-time time | retransmit-interval interval |

lsa-checking-ignore | planned-only ]

OSPFv3 GR is enabled.

By default, OSPFv3 GR is disabled.

ack-time is optional. After ack-time is specified, the restarter can discover more neighbors in the time period.

----End

6.10.3 Enabling the Helper of OSPFv3 GR

The GR Helper, which is a neighbor of the GR Restarter, can identify GR signaling, maintain the adjacency with the Restarter during the active/standby switchover of the Restarter, and help the Restarter to restore the network topology.

Context

Do as follows on the router that runs OSPFv3:

Procedure

Step 1 Run:

system-view

The system view is displayed.

Step 2 Run:

ospfv3 process-id

The OSPFv3 view is displayed.

Step 3 Run:

helper-role [ { ip-prefix ip-prefix-name | acl-number acl-number | acl-name acl-

name } | max-grace-period period | planned-only | lsa-checking-ignore ]

The helper of OSPFv3 GR is enabled.

By default, the helper of OSPFv3 GR is disabled.

----End

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6.10.4 Check the Configuration

After OSPFv3 GR is configured, you can check GR information.

Prerequisites

The configurations for OSPFv3 GR are complete.

Procedure

l Run the display ospfv3 [ process-id ] graceful-restart-information command to check the status of OSPFv3 GR.

----End

6.11 Configuring the Network Management Function of

OSPFv3

OSPFv3 supports the network management function. You can bind the OSPFv3 MIB to a certain

OSPFv3 process.

6.11.1 Establishing the Configuration Task

Before configuring the network management function for OSPFv3, familiarize yourself with the applicable environment, complete pre-configuration tasks, and obtain the required data. This can help you complete the configuration task quickly and accurately.

Applicable Environment

OSPFv3 supports the network management function. You can bind OSPFv3 MIB and a certain

OSPFv3 process. In addition, OSPFv3 also supports the trap function and the log function.

Pre-configuration Tasks

Before configuring the network management function of OSPFv3, complete the following tasks: l Configuring IP addresses for interfaces to make neighboring nodes reachable l

Data Preparation

None.

6.11.2 Configuring OSPFv3 MIB Binding

The MIB is a virtual database of the device status maintained by the managed devices.

Context

When multiple OSPFv3 processes are enabled, you can configure OSPFv3 MIB to select the process to be processed, that is, that is, configure OSPFv3 MIB to select the process to which it is bound.

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Do as follows on the OSPFv3 router.

6 OSPFv3 Configuration

Procedure

Step 1 Run:

system-view

The system view is displayed.

Step 2 Run:

ospfv3 mib-binding process-id

OSPFv3 MIB binding is configured.

----End

6.11.3 Configuring OSPFv3 Trap

Traps are the notifications sent from a router to inform the NMS of the fault detected by the system.

Context

Do as follows on the OSPFv3 router.

Procedure

Step 1 Run:

system-view

The system view is displayed.

Step 2 Run:

snmp-agent trap enable feature-name ospfv3 [ trap-name { ifconfigerror |

ifrxbadpacket | ifstatechange | nbrrestarthelperstatuschange | nbrstatechange |

nssatranslatorstatuschange | restartstatuschange | virtifconfigerror |

virtifrxbadpacket | virtifstatechange | virtnbrrestarthelperstatuschange |

virtnbrstatechange } ]

The trap function for the OSPFv3 module is enabled.

----End

6.11.4 Check the Configuration

After the network management function is configured for OSPFv3, you can check the contents of the information channel, and information recorded in the information center, log buffer, and trap buffer.

Prerequisites

The configurations of the Network Management Function of OSPFv3 are complete.

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Procedure

6 OSPFv3 Configuration l Run the display current-configuration command to check the configuration parameters currently validated on the router.

----End

6.12 Maintaining OSPFv3

Maintaining OSPFv3 and Debugging OSPFv3 involve resetting OSPFv3.

6.12.1 Resetting OSPFv3

Restarting OSPFv3 can reset OSPFv3. In addition, you can reset OSPFv3 through GR.

Context

CAUTION

The OSPFv3 adjacency is removed when you reset the OSPFv3 connection by using the reset

ospfv3 command. Exercise caution when running this command.

After modifying the OSPFv3 routing policy or protocol, reset the OSPFv3 connection to validate the modification. To reset OSPFv3 connections, run the following reset ospfv3 command in the user view.

Procedure

l To validate the new configuration, run the following commands:

– reset ospfv3 { process-id | all } [ graceful-restart [ extend-period period ] ]

–

reset ospfv3 { process-id | all } counters [ neighbor [ interface-type interface-

number ] [ router-id ] ]

----End

6.13 Configuration Examples

6.13.1 Example for Configuring OSPFv3 Areas

This part provides an example for configuring basic OSPFv3 functions. Detailed operations include enabling OSPFv3 on each router and specifying network segments in different areas.

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Networking Requirements

7.1 Basic Concepts of IS-IS

Figure 6-1

, all routers run OSPFv3. The entire autonomous system is divided into three areas. Router B and Router C serve as ABRs to forward the inter-area routes.

It is required that Area 2 be configured as a stub area to decrease the LSAs advertised to this area, without affecting route reachability.

NOTE

AR150/200 is RouterD.

Figure 6-1 Networking diagram of configuring OSPFv3 areas

RouterB Area0

RouterC

Eth1/0/0

1000::1/64

Eth1/0/0

1000::2/64

Eth2/0/0

1002::1/64

Eth2/0/0

1001::1/64

Eth2/0/0

1001::2/64

RouterA

Eth1/0/0

2000::1/64

Area1

Eth1/0/0

1002::2/64

RouterD

Area2

Stub

Configuration Roadmap

The configuration roadmap is as follows:

Enable basic OSPFv3 function on each router.

Configure Area 2 as a stub area and check the OSPFv3 routing table of Router D.

Configure Area 2 as a totally stub area and check the OSPFv3 routing table of Router D.

Data Preparation

To complete the configuration, you need the following data: l Router ID of Router A as 1.1.1.1 of Area 1 l Router ID of Router B as 2.2.2.2 of Areas 0 and 1 l Router ID of Router C as 3.3.3.3 of Areas 0 and 2 l Router ID of Router D as 4.4.4.4 of Area 2

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Procedure

Step 1 Assign an IPv6 address for each interface.

The details are not mentioned here.

Step 2 Configure basic OSPFv3 functions.

# Configure Router A.

[RouterA] ipv6

[RouterA] ospfv3

[RouterA-ospfv3-1] router-id 1.1.1.1

[RouterA-ospfv3-1] quit

[RouterA] interface ethernet 1/0/0

[RouterA-Ethernet1/0/0] ospfv3 1 area 1

[RouterA-Ethernet1/0/0] quit

[RouterA] interface ethernet 2/0/0

[RouterA-Ethernet2/0/0] ospfv3 1 area 1

[RouterA-Ethernet2/0/0] quit

# Configure Router B.

[RouterB] ipv6

[RouterB] ospfv3

[RouterB-ospfv3-1] router-id 2.2.2.2

[RouterB-ospfv3-1] quit

[RouterB] interface ethernet 1/0/0

[RouterB-Ethernet1/0/0] ospfv3 1 area 0

[RouterB-Ethernet1/0/0] quit

[RouterB] interface ethernet 2/0/0

[RouterB-Ethernet2/0/0] ospfv3 1 area 1

[RouterB-Ethernet2/0/0] quit

# Configure Router C.

[RouterC] ipv6

[RouterC] ospfv3

[RouterC-ospfv3-1] router-id 3.3.3.3

[RouterC-ospfv3-1] quit

[RouterC] interface ethernet 1/0/0

[RouterC-Ethernet1/0/0] ospfv3 1 area 0

[RouterC-Ethernet1/0/0] quit

[RouterC] interface ethernet 2/0/0

[RouterC-Ethernet2/0/0] ospfv3 1 area 2

[RouterC-Ethernet2/0/0] quit

# Configure Router D.

[RouterD] ipv6

[RouterD] ospfv3

[RouterD-ospfv3-1] router-id 4.4.4.4

[RouterD-ospfv3-1] quit

[RouterD] interface ethernet 1/0/0

[RouterD-Ethernet1/0/0] ospfv3 1 area 2

[RouterD-Ethernet1/0/0] quit

# Display the OSPFv3 neighbors of Router B.

[RouterB] display ospfv3 peer

OSPFv3 Process (1)

OSPFv3 Area (0.0.0.1)

Neighbor ID Pri State Dead Time Interface Instance ID

1.1.1.1 1 Full/ - 00:00:34 Ethernet2/0/0 0

OSPFv3 Area (0.0.0.0)

Neighbor ID Pri State Dead Time Interface Instance ID

3.3.3.3 1 Full/ - 00:00:32 Ethernet1/0/0 0

# Display OSPFv3 neighbors of Router C.

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[RouterC] display ospfv3 peer

OSPFv3 Process (1)

OSPFv3 Area (0.0.0.0)

Neighbor ID Pri State Dead Time Interface Instance ID

2.2.2.2 1 Full/ - 00:00:37 Ethernet1/0/0 0

OSPFv3 Area (0.0.0.2)

Neighbor ID Pri State Dead Time Interface Instance ID

4.4.4.4 1 Full/ - 00:00:33 Ethernet2/0/0 0

# Display the OSPFv3 routing table of Router D.

[RouterD] display ospfv3 routing

Codes : E2 - Type 2 External, E1 - Type 1 External, IA - Inter-Area,

N - NSSA, U - Uninstalled

OSPFv3 Process (1)

Destination Metric

Next-hop

IA 1000::/64 2

via FE80::1572:0:5EF4:1, Ethernet1/0/0

IA 1001::/64 3

via FE80::1572:0:5EF4:1, Ethernet1/0/0

1002::/64 1

directly-connected, Ethernet1/0/0

IA 2000::/64 4

via FE80::1572:0:5EF4:1, Ethernet1/0/0

Step 3 Configure stub areas.

# Configure the stub area of Router D.

[RouterD] ospfv3

[RouterD-ospfv3-1] area 2

[RouterD-ospfv3-1-area-0.0.0.2] stub

[RouterD-ospfv3-1-area-0.0.0.2] quit

# Configure the stub area of Router C, and set the cost of the default route advertised to the stub area to 10.

[RouterC] ospfv3

[RouterC-ospfv3-1] area 2

[RouterC-ospfv3-1-area-0.0.0.2] stub

[RouterC-ospfv3-1-area-0.0.0.2] default-cost 10

[RouterC-ospfv3-1-area-0.0.0.2] quit

# Display the OSPFv3 routing table of Router D, and you can view a new default route in the routing table. Its cost is the sum of the cost of the directly connected routes and the configured cost.

[RouterD] display ospfv3 routing

Codes : E2 - Type 2 External, E1 - Type 1 External, IA - Inter-Area,

N - NSSA, U - Uninstalled

OSPFv3 Process (1)

Destination Metric

Next-hop

IA ::/0 11

via FE80::1572:0:5EF4:1, Ethernet1/0/0

IA 1000::/64 2

via FE80::1572:0:5EF4:1, Ethernet1/0/0

IA 1001::/64 3

via FE80::1572:0:5EF4:1, Ethernet1/0/0

1002::/64 1

directly-connected, Ethernet1/0/0

IA 2000::/64 4

via FE80::1572:0:5EF4:1, Ethernet1/0/0

Step 4 Configure totally stub areas.

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# Configure Router C and configure Area 2 as a totally stub area.

[RouterC] ospfv3

[RouterC-ospfv3-1] area 2

[RouterC-ospfv3-1-area-0.0.0.2] stub no-summary

[RouterC-ospfv3-1-area-0.0.0.2] quit

Step 5 Verify the configuration.

# Display the OSPFv3 routing table of Router D, and you can view that the entries in the routing table decrease; other non-directly connected routes are suppressed; only the default route is reserved.

[RouterD] display ospfv3 routing

Codes : E2 - Type 2 External, E1 - Type 1 External, IA - Inter-Area,

N - NSSA, U - Uninstalled

OSPFv3 Process (1)

Destination Metric

Next-hop

IA ::/0 11

via FE80::1572:0:5EF4:1, Ethernet1/0/0

1002::/64 1

directly-connected, Ethernet1/0/0

----End

Configuration Files

l Configuration file of Router A

sysname RouterA

ipv6

# interface Ethernet1/0/0

ipv6 enable

ipv6 address 2000::1/64

ospfv3 1 area 0.0.0.1

# interface Ethernet2/0/0

ipv6 enable

ipv6 address 1001::2/64

ospfv3 1 area 0.0.0.1

# ospfv3 1

router-id 1.1.1.1

area 0.0.0.1

# return l Configuration file of Router B

sysname RouterB

ipv6

# interface Ethernet1/0/0

ipv6 enable

ipv6 address 1000::1/64

ospfv3 1 area 0.0.0.0

# interface Ethernet2/0/0

ipv6 enable

ipv6 address 1001::1/64

ospfv3 1 area 0.0.0.1

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router-id 2.2.2.2

area 0.0.0.0

area 0.0.0.1

# return l Configuration file of Router C

sysname RouterC

ipv6

# interface Ethernet1/0/0

ipv6 enable

ipv6 address 1000::2/64

ospfv3 1 area 0.0.0.0

# interface Ethernet2/0/0

ipv6 enable

ipv6 address 1002::1/64

ospfv3 1 area 0.0.0.2

# ospfv3 1

router-id 3.3.3.3

area 0.0.0.0

area 0.0.0.2

stub no-summary

default-cost 10

# return l Configuration file of Router D

sysname RouterD

ipv6

# interface Ethernet1/0/0

ipv6 enable

ipv6 address 1002::2/64

ospfv3 1 area 0.0.0.2

# ospfv3 1

router-id 4.4.4.4

area 0.0.0.2

stub

# return

6.13.2 Example for Configuring OSPFv3 DR Election

This part provides an example for setting the DR priority on an interface for DR election on a broadcast network.

Networking Requirements

Figure 6-2

, Router A has a DR priority of 100, which is the highest in the network, so it is elected as the DR. Router C has the second highest priority, so it is elected as the BDR. The priority of Router B is 0 so that it cannot be elected as the DR. Router D does not have a priority and the priority is 1 by default.

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Figure 6-2 Networking diagram of configuring OSPFv3 DR election

RouterA RouterB

6 OSPFv3 Configuration

Eth1/0/0

1001::1/64

Eth1/0/0

1001::3/64

Eth1/0/0

1001::2/64

Eth1/0/0

1001::4/64

RouterC RouterD

Configuration Roadmap

The configuration roadmap is as follows:

Configure the router ID on each router, enable OSPFv3, and specify the network segment.

Check the DR/BDR status with the default priority.

Configure the DR priority on the interface and check the DR/BDR status.

Data Preparation

To complete the configuration, you need the following data: l Router A uses the router ID of 1.1.1.1 and DR priority 100.

l Router B uses the router ID of 2.2.2.2 and DR priority 0.

l Router C uses the router ID of 3.3.3.3 and DR priority 2.

l Router D uses the router ID of 4.4.4.4 and default DR priority 1.

Procedure

Step 1 Assign an IPv6 address for each interface.

The details are not mentioned here.

Step 2 Configure basic OSPFv3 functions.

# Configure Router A, enable OSPFv3, and set its router ID to 1.1.1.1.

[RouterA] ipv6

[RouterA] ospfv3

[RouterA-ospfv3-1] router-id 1.1.1.1

[RouterA-ospfv3-1] quit

[RouterA] interface ethernet 1/0/0

[RouterA-Ethernet1/0/0] ospfv3 1 area 0

[RouterA-Ethernet1/0/0] quit

# Configure Router B, enable OSPFv3, and set its Router ID to 2.2.2.2.

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[RouterB] ipv6

[RouterB] ospfv3

[RouterB-ospfv3-1] router-id 2.2.2.2

[RouterB-ospfv3-1] quit

[RouterB] interface ethernet 1/0/0

[RouterB-Ethernet1/0/0] ospfv3 1 area 0

[RouterB-Ethernet1/0/0] quit

# Configure Router C, enable OSPFv3, and set its Router ID to 3.3.3.3.

[RouterC] ipv6

[RouterC] ospfv3

[RouterC-ospfv3-1] router-id 3.3.3.3

[RouterC-ospfv3-1] quit

[RouterC] interface ethernet 1/0/0

[RouterC-Ethernet1/0/0] ospfv3 1 area 0

[RouterC-Ethernet1/0/0] quit

# Configure Router D, enable OSPFv3, and set its Router ID to 4.4.4.4.

[RouterD] ipv6

[RouterD] ospfv3

[RouterD-ospfv3-1] router-id 4.4.4.4

[RouterD-ospfv3-1] quit

[RouterD] interface ethernet 1/0/0

[RouterD-Ethernet1/0/0] ospfv3 1 area 0

[RouterD-Ethernet1/0/0] quit

# Display the neighbors of Router A. You can view the DR priority (its default value is 1) and the neighbor status. Router D is the DR and Router C is the BDR.

NOTE

The router with the greater router ID is the DR when routers have the same priority. If a certain Ethernet interface of a router becomes a DR, the other broadcast interfaces of the router have the highest priority in

DR election. That is, the DR router is elected as the DR.

[RouterA] display ospfv3 peer

OSPFv3 Process (1)

OSPFv3 Area (0.0.0.0)

Neighbor ID Pri State Dead Time Interface Instance ID

2.2.2.2 1 2-Way/DROther 00:00:32 Ethernet1/0/0 0

3.3.3.3 1 Full/Backup 00:00:36 Ethernet1/0/0 0

4.4.4.4 1 Full/DR 00:00:38 Ethernet1/0/0 0

# Display the neighbors of Router D, and you can view that all neighbors of Router D are in the

Full state.

[RouterD] display ospfv3 peer

OSPFv3 Process (1)

OSPFv3 Area (0.0.0.0)

Neighbor ID Pri State Dead Time Interface Instance ID

1.1.1.1 1 Full/DROther 00:00:32 Ethernet1/0/0 0

2.2.2.2 1 Full/DROther 00:00:35 Ethernet1/0/0 0

3.3.3.3 1 Full/Backup 00:00:30 Ethernet1/0/0 0

Step 3 Set the DR priority of the interface.

# Set the DR priority of Router A to 100.

[RouterA] interface ethernet 1/0/0

[RouterA-Ethernet1/0/0] ospfv3 dr-priority 100

[RouterA-Ethernet1/0/0] quit

# Set the DR priority of Router B to 0.

[RouterB] interface ethernet 1/0/0

[RouterB-Ethernet1/0/0] ospfv3 dr-priority 0

[RouterB-Ethernet1/0/0] quit

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# Set the DR priority of Router C to 2.

[RouterC] interface ethernet 1/0/0

[RouterC-Ethernet1/0/0] ospfv3 dr-priority 2

[RouterC-Ethernet1/0/0] quit

# Display the neighbors of Router A, and you can view that the DR priority is updated and the

DR and BDR remain unchanged.

[RouterA] display ospfv3 peer

OSPFv3 Process (1)

OSPFv3 Area (0.0.0.0)

Neighbor ID Pri State Dead Time Interface Instance ID

2.2.2.2 0 2-Way/DROther 00:00:34 Ethernet1/0/0 0

3.3.3.3 2 Full/Backup 00:00:38 Ethernet1/0/0 0

4.4.4.4 1 Full/DR 00:00:31 Ethernet1/0/0 0

# Display the neighbors of Router D, and you can view that Router D remains as the DR.

[RouterD] display ospfv3 peer

OSPFv3 Process (1)

OSPFv3 Area (0.0.0.0)

Neighbor ID Pri State Dead Time Interface Instance ID

1.1.1.1 100 Full/DROther 00:00:36 Ethernet1/0/0 0

2.2.2.2 0 Full/DROther 00:00:30 Ethernet1/0/0 0

3.3.3.3 2 Full/Backup 00:00:36 Ethernet1/0/0 0

Step 4 Re-elect the DR/BDR.

# Restart all routers (or run the shutdown and undo shutdown commands on the interface that establishes the OSPFv3 neighbor relationship), and make OSPFv3 re-elect the DR/BDR.

Step 5 Verify the configuration.

# Display the neighbors of Router A, and you can view that Router C is the BDR.

[RouterA] display ospfv3 peer

OSPFv3 Process (1)

OSPFv3 Area (0.0.0.0)

Neighbor ID Pri State Dead Time Interface Instance ID

2.2.2.2 0 Full/DROther 00:00:31 Ethernet1/0/0 0

3.3.3.3 2 Full/Backup 00:00:36 Ethernet1/0/0 0

4.4.4.4 1 Full/DROther 00:00:39 Ethernet1/0/0 0

# Display the neighbors of Router D, and you can view that Router A is the DR.

[RouterD] display ospfv3 peer

OSPFv3 Process (1)

OSPFv3 Area (0.0.0.0)

Neighbor ID Pri State Dead Time Interface Instance ID

1.1.1.1 100 Full/DR 00:00:39 Ethernet1/0/0 0

2.2.2.2 0 2-Way/DROther 00:00:35 Ethernet1/0/0 0

3.3.3.3 2 Full/Backup 00:00:39 Ethernet1/0/0 0

----End

Configuration Files

l Configuration file of Router A

sysname RouterA

ipv6

# interface Ethernet1/0/0

ipv6 enable

ipv6 address 1001::1/64

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ospfv3 1 area 0.0.0.0

ospfv3 dr-priority 100

# ospfv3 1

router-id 1.1.1.1

# return l Configuration file of Router B

sysname RouterB

ipv6

# interface Ethernet1/0/0

ipv6 enable

ipv6 address 1001::2/64

ospfv3 1 area 0.0.0.0

ospfv3 dr-priority 0

# ospfv3 1

router-id 2.2.2.2

# return l Configuration file of Router C

sysname RouterC

ipv6

# interface Ethernet1/0/0

ipv6 enable

ipv6 address 1001::3/64

ospfv3 1 area 0.0.0.0

ospfv3 dr-priority 2

# ospfv3 1

router-id 3.3.3.3

# return l Configuration file of Router D

sysname RouterD

ipv6

# interface Ethernet1/0/0

ipv6 enable

ipv6 address 1001::4/64

ospfv3 1 area 0.0.0.0

# ospfv3 1

router-id 4.4.4.4

# return

6 OSPFv3 Configuration

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Configuration Guide - IP Routing 7 IS-IS Configuration

IS-IS Configuration

About This Chapter

Issue 02 (2012-03-30)

This chapter describes the basic principle of IS-IS and procedures for configuring IS-IS, and provides configuration examples.

As an IGP, IS-IS is used inside an AS. IS-IS is a link-state protocol. It uses the SPF algorithm to calculate routes.

7.2 IS-IS Features Supported by the AR150/200

The AR150/200 supports various Intermediate System-to-Intermediate System (IS-IS) protocol features, including multi-instance, multi-process, hot standby (HSB), multi-topology, local multicast-topology (MT), graceful restart (GR), traffic engineering (TE), DiffServ-aware traffic engineering (DS-TE), administrative tags, Link State Protocol Data Unit (LSP) fragment extension, dynamic host name exchange, fast convergence, Bidirectional Forwarding Detection

(BFD), and three-way handshake.

7.3 Configuring Basic IPv4 IS-IS Functions

This section describes the procedures for configuring basic IPv4 IS-IS functions, including the procedures for configuring IS-IS processes and interfaces, to implement communication between nodes on an IPv4 IS-IS network.

7.4 Establishing or Maintaining IS-IS Neighbor Relationships or Adjacencies

This section describes how to configure the parameters that affect the IS-IS neighbor relationship.

7.5 Configuring IPv4 IS-IS Route Selection

Configuring IS-IS route selection can achieve refined control over route selection.

7.6 Configuring IPv4 IS-IS Route Summarization

To improve the route searching efficiency and simplify route management on a large-scale IS-

IS network, configure IS-IS route summarization to reduce the number of IS-IS routes in a routing table.

7.7 Configuring IPv4 IS-IS to Interact with Other Routing Protocols

If other routing protocols are configured on an IS-IS network, you need to configure IS-IS to interact with these protocols to ensure successful communication between them.

7.8 Configuring the IPv4 IS-IS Route Convergence Speed

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Accelerating IS-IS route convergence can improve the fault location efficiency and improve the network reliability.

7.9 Configuring Static IPv4 BFD for IS-IS

BFD can provide link failure detection featuring light load and high speed (at the millisecond level). Static IPv4 BFD can be configured to monitor IS-IS links.

7.10 Configuring Dynamic IPv4 BFD for IS-IS

Dynamic IPv4 BFD for IS-IS can accelerate IS-IS route convergence.

7.11 Configuring Basic IPv6 IS-IS Functions

This section describes the procedures for configuring basic IPv6 IS-IS functions, including the procedures for configuring IS-IS processes and interfaces, to implement communication between nodes on an IPv6 IS-IS network.

7.12 Configuring IPv6 IS-IS Route Selection

Configuring IS-IS route selection can achieve refined control over route selection.

7.13 Configuring IPv6 IS-IS Route Summarization

To improve the route searching efficiency and simplify route management on a large-scale IS-

IS network, configure IS-IS route summarization to reduce the number of IS-IS routes in a routing table.

7.14 Configuring IPv6 IS-IS to Interact with Other Routing Protocols

If other routing protocols are configured on an IS-IS network, you need to configure IS-IS to interact with these protocols to ensure successful communication between them.

7.15 Configuring the IPv6 IS-IS Route Convergence Speed

Accelerating IS-IS route convergence can improve the fault location efficiency and improve the network reliability.

7.16 Configuring IS-IS GR

By configuring IS-IS GR, you can enable Router to restart gracefully and avoid temporary black holes.

7.17 Maintaining IS-IS

Maintaining IS-IS involves resetting IS-IS and clearing IS-IS statistics.

7.18 Configuration Examples

This section provides several configuration examples of IS-IS together with the configuration flowchart. The configuration examples explain networking requirements, configuration notes, and configuration roadmap.

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7.1 Basic Concepts of IS-IS

As an IGP, IS-IS is used inside an AS. IS-IS is a link-state protocol. It uses the SPF algorithm to calculate routes.

The Intermediate System-to-Intermediate System (IS-IS) is a dynamic routing protocol that was originally created by the International Organization for Standardization (ISO) for its

Connectionless Network Protocol (CLNP).

To support the IP routing, the Internet Engineering Task Force (IETF) extended and modified

IS-IS in RFC 1195. IS-IS can thus be applied to both TCP/IP and OSI environments. This type of IS-IS is called the Integrated IS-IS or Dual IS-IS.

As an Interior Gateway Protocol (IGP), IS-IS is used in Autonomous Systems (ASs). IS-IS is a link-state protocol. It uses the Shortest Path First (SPF) algorithm to calculate routes. It resembles the Open Shortest Path First (OSPF) protocol.

IS-IS Areas

To support large-scale networks, the IS-IS adopts a two-level structure in a Routing Domain

(RD). A large RD is divided into one or more areas. The intra-area routes are managed by the

Level-1 routers, whereas the inter-area routes are managed by the Level-2 routers.

Figure 7-1

shows an IS-IS network. Its topology is similar to that of a multi-area OSPF network.

Area 1 is a backbone area. All routers in this area are Level-2 routers. The other four areas are non-backbone areas. They are connected to Area 1 through Level-1-2 routers.

Figure 7-1 IS-IS topology

Area2

L1/2

Area3

L2 Area1

Area4

L1/2

Area5

Issue 02 (2012-03-30)

Figure 7-2

shows another type of IS-IS topology. The Level-1-2 routers are used to connect the

Level-1 and the Level-2 routers, and are used to establish the backbone network together with

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Configuration Guide - IP Routing 7 IS-IS Configuration the other Level-2 routers. In this topology, no area is specified as a backbone area. All the Level-2 routers constitute an IS-IS backbone network. The devices may belong to different areas, but the areas must be successive.

Figure 7-2 IS-IS topology II

Area1

Area2

L1/L2

Area4

Area3

NOTE

The IS-IS backbone network does not refer to a specific area.

This type of networking shows differences between IS-IS and OSPF. For OSPF, the inter-area routes are forwarded by the backbone area and the SPF algorithm is used in the same area. For

IS-IS, both Level-1 routers and Level-2 routers use the SPF algorithm to generate Shortest Path

Trees (SPTs).

Network Types

IS-IS supports only two network types, which can classified as follows according to physical links: l Broadcast links such as Ethernet and Token-Ring.

l Point-to-point links such as PPP and HDLC.

NOTE

For a Non-Broadcast Multi-Access (NBMA) network such as ATM, you need to configure sub-interfaces for it. The type of subnets cannot be Point-to-Multipoint (P2MP). IS-IS cannot run on P2MP networks.

7.2 IS-IS Features Supported by the AR150/200

(BFD), and three-way handshake.

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NOTE

The IS-IS for IPv6 function is used with a license. To use the IS-IS for IPv6 function, apply for and purchase the following license from the Huawei local office: l

AR150&200 Value-Added Data Package

Multi-Instance and Multi-Process

IS-IS supports multi-process and multi-instance, facilitating management and improving control efficiency of IS-IS.

l Multi-process

Multi-process allows a group of interfaces to be associated with a specific IS-IS process.

This ensures that the specific IS-IS process performs all the protocol-based operations only on the group of interfaces. Multiple IS-IS processes can run on a single router and each process is responsible for a unique group of interfaces.

l Multi-instance

After the VPN feature is enabled, multi-instance allows an IS-IS process to be associated with a specific VPN instance so that all the interfaces of this IS-IS process will be associated with the VPN instance.

IS-IS GR

GR is a function used to restart a router gracefully. It ensures uninterrupted traffic forwarding during the restart of a router in a short time.

If IS-IS restarts in a non-graceful mode, IS-IS sessions are reset and Link State Protocol Data

Units (LSPs) are regenerated and flooded. This triggers the SPF calculation in the entire area, which causes route flapping and forwarding interruption in the area. The IETF defines IS-IS GR in RFC 3847, in which the specifications of protocol restart with FIB tables reserved and unreserved are stated.

NOTE

For details about IS-IS GR, see the "IS-IS" chapter in the Huawei AR150&200 Series Enterprise Routers

Feature Description-IP Routing.

Administrative Tag

The use of administrative tags simplifies management. Administrative tags can advertise IP address prefixes in the IS-IS area to control routes. The administrative tag carries the administrative information about an IP address prefix. It is used to control the routes of different levels and routes imported from different areas, various routing protocols, multiple IS-IS instances running on a router, and carrying of tags.

Each administrative tag is associated with certain attributes. If the prefix of the reachable IP address to be advertised by IS-IS has this attribute, IS-IS adds the administrative tag to the reachability TLV in the prefix. In this manner, the tag is advertised throughout the entire IS-IS area.

LSP Fragment Extension

When more information is carried in an LSP to be advertised by IS-IS, IS-IS advertises multiple

LSP fragments. Each LSP fragment is identified by the LSP identifier field of an LSP. The LSP identifier field is 1 byte long. Therefore, the maximum number of fragments that can be generated by an IS-IS router is 256.

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The IS-IS fragment extension feature allows an IS-IS router to generate more LSP fragments.

To implement this feature, you can use the network manager to configure additional system IDs for the router. Each system ID represents a virtual system, which can generate 256 LSP fragments. With more additional system IDs (up to 50 virtual systems), an IS-IS router can generate a maximum of 13056 LSP fragments.

l Related terms are as follows:

– Originating system

In this document, the originating system is the router that actually runs the IS-IS protocol, and each IS-IS process is regraded as multiple virtual routers to generate LSP fragments.

– Normal system ID

It is the system ID of the originating system.

–

Additional System-ID

An additional system ID, assigned by the network administrator, represents a virtual system. Each virtual system is allowed to generate up to 256 extended LSP fragments.

Like a normal system ID, an additional system ID must be unique in a routing domain.

–

Virtual system

It is a virtual system for generating extended LSP fragments. Each virtual system has a unique additional system ID, and each extended LSP fragment carries an additional system ID.

l Operating mode

An IS-IS router can run the LSP fragment extension feature in the following modes:

–

Mode 1: The originating system sends a link to each virtual system. Then each virtual system sends a link to the originating system. The virtual systems function as the routers that are connected to the originating system on the network. This mode is used when some routers on the network do not support the LSP fragment extension feature.

In this mode, only the routing information can be advertised in the LSPs of the virtual systems.

– Mode 2: All the routers on the network can learn that the LSPs generated by the virtual systems actually belong to the originating system. This mode is used when all the routers on the network support the LSP fragment extension feature. In this mode, all link state information can be advertised in the LSPs of the virtual systems.

Dynamic Host Name Exchange Mechanism

The dynamic host name exchange mechanism is introduced to conveniently manage and maintain IS-IS networks. The mechanism provides a service of mapping host names to system

IDs for the IS-IS routers. The dynamic host name information is advertised in the form of a dynamic host name TLV in an LSP.

The dynamic host name exchange mechanism also provides a service to associate a host name with the designated intermediate system (DIS) on a broadcast network. Then LSPs of pseudo nodes advertise this association in the form of a dynamic host name TLV.

It is easier to identify and memorize the host name than the system ID. After this function is configured, the host name will displays when display command is used.

IS-IS Route Summarization

Route summarization is a function for summarizing routes with the same IP prefix into one route.

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On a large-scale IS-IS network, you can configure route summarization to reduce the number of IS-IS routes in the routing table. This improve the usage of system resources and facilitates route management.

IP network segments are not affected when a link frequently alternates between Up and Down on an IP network segment. This prevents route flapping and improves the network stability.

The router supports classless network-based route summarization.

IS-IS Load Balancing

If there are redundant links on an IS-IS network, there may be multiple equal-cost routes.

Configuring IS-IS load balancing can evenly distribute traffic to each link. This increases the bandwidth usage of each link and prevents network congestion caused by some overloaded links.

IS-IS load balancing, however, may affect traffic management because traffic will be randomly forwarded in this mode.

IS-IS Preference

If there are redundant links on an IS-IS network, there may be multiple equal-cost routes.

The router allows you to configure preference values for equal-cost IS-IS routes so that only the route with the highest preference will be used and the others will function as backups.

This facilitates traffic management, improves the network reliability, and avoids configuration change.

IS-IS Fast Convergence

l Incremental SPF (I-SPF)

I-SPF calculates only changed routes at a time, but not all routes.

ISO-10589 defines Dijkstra as the algorithm to calculate routes. When a node is added to or removed from a network topology, all routes of all nodes need to be calculated if the

Dijkstra algorithm is adopted. As a result, it takes a long time and occupies excessive resources, reducing the route convergence speed of the entire network.

I-SPF improves this algorithm. Except for the first time, only changed nodes instead of all nodes are involved in calculation. The SPT generated at last is the same as that generated by the Dijkstra algorithm. This decreases the CPU usage and speeds up route convergence.

l Partial route calculation (PRC)

Similar to I-SPF, only changed nodes are involved in PRC. PRC, however, does not calculate the shortest path but updates leaf routes based on the SPT calculated by I-SPF.

In route calculation, a leaf represents a route, and a node represents a router. If the SPT calculated using I-SPF changes, PRC calculates all the leaves on only the changed node; if the SPT calculated using I-SPF does not change, PRC calculates only the changed leaf.

For example, if an interface of a node is enabled with IS-IS, the SPT of the entire network remains unchanged. In this case, PRC updates the routes on only the interface of this node, reducing the CPU usage.

PRC working with I-SPF further improves the convergence performance of the network.

As an improvement of the original SPF algorithm, RPC and I-SPF replace the original algorithm.

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NOTE

In real world applications of AR150/200s, only I-SPF and PRC are used to calculate IS-IS routes.

l LSP fast flooding

Based on the RFC, when IS-IS receives LSPs from other routers and the LSPs are more updated than those in its own LSDB, IS-IS uses a timer to flood out the LSPs in the LSDB at specified intervals. Therefore, the LSDB synchronization is slow.

LSP fast flooding addresses the problem. When a router configured with this feature receives one or more LSPs, it floods out the LSPs less than the specified number before route calculation. This accelerates the LSDB synchronization and speeds up network convergence to the great extent.

l Intelligent timer

Although the route calculation algorithm is improved, the long interval for triggering route calculation also affects the convergence speed. Using a millisecond timer can shorten the interval, however, excessive CPU resources will be consumed if the network topology changes frequently. An SPF intelligent timer can quickly respond to certain emergent events and also prevent excessive CPU resource consumption.

An IS-IS network running normally is stable. The network seldom changes frequently, and an IS-IS router does not calculate routes frequently. Therefore, you can set a short interval

(in milliseconds) for triggering the route calculation for the first time. If the network topology changes frequently, the value of the intelligent timer increases with the calculation times, and the interval for route calculation becomes longer. This prevents excessive CPU resource consumption.

The LSP generation intelligent timer is similar to the SPF intelligent timer. In IS-IS, when the LSP generation timer expires, the system regenerates its own LSP according to the current topology. In the original implementation mechanism, a timer with a fixed value is used, which, however, cannot meet the requirements on fast convergence and low CPU usage. Therefore, the LSP generation timer is designed as an intelligent timer so that it can respond quickly to some emergent events (such as interface alternation between Up an

Down) to speed up network convergence. In addition, when the network changes frequently, the value of the intelligent timer becomes greater automatically to prevent excessive CPU resource consumption.

NOTE

Determine whether to configure intelligent timers based on actual network situations and specifications of deployed routers.

BFD for IS-IS

The AR150/200 supports BFD for IS-IS to detect IS-IS neighbor relationships. BFD can fast detect the faults on links between IS-IS neighbors and reports them to IS-IS. Fast convergence of IS-IS is then implemented.

NOTE

BFD detects only one-hop links between IS-IS neighbors. This is because IS-IS establishes only one-hop neighbors.

l Static BFD

To configure static BFD, use command lines to configure single-hop BFD parameters, such as local and remote discriminators. Then configure the device to send BFD session setup requests.

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A static BFD session can only be established and released manually. A configuration error will lead to a BFD failure. For example, if the configured local discriminator or remote discriminator is incorrect, a BFD session will not work properly.

The AR150/200 supports static IPv4 BFD for IS-IS.

l Dynamic BFD

Dynamic BFD refers to the dynamic establishment of BFD sessions using routing protocols.

When a new IS-IS neighbor relationship is set up, BFD is notified of the parameters of the neighbor and the detection parameters (including source and destination IP addresses).

Then a BFD session will be established based on the received parameters of the neighbor.

Dynamic BFD is more flexible than static BFD.

Connection status between an IS-IS device and its neighbors can be monitored by exchanging Hello packets at intervals. The sending interval is usually set to 10s, and a neighbor is declared Down after at least three intervals (during which no response Hello packet is received from the neighbor). It takes IS-IS some seconds to sense a Down neighbor, resulting in loss of a large amount of high-speed data.

Dynamic BFD can provide link failure detection with light load and high speed (at the millisecond level). Dynamic BFD does not take the place of the Hello mechanism of IS-

IS, but helps IS-IS to detect the faults on neighbors or links more quickly, and instruct IS-

IS to recalculate routes to correctly guide packet forwarding.

The AR150/200 supports dynamic IPv4 and IPv6 BFD for IS-IS.

NOTE

For details about IS-IS GR, see the "IS-IS" chapter in the Huawei AR150&200 Series Enterprise

Routers Feature Description-IP Routing.

IS-IS Three-Way Handshake

A reliable link layer protocol is required when IS-IS runs on a point-to-point (P2P) link. Based on ISO 10589, the two-way handshake mechanism of IS-IS uses Hello packets to set up P2P adjacencies between neighboring routers. Once the router receives a Hello packet from its peer, it regards the status of the peer as Up and sets up an adjacency with the peer.

This mechanism has obvious defects. For example, when an adjacency is set up, the unstable link status causes the loss of Complete Sequence Number Packets (CSNPs). As a result, the

LSDB fails to be synchronized during the update period of an LSP. If two or more links exist between two routers, an adjacency can still be set up when one link is Down and the other is Up in the same direction. The parameters of the other link, however, are also used in SPF calculation.

Therouter does not detect any fault of the link that is in the Down state and still tries to forward packets over this link.

The three-way handshake mechanism addresses the problem on the unreliable P2P link. In threeway handshake mode, the router regards the neighbor as Up only after confirming that the neighbor receives the packet that it sends and then sets up an adjacency with the neighbor. In addition, a 32-bit circuit ID is used in the three-way handshake mechanism, which is an extension of the local 8-bit circuit ID that defines 255 P2P links.

7.3 Configuring Basic IPv4 IS-IS Functions

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7.3.1 Establishing the Configuration Task

Before configuring basic IPv4 IS-IS functions, familiarize yourself with the applicable environment, complete the pre-configuration tasks, and obtain the required data.

Applicable Environment

To deploy IS-IS on an IPv4 network, configure basic IS-IS functions to implement communication between different nodes on the network.

Other IS-IS functions can be configured only after basic IS-IS functions are configured.

Configuring basic IPv4 IS-IS functions includes the following operations:

Create IPv4 IS-IS processes.

Configure IPv4 IS-IS interfaces.

Pre-configuration Tasks

Before configuring basic IPv4 IS-IS functions, complete the following tasks: l Configure a link layer protocol.

Assign an IP address to each interface to ensure IP connectivity.

Data Preparation

To configure basic IPv4 IS-IS functions, you need the following data.

No.

Data

IS-IS process ID

NTE of an IS-IS process

Level of each device and level of each interface

7.3.2 Creating IPv4 IS-IS Processes

Before configuring basic IPv4 IS-IS functions, create IPv4 IS-IS processes and then enable IPv4

IS-IS interfaces.

Context

To create an IPv4 IS-IS process, perform the following operations: l

Create an IS-IS process and configure the NET of a device.

(Optional) Configure the level of a device.

The level of a device is level-1-2 by default.

Configure the device level based on the network planning. If no device level is configured,

IS-IS establishes separate neighbor relationships for Level-1 and Level-2 devices and maintains two identical LSDBs, consuming excessive system resources.

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(Optional) Configure IS-IS host name mapping.

After IS-IS host name mapping is configured, a host name but not the system ID of a device will display by using display commands. This configuration improves the maintainability on an IS-IS network.

(Optional) Enable the output of the IS-IS adjacency status

If the local terminal monitor is enabled and the output of the IS-IS adjacency status is enabled, IS-IS adjacency changes will be output to the router until the output of the adjacency status is disabled.

Procedure

l Create an IS-IS process and configure the NET of a device.

Run:

system-view

The system view is displayed.

Run:

isis [ process-id ]

An IS-IS process is created, and the IS-IS process view is displayed.

The process-id parameter specifies the ID of an IS-IS process. The default value of

process-id is 1. To associate an IS-IS process with a VPN instance, run the isis

[ process-id ] [ vpn-instance vpn-instance-name ] command.

Run:

network-entity net

A NET is configured.

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CAUTION

Configuring loopback interface addresses based on NETs is recommended to ensures that a NET is unique on the network. If NETs are not unique, route flapping will easily occur.

Area addresses of NETs are checked when Level-1 IS-IS neighbor relationships are being established, but not checked when Level-2 IS-IS neighbor relationships are being established. Level-1 IS-IS neighbor relationships can be established only if area addresses of NETs are the same.

l (Optional) Configure the level of a device.

Run:

system-view

The system view is displayed.

Run:

isis [ process-id ]

An IS-IS process is created, and the IS-IS process view is displayed.

Run:

is-level { level-1 | level-1-2 | level-2 }

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The level of the router is configured.

(Optional) Configure IS-IS host name mapping.

Run:

system-view

The system view is displayed.

Run:

isis [ process-id ]

An IS-IS process is created, and the IS-IS process view is displayed.

Run:

is-name symbolic-name

IS-IS dynamic host name mapping is configured. The system ID of the local device is mapped to the specified host name.

The value of symbolic-name is contained in LSP packets and advertised to other IS-

IS devices.

On another IS-IS device displays the value of symbolic-name, but not the system ID, of the local IS-IS device.

Run:

is-name map system-id symbolic-name

IS-IS static host name mapping is configured. The system ID of a peer IS-IS device is mapped to the specified host name.

This command configuration takes effect only on the local IS-IS device. The value of

symbolic-name will not be added to LSP packets.

If dynamic host name mappings is configured on an IS-IS network, the mappings on the network overwrite the mappings configured on the local router.

l (Optional) Enable the output of the IS-IS adjacency status.

Run:

system-view

The system view is displayed.

Run:

isis [ process-id ]

An IS-IS process is created, and the IS-IS view is displayed.

Run:

log-peer-change

The output of the adjacency status is enabled.

----End

7.3.3 Configuring IPv4 IS-IS Interfaces

To configure an interface on an IS-IS device to send Hello packets or flood LSPs, IS-IS must be enabled on this interface.

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Context

7 IS-IS Configuration

The level of an IS-IS device and level of an interface together determine the level of a neighbor relationship. By default, Level-1 and Level-2 neighbor relationships will be established between two Level-1-2 devices. If only one level of neighbor relationships is required, you can configure the level of an interface to prevent the establishment of the other level of neighbor relationships.

After IS-IS is enabled on an interface, the interface will automatically send Hello packets, attempting to establish neighbor relationships. If a peer device is not an IS-IS device or if an interface is not expected to send Hello packets, suppress the interface. Then this interface only advertises routes of the network segment where the interface reside, but does not send Hello packets. This suppression improves the link bandwidth usage.

Procedure

l Configure an IS-IS interface.

Run:

system-view

The system view is displayed.

Run:

interface interface-type interface-number

The interface view is displayed.

Run:

isis enable [ process-id ]

An IS-IS interface is configured.

After this command is run, the IS-IS device uses the specified interface to send Hello packets and flood LSPs.

NOTE

No neighbor relationship needs to be established between loopback interfaces. Therefore, if this command is run on a loopback interface, the routes of the network segment where the loopback interface resides will be advertised through other IS-IS interfaces.

(Optional) Configure the level of an IS-IS interface.

Run:

system-view

The system view is displayed.

Run:

interface interface-type interface-number

The interface view is displayed.

Run:

isis circuit-level [ level-1 | level-1-2 | level-2 ]

The level of the interface is configured.

By default, the level of an interface is level-1-2.

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NOTE

Changing the level of an IS-IS interface is valid only when the level of the IS-IS device is

Level-1-2. If the level of the IS-IS device is not a Level-1-2, the level of the IS-IS device determines the level of the adjacency to be established.

l (Optional) Suppress an IS-IS interface.

Run:

system-view

The system view is displayed.

Run:

interface interface-type interface-number

The interface view is displayed.

Run:

isis silent

The IS-IS interface is suppressed.

A suppressed IS-IS interface does not send or receive IS-IS packets. The routes of the network segment where the interface resides, however, can still be advertised to other routers within the area.

----End

7.3.4 (Optional) Configuring the IPv4 IS-IS Interfaces

Configuring the IS-IS interface costs can control IS-IS route selection.

Context

The costs of IS-IS interfaces can be determined in the following modes in descending order by priority: l Interface cost: is configured for a specified interface.

Global cost: is configured for all interfaces.

l Automatically calculated cost: is automatically calculated based on the interface bandwidth.

If none of the preceding configurations is performed, the default cost of an IS-IS interface is 10, and the default cost style is narrow.

Procedure

Configure the IS-IS cost type.

Run:

system-view

The system view is displayed.

Run:

isis [ process-id ]

The IS-IS view is displayed.

Run:

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cost-style { narrow | wide | wide-compatible | { { narrow-compatible |

compatible } [ relax-spf-limit ] } }

The IS-IS cost type is configured.

The cost range of an interface and a route received by the interface vary with the cost type.

– If the cost type is narrow, the cost of an interface ranges from 1 to 63. The maximum cost of a route received by the interface is 1023.

–

If the cost style is narrow-compatible or compatible, the cost of an interface ranges from

1 to 63. The cost of a received route is related to relax-spf-limit.

–

If relax-spf-limit is not specified, the cost of a route works as follows:

If the cost of a route is not greater than 1023 and the cost of every interface that the route passes through is smaller than or equal to 63, the cost of the route received by the interface is the actual cost.

If the cost of a route is not greater than 1023 but the costs of all interfaces that the route passes through are greater than 63, the IS-IS device can learn only the routes to the network segment where the interface resides and the routes imported by the interface. The cost of the route received by the interface is the actual cost. Subsequent routes forwarded by the interface are discarded.

If the cost of a route is greater than 1023, the IS-IS device can learn only the interface whose route cost exceeds 1023 for the first time. That is, the cost of each interface before this interface is not greater than 63. The routes of the network segment where the interface resides and the routes imported by the interface can all be learned. The cost of the route is 1023. Subsequent routes forwarded by the interface are discarded.

– If relax-spf-limit is specified, the cost of a route works as follows:

There is no limit on costs of interfaces or route costs. The cost of a route received by an interface is the actual cost.

– If the cost style is wide-compatible or wide, the cost of the interface ranges from 1 to

16777215. When the cost is 16777215, the neighbor TLV generated on the link cannot be used for route calculation but for the transmission of TE information. The maximum cost of a received route is 0xFFFFFFFF.

l Configure the cost of an IS-IS interface.

Run:

system-view

The system view is displayed.

Run:

interface interface-type interface-number

The interface view is displayed.

Run:

isis cost cost [ level-1 | level-2 ]

The cost of the IS-IS interface is configured.

You can use the isis cost command to configure the cost of a specified interface.

l Configure the global IS-IS cost.

Run:

system-view

The system view is displayed.

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Run:

isis [ process-id ]

The IS-IS view is displayed.

Run:

circuit-cost cost [ level-1 | level-2 ]

The global IS-IS cost is configured.

You can use the circuit-cost command to configure the costs of all interfaces at a time.

l Enable IS-IS to automatically calculate interface costs.

Run:

system-view

The system view is displayed.

Run:

isis [ process-id ]

The IS-IS view is displayed.

Run:

bandwidth-reference value

The reference value of the bandwidth is configured. By default, the bandwidth reference value is 100 Mbit/s.

Run:

auto-cost enable

The interface is configured to automatically calculate its cost.

The configuration of the bandwidth reference value takes effect only when the cost type is wide or wide-compatible. In this case, Cost of each interface = (Value of bandwidth-

reference/Interface bandwidth) x 10.

If the cost-style is narrow, narrow-compatible, or compatible, the cost of each interface is based on costs listed in

Table 7-1

Table 7-1 Mapping between IS-IS interface costs and interface bandwidth

Cost

Bandwidth Range

Interface bandwidth ≤ 10 Mbit/s

10 Mbit/s < interface bandwidth ≤ 100 Mbit/ s

100 Mbit/s < interface bandwidth ≤ 155 Mbit/ s

155 Mbit/s < interface bandwidth ≤ 622 Mbit/ s

622 Mbit/s < Interface bandwidth ≤ 2.5 Gbit/ s

Interface bandwidth > 2.5 Gbit/s

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NOTE

To change the cost of a loopback interface, run the isis cost command only in the loopback interface view.

----End

7.3.5 (Optional) Configuring IPv4 IS-IS Attributes for Interfaces on

Different Types of Networks

Different IS-IS attributes can be configured for different types of network interfaces.

Context

The establishment modes of IS-IS neighbor relationships are different on a broadcast network and on a P2P network. Different IS-IS attributes can be configured for interfaces on different types of networks.

IS-IS is required to select a DIS on a broadcast network. Configure the DIS priorities of IS-IS interfaces so that the interface with the highest priority will be selected as the DIS.

The network types of the IS-IS interfaces on both ends of a link must be the same; otherwise, the IS-IS neighbor relationship cannot be established between the two interfaces. For example, if the type of an interface on a peer device is P2P, you can configure the type of an interface on the local device to P2P so that an IS-IS neighbor relationship can be established between the two devices.

IS-IS on a P2P network is not required to select a DIS. Therefore, you do not need to configure

DIS priorities. To ensure the reliability of P2P links, configure IS-IS to use the three-way handshake mode for IS-IS neighbor relationship establishment so that faults on a unidirectional link can be detected.

Procedure

l Configure the DIS priority of an IS-IS interface.

Run:

system-view

The system view is displayed.

Run:

interface interface-type interface-number

The interface view is displayed.

Run:

isis dis-priority priority [ level-1 | level-2 ]

The DIS priority is configure on the interface. The greater the value, the higher the priority.

l Configure the network type of an IS-IS interface.

Run:

system-view

The system view is displayed.

Run:

interface interface-type interface-number

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7 IS-IS Configuration

The interface view is displayed.

Run:

isis circuit-type p2p

The network type of the interface is set to P2P.

The network type of an interface is determined by the physical type of the interface by default.

When the network type of an IS-IS interface changes, interface configurations change accordingly.

– After a broadcast interface is configured as a P2P interface using the isis circuit-

type p2p command, the default settings are restored for the interval for sending

Hello packets, the number of Hello packets that IS-IS fails to receive from a neighbor before the neighbor is declared Down, interval for retransmitting LSPs on a P2P link, and various IS-IS authentication modes. Consequently, other configurations such as the DIS priority, DIS name, and interval for sending CSNPs on a broadcast network become invalid.

–

After the undo isis circuit-type command is run to restore the network type, the default settings are restored for the interval for sending Hello packets, the number of Hello packets that IS-IS fails to receive from a neighbor before the neighbor is declared Down, interval for retransmitting LSPs on a P2P link, various IS-IS authentication modes, DIS priority, and interval for sending CSNPs on a broadcast network.

l Set the negotiation mode in which P2P neighbor relationships can be set up.

Run:

system-view

The system view is displayed.

Run:

interface interface-type interface-number

The interface view is displayed.

Run:

isis ppp-negotiation { 2-way | 3-way [ only ] }

The negotiation mode is specified on the interface.

By default, the 3-way handshake negotiation mode is adopted.

The isis ppp-negotiation command can only be used for the establishment of the neighbor relationships on P2P links. In the case of a broadcast link, you can run the

isis circuit-type p2p command to set the link type to P2P, and then run the isis ppp-

negotiation command to set the negotiation mode for the establishment of the neighbor relationship.

l Configure OSICP negotiation check on PPP interfaces.

Run:

system-view

The system view is displayed.

Run:

interface interface-type interface-number

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The interface view is displayed.

Run:

isis ppp-osicp-check

The OSICP negotiation status is checked on a PPP interface.

By default, the OSICP negotiation status of a PPP interface does not affect the status of an IS-IS interface.

The isis ppp-osicp-check command is applicable only to PPP interfaces. This command is invalid for other P2P interfaces.

After this command is run, the OSICP negotiation status of a PPP interface affects the status of an IS-IS interface. When PPP detects that the OSI network fails, the link status of the IS-IS interface goes Down and the route to the network segment where the interface resides is not advertised through LSPs.

l Configure IS-IS not to check whether the IP addresses of received Hello packets are on the same network segment.

Run:

system-view

The system view is displayed.

Run:

interface interface-type interface-number

The interface view is displayed.

Run:

isis peer-ip-ignore

IS-IS is configured not to check whether the IP addresses of received Hello packets are on the same network segment.

----End

7.3.6 Checking the Configuration

After basic IPv4 IS-IS functions are configured, you can view information about IS-IS neighbors, interfaces, and routes.

Prerequisites

The configurations of basic IPv4 IS-IS functions are complete.

Procedure

Step 1 Run the display isis name-table [ process-id | vpn-instance vpn-instance-name ] command to check the mapping from the name of the local device to the system ID.

Step 2 Run the display isis peer [ verbose ] [ process-id | vpn-instance vpn-instance-name ] command to check information about IS-IS neighbors.

Step 3 Run the display isis interface [ verbose ] [ process-id | vpn-instance vpn-instance-name ] command to check information about IS-IS interfaces.

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Step 4 Run the display isis route [ process-id | vpn-instance vpn-instance-name ] [ ipv4 ] [ verbose |

[ level-1 | level-2 ] | ip-address [ mask | mask-length ] ]

command to check information about

IS-IS routes.

----End

7.4 Establishing or Maintaining IS-IS Neighbor

Relationships or Adjacencies

This section describes how to configure the parameters that affect the IS-IS neighbor relationship.

7.4.1 Establishing the Configuration Task

Before configuring the parameters that affect the IS-IS neighbor relationship, familiarize yourself with the applicable environment, complete the pre-configuration tasks, and obtain the required data. This can help you complete the configuration task quickly and accurately.

Applicable Environment

This section describes how to establish or maintain the IS-IS neighbor relationship, covering: l Adjusting timers of various IS-IS packets, including Hello packets, CSNPs, and LSPs l Adjusting parameters of LSPs

Pre-configuration Tasks

Before establishing or maintaining IS-IS neighbor relationships or adjacencies, complete the following tasks: l

Configuring IP addresses of interfaces to make neighboring nodes reachable l

7.3 Configuring Basic IPv4 IS-IS Functions

Data Preparation

To establish or maintain IS-IS neighbor relationships or adjacencies, you need the following data.

No.

Data

1 Parameters of IS-IS timers

2 LSP parameters

7.4.2 Configuring IS-IS Timers for Packets

This part describes how to set the intervals for sending Hello packets, Complete Sequence

Number PDUs (CSNPs), and Link State PDUs (LSPs).

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Context

Do as follows on the router that runs IS-IS.

Procedure

7 IS-IS Configuration l Configuring the Interval for Sending Hello Packets

Run:

system-view

The system view is displayed.

Run:

interface interface-type interface-number

The interface view is displayed.

Run:

isis timer hello hello-interval [ level-1 | level-2 ]

The interval for sending the Hello packets is set on an interface.

On a broadcast link, there are Level-1 and Level-2 Hello packets. For different types of packets, you can set different intervals. If no level is specified, both the Level-1 timer and Level-2 timer are configured. On a P2P link, there are only one type of Hello packets. Thus, neither level-1 nor level-2 is required.

NOTE

Parameters level-1 and level-2 are configured only on a broadcast interface.

l Configuring the Invalid Number of Hello Packets

Run:

system-view

The system view is displayed.

Run:

interface interface-type interface-number

The interface view is displayed.

Run:

isis timer holding-multiplier number [ level-1 | level-2 ]

The invalid number of Hello packets is set.

If no level is specified, both the Level-1 timer and Level-2 timer are configured.

NOTE

level-1 and level-2 can be found only on the broadcast interface.

IS-IS maintains neighbor relationships with neighbors through Hello packets. If the local router does not receive any Hello packet from a neighbor within holding time, the local router declares that the neighbor is invalid.

In IS-IS, the period during which the local router and its neighbor keep the neighbor relationship is determined by the invalid number of Hello packets and the interval for sending Hello packets.

l Configuring the Interval for Sending CSNPs

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Run:

system-view

The system view is displayed.

Run:

interface interface-type interface-number

The interface view is displayed.

Run:

isis timer csnp csnp-interval [ level-1 | level-2 ]

The interval for sending CSNPs is set.

CSNPs are transmitted by the Designated IS (DIS) to synchronize an LSDB in a broadcast network. If the level is not specified, the timer of the current level is configured.

l Configuring the Interval for Retransmitting LSPs

Run:

system-view

The system view is displayed.

Run:

interface interface-type interface-number

The interface view is displayed.

Run:

isis circuit-type p2p

Sets the interface network type as P2P.

Run:

isis timer lsp-retransmit retransmit-interval

The interval for retransmitting LSPs on a P2P link is set.

On a P2P link, if the local router does not receive the response within a period of time after it sends an LSP, it considers that the LSP is lost or dropped. To ensure the reliable transmission, .the local router retransmits the LSP according to the retransmit-interval. By default, the interval for retransmitting the LSP packet on the P2P link is 5 seconds.

The LSPs sent on a broadcast link do not need any response.

l Configuring the Minimum Interval for Sending LSPs

Run:

system-view

The system view is displayed.

Run:

interface interface-type interface-number

The interface view is displayed.

Run:

isis timer lsp-throttle throttle-interval [ count count ]

The minimum interval for sending LSPs is set.

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count: specifies the maximum number of LSP packets to be sent within the period specified by throttle-interval. The value ranges from 1 to 1000.

You can set the minimum interval for sending LSPs on an IS-IS interface, that is, the delay between two consecutive LSPs. The value is also the interval for sending fragments of a

CSNP.

----End

7.4.3 Configuring LSP Parameters

By configuring the LSP generation timer, you can adjust the time that an IS-IS network generates

LSPs. Setting the size of the LSP to be generated or received by IS-IS can affect the transmission of LSPs.

Context

Do as follows on the router that runs IS-IS.

Procedure

Configuring the Interval for Refreshing LSPs

Run:

system-view

The system view is displayed.

Run:

isis [ process-id ]

The IS-IS view is displayed.

Run:

timer lsp-refresh refresh-time

The LSP refreshment period is set.

To synchronize all the LSPs in an area, the routers in the area periodically send all the current LSPs.

By default, the LSP refreshment period is 900 seconds, and the maximum lifetime of an

LSP is 1200 seconds. When performing configurations, ensure that the LSP refresh interval is 300 seconds shorter than the maximum LSP Keepalive time. In this way, new LSPs can reach all routers in an area before existing LSPs expire.

NOTE

It is recommended to adjust the difference between the LSP refresh period and the maximum

Keepalive time of the LSP depending on the network scale.

l Configuring the Max Lifetime of an LSP

Run:

system-view

The system view is displayed.

Run:

isis [ process-id ]

The IS-IS view is displayed.

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Run:

timer lsp-max-age age-time

The lifetime of an LSP is set.

When a router generates an LSP, it sets the max lifetime for the LSP. After the LSP is received by other routers, its lifetime decreases as time passes. If a router does not receive any updated LSP and the lifetime of this LSP decreases to 0, the lifetime of the LSP lasts

60s. If a new LSP is still not received, this LSP is deleted from the LSDB.

l Configuring the Intelligent Timer Used to Generate LSPs

Run:

system-view

The system view is displayed.

Run:

isis [ process-id ]

The IS-IS view is displayed.

Run:

timer lsp-generation max-interval [ init-interval [ incr-interval ] ]

[ level-1 | level-2 ]

The intelligent timer used to generate LSPs is set.

If no level is configured, both Level-1 and Level-2 are configured.

The initial delay for generating the same LSPs (or LSP fragments) is init-interval. The delay for generating the same LSPs (or LSP fragments) secondly is incr-interval. When the routes change each time, the delay for generating the same LSPs (or LSP fragments) is twice as the previous value until the delay is up to max-interval. After the delay reaches max-

interval for three times or reset the IS-IS process, the interval is reduced to init-interval.

When incr-interval is not used and generating the same LSPs (or LSP fragments) for the first time, init-interval is used as the initial delay. Then, the delay for generating the same

LSPs (or LSP fragments) is max-interval. After the delay reaches max-interval for three times or the IS-IS process is reset, the interval is reduced to init-interval.

When only max-interval is used, the intelligent timer changes into a normal one-short timer.

l Configuring the Size of an LSP

Run:

system-view

The system view is displayed.

Run:

isis [ process-id ]

The IS-IS view is displayed.

Run:

lsp-length originate max-size

The size of an LSP generated by the system is set.

Run:

lsp-length receive max-size

The size of a received LSP is set.

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NOTE

When using max-size, ensure that the value of the max-size of the generated LSP packet (or the forwarded LSP packet) must be smaller than or equal to that of the received LSP packet.

The value of max-size set by using the lsp-length command must meet the following conditions.

– The MTU value of an Ethernet interface must be greater than or equal to the sum of

max-size and 3.

–

The MTU value of a P2P interface must be greater than or equal to the value of max-

size.

l Adding an Interface to a Mesh Group

Run:

system-view

The system view is displayed.

Run:

interface interface-type interface-number

The VLANIF interface view is displayed.

Run:

isis mesh-group { mesh-group-number | mesh-blocked }

The interface is added to a mesh group.

On the Non Broadcast Multiple Access (NBMA) network, after receiving an LSP, the interface of a router floods the LSP to the other interfaces. In a network with higher connectivity and multiple P2P links, however, the flooding method causes repeated LSP flooding and wastes bandwidth.

To avoid the preceding problem, you can configure several interfaces to form a mesh group.

The router in the mesh group does not flood the LSP received from an interface of the group to the other interfaces of the group, but floods it to interfaces of other groups or interfaces that do not belong to any group.

When mesh-blocked is configured on an interface, the interface is blocked and cannot flood LSPs outside. All the interfaces added to a mesh group implement global LSDB synchronization through CSNP and PSNP mechanisms.

NOTE

In an ATM or FR network, IS-IS routers are connected through Virtual Circuits (VCs), and the interface here is the logical P2P sub-interface.

l Configuring LSP Fragments Extension

Run:

system-view

The system view is displayed.

Run:

isis [ process-id ]

The IS-IS view is displayed.

Run:

lsp-fragments-extend [ [ level-1 | level-2 | level-1-2 ] | [ mode-1 |

mode-2 ] ] *

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LSP fragments extension is enabled in an IS-IS process.

Run:

virtual-system virtual-system-id

A virtual system is configured.

To configure a router to generate extended LSP fragments, you must configure at least one virtual system. The ID of the virtual system must be unique in the domain.

An IS-IS process can be configured with up to 50 virtual system IDs.

If neither the mode nor the level is specified when LSP fragments extension is configured, mode-1 and Level-1-2 are used by default.

----End

7.4.4 Checking the Configuration

After configuring parameters that affect the IS-IS neighbor relationship, you can check information about the IS-IS interface and statistics about the IS-IS process.

Prerequisites

The configurations of Establishing or Maintaining IS-IS Neighbor Relationships or Adjacencies are complete.

Procedure

l Run display isis interface [ verbose ] [ process-id | vpn-instance vpn-instance-name ] command to check information about the interface enabled with IS-IS.

l Check the statistics of the IS-IS process:

–

display isis statistics [ level-1 | level-2 | level-1-2 ] [ process-id | vpn-instance vpn-

instance-name ]

– display isis statistics packet [ interface interface-type interface-number ]

– display isis process-id statistics [ updated-lsp [ history ] ] [ level-1 | level-2 |

level-1-2 | packet ]

----End

7.5 Configuring IPv4 IS-IS Route Selection

Configuring IS-IS route selection can achieve refined control over route selection.

7.5.1 Establishing the Configuration Task

Before configuring IPv4 IS-IS route selection, familiarize yourself with the applicable environment, complete the pre-configuration tasks, and obtain the data required for the configuration. This will help you complete the configuration task quickly and efficiently.

Applicable Environment

After basic IPv4 IS-IS functions are configured, IS-IS routes will be generated, enabling communication between different nodes on a network.

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If multiple routes are available, a route discovered by IS-IS may not the optimal route. This does not meet network planning requirements nor facilitates traffic management. Therefore, configure

IPv4 IS-IS route selection to implement refined control over route selection.

To implement refined control over IPv4 IS-IS route selection, perform the following operations: l

Configuring the IPv4 IS-IS Interfaces

NOTE

Changing the IS-IS cost for an interface can achieve the function of controlling route selection, but requires routes on the interface to be recalculated and reconverged when a network topology changes, especially on a large-scale network. In addition, the configuration result may not meet your expectation.

Therefore, the configuration of changing IS-IS costs has best to be finished when configuring basic

IS-IS functions.

l Configure IPv4 IS-IS route leaking.

l Configure principles for selecting equal-cost IPv4 IS-IS routes.

l Filter IPv4 IS-IS routes.

Configure an overload bit for an IPv4 IS-IS device.

Pre-configuration Tasks

Before configuring IPv4 IS-IS route selection, complete the following tasks: l Configuring IP addresses for interfaces to ensure that neighboring nodes are reachable at the network layer l

Data Preparation

To configure IPv4 IS-IS route selection, you need the following data.

No.

Data

ACL for filtering routes, IP prefix list, or routing policy

Maximum number of load-balancing equal-cost IS-IS routes

Preference of the next hop

Time when an IS-IS device enters the overload state

7.5.2 Configuring IPv4 IS-IS Route Leaking

Configuring IS-IS route leaking enables you to optimize IS-IS route selection on a two-levelarea network.

Context

If multiple Level-1-2 devices in a Level-1 area are connected to devices in the Level-2 area, a

Level-1 LSP sent by each Level-1-2 device carries an ATT flag bit of 1. This Level-1 area will have multiple routes to the Level-2 area and to other Level-1 areas.

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By default, routes in a Level-1 area can be leaked into the Level-2 area so that Level-1-2 and

Level-2 devices can learn about the topology of the entire network. Devices in a Level-1 area are unaware of the entire network topology because they only maintain LSDBs in the local

Level-1 area. Therefore, a device in a Level-1 area can forward traffic to a Level-2 device only through the nearest Level-1-2 device. The route used may not be the optimal route to the destination.

To enable a device in a Level-1 area to select the optimal route, configure IPv4 IS-IS route leaking so that specified routes in the Level-2 area can be leaked into the local Level-1 area.

Routes of services deployed only in the local Level-1 area do not need to be leaked into the

Level-2 area. A policy can be configured to leak only desired routes into the Level-2 area.

Procedure

l Specify routes in the Level-2 area and other Level-1 areas that can be leaked into the local

Level-1 area.

Run:

system-view

The system view is displayed.

Run:

isis [ process-id ]

The IS-IS view is displayed.

Run:

import-route isis level-2 into level-1 [ tag tag | filter-policy { acl-

number | acl-name acl-name | ip-prefix ip-prefix-name | route-policy route-

policy-name } ]

Routes in the Level-2 area and other Level-1 areas that meet the specified conditions are leaked into the local Level-1 area.

NOTE

The command is run on the Level-1-2 device that is connected to an external area.

By default, routes in the Level-2 area are not leaked into Level-1 areas. After this command is run, only routes that meet the specified conditions can be leaked into Level-1 areas.

l Configure routes in Level-1 areas to leak into the Level-2 area.

Run:

system-view

The system view is displayed.

Run:

isis [ process-id ]

The IS-IS view is displayed.

Run:

import-route isis level-1 into level-2 [ tag tag | filter-policy { acl-

number | acl-name acl-name | ip-prefix ip-prefix-name | route-policy route-

policy-name } ]

Routes that meet the specifies conditions in Level-1 areas are leaked into the Level-2 area.

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NOTE

The command is run on the Level-1-2 device that is connected to an external area.

By default, all routes in a Level-1 area are leaked into the Level-2 area. After this command is run, only routes that meet the specified conditions can be leaked into the Level-2 area.

----End

7.5.3 Configuring Principles for Using Equal-Cost IPv4 IS-IS

Routes

If multiple equal-cost IS-IS routes are available on a network, configure the equal-cost IS-IS routes to work in load-balancing mode to increase the bandwidth usage of each link, or configure preference values for the equal-cost IS-IS routes to facilitate traffic management.

Context

If there are redundant IS-IS links, multiple routes may have an equal cost. Choose either of the following methods to use these equal-cost IS-IS routes: l Configure load balancing for equal-cost IS-IS routes so that traffic will be evenly balanced among these links.

This mechanism increases the link bandwidth usage and prevents network congestion caused by link overload. However, this mechanism may make traffic management more difficult because traffic will be randomly forwarded.

l Configure preference values for equal-cost IS-IS routes so that only the route with the highest preference will be used and the others function as backups.

This configuration facilitates traffic management and improves the network reliability, without the need to change original configurations.

Procedure

l Configure equal-cost IS-IS routes to work in load-balancing mode.

Run:

system-view

The system view is displayed.

Run:

isis [ process-id ]

The IS-IS view is displayed.

Run:

maximum load-balancing number

The maximum number of load-balancing equal-cost IS-IS routes is set.

NOTE

If the number of IS-IS equal-cost routes is greater than the value of number, the number of IS-

IS equal-cost routes to work in load-balancing mode is determined by number. If the number of IS-IS equal-cost routes is smaller than the value of number, IS-IS equal-cost routes of the actual number work in load-balancing mode.

l Configure preference values for equal-cost IS-IS routes.

Run:

system-view

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The system view is displayed.

Run:

isis [ process-id ]

The IS-IS view is displayed.

Run:

nexthop ip-address weight value

A preference value is configured for an equal-cost IS-IS route.

NOTE

A larger value of the value parameter indicates a higher preference.

----End

7.5.4 Filtering IPv4 IS-IS Routes

If some IS-IS routes are not preferred, configure conditions to filter IS-IS routes. Only IS-IS routes meeting the specified conditions can be added to an IP routing table.

Context

Only routes in an IP routing table can be used to forward IP packets. An IS-IS route can take effect only after this IS-IS route has been successfully added to an IP routing table.

If an IS-IS route does not need to be added to a routing table, specify conditions, such as a basic

ACL, IP prefix, and routing policy, to filter routes so that only IS-IS routes that meet the specified conditions can added to an IP routing table. IS-IS routes that do not meet the specified conditions cannot be added to the IP routing table and cannot be selected to forward IP packets.

Procedure

Step 1 Run:

system-view

The system view is displayed.

Step 2 Run:

isis [ process-id ]

The IS-IS view is displayed.

Step 3 Run:

filter-policy { acl-number | acl-name acl-name | ip-prefix ip-prefix-name | route-

policy route-policy-name } import

Conditions for filtering IS-IS routes are configured.

----End

7.5.5 Configuring an Overload Bit for an IPv4 IS-IS Device

If an IS-IS device needs to be temporarily isolated, configure the IS-IS device to enter the overload state to prevent other devices from forwarding traffic to this IS-IS device and prevent blackhole routes.

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Context

Procedure

Step 1 Run:

system-view

The system view is displayed.

Step 2 Run:

isis [ process-id ]

The IS-IS view is displayed.

Step 3 Run:

set-overload [ on-startup [ timeout1 | start-from-nbr system-id [ timeout1

[ timeout2 ] ] | wait-for-bgp [ timeout1 ] ] ] [ allow { interlevel | external }

]

The overload bit is configured.

----End

7.5.6 Checking the Configuration

After configuring IPv4 IS-IS route selection, run the following commands to verify that the configurations are correct.

Procedure

If an IS (for example, an IS to be upgraded or maintained) needs to be temporarily isolated, configure the IS to enter the overload state so that no device will forward traffic to this IS.

IS-IS routes converge more quickly than BGP routes. To prevent blackhole routes on a network where both IS-IS and BGP are configured, set an overload bit to instruct an IS to enter the overload state during its start or restart. After BGP convergence is complete, cancel the overload bit.

l Run the display isis route [ process-id | [ vpn-instance vpn-instance-name ] ] [ ipv4 ]

[ verbose | [ level-1 | level-2 ] | ip-address [ mask | mask-length ] ]

[ | count ] command to check IS-IS routing information.

l Run the display isis lsdb [ { level-1 | level-2 } | verbose | { local | lsp-id | is-name symbolic-

name } ]

[ process-id | vpn-instance vpn-instance-name ] command to check information in the IS-IS LSDB.

----End

7.6 Configuring IPv4 IS-IS Route Summarization

To improve the route searching efficiency and simplify route management on a large-scale IS-

IS network, configure IS-IS route summarization to reduce the number of IS-IS routes in a routing table.

Context

Route summarization is used to summarize routes with the same IP prefix into one route.

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On a large-scale IS-IS network, route summarization can be configured to reduce the number of IS-IS routes in a routing table. This summarization improves the usage of system resources and facilitates route management.

If a link on an IP network segment that is summarized frequently alternates between Up and

Down states, IP network segments that are not summarized will not be affected, preventing route flapping and improving the network stability.

Procedure

Step 1 Run:

system-view

The system view is displayed.

Step 2 Run:

isis [ process-id ]

The IS-IS view is displayed.

Step 3 Run:

summary ip-address mask [ avoid-feedback | generate_null0_route | tag tag |

[ level-1 | level-1-2 | level-2 ] ]

The specified IS-IS routes are summarized into one IS-IS route.

NOTE

After route summarization is configured on an IS, the local routing table still contains all specific routes before the summarization.

The routing tables on other ISs contain only the summary route, and the summary route is deleted only after all its specific routes are deleted.

----End

Checking the Configuration

After the route summarization function is configured, perform the following steps to check whether the route summarization function has taken effect.

l Run the display isis route command to check summary routes in the IS-IS routing table.

l Run the display ip routing-table [ verbose ] command to check summary routes in the IP routing table.

7.7 Configuring IPv4 IS-IS to Interact with Other Routing

Protocols

If other routing protocols are configured on an IS-IS network, you need to configure IS-IS to interact with these protocols to ensure successful communication between them.

7.7.1 Establishing the Configuration Task

Before configuring IPv4 IS-IS to interact with other routing protocols, familiarize yourself with the applicable environment, complete the pre-configuration tasks, and obtain the data required for the configuration. This will help you complete the configuration task quickly and efficiently.

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Applicable Environment

If other routing protocols are configured on an IS-IS network, the following issues need to be considered: l Preference of IS-IS routes

If multiple routes to the same destination are discovered by different routing protocols running on the same device, the route discovered by the protocol with the highest preference is selected. For example, if both OSPF and IS-IS are configured, the route discovered by

OSPF is used because OSPF enjoys a higher preference than IS-IS by default.

Therefore, if you want the route discovered by IS-IS to be used, configure IS-IS to have the highest preference.

l Communication between an IS-IS area and other areas

If other routing protocols are configured on an IS-IS network, you need to configure IS-IS to interact with those routing protocols so that IS-IS areas can communicate with non-IS-

IS areas.

NOTE

The LSDBs of different IS-IS processes on a device are independent of each other. Therefore, each

IS-IS process on the device considers routes of the other IS-IS processes as external routes.

To ensure successful traffic forwarding, configure IS-IS to interact with other routing protocols on a device where external routes are configured, for example, a Level-1-2 IS-

IS router. Available methods are as follows:

–

Configure IS-IS to advertise a default route.

This mode is easy to configure and does not require devices in IS-IS areas to learn external routes. After a default route is advertised, all traffic in an IS-IS area is forwarded through the default route.

–

Configure IS-IS to import external routes.

This mode enables all devices in IS-IS areas to learn external routes, implementing refined control over traffic forwarding.

To ensure successful forwarding of traffic destined for IS-IS areas, you must also enable the other routing protocols to interact with IS-IS.

Pre-configuration Tasks

Before configuring IPv4 IS-IS to interact with other routing protocols, complete the following tasks: l Configuring the link layer protocol on interfaces l

Configuring IP addresses for interfaces to ensure that neighboring nodes are reachable at the network layer l

l Configuring basic functions of other routing protocols

Data Preparation

To configure the IPv4 IS-IS route convergence speed, you need the following data.

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Run:

isis [ process-id ]

The IS-IS view is displayed.

Run:

preference preference

The IS-IS preference value is configured.

NOTE

A smaller preference value indicates a higher preference.

The default IS-IS preference value is 15.

l Configure preference values for specified IS-IS routes.

Run:

system-view

The system view is displayed.

Run:

isis [ process-id ]

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No.

Data

ACL for filtering routes, IP prefix list, or routing policy

Preference value of IS-IS

7.7.2 Configuring a Preference Value for IPv4 IS-IS

If multiple routes to the same destination are discovered by different routing protocols, configuring the highest preference value for IS-IS allows a route discovered by IS-IS to be selected preferentially.

Context

If multiple routes to the same destination are discovered by different routing protocols running on the same device, the route discovered by the protocol with the highest preference is selected.

For example, if both OSPF and IS-IS are configured on a network, the route discovered by OSPF is used because OSPF has a higher preference than IS-IS by default.

To prefer a route discovered by IS-IS, configure a higher preference value for IS-IS. In addition, a routing policy can be configured to increase the preferences of specified IS-IS routes, without affecting route selection.

Procedure

l Configure the IS-IS preference value.

Run:

system-view

The system view is displayed.

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The IS-IS view is displayed.

Run:

preference preference route-policy route-policy-name

The preference values are configured for the specified IS-IS routes.

NOTE

preference takes effect only for IS-IS routes that match the specified routing policy.

----End

7.7.3 Configuring IPv4 IS-IS to Advertise a Default Route

To forward all traffic in an IS-IS area through a default route, configure IS-IS on a Level-1-2 device to advertise the default route.

Context

Only the route 0.0.0.0/0 can be advertised as a default route on a Level-1-2 device. All traffic destined for other areas is first forwarded to the Level-1-2 device.

To ensure successful traffic forwarding, external routes must be learned on the Level-1-2 device.

NOTE

Configuring static default routes can also achieve the function of interaction between different routing protocols, but require large configurations and are difficult to manage.

If multiple Level-1-2 devices are deployed, a routing policy can be configured to allow only the Level-1-2 device that meets the specified conditions to advertise a default route, preventing blackhole routes.

Procedure

Step 1 Run:

system-view

The system view is displayed.

Step 2 Run:

isis [ process-id ]

The IS-IS view is displayed.

Step 3 Run:

default-route-advertise [ always | match default | route-policy route-policy-name ]

[ cost cost | tag tag | [ level-1 | level-1-2 | level-2 ] ]

[ avoid-learning ]

IS-IS is configured to advertise a default route.

----End

7.7.4 Configuring IPv4 IS-IS to Import External Routes

If devices in an IS-IS area need to learn external routes, configure IS-IS on a Level-1-2 device of this area to import external routes.

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Context

7 IS-IS Configuration

If IS-IS is configured on a Level-1-2 device to advertise a default route, all traffic in IS-IS areas will be forwarded by this Level-1-2 device. This will burden this Level-1-2 device because no external route can be learned on the devices in the IS-IS areas.

If multiple Level-1-2 devices are deployed, optimal routes to other areas need to be selected. To ensure optimal routes are selected, all the other devices in the IS-IS areas must learn all or some external routes.

Routing policies can be configured to import or advertise external routes that meet specified conditions to the IS-IS areas.

Procedure

l Configure IS-IS to import external routes.

Run:

system-view

The system view is displayed.

Run:

isis [ process-id ]

The IS-IS view is displayed.

Configuring IS-IS to Import External Routes

–

If you want to set the cost for the imported route, you can run the import-route

protocol [ process-id ] [ cost-type { external | internal } | cost cost | tag tag |

route-policy route-policy-name | [ level-1 | level-2 | level-1-2 ] ]

command to import the external routes.

–

If you want to keep the original cost for the imported route, you can run the import-

route { { rip | isis | ospf } [ process-id ] | direct | unr | bgp } inherit-cost [ tag

tag | route-policy route-policy-name | [ level-1 | level-2 | level-1-2 ] ]

command to import the external routes. When configuring IS-IS to retain the original cost value of the imported route, the source routes cannot be static.

NOTE

IS-IS will advertise all imported external routes to the IS-IS areas by default.

If only some imported external routes need to be advertised, run the filter-policy export command to set a filtering policy.

(Optional) Configure IS-IS to advertise some external routes to the IS-IS areas.

Run:

system-view

The system view is displayed.

Run:

isis [ process-id ]

The IS-IS view is displayed.

Run:

filter-policy { acl-number | acl-name acl-name | ip-prefix ip-prefix-name

| route-policy route-policy-name } export [ protocol [ process-id ] ]

IS-IS is configured to advertise specified external routes to the IS-IS areas.

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NOTE

After this command is run, only external routes that meet the specified conditions can be advertised to the IS-IS areas.

----End

7.7.5 Checking the Configuration

After IS-IS is enabled to import routes from other protocols, run the following commands to verify that the configurations are correct.

Procedure

l Run the display isis lsdb [ { level-1 | level-2 } | verbose | { local | lsp-id | is-name symbolic-

name } ]

[ process-id | vpn-instance vpn-instance-name ] command to check IS-IS LSDB information.

l Run the display isis route [ process-id | [ vpn-instance vpn-instance-name ] ] [ ipv4 ]

[ verbose | [ level-1 | level-2 ] | ip-address [ mask | mask-length ] ]

[ | count ] command to check IS-IS routing information.

l Run the display ip routing-table ip-prefix ip-prefix-name [ verbose ] command to check the IP routing table.

----End

7.8 Configuring the IPv4 IS-IS Route Convergence Speed

Accelerating IS-IS route convergence can improve the fault location efficiency and improve the network reliability.

7.8.1 Establishing the Configuration Task

Before configuring the IPv4 IS-IS route convergence speed, familiarize yourself with the applicable environment, complete the pre-configuration tasks, and obtain the data required for the configuration. This will help you complete the configuration task quickly and efficiently.

Applicable Environment

The procedure for implementing IS-IS is as follows: l Establishment of neighboring relationships: establishes neighboring relationships by exchanging Hello packets between two devices.

l LSP flooding: implements LSDB synchronization between devices in the same area.

l SPF calculation: uses the SPF algorithm to calculate IS-IS routes, and delivers the IS-IS routes to the routing table.

To accelerate the IS-IS route convergence speed, configure the following parameters: l Interval for detecting IS-IS neighboring device failures l Flooding parameters of CSNPs and LSPs l Interval for SPF calculation

You can also configure convergence priorities for IPv4 IS-IS routes so that key routes can be converged by preference when a network topology changes. This minimizes adverse impacts on key services.

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Pre-configuration Tasks

Before configuring the IPv4 IS-IS route convergence speed, complete the following tasks: l Configuring the link layer protocol on interfaces l Configuring IP addresses for interfaces to ensure that neighboring nodes are reachable at the network layer l

Configuring Dynamic IPv4 BFD for IS-IS.

Data Preparation

To configure the IPv4 IS-IS route convergence speed, you need the following data.

No.

Data

Interval at which Hello packets are sent and the holding time of neighboring devices

Flooding time of CSNPs and LSPs

Interval for SPF calculation

Route convergence priority

7.8.2 Configuring the Interval for Detecting IS-IS Neighboring

Device Failures

To minimize the effects caused by neighboring device failures on an IS-IS network, accelerate the speed of detecting IS-IS neighboring device failures.

Context

Connection status between an IS-IS device and its neighboring devices can be monitored by exchanging Hello packets at intervals. An IS-IS neighboring device is considered Down if the

IS-IS device does not receive any Hello packets from the neighboring device within the specified period (called the holding time). A failure in an IS-IS neighboring device will trigger LSP flooding and SPF calculation, after which IS-IS routes are reconverged.

To speed up fault detection, use the following methods to accelerate the speed of detecting IS-

IS neighboring device failures: l Shorten the interval at which Hello packets are sent.

l Shorten the holding time of neighboring devices.

NOTE

Configuring IPv4 BFD for IS-IS is recommended because this method provides a faster fault detection speed than the other two methods.

Procedure

l Set an interval at which Hello packets are sent.

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Run:

system-view

The system view is displayed.

Run:

interface interface-type interface-number

The interface view is displayed.

Run:

isis timer hello hello-interval [ level-1 | level-2 ]

The interval at which Hello packets are sent is set.

NOTE

A broadcast link can transmit both Level-1 and Level-2 Hello packets. You can set different sending intervals for these two types of Hello packets. By default, both Level-1 and Level-2

Hello packets are sent.

A P2P link can transmit only one type of Hello packets. Therefore, there is no need to specify the level-1 or level-2 parameter if a P2P link is used.

l Set the holding multiplier for neighboring devices.

Run:

system-view

The system view is displayed.

Run:

interface interface-type interface-number

The interface view is displayed.

Run:

isis timer holding-multiplier number [ level-1 | level-2 ]

The holding multiplier of neighboring devices is set.

NOTE

A broadcast link can transmit both Level-1 and Level-2 Hello packets. You can set different sending intervals for these two types of Hello packets. By default, both Level-1 and Level-2

Hello packets are sent.

A P2P link can transmit only one type of Hello packets. Therefore, there is no need to specify the level-1 or level-2 parameter if a P2P link is used.

----End

7.8.3 Setting Flooding Parameters of SNPs and LSPs

To speed up LSDB synchronization between devices, set flooding parameters of SNPs and LSPs to proper values.

Context

7 IS-IS Configuration

SNPs consist of CSNPs and PSNPs. CSNPs carry summaries of all LSPs in LSDBs, ensuring

LSDB synchronization between neighboring routers. SNPs are processed differently on broadcast links and P2P links.

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Configuration Guide - IP Routing 7 IS-IS Configuration l On a broadcast link, CSNPs are periodically sent by a DIS device. If a router detects that its LSDB is not synchronized with that on its neighboring router, the router will send PSNPs to apply for missing LSPs.

l On a P2P link, CSNPs are sent only during initial establishment of neighboring relationships. If a request is acknowledged, a neighboring router will send a PSNP in response to a CSNP. If a router detects that its LSDB is not synchronized with that on its neighboring router, the router will also send PSNPs to apply for missing LSPs.

To speed up LSDB synchronization, modify the following parameters of SNPs and LSPs on the

AR150/200: l

Interval at which CSNPs are sent

Intelligent timer controlling LSP generation

Maximum length of LSPs

Refresh interval of LSPs

Maximum lifetime of LSPs

Minimum interval at which LSPs are sent

LSP fast flooding

Interval at which LSPs are retransmitted over a P2P link

Procedure

l Set an interval at which CSNPs are sent.

Run:

system-view

The system view is displayed.

Run:

interface interface-type interface-number

The interface view is displayed.

Run:

isis timer csnp csnp-interval [ level-1 | level-2 ]

The interval at which CSNPs are sent is set on the specified interface.

NOTE

Configure Level-1 and Level-2 only when a broadcast interface is specified.

Configure the intelligent timer controlling LSP generation.

Run:

system-view

The system view is displayed.

Run:

isis [ process-id ]

The IS-IS view is displayed.

Run:

timer lsp-generation max-interval [ init-interval [ incr-interval ] ]

[ level-1 | level-2 ]

The intelligent timer controlling LSP generation is configured.

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If a level is not specified, both level-1 and level-2 are used by default.

The delay in generating an LSP or an LSP fragment for the first time is determined by init-interval; the delay in generating an LSP or an LSP fragment for the second time is determined by incr-interval. From the third time on, the delay in generating an LSP increases twice every time until the delay reaches the value specified by max-

interval. After the delay remains at the value specified by max-interval for three times or the IS-IS process is restarted, the delay decreases to the value specified by init-

interval.

If incr-interval is not specified, the delay in generating an LSP or LSP fragment for the first time is determined by init-interval. From the second time on, the delay in generating an LSP is determined by max-interval. After the delay remains at the value specified by max-interval for three times or the IS-IS process is restarted, the delay decreases to the value specified by init-interval.

When only max-interval is specified, the intelligent timer functions as an ordinary one-time triggering timer.

l Set the maximum length for LSPs.

Run:

system-view

The system view is displayed.

Run:

isis [ process-id ]

The IS-IS view is displayed.

Run:

lsp-length originate max-size

The maximum length is set for each LSP to be generated.

Run:

lsp-length receive max-size

The maximum length is set for each LSP to be received.

NOTE

Ensure that the value of max-size for LSPs to be generated must be smaller than or equal to the value of max-size for LSPs to be received.

The value of max-size in the lsp-length command must meet the following conditions.

–

The MTU of an Ethernet interface must be greater than or equal to the sum of the value of max-size and 3.

–

The MTU of a P2P interface must be greater than or equal to the value of max-

size.

l Set the refresh interval for LSPs.

Run:

system-view

The system view is displayed.

Run:

isis [ process-id ]

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The IS-IS view is displayed.

Run:

timer lsp-refresh refresh-time

A refresh interval is set for LSPs.

To synchronize all LSPs in the areas, IS-IS regularly transmits all the current LSPs to neighbors.

By default, the LSP refresh interval is 900s, and the maximum lifetime of an LSP is

1200s. Ensure that the LSP refresh interval is more than 300s shorter than the maximum LSP lifetime. This allows new LSPs to reach all routers in an area before existing LSPs expire.

NOTE

The larger a network, the greater the deviation between the LSP refresh interval and the maximum LSP lifetime.

l Set the maximum lifetime for LSPs.

Run:

system-view

The system view is displayed.

Run:

isis [ process-id ]

The IS-IS view is displayed.

Run:

timer lsp-max-age age-time

The maximum lifetime is set for LSPs.

When a router generates the system LSP, it fills in the maximum lifetime for this LSP.

After this LSP is received by other routers, the lifetime of the LSP is reduced gradually.

If the router does not receive any more update LSPs and the lifetime of the LSP is reduced to 0, the LSP will be deleted from the LSDB 60s later if no more updated

LSPs are received.

l Set the minimum interval at which LSPs are sent.

Run:

system-view

The system view is displayed.

Run:

interface interface-type interface-number

The interface view is displayed.

Run:

isis timer lsp-throttle throttle-interval [ count count ]

The minimum interval at which LSPs are sent is set.

The count parameter specifies the maximum number of LSPs that can be sent within the interval specified by throttle-interval. The value of count is an integer ranging from 1 to 1000.

l Enable LSP fast flooding.

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Run:

system-view

The system view is displayed.

Run:

isis [ process-id ]

The IS-IS view is displayed.

Run:

flash-flood [ lsp-count | max-timer-interval interval | [ level-1 |

level-2 ] ]

The LSP fast flooding is enabled.

Running the flash-flood command speeds up LSP flooding. The lsp-count parameter specifies the number of LSPs flooded each time, which is applicable to all interfaces.

If the number of LSPs to be sent is greater than the value of lsp-count, lsp-count takes effect. If the number of LSPs to be sent is smaller than the value of lsp-count, LSPs of the actual number are sent. If a timer is configured and the configured timer does not expire before the route calculation, the LSPs are flooded immediately when being received; otherwise, the LSPs are sent when the timer expires.

When LSP fast flooding is enabled, Level-1 LSPs and Level-2 LSPs are fast flooded by default if no level is specified.

l Set an interval at which LSPs are retransmitted over a P2P link.

Run:

system-view

The system view is displayed.

Run:

interface interface-type interface-number

The interface view is displayed.

(Optional) Run:

isis circuit-type p2p

Emulate a broadcast interface to the P2P interface.

Run:

isis timer lsp-retransmit retransmit-interval

The interval at which LSPs are retransmitted over a P2P link is set.

----End

7.8.4 Setting the SPF Calculation Interval

To improve the fault location efficiency on an IS-IS network and prevent SPF calculation from consuming excessive system resources, set the SPF calculation interval to a proper value.

Context

7 IS-IS Configuration

A network change always triggers IS-IS to perform SPF calculation. Frequent SPF calculation will consume excessive CPU resources, affecting services.

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To solve this problem, configure an intelligent timer to control the interval for SPF calculation.

For example, to speed up IS-IS route convergence, set the interval for SPF calculation to a small value, and set the interval to a large value after the IS-IS network becomes stable.

Procedure

Step 1 Run:

system-view

The system view is displayed.

Step 2 Run:

isis [ process-id ]

The IS-IS view is displayed.

Step 3 Run:

timer spf max-interval [ init-interval [ incr-interval ] ]

The SPF intelligent timer is configured.

The intelligent timer changes as follows: l The delay for the first SPF calculation is determined by init-interval; the delay for the second

SPF calculation is determined by incr-interval. From the third time on, the delay in SPF calculation increases twice every time until the delay reaches the value specified by max-

interval. After the delay remains at the value specified by max-interval for three times or the

IS-IS process is restarted, the delay decreases to the value specified by init-interval.

l If incr-interval is not specified, the delay in SPF calculation for the first time is determined by init-interval. From the second time on, the delay in SPF calculation is determined by max-

interval. After the delay remains at the value specified by max-interval for three times or the

IS-IS process is restarted, the delay decreases to the value specified by init-interval.

l When only max-interval is specified, the intelligent timer functions as an ordinary one-time triggering timer.

----End

7.8.5 Configuring Convergence Priorities for IPv4 IS-IS Routes

If some IS-IS routes need to be converged by preference to minimize adverse impacts on services, configure those routes to have the highest convergence priority.

Context

By default, the convergence priority of 32-bit host routes is medium, and the convergence priority of the other IS-IS routes is low.

The AR150/200 allows you to configure the highest convergence priority for specific IS-IS routes so that those IS-IS routes will be converged first when a network topology changes.

Procedure

Step 1 Run:

system-view

The system view is displayed.

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Step 2 Run:

isis [ process-id ]

The IS-IS view is displayed.

Step 3 Run:

prefix-priority [ level-1 | level-2 ] { critical | high | medium } { ip-prefix

prefix-name | tag tag-value }

Convergence priorities are set for IS-IS routes.

The application rules of the convergence priorities for IS-IS routes are as follows: l Existing IS-IS routes are converged based on the priorities configured in the prefix-

priority command.

l New IS-IS routes are converged based on the priorities configured in the prefix-priority command.

l If an IS-IS route conforms to the matching rules of multiple convergence priorities, the highest convergence priority is used.

l The convergence priority of a Level-1 IS-IS route is higher than that of a Level-2 IS-IS route.

l If the route level is not specified, the configuration of the prefix-priority command takes effect for both Level-1 and Level-2 IS-IS routes.

NOTE

The prefix-priority command is only applicable to the public network.

After the prefix-priority command is run, the convergence priority of 32-bit host routes is low, and the convergence priorities of the other routes are determined as specified in the prefix-priority command.

Step 4 (Optional) Run:

quit

The system view is displayed.

Step 5 (Optional) Run:

ip route prefix-priority-scheduler critical-weight high-weight medium-weight low-

weight

The preference-based scheduling ratio of IPv4 routes is configured.

By default, the preference-based scheduling ratio of IPv4 routes is 8:4:2:1.

----End

7.8.6 Checking the Configuration

After the parameters specifying the IPv4 IS-IS route convergence speed are set, run the following commands to verify that the configurations are correct.

Procedure

l Run the display isis interface [ verbose ] [ process-id | vpn-instance vpn-instance-

name ] command to check IS-IS packet information.

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Configuration Guide - IP Routing 7 IS-IS Configuration l Run the display isis route [ process-id | vpn-instance vpn-instance-name ] [ ipv4 ]

[ verbose | [ level-1 | level-2 ] | ip-address [ mask | mask-length ] ]

[ | count ] command to check the preference of IS-IS routes.

----End

7.9 Configuring Static IPv4 BFD for IS-IS

BFD can provide link failure detection featuring light load and high speed (at the millisecond level). Static IPv4 BFD can be configured to monitor IS-IS links.

Context

In a static BFD session scenario, you need to configure single-hop BFD parameters, such as local and remote discriminators and then configure the device to send BFD session setup requests.

A static BFD session can only be established and released manually. A configuration error will lead to a BFD failure. For example, if a local or remote discriminator is incorrectly configured, a BFD session will not work properly.

NOTE

Pre-configuration Tasks

Before configuring static IPv4 BFD for IS-IS, complete the following tasks: l Assign an IP address to each interface to ensure IP connectivity.