IEEE 802.1ah Basics
(Provider Backbone Bridges)
Ronald van der Pol
rvdp@sara.nl
SARA
Overview
!   Advantages of IEEE 802.1ah
!   Ethernet Evolution (1Q à 1ad à 1ah)
(VLANS à Q-in-Q à mac-in-mac)
!   Frame Formats
!   IEEE 802.1ah functionality
!   Ethernet OAM (IEEE 802.1ag)
Autgole Telconf, 24 March 2011
Ronald van der Pol <rvdp@sara.nl>
2/17
Advantages of IEEE 802.1ah
!
!
!
!
 
 
 
 
Separation between carrier and customer VLANs
MAC address separation between provider and customer
Learning of customer MAC addresses limited to edge ports
Support for more simultaneous services than with VLANs
!   I-SIDs provide 2^20 services instead of 4K VLANs
!   VLAN remapping
Autgole Telconf, 24 March 2011
Ronald van der Pol <rvdp@sara.nl>
3/17
Ethernet Evolution
!   802.1Q: introduction of VLAN tags
!   802.1ad: introduction of S-tag and C-tag
!
!
!
!
!
!
 
 
 
 
 
 
Also called Q-in-Q
Inner tag: customer tag
Outer tag: service tag
Customer frames encapsulated with service tag
Still limited to 4096 services
Still all customer MAC addresses in backbone bridges
!   802.1ah: introduction of I-SID
!
!
!
!
!
 
 
 
 
 
Also called Provider Backbone Bridges (PBB)
Also called mac-in-mac
20 bit I-SID service identifier
Supports 2^20 services via I-SID
Customer MAC addresses learned at edge ports only
Autgole Telconf, 24 March 2011
Ronald van der Pol <rvdp@sara.nl>
4/17
Frame Formats
Autgole Telconf, 24 March 2011
Ronald van der Pol <rvdp@sara.nl>
5/17
Typical 802.1ah Network
Autgole Telconf, 24 March 2011
Ronald van der Pol <rvdp@sara.nl>
6/17
802.1ah Functionality
!
!
!
!
!
 
 
 
 
 
For each service an I-SID is configured on the switch
Each I-SID is associated with two or more physical ports
Traffic on a port can be tagged or untagged
Mapping to I-SID can be based on 802.1Q or 802.1ad tags
Mapping of 802.1ad tags on:
!   Outer tag only
!   Both inner and outer tag
!   Ports in the same I-SID can have different mappings
!   Combination of tagged and untagged
!   Multiple tags over the same I-SID
!   Different tags (tag re-mapping)
!   Each port can be associated with multiple I-SIDs (services)
Autgole Telconf, 24 March 2011
Ronald van der Pol <rvdp@sara.nl>
7/17
Supported Services in 802.1ah
tag A
I-SID 1
tag A
tag B
I-SID 2
untagged
tag C
I-SID 3
tag B
tag E
I-SID 4
tag D
tag E
IEEE 802.1ah
Ethernet switch
Autgole Telconf, 24 March 2011
Ronald van der Pol <rvdp@sara.nl>
8/17
More Services
tag A,B
I-SID 1
tag A,B
tag C,D,E,F
I-SID 2
tag C
I-SID 3
tag D
I-SID 4
tag E,F
tag E,F
IEEE 802.1ah
Ethernet switch
Autgole Telconf, 24 March 2011
Ronald van der Pol <rvdp@sara.nl>
9/17
Ethernet OAM / IEEE 802.1ag
!   Terminology
!
!
!
!
!
 
 
 
 
 
Operations, Administration and Maintenance (OAM)
Connectivity Fault management (CFM)
Maintenance Domain & Maintenance Level (0-7)
Maintenance End Point (MEP)
Maintenance Intermediate Point (MIP)
!   OAM types
!   CC: Continuity Check (“hello”)
!   LBM/LBR: Loopback Message/Reply (“L2 ping”)
!   LTM/LTR Link Trace Message/Reply (“L2 traceroute”)
!   Normal Ethernet frames, ethertype 0x8902
!   Bridges that do not support 802.1ag should forward them
like other frames
!   Usually configured per VLAN
Autgole Telconf, 24 March 2011
Ronald van der Pol <rvdp@sara.nl>
10/17
802.1ag MEPs and MIPs
MIP
MEP
customer
ISP
ISP
ISP
ISP
customer
MD level 7
MD level 5
MD level 0
Autgole Telconf, 24 March 2011
Ronald van der Pol <rvdp@sara.nl>
11/17
OAM Types
!   Continuity Check (CC)
!   Periodic hello messages
!   Detect loss of connectivity
!   Sent by MEP (multicast), processed by MEPs
!   L2 Ping (LBM/LBR)
!   Sent manually from CLI
!   Unicast request, unicast reply
!   Source MEP, destination MEP/MIP
!   L2 Traceroute (LTM/LTR)
!   Sent manually from CLI
!   Multicast request, unicast replies
!   All MIPs in the path reply, until reply from destination MEP
Autgole Telconf, 24 March 2011
Ronald van der Pol <rvdp@sara.nl>
12/17
What are Linux 802.1ag Utils?
!   Implementation of IEEE 802.1ag on Linux
!   L2 ping (LBM) client
!   L2 traceroute (LTM) client
!   Daemon sending CC and answering LBM and LTM probes
!   Open Source (BSD License)
!   User space implementation (raw Ethernet sockets)
!   Work In Progress
Autgole Telconf, 24 March 2011
Ronald van der Pol <rvdp@sara.nl>
13/17
L2 ping example
MEP
MIP
Ciena
Ethernet
switch
Juniper
router
Linux server
"donder"
00:14:0d:0b:10:c4
00:1b:c0:97:38:c6
00:14:0d:0b:11:10
00:14:0d:0b:10:c0
00:14:0d:0b:10:c1
root@donder:~# l2ping -i eth5 -v 123 -l 7 -c 10 00:1b:c0:97:38:c6
CFM LBM to 00:1b:c0:97:38:c6
60 bytes from 00:1b:c0:97:38:c6, sequence 477635892, 0.839 ms
60 bytes from 00:1b:c0:97:38:c6, sequence 477635893, 0.872 ms
60 bytes from 00:1b:c0:97:38:c6, sequence 477635894, 0.817 ms
60 bytes from 00:1b:c0:97:38:c6, sequence 477635895, 0.829 ms
60 bytes from 00:1b:c0:97:38:c6, sequence 477635896, 0.851 ms
60 bytes from 00:1b:c0:97:38:c6, sequence 477635897, 0.718 ms
60 bytes from 00:1b:c0:97:38:c6, sequence 477635898, 0.713 ms
60 bytes from 00:1b:c0:97:38:c6, sequence 477635899, 0.917 ms
60 bytes from 00:1b:c0:97:38:c6, sequence 477635900, 0.731 ms
60 bytes from 00:1b:c0:97:38:c6, sequence 477635901, 0.713 ms
root@donder:~#
Autgole Telconf, 24 March 2011
Ronald van der Pol <rvdp@sara.nl>
14/17
L2 trace example
MEP
MIP
Ciena
Ethernet
switch
Juniper
router
Linux server
"donder"
00:14:0d:0b:10:c4
00:1b:c0:97:38:c6
00:14:0d:0b:11:10
00:14:0d:0b:10:c0
00:14:0d:0b:10:c1
I do not understand this Ciena behaviour yet
root@donder:~# l2trace -i eth5 -v 123 -l 7 00:1b:c0:97:38:c6
Sending CFM LTM probe to 00:1b:c0:97:38:c6
ttl 1: LTM with id 1784875395
reply from 00:14:0d:0b:10:c1, id=1784875395, ttl=0, RlyFDB
ttl 2: LTM with id 1784875396
reply from 00:14:0d:0b:10:c4, id=1784875396, ttl=0, RlyFDB
reply from 00:14:0d:0b:10:c1, id=1784875396, ttl=1, RlyFDB
ttl 3: LTM with id 1784875397
reply from 00:14:0d:0b:10:c4, id=1784875397, ttl=1, RlyFDB
reply from 00:14:0d:0b:10:c1, id=1784875397, ttl=2, RlyFDB
reply from 00:1b:c0:97:38:c6, id=1784875397, ttl=0, RlyHit
root@donder:~#
Autgole Telconf, 24 March 2011
Ronald van der Pol <rvdp@sara.nl>
15/17
Implementation status
LBM (L2 ping)
alpha
LTM (L2 trace)
alpha
Daemon (CC, LBR, LTR)
Not yet started
  Beta release planned in May 2011
  First release planned in Summer 2011
  Also looking at porting to BSD
  Looking for testers
  Testing with 802.1ag capable switches
  Testing with PC connected to non 802.1ag switch
  Please contact me: rvdp@sara.nl
Autgole Telconf, 24 March 2011
Ronald van der Pol <rvdp@sara.nl>
16/17
Thank You
Ronald van der Pol
SARA
rvdp@sara.nl
Download PDF
Similar pages