Is it platform specific
Specific to UT2 topology
Importance or Severity
Critical
Previous Working Version
202511
Steps to Reproduce
Executes TSA on a UT2 device with CONFED BGP config and note that the UT2 stops advertising routes to the LT2 but still advertises routes to the T3:
> show ip bgp summary
Neighbhor V AS MsgRcvd MsgSent TblVer InQ OutQ Up/Down State/PfxRcd NeighborName
----------- --- ----- --------- --------- -------- ----- ------ --------- -------------- --------------
10.0.0.1 4 65200 7374 6679 306965 0 0 00:13:25 34050 VM01T3
10.0.0.3 4 65200 7386 6721 306965 0 0 00:13:22 34050 VM02T3
10.0.0.5 4 65200 7384 6702 306965 0 0 00:13:20 34050 VM03T3
10.0.0.101 4 65300 6938 7331 306965 0 0 04:54:35 257 VM05LT2
10.0.0.103 4 65300 6947 7331 306965 0 0 04:54:35 257 VM07LT2
# TSC no-stats
System Mode: Maintenance
root@ctn104:~# show ip bgp neighbors 10.0.0.101 advertised-routes | tail -n 5
Network Next Hop Metric LocPrf Weight Path
*> 10.1.0.1/32 0.0.0.0 0 100 32768 i
Total number of prefixes 1, total number of paths 1
root@ctn104:~# show ip bgp neighbors 10.0.0.103 advertised-routes | tail -n 5
Network Next Hop Metric LocPrf Weight Path
*> 10.1.0.1/32 0.0.0.0 0 100 32768 i
Total number of prefixes 1, total number of paths 1
root@ctn104:~# show ip bgp neighbors 10.0.0.1 advertised-routes | tail -n 5
*> 194.55.243.0/25 0.0.0.0 0 65200 64999 65900 i
*> 194.55.243.128/25
0.0.0.0 0 65200 64999 65900 i
Total number of prefixes 51207, total number of paths 51207
The issue is evident when looking at the vtysh -c "show run", the LT2 neighbors are in the peer-group PEER_V4 while the T3 neighbors aren't:
router bgp 66000
neighbor 10.0.0.101 remote-as 65300
neighbor 10.0.0.101 peer-group PEER_V4 <----- MISSING on T3
neighbor 10.0.0.101 description VM05LT2
neighbor 10.0.0.101 timers 3 10
neighbor 10.0.0.101 timers connect 10
neighbor 10.0.0.1 remote-as 65200
neighbor 10.0.0.1 description VM01T3
neighbor 10.0.0.1 timers 3 10
neighbor 10.0.0.1 timers connect 10
When I try to add the T3 neighbor into this peer group it gets rejected:
# config
(config)# router bgp 66000
(config-router)# neighbor 10.0.0.1 peer-group PEER_V4
% Peer-group members must be all internal or all external.
It appears the issue is in CONFED BGP the LT2 neighbors are treated as internal while the T3 neighbors are treated as external and they aren't allowed to share a peer-group.
Impact of this regression
TSA is broken on UT2
Relevant log output
Output of show version, show techsupport
Attach files (if any)
No response
Is it platform specific
Specific to UT2 topology
Importance or Severity
Critical
Previous Working Version
202511
Steps to Reproduce
Executes
TSAon a UT2 device with CONFED BGP config and note that the UT2 stops advertising routes to the LT2 but still advertises routes to the T3:The issue is evident when looking at the
vtysh -c "show run", the LT2 neighbors are in the peer-groupPEER_V4while the T3 neighbors aren't:When I try to add the T3 neighbor into this peer group it gets rejected:
It appears the issue is in CONFED BGP the LT2 neighbors are treated as
internalwhile the T3 neighbors are treated asexternaland they aren't allowed to share a peer-group.Impact of this regression
TSA is broken on UT2
Relevant log output
Output of
show version,show techsupportAttach files (if any)
No response