Wierd BGP IPv6 ll nh behavior about frr HOT 7 OPEN

Can you enable debug bgp updates, debug bgp neighbor, debug bgp nht and then send us the logs?

Also, just in case the following commands outputs would be handy too:

show ipv6 nht
show bgp nexthop
show bgp import-check-table

from frr.

Done

VRF default:
 Resolve via default: on
fe80:14:fc01:1::1(Connected)
 resolved via connected
 is directly connected, ens13f0np0.80 (vrf default)
 Client list: bgp(fd 18)
fe80:14:fc01:2::1(Connected)
 resolved via connected
 is directly connected, ens28f0np0.80 (vrf default)
 Client list: bgp(fd 18)
el-fw1.cdnwb.ru# show bgp nexthop
Current BGP nexthop cache:
 fe80:14:fc01:1::1 valid [IGP metric 0], #paths 0, peer fe80:14:fc01:1::1
  if ens13f0np0.80
  Last update: Mon May 27 16:26:58 2024
 fe80:14:fc01:2::1 valid [IGP metric 0], #paths 1, peer fe80:14:fc01:2::1
  if ens28f0np0.80
  Last update: Mon May 27 16:35:25 2024
 fe80:14:fc01:1::1 invalid, #paths 1
  Must be Connected
  Last update: Wed May 22 17:20:29 2024
el-fw1.cdnwb.ru# show bgp import-check-table
Current BGP import check cache:
el-fw1.cdnwb.ru#_ 

debug.txt

from frr.

You have something strange in next-hop cache:

 fe80:14:fc01:1::1 valid [IGP metric 0], #paths 0, peer fe80:14:fc01:1::1
  if ens13f0np0.80
  Last update: Mon May 27 16:26:58 2024

 fe80:14:fc01:1::1 invalid, #paths 1
  Must be Connected
  Last update: Wed May 22 17:20:29 2024

Two entries for the same next-hop, but one is invalid. And the last update is way older. Does this happens (bad behavior) even when the router is restarted? Or is that starting to happen after some time?

from frr.

I dont know its related or not.
I have similar issue like this after restore config from 9.1 to 10.0 (which is enforce-first-as as default). Triggering command with no neighbor XXX enforce-first-as bring still showing weird low number of received-routes. Clear ip bgp also not works until solved by neighbor XXX shutdown and no shutdown.

So command no neighbor XXX enforce-first-as need shut and no shut the peer then the command will aplied.

from frr.

You have something strange in next-hop cache:

 fe80:14:fc01:1::1 valid [IGP metric 0], #paths 0, peer fe80:14:fc01:1::1
  if ens13f0np0.80
  Last update: Mon May 27 16:26:58 2024

 fe80:14:fc01:1::1 invalid, #paths 1
  Must be Connected
  Last update: Wed May 22 17:20:29 2024

Two entries for the same next-hop, but one is invalid. And the last update is way older. Does this happens (bad behavior) even when the router is restarted? Or is that starting to happen after some time?

It's a new router with new ipv6 design. A have got this problem just after the frr and host configurations were completed. There was one period when everything was working, about 15 minutes. It seems to me that after the restart FRR the situation may change. Both nexthops can become invalid, for example, or both can work, anything is possible. By the way, now nh table is
el-fw1.cdnwb.ru# sh bgp nexthop
Current BGP nexthop cache:
fe80:14:fc01:1::1 valid [IGP metric 0], #paths 0, peer fe80:14:fc01:1::1
if ens13f0np0.80
Last update: Mon May 27 16:26:58 2024
fe80:14:fc01:2::1 valid [IGP metric 0], #paths 1, peer fe80:14:fc01:2::1
if ens28f0np0.80
Last update: Mon May 27 16:35:25 2024
fe80:14:fc01:1::1 invalid, #paths 1
Must be Connected
Last update: Wed May 22 17:20:29 2024
el-fw1.cdnwb.ru#

from frr.

I dont know its related or not. I have similar issue like this after restore config from 9.1 to 10.0 (which is enforce-first-as as default). Triggering command with no neighbor XXX enforce-first-as bring still showing weird low number of received-routes. Clear ip bgp also not works until solved by neighbor XXX shutdown and no shutdown.

So command no neighbor XXX enforce-first-as need shut and no shut the peer then the command will aplied.

Sorry, it didn't help me

from frr.

Could you also show "show ipv6 route"?

from frr.