[FROG] Issue with BFD/BGP Session Recovery on FRR 10.3 and Arista Router

[Julien Cosmao]

Hi everyone,


I have a setup with a BFD/BGP session between an FRR instance (version 10.3) and an Arista router. Generally, everything works well, and routes are learned correctly between the devices.


However, during failure testing, specifically when the Arista device is reloaded, issues arise. In this scenario, the BGP and BFD sessions fail to establish properly. The FRR instance sends BFD packets (UDP 3784) to the peer while the Arista device attempts to establish a BGP session. FRR bgp state stay in Idle.


>From the documentation, it seems that FRR operates like BFD strict mode ? refusing to establish BGP before the BFD session is up.

Here is the relevant documentation link: https://docs.frrouting.org/en/latest/bfd.html#clicmd-neighbor-A.B.C.D-X-X-X-X-WORD-bfd-strict-hold-time-seconds



Here is a sample of my FRR conf:


frr version 10.3
frr defaults traditional
!
hostname frr1
!
! Setup logging
log daemon bgpd file /var/log/frr/bgpd.log debugging
log daemon bfdd file /var/log/frr/bfdd.log debugging
!
debug bgp updates
debug bgp neighbor-events
debug bgp keepalives
debug bgp bfd
debug bfd distributed
debug bfd peer
debug bfd network


router bgp 64512
 bgp router-id 192.168.0.5
 no bgp default ipv4-unicast
 neighbor PG_EDGE_V4 peer-group
 neighbor PG_EDGE_V4 remote-as 64534
 neighbor PG_EDGE_V4 bfd
 neighbor PG_EDGE_V4 bfd profile edge
 neighbor 192.168.0.1 peer-group PG_EDGE_V4
 neighbor 192.168.0.2 peer-group PG_EDGE_V4
 !
 address-family ipv4 unicast
  neighbor PG_EDGE_V4 activate
  neighbor PG_EDGE_V4 addpath-tx-all-paths
  neighbor PG_EDGE_V4 soft-reconfiguration inbound
 exit-address-family
 !
!
bfd
 profile edge
  detect-multiplier 8
  transmit-interval 500
  receive-interval 500
 exit
 !
 peer 192.168.0.1
  profile edge
 exit
 !
 peer 192.168.0.2
  profile edge
 exit
 !
 !
exit
!
end



The only way I have found to recover the sessions is to disable and then re-enable BFD on the router BGP configuration:


configure terminal
router bgp 64512
no neighbor PG_EDGE_V4 bfd
no neighbor PG_EDGE_V4 bfd profile edge
do clear bgp external
neighbor PG_EDGE_V4 bfd
neighbor PG_EDGE_V4 bfd profile edge



Has anyone encountered a similar issue or have suggestions on how to resolve this?

Thank you in advance for your help.


Regards,

Julien
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://lists.frrouting.org/pipermail/frog/attachments/20250626/b136791b/attachment.htm>