bfd missed-hellos

[Harkanwaljeet_S]

Hello community,
We have 2 bfd sessions for OSPF and can see the missed-hellos counter is incremented and resulting in bfd and ofpf to go down when 3 missed-hellos are reported.
I also see the counter Rx session Not Found as non-zero in the output of show bfd counters.

Please help me to troubleshoot and understand
1) Missed-hellos means that the neighbor did not sent the bfd hello or does it mean that neighbor sent the hello but EXOS did not process it. I did not see any good explanation in the EXOS reference document.

2) What is Rx session Not Found here.

It is BD8806 (EXOS 16.2) having two bfd sessions (ospf ) with 300msx3 timers and I did not see any other abnormal thing which can bring the bfd down.

Any responses on the troubleshooting are highly appreciated.

Thanks in advance

Harkanwal

[Harkanwaljeet_S]

No reply? Sounds that this issue is new to community or TAC itself?

No worries.

I was able to find out that it is the switch itself which is actually creating issues for the missed-hellos.

The far end node and the switch are exchanging bfd hellos at expected intervals. This is proved by the port capture. bfd timers were increased and the missed hellos count was improved by almost 50%.

Successfully replicated the scenario with BD-Juniper and BD-Ericsson SmartEdge. Even Extreme TAC was also able to simulate. The case is now with Engineering to decode the problematic area.