Whenever the BFD status is down, it typically means that there is an issue in the communication between the two configured BFD mechanisms. This can be due to various factors including:
- Link failure
- firewall or security device
Since BFD is configured by default in an SDWAN environment, this is not something that has resulted from a misconfiguration of BFD itself. For this reason, don’t just look at the status of BFD but at the whole functionality of the topology. The BFD failure should be approached as a symptom of the underlying issue. I suggest you approach it like so:
- Check basic connectivity
- validate SD-WAN overlay connectivity
- check out the BFD sessions using
show bfd sessions
- check firewall and ACLs (which I assume you have none in your topology)
- Examine syslogs and system messages
This should give you an idea of where to start in your troubleshooting process. Let us know more information bout your progress so we can help you further.
I hope this has been helpful!