BFD starts to flap either by network event or manually shut down neighbor interface and it won't come back anymore.
BFD packets can be seen at neighbor router but they won't create the session, they will take 3-4 seconds, then from the session and drop (and then this cycle repeats)
Workaround being used is either define a source interface or source address and if it doesn't work delete all bfd and ospf config from that interface. Also if this does not work, deleting all the configuration from that interface > commit > and add the ospf and bfd command without source address/interface > bfd session will turn up again.
```
set interfaces ethernet eth0 address '10.221.3.18/30'
set interfaces ethernet eth0 mtu '9000'
set interfaces ethernet eth0 offload gro
set interfaces ethernet eth0 offload gso
set interfaces ethernet eth0 offload sg
set interfaces ethernet eth0 offload tso
set protocols ospf interface eth0 area '0'
set protocols ospf interface eth0 bfd
set protocols ospf interface eth0 network 'point-to-point'
set protocols bfd peer 10.221.3.17 interval multiplier '5'
set protocols bfd peer 10.221.3.17 interval receive '100'
set protocols bfd peer 10.221.3.17 interval transmit '100'
```
This may be related to https://phabricator.vyos.net/T2616 as well
Attached there is a packet capture of BFD control packets from the peer's side (routerboard/mikrotik)