On Tue, Mar 12, 2019 at 01:04:28PM -0400, Arzhel Younsi wrote:
Bingo! As soon as I the system TTL to 255, the session went up. Thanks a lot!
Now that we know where to look, we started to dig a bit in the code to not have to change the TTL system wide but only for Bird.
It seems like there a TODO to make the TTL value customizable: https://github.com/BIRD/bird/blob/master/proto/bfd/packets.c#L453 And in some (so far unknown) cases, it sets the TTL to 255 https://github.com/BIRD/bird/blob/master/proto/bfd/packets.c#L456
That is for single-hop BFD cases. As i wrote in the previous e-mail:
For single-hop BFD sessions, the RFC 5880 requires TTL security mechanism and therefore BIRD specifies outgoing TTL 255.
You can just change it to "sk->ttl = 255;" and recompile. Is this 'min-recv-TTL 254' some special setting in Juniper, or its default BFD behavior? If the second case, then perhaps it would be best to make a bugreport to Juniper as they have packet checks that are not requested by BFD specifications. -- Elen sila lumenn' omentielvo Ondrej 'Santiago' Zajicek (email: santiago@crfreenet.org) OpenPGP encrypted e-mails preferred (KeyID 0x11DEADC3, wwwkeys.pgp.net) "To err is human -- to blame it on a computer is even more so."