BFD for routes learned trough Route-servers in IXPs

Zbyněk Pospíchal zbynek at
Wed Sep 16 08:14:21 UTC 2020


In some IXPs, getting a BFD protected BGP sessions with their
route-servers is possible. However, it is usualy optional, so there is
no way how to discover know who of your MLPA peering partners has their
sessions protected the same way and who don't.

You can also ask peers you have a session with to enable BFD there. If
they run carrier-grade border routes connected to IXP switches just with
fibers, it works pretty well.

So just try to talk with your peers about BFD.

S pozdravem/Best Regards,

Zbyněk Pospíchal

Dne 16.09.20 v 2:55 Douglas Fischer napsal(a):
> Time-to-time, in some IXP in the world some issue on the forwarding
> plane occurs.
> When it occurs, this topic comes back.
> The failures are not big enough to drop the BGP sessions between IXP
> participants and route-servers.
> But are enough to prejudice traffic between participants.
> And then the problem comes:
> "How can I check if my communication against the NextHop of the routes
> that I learn from the route-servers are OK?
> If it is not OK, how can I remove it from my FIB?"
> Some other possible causes of this feeling are:
> - ARP Resolution issues
> (CPU protection and lunatic Mikrotiks with 30 seconds ARP timeout is a
> bombastic recipe)
> - MAC-Address Learning limitations on the transport link of the
> participants can be a pain in the a..rm.
> So, I was searching on how to solve that and I found a draft (8th
> release) with the intention to solve that...
> If understood correctly, the effective implementation of it will depend
> on new code on any BGP engine that will want to do that check.
> It is kind of frustrating... At least 10 years after the release of RFC
> until the refresh os every router involved in IXPs in the world.
> Some questions come:
> A) There is anything that we can do to rush this?
> B) There is any other alternative to that?
> P.S.1: I gave up of inventing crazy BGP filter polices to test
> reachability of NextHop. The effectiveness of it can't even be compared
> to BFD, and almost kill de processing capacity of my router.
> P.S.2: IMHO, the biggest downside of those problems is the evasion of
> route-servers from some participants when issues described  above occurs.

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