Babel in Bird

[Toke Høiland-Jørgensen]

Ondrej Zajicek <santiago at crfreenet.org> writes:

> I have two questions w.r.t. this sequence of events:
>
> 1) How is router restart and seqnos supposed to be handled without
> waiting for route timeout?

This is indeed a problem. Babeld sends a wildcard retraction before
shutting down (which I just taught Bird to handle; will send off the
patch tonight after testing it properly). I can add in sending such
retractions when an interface goes away as well.

But this problem can still occur on a crash, or if the retraction was
lost for whatever reason. In that case, waiting for things to expire is
the only option.

> 2) If a route is selected, then becomes unreachable/retracted, and
> there is no other route to be selected, is it still considered
> selected? I would say that no as the selection process (3.6) forbids
> retracted routes to be selected, but the BIRD implementation keeps the
> old selected route (now unreachable) in this case.

It is kept for a while (and installed as unreachable) to avoid transient
routing loops. This is described in section 2.8 of the RFC.

-Toke
-------------- next part --------------
A non-text attachment was scrubbed...
Name: signature.asc
Type: application/pgp-signature
Size: 472 bytes
Desc: not available
URL: <http://trubka.network.cz/pipermail/bird-users/attachments/20160502/b329c157/attachment.asc>