Ondrej Zajicek <santiago@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