[Babel-users] Anybody else seeing disruption when restarting babeld?y

[Daniel Gröber]

Hi,

On Sat, Feb 25, 2023 at 01:01:20AM +0100, Daniel Gröber wrote:
> > If you're really keen on avoiding disruptions, you should first increase
> > the metric to something very lare (say, 2^15), then wait a couple of
> > seconds, then send a retraction, then wait 200ms.
> 
> Could you go into a bit more detail as to why that would be better? I think
> I get the jist, we want to avoid other nodes installing an unreachable
> route in response to our retraction while they do the seqno request dance,
> right? I just don't see why the high (but non-infinite) metric would
> prevent this?

I think I figured it out. babeld sends seqno requests when a just received
unfeasible update has a much larger metric than the current route. In
send_unfeasible_request:

    if(force || !route || route_metric(route) >= metric + 512)
        send_unicast_multihop_request(neigh, src->prefix, src->plen, ...);

I guess that's another thing for my bird TODO list :)

Any reason this (and the route_old() logic) isn't mentioned in the RFC or
did I miss it?

--Daniel