Babel in Bird

[Toke Høiland-Jørgensen]

Ondrej Zajicek <santiago at crfreenet.org> writes:

> Perhaps sending wildcard retraction not only in the last packet, but also
> in the first one?

Don't see why not (and I think babeld does the same, actually).
Currently we are doing this when an iface comes up:

  babel_send_hello(ifa, 0);
  babel_send_wildcard_request(ifa);
  babel_send_update(ifa, 0);	/* Full update */

Guess sticking a wildcard retraction in after the hello wouldn't hurt.

>> > 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.
>
> Well, section 2.8 (and in more detail section 3.5.5) specifies that we
> should keep unreachable entries, but IMHO it does not specify that the
> old route is considered selected/installed for a purpose of conditions
> in section 3.5.4. The unreachable entry after retraction could be
> undestood as a special case, unrelated to any route.

Hmm, you mean babel_select_route() should clear selected_in after
announcing the unreachable route to the core? Yes, that would appear to
be needed for the retraction to have any effect if the same router comes
back up before the entries are garbage collected...

-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/20160502/9520adcb/attachment.asc>