Babel + IPv4 = parse error

[Toke Høiland-Jørgensen]

Ondrej Zajicek <santiago at crfreenet.org> writes:

> On Sun, Jun 10, 2018 at 02:48:45PM +0200, Toke Høiland-Jørgensen wrote:
>> Ondrej Zajicek <santiago at crfreenet.org> writes:
>> 
>> > On Sun, Jun 10, 2018 at 11:22:17AM +0200, Julian Schuh wrote:
>> >> Hi all,
>> >> 
>> >> for a current project I’m planning on using Babel as a lightweight, dual-stack routing protocol for a couple of simple tasks. For a proof of concept I’ve been using BIRD, and a plan to continue using BIRD at least in the backend.
>> >> 
>> >> Sadly, I quickly hit a showstopper: none of the routes (neither v4 nor v6) exported from one side were imported on the other side. While investigating the problem I quickly stumbled over the following line in the debug log:
>> >> “bird: bb: Bad TLV from fe80::xxx via vh type 8 pos 16 - parse error”
>> >> After playing around for a little bit I found out: The problem appears whenever the route advertisement contains v4 routes.
>> >> 
>> >> I’m using BIRD 2.0.2. I used the following setup to reproduce the problem:
>> >> Two network namespaces, “default" and “test", connected via an veth pair.
>> >> In both namespaces I’m running a BIRD instance with the following configs:
>> >
>> > Hi
>> >
>> > Tested it, works for me. Do you have IPv4 addresses on veth ifaces? Otherwise
>> > it would complain about no IPv4 next hop, probably send IPv4 routes without
>> > one and report parse error on the other side.
>> 
>> Yeah, my thought went to missing v4 addresses as well; maybe we should
>> avoid sending the TLV entirely if no nexthop is found (and make the
>> warning louder or something)?
>
> Hi
>
> Avoid sending the TLV would make sense to me if it is forbidden by
> spec.

Hmm, the spec doesn't actually say anything about this; but maybe it
should. I'll bring it up on the Babel list :)

-Toke