Babel + IPv4 = parse error

[Toke Høiland-Jørgensen]

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)?

-Toke