OSPFv3 and stub interfaces without lladdr

[Hans van Kranenburg]

tldr: +1metoo

On 05/28/2015 06:33 PM, Christian Tacke wrote:
>
> [...]
>
> openvpn does not add link level addrs to its interfaces.
> That's why ospf ignores this interface.  Ignoring it for
> doing ospf on it is okay, as ospf really wants to run over
> lladdrs.  But do stub networks require a lladdr to be used
> in ospf?  This is at least confusing to me.

Previous occurence:
http://bird.network.cz/pipermail/bird-users/2012-August/007868.html

And I stumbled into it in the past, (ending up using stubnet for now, 
hardcoding an extra copy of the set of addresses into the bird config) 
and I know some more, the latest being a user only a few minutes ago on 
IRC, running into the same issue.

I just scanned RFC5340 and it looks like there's no mandatory "ignore if 
no link local" policy in there. It says that Link-LSAs are allowed in a 
stub network, so for them you'd need the lladdr, but that's not the case 
in "normal" simple usage.

In favor of intuitive behaviour for users, I'd vote to have bird6 just 
happily treat stub without ipv6 link local the same way as it does with 
IPv4 on stub interfaces. So addresses on the lo in linux, and e.g. also 
the openvpn example (which I fixed in the same way, putting some fe80 on 
the link to satisfy bird) would work out of the box as stub.

If not, adding more logging, like the following suggestion would be 
useful to prevent users from wasting too much time and getting 
frustrated: "bird6: ospfX: Not adding OSPFv3 interface $FOO to area 
a.b.c.d because it has no link local address configured".

-- 
Hans van Kranenburg - System / Network Engineer
T +31 (0)10 2760434 | hans.van.kranenburg at mendix.com | www.mendix.com