OSPFv3 doesn't announce loopback IPv6 network

[Martin Huněk]

Hi,

On Linux, I would suggest using a dummy interface for anything other than real loopback addresses (::1 and 127.0.0.1) and physical connections. The dummy interfaces as they have both link-local IPv6 and "real like" MAC address, so it is acting more like a physical device. This way, you would not need direct protocol either.

Best Regards,
Martin Hunek

Dne pondělí 12. prosince 2022 9:28:31 CET, Bernhard Ehlers via Bird-users napsal(a):
> On 11.12.22 21:50 Bernd Naumann via Bird-users wrote:
> > On 11.12.22 18:50, Ondrej Zajicek via Bird-users wrote:
> >> On Sun, Dec 11, 2022 at 06:30:46PM +0100, Bernhard Ehlers via 
> >> Bird-users wrote:
> >>> I want to use OSPF with BIRD v2.0.10 on Linux.
> >>>
> >>> That works well, except that the IPv6 network of the lo interface isn't
> >>> announced on OSPFv3. The IPv6 networks of the ethernet interfaces are
> >>> announced as well as the IPv4 networks of all interfaces (ethernet 
> >>> and lo).
> >>> The only missing is the IPv6 network of lo.
> >>
> >> Hi
> >>
> >> Due to some implementation details, OSPFv3 ignores interfaces that do not
> >> have link-local addresses (even if they are just stub). Just use:
> >>
> >> ip address add fe80::1/128 dev lo
> >>
> > 
> > May I ask why not using the direct protocol to get the loopback addresses?
> 
> I tried that as well and it worked.
> 
> But I was concerned by this part of the documentation of the direct 
> protocol:
> 
> > The question is whether it is a good idea to have such device routes
> > in BIRD routing table. OS kernel usually handles device routes for
> > directly connected networks by itself so we don't need (and don't
> > want) to export these routes to the kernel protocol. OSPF protocol
> > creates device routes for its interfaces itself and BGP protocol is
> > usually used for exporting aggregate routes.
> 
> So for OSPF the direct protocol should not be necessary and indeed it 
> worked without it for the ethernet interfaces (both for IPv4 and IPv6) 
> and for the lo interface on IPv4. Therefore my question.
> 
> I think it is just personal choice, if one prefers adding the link-local 
> address or using the direct protocol.
> 
> 

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