ipv4 inside ipv6 for ospf

[Ondrej Zajicek]

On Mon, Jun 23, 2014 at 10:46:16AM +0200, Ondrej Filip wrote:
> On 23.6.2014 10:39, Vasiliy Tolstov wrote:
> > Hi. Does bird supports
> > http://tools.ietf.org/html/draft-ietf-ospf-ipv4-embedded-ipv6-routing-14
> > ?
> > If yes, how can i configure it?
> 
> Hi Vasiliy,
> unfortunately it does not.

Hi

The draft (now published as RFC 6992) is just informational draft
specifying how to use existing features of OSPFv3 to do that and BIRD
already supports almost everything needed, so i would say it is
more or less supported.

You can just configure separate OSPFv3 instance (protocol block
in BIRD), use 'instance' parameter for all interfaces in that
OSPFv3 specifying chosen instance ID and use import and export
filters to filter out other prefixes than the one used for
IPv4-embedded IPv6 addresses.

There are some minor details:

1) RFC 6992 assumes that routers supports RFC 5838, which BIRD
does not, esp. it does not set AF-bit in Hello packets,
which means that it may fail to establish adjacency with other
implementations that implement RFC 5838.

2) BIRD does not support DN-bit (from RFC 4576, as requested by
RFC 6992 section 9), but that should not cause problems.

3) BIRD would also push local IPv6 prefixes to IPv4-embedded-IPv6
topology, which are not needed here. This may be limited by 'stubnet
::/0 { hidden };' option for stub networks, but prefixes related to
broadcast transit networks would still be added.


Alternatively, you could just use regular OSPFv3 instance for propagating
IPv4-embedded IPv6 prefixes together with regular IPv6 network topology.
This would make the setup simpler, as you would not need separate OSPFv3
instances and IPv6 routing tables. This is a bit different approach than
specified in RFC 6992, but it works in almost identically.

-- 
Elen sila lumenn' omentielvo

Ondrej 'Santiago' Zajicek (email: santiago at crfreenet.org)
OpenPGP encrypted e-mails preferred (KeyID 0x11DEADC3, wwwkeys.pgp.net)
"To err is human -- to blame it on a computer is even more so."
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