ipv4 inside ipv6 for ospf

Vasiliy Tolstov v.tolstov at selfip.ru
Mon Jun 23 12:16:00 CEST 2014

2014-06-23 14:44 GMT+04:00 Ondrej Zajicek <santiago at crfreenet.org>:
> 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.

Nice. Thanks! Last question - does bird developers have plans to fix
ecmp routing for ipv6?
(Periodic scan routing table remove multipath routes)

Vasiliy Tolstov,

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