Hi Nico,
On 30. Jan 2024, at 10:32, Nico Schottelius via Bird-users <bird-users@network.cz> wrote: OSPFv3 works fine on IPv6 and when creating two instances, one for IPv6 one for IPv4, things look correct. But how does OSFPv3 conceptually work if the interface of the ospf area do not have IPv4 addresses themselves?
In the BGP case we can use "extended next hop on;" to use the IPv6 nexthop for IPv4, but I did not find a similar setting for OSPF to accept IPv6 nexthops for IGP IPv4 addresses.
Is there a way to purely go IPv6 only and still relay stub network IPv4 information via an IPv6 only internal area?
I was facing the same issue before, and unfortunately, RFC 5838 explicitly forbids IPv4 over IPv6 for OSPF. As an alternative suggestion, I have since evaluated babel which mostly suits my purposes (except for some features not yet implemented in bird, like strict bind) - but maybe it works for you? Cheers Sebastian