chr...@openbsd.org(chr...@openbsd.org) on 2020.01.18 06:18:21 +0100: > On Wed, Jan 15, 2020 at 12:47:28PM +0100, Sebastian Benoit wrote: > >Christopher Zimmermann(chr...@openbsd.org) on 2020.01.15 11:55:43 +0100: > >>Hi, > >> > >>as far as I can see a dual stack carp interface does not care whether it > >>receives advertisements addressed to IPv4 or IPv6. Any one will do. > >>So I propose to send IPv6 advertisements only when IPv4 is not possible. > >> > >>Why? > >> > >>- Noise can be reduced by using unicast advertisements. > >> This is only possible for IPv4 by ``ifconfig carppeer``. > >> I don't like flooding the whole network with carp advertisements when > >> I may also unicast them. > > > >Maybe i'm getting confused, but in the problem description you were talking > >about v6 vs v4, and here you argue about unicast (vs multicast?) being > >better. Thats orthogonal, isnt it? > > Yes, kind of. The point is we support ``carppeer`` for IPv4, but not for > IPv6. > > >>- breaking IPv6 connectivity (for example by running iked without -6) > >> will start a preempt-war, because failing ip6_output will cause the > >> demote counter to be increased. That's what hit me. > > > >But the whole point of carp is to notice broken connectivity. If you run v6 > >on an interface, you want to know if its working, no? > > I grant you that much. But what kind of failures do you hope to detect > on the _sending_ carp master, that would not also affect the backup?
sure: misconfigured pf. Missing routes. Buggy switch. > >At the very least, this needs some more thought and testing in all the ways > >carp can be configured. > > Anyway, my main concern indeed is the broadcast noise generated by carp > and I would be equally happy if we had a ``carppeer6`` option. Would > that be considered? of course carppeer should work with v6, and as claudio says without an extra keyword in ifconfig, but thats a trivial detail.
