"kernel: carp_input: received len 20 < sizeof(struct carp_header)" messages

[Will Andrews]

On Fri, Nov 5, 2010 at 4:47 PM, Ask Bjørn Hansen <ask at develooper.com> wrote:
> I agree that it was pretty dumb of the OpenBSD developers to just stomp on another protocol ID for their (and ours in FreeBSD ...) implementation.

Actually, in this particular case I think it was justified.  The IANA
refused to allocate a separate protocol number for CARP.  Given that,
and the fact that CARP and VRRP serve generally the same purpose, it
makes sense that they use the same number.  Using an "unused" number
runs the risk of conflicting with a different unregistered protocol,
or one that was registered after the number was chosen.

FreeBSD could require administrators to configure the number on all
participating hosts on a given network, but that may be non-trivial to
implement in a particular network stack.  With the recent changes to
CARP in FreeBSD, however, it could be made to attach to a different
protocol number relatively easily.

FreeBSD could allow configuring CARP to silently ignore invalid
packets.  That would definitely be trivial to implement, but it
doesn't solve the issue that a particular network segment might be
running fussy VRRP hosts.

--Will.