advice on BGP + CARP setup on FreeBSD

Nick Hilliard nick at
Thu Nov 7 19:34:13 UTC 2013

On 07/11/2013 16:26, Antoine Beaupré wrote:
> and because VRRP is patent-encumbered

CARP is probably patent encumbered too.  I don't understand why people
claim that using CARP as a default gateway isn't patent encumbered because
it uses pretty much exactly the same process that the VRRP patent covers.
To be honest, I wouldn't get too upset about it as the patent expires early
next year, so this is not important.

Also bear in mind that if you decide to migrate to VRRP later on and for
some reason use the same VRRP group as CARP vhid, you will trash your
network connectivity.  The OpenBSD people specifically designed CARP so
that it would break VRRP on the same network if they use the same
parameters, but sadly they refuse to document this.  It's documented
elsewhere on the web though, so bear it in mind if you ever implement CARP
and then move to VRRP.

> I am worried, however, of rumours of kernel panics associated with CARP,
> but I am confident that the very responsive FreeBSD community will be
> able to help with that.

I hope so. There have been some long-standing problems, but hopefully the
work done on fixing carp in freebsd 10 will finally see the end of these


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