[nycbug-talk] ucarp question

Yarema yds at CoolRat.org
Wed Sep 20 13:48:34 EDT 2006

--On Wednesday, September 20, 2006 10:48 AM -0400 David Lawson 
<dave at donnerjack.com> wrote:

> Huh, that looks really interesting.  I ran into some problems
> with a heavily loaded box running CARP interfaces where some
> interfaces would fail to the secondary and others wouldn't,
> leading to some obvious routing problems.  I couldn't find a
> pure CARP way of dealing with the problem, it looks like this
> might be something that'd solve that issue reasonably elegantly.

from the FreeBSD carp(4) man page:

net.inet.carp.preempt -- Allow virtual hosts to preempt each other.  It is 
also used to failover carp interfaces as a group.  When the option is 
enabled and one of the carp enabled physical interfaces goes down, advskew 
is changed to 240 on all carp interfaces.  See also the first example. 
Disabled by default.

I've had other problems with carp(4), but with net.inet.carp.preempt set 
the failover does happen as a group in a "pure CARP way".


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