CARP interfaces and mastership issue

[Patrick Lamaiziere]

Le Sat, 17 Sep 2011 23:40:06 -0400 (EDT),
"Brian Seklecki (Mobile)" <lavalamp at probikesllc.com> a écrit :

> >
> >> What would help here, is for a carp interface to wait a given delay
> >> (tunable through a sysctl ?) after creation or after being brought
> >> up
> 
> I see now.
> 
> The tunable sounds like a good idea; we should check OpenBSD, they 
> probably already implemented something and we're behind.
> 
> If not, a "preempt dampener" feature would be an awesome return
> feature.
> 
> Might need to implment another state: MASTER-LISTENING (or LEARNING)
> ah a STP.

OpenBSD uses a "carp demote counter" that prevents to become master
(but it will become master anyway if there is not carp advertizement on
the interface). There is a sysctl in FreeBSD but it's readonly.

This is used to delay carp until pfsync synchronization is done and by
daemons like bgpd.
 
Anyway if carp becomes master when the interface is set up, it looks to
be a bug on FreeBSD (and if you are sure that the problem does not
come from the switch). That works fine on OpenBSD.

Regards.