CARP interfaces and mastership issue

[Damien Fleuriot]

On 18 Sep 2011, at 12:44, Patrick Lamaiziere <patfbsd at davenulle.org> wrote:

> 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).


This can be easily verified.

When our vlan13 is forwarding on the switch, destroy and recreate the carp13 interface.
It still assumes mastership during a short time, then yields and becomes backup.