CARP over VLAN over LAGG

[Julien Cigar]

On Fri, Aug 28, 2020 at 04:52:01PM +0200, Julien Cigar wrote:
> Hello,
> 
> I have a "highly available" router/firewall with the following
> configuration (1). Those are plugged in two 2930F (with VSF) using LACP.
> It works well, except that I have some weird issues with the CARP 
> demotion counter when I'm unplugging some interfaces involved in the 
> lagg/carp setup, for example if I unplug/replug igb0 and igb1 in this 
> case:
> 
> (dmesg):
> igb0: link state changed to DOWN
> igb1: link state changed to DOWN
> carp: demoted by 240 to 240 (send error 50 on vlan11)
> carp: 11 at vlan11: MASTER -> BACKUP (more frequent advertisement received)
> vlan11: deletion failed: 3
> igb1: link state changed to UP
> igb0: link state changed to UP
> 
> then the CARP status stays to BACKUP unless I demote the CARP demotion
> counter manually with: sudo sysctl net.inet.carp.demotion=-240:
> 
> (dmesg):
> carp: demoted by -240 to 0 (sysctl)
> carp: 11 at vlan11: BACKUP -> MASTER (preempting a slower master)
> 
> I guess this is because it takes some time for lagg/lacp to converge and
> thus carp thinks that there is a problematic condition as it experiences
> problems with sending announcements..
> 
> What it the best way to handle this?

I'm wondering if setting net.inet.carp.senderr_demotion_factor to "0"
could be a solution? Are there any downsides of setting this to "0"
instead of "240"?

> 
> Thanks,
> Julien
> 
> (1) https://gist.github.com/silenius/577606b596ff1d220bbfd9956d05baef
> 
> -- 
> Julien Cigar
> Belgian Biodiversity Platform (http://www.biodiversity.be)
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-- 
Julien Cigar
Belgian Biodiversity Platform (http://www.biodiversity.be)
PGP fingerprint: EEF9 F697 4B68 D275 7B11  6A25 B2BB 3710 A204 23C0
No trees were killed in the creation of this message.
However, many electrons were terribly inconvenienced.