Re: CARP misbehaving on RPi2+ / RPI3

[mlelstv%serpens.de@localhost (Michael van Elst)]

relayer%gmail.com@localhost (Greywolf) writes:

>Greetings; I have a couple RPi that I will refer to here as 'thing1'
>and 'thing2'.  Both are running evbarm-earmv7h, NetBSD 10-BETA.

The carp driver sent advertising packets through the carp interface
which sets the source MAC address to the CARP virtual MAC address
(computed from the vhid value).

A normal ethernet switch will then learn that this MAC address
exists on multiple ports and change its forwarding table all
the time, resulting in lots of packet drops. The CARP election
protocol then doesn't work.

I have comitted a change to send advertisments through the backing
'carpdev' interface instead. This uses its own distinct MAC
address, and the switch stays happy.

With the consumer switches here, it still takes up to 20 seconds to notice
when CARP moves the virtual MAC address to the other machine.