on the master
$ sudo ifconfig carp0 192.0.2.19 vhid 1 $ sudo ifconfig carp1 192.168.1.1 vhid 2
on the backup
$ sudo ifconfig carp0 192.0.2.19 vhid 1 advskew 100 $ sudo ifconfig carp1 192.168.1.1 vhid 2 advskew 100
the master announces every (1 + 0/256) seconds
the backup announces every (1 + 100/256) seconds
Note Multicast. Use carppeer option for unicast
Also see Henning Brauer's notes