CARP: ifconfig

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