Du trenger sysctl-verdiene
$ sysctl net.inet.carp.allow net.inet.carp.allow=1
$ sysctl net.inet.carp net.inet.carp.allow=1 net.inet.carp.preempt=0 net.inet.carp.log=0 net.inet.carp.arpbalance=0
magien starter med
$ sudo sysctl net.inet.carp.preempt=1