nagios redundant and failover

Am trying to implement redundant and failover so the when one of my
nagios server goes down or nagios processes stopped runing on one
server the other server will takes over automatically.

I have installed nagios 1.2 on two server mornitoring the same hosts
just as instructed on
http://nagios.sourceforge.net/docs/1_0/redundancy.html

now, I need a way to tell if the master nagios server is down so that
the slave can take over, I tried using check_nagios to tell me if the
master process is down but check_nagios is just reporting nagios
process locally.

is they any way of making nagios slave aware that nagios process on
master has stopped running, so that the slave can take over
mornitoring?