The roadwarriors <b>carol</b> and <b>dave</b> set up a connection each 
to the virtual gateway <b>mars</b> implemented by the two real gateways
<b>alice</b> and <b>moon</b> in a <b>High Availability</b> (HA) setup 
based on <b>ClusterIP</b>. The HA synchronisation link between the two
gatways is secured by an IPsec transport connection. At the outset
<b>alice</b> is the active and <b>moon</b> is the passive gateway.
After <b>alice</b> gets killed <b>moon</b> automatically takes over
all existing IKE_SAs and CHILD_SAs.