The roadwarriors <b>carol</b> and <b>dave</b> set up a connection each using
multiple key exchanges 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 synchronization link between the
two gateways 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.
