The roadwarrior alice is sitting behind the router moon but at the outset of the scenariou is also directly connected to the 192.168.0.0/24 network via an additional eth1 interface. alice builds up a tunnel to gateway sun in order to reach bob in the subnet behind. When the eth1 interface goes away, alice switches to eth0 and signals the IP address change via a MOBIKE ADDRESS_UPDATE notification to peer sun. alice sets a virtual IP of 10.3.0.3, so that the IPsec policies don't have to be changed.