The roadwarrior <b>alice</b> is sitting behind the NAT router <b>moon</b> but
at the outset of the scenario is also directly connected to the 192.168.0.0/24 network
via an additional <b>eth1</b> interface. <b>alice</b> builds up a tunnel to gateway <b>sun</b>
in order to reach <b>bob</b> in the subnet behind. When the <b>eth1</b> interface
goes away, <b>alice</b> switches to <b>eth0</b> and signals the IP address change
via a MOBIKE ADDRESS_UPDATE notification to peer <b>sun</b>. Later the interface
comes back up again and because the best path is preferred (charon-systemd.prefer_best_path)
there is another switch to the directly connected path.  <b>alice</b> sets
a virtual IP of 10.3.0.3, so that the IPsec policies don't have to be changed.
