The roadwarriors carol and dave set up a connection each to
gateway moon and request a virtual IP. moon negotiates
broadcast and multicast traffic selectors with the clients, and uses
%unique marks to avoid any policy conflicts. The enabled forecast
plugin on moon installs the required Netfilter rules to make use of these
policies, and additionally starts forwarding broadcast and multicast packets
between the clients.
To test forwarding, the hosts send multicast and broadcast ping messages.