airship-in-a-bottle/tools/multi_nodes_gate/airship_gate/templates/l3network-definition.sub

<network>
  <name>${NETNAME}</name>
  <bridge name='${NETNAME}' stp='on' delay='0'/>
  <ip address="${NETIP}" netmask="${NETMASK}" />
  <mac address='${NETMAC}'/>
  <forward mode="nat"/>
</network>