Chapter 11 IPsec VPN for FortiOS 5.0 : IPv6 IPsec VPNs : Site-to-site IPv6 over IPv4 VPN example : Configure FortiGate A interfaces
  
Configure FortiGate A interfaces
Port 2 connects to the IPv4 public network and port 3 connects to the IPv6 LAN.
config system interface
edit port2
set 10.0.0.1/24
next
edit port3
config ipv6
set ip6-address fec0::0001:209:0fff:fe83:25f3/64
end