A variation on tunnelling IPv6 through IPv4 is to use an IPsec VPN tunnel between two FortiGate devices. FortiOS supports IPv6 over IPsSec. In this sort of scenario, two networks using IPv6 behind FortiGate units are separated by the Internet, which uses IPv4. An IPsec VPN tunnel is created between the FortiGate units and a tunnel is created over the IPv4-based Internet, but the traffic in the tunnel is IPv6. This has the additional advantage of securing the traffic.

For configuration information, see IPv6 IPsec VPN.