Automatic Tunnels

The automatic tunnels have a more limited use during early experimental deployment. They require IPv4 compatible addresses and can be used to connect IPv6 nodes when there are no IPv6 routers available. These tunnels can originate either on a dual host or on a dual router (by configuring an automatic tunneling network interface), and they always terminate on the dual host. These tunnels work by dynamically determining the destination IPv4 address (the endpoint of the tunnel) by extracting it from the IPv4 compatible destination address.