There are a few ways in which the tunnelling can be performed depending on which segment of the path between the end points of the session the encapsulation takes place.

Host to Host: Dual Stack capable hosts that are interconnected by an IPv4 infrastructure can tunnel IPv6 packets between themselves. In this case, the tunnel spans the entire path taken by the IPv6 packets.

Network Device to Host: Dual Stack capable network devices can tunnel IPv6 packets to their final destination IPv6 or IPv4 host. This tunnel spans only the last segment of the path taken by the IPv6 packets.

Regardless of whether the tunnel starts at a host or a network device, the node that does the encapsulation needs to maintain soft state information, such as the maximum transmission unit (MTU), about each tunnel in order to process the IPv6 packets.

Use the following command to tunnel IPv6 traffic over an IPv4 network. The IPv6 interface is configured under config system interface. The command to do the reverse is config system ipv6-tunnel. These commands are not available in Transparent mode.