Create an IPv6-in-IPv4 tunnel.
        create tunnel tunnel_name
                ipv6-in-ipv4
                destination
                destination-address
                source
                source-address
        
        The source-address refers to
          an existing address in the switch, and the destination-address is a
          remote destination accessible from the switch. A maximum of 255 IPv6-in-IPv4 tunnels can
          be configured.