Overview of IPv4 over IPv6 Tunnels

During the later stage of IPv4 to IPv6 transition, a large number of IPv6 networks have been deployed and isolated IPv4 sites may exist. You can create a tunnel on an IPv6 network to connect isolated IPv4 sites, which is similar to deploying a VPN on the IP network using tunneling technology. The tunnel connecting isolated IPv4 sites on the IPv6 network is called an IPv4 over IPv6 tunnel.

Figure 1 Networking diagram for applying the IPv4 over IPv6 tunnel

Figure 1 shows how to apply the IPv4 over IPv6 tunnel.

1. On the border device, the IPv4/IPv6 dual protocol stack is enabled and the IPv4 over IPv6 tunnel is configured.

2. After the border device receives a packet not destined for it from the IPv4 network, the device appends an IPv6 header to the IPv4 packet and encapsulates the IPv4 packet as an IPv6 packet.

3. On the IPv6 network, the encapsulated packet is transmitted to the remote border device.

4. The remote border device decapsulates the packet, removes the IPv6 header, and sends the decapsulated IPv4 packet to the IPv4 network.