IPv6 over IPv6 tunneling

IPv6 over IPv6 tunneling (specified in RFC 2473) is developed for IPv6 data packet encapsulation so that encapsulated packets can be transmitted over an IPv6 network. The encapsulated packets are IPv6 tunnel packets.

Figure 87 shows the encapsulation and de-encapsulation processes.

• Encapsulation

  1. After receiving the IPv6 packet, the interface of Device A connecting private network A submits it to the IPv6 module for processing. The IPv6 module then determines how to forward the packet.

  2. If the packet is destined for Host B connected to Device B, the packet is sent to Router A’s tunnel interface that is connected to Device B.

  3. After receiving the packet, the tunnel interface adds an IPv6 header to it and submits it to the IPv6 module for processing.

  4. The IPv6 module re-determines how to forward the packet according to the destination address in the IPv6 header.

• De-encapsulation

  The de-encapsulation follows these steps:

  1. The packet received from the IPv6 network interface is sent to the IPv6 module for processing.

  2. The IPv6 module checks the protocol type of the data portion encapsulated in the IPv6 packet. If the encapsulation protocol is IPv6, the packet is sent to the tunnel processing module for de-encapsulation.

  3. The de-encapsulated packet is sent to the IPv6 protocol module for the secondary routing process.