H3C Technologies H3C S10500 Series Switches - Manual (Page 163)

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NOTE:
The encapsulation and de-encapsulation of the IPv4-over-IPv6 GRE tunnel is slightly different from
“
Encapsulation and de-encapsulation .” For more information about GRE, see the chapter “GRE
configuration.”
IPv6 over IPv6 tunneling
Introduction
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.
Encapsulation and de-encapsulation
Figure 69 Principle of IPv6 over IPv6 tunneling
Figure 69 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.