H3C S7500E Series Operation Manual page 598

Operation Manual – IPv6 Configuration
H3C S7500E Series Ethernet Switches
Caution:
The devices at both ends of an IPv6 over IPv4 tunnel must support IPv4/IPv6 dual
stack.
Figure 3-1 Principle of IPv6 over IPv4 tunnel
The IPv6 over IPv4 tunnel processes packets in the following way:
1) A host in the IPv6 network sends an IPv6 packet to the device at the source end of
the tunnel.
2) After determining according to the routing table that the packet needs to be
forwarded through the tunnel, the device at the source end of the tunnel
encapsulates the IPv6 packet with an IPv4 header the and forwards it through the
physical interface of the tunnel.
3) The encapsulated packet goes through the tunnel to reach the device at the
destination end of the tunnel. The device at the destination end decapsulates the
packet if the destination address of the encapsulated packet is the device itself.
4) The destination device forwards the packet according to the destination address in
the decapsulated IPv6 packet. If the destination address is the device itself, the
device forwards the IPv6 packet to the upper-layer protocol for processing.
II. Configured tunnel and automatic tunnel
An IPv6 over IPv4 tunnel can be established between hosts, between hosts and
devices, and between devices. The tunnel destination needs to forward packets if the
tunnel destination is not the eventual destination of the IPv6 packet.
According to the way the IPv4 address of the tunnel destination is acquired, tunnels are
divided into configured tunnel and automatic tunnel.
Chapter 3 Tunneling Configuration
3-2