H3C Technologies H3C SecPath F1000-E - Manual (Page 91)

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Figure 64 IPv6 over IPv4 tunnel
The IPv6 over IPv4 tunnel processes packets in the following ways:
1. A host in the IPv6 network sends an IPv6 packet to Device A at the tunnel source.
2. After determining according to the routing table that the packet needs to be forwarded through the
tunnel, Device A encapsulates the IPv6 packet with an IPv4 header and forwards it through the
physical interface of the tunnel.
3. Upon receiving the packet, Device B de-encapsulates the packet.
4. Device B forwards the packet according to the destination address in the de-encapsulated IPv6
packet. If the destination address is the device itself, Device B forwards the IPv6 packet to the
upper-layer protocol for processing.
Tunnel types
IPv6 over IPv4 tunnels are divided into manually configured tunnels and automatic tunnels, depending
on how the IPv4 address of the tunnel destination is acquired.
• Manually configured tunnel—The destination address of the tunnel cannot be automatically
acquired through the destination IPv6 address of an IPv6 packet at the tunnel source, and must be
manually configured.
• Automatic tunnel—The destination address of the tunnel is an IPv6 address with an IPv4 address
embedded, and the IPv4 address can be automatically acquired through the destination IPv6
address of an IPv6 packet at the tunnel source.
Table 4 IPv6 over IPv4 tunnel modes and key parameters
Tunnel type Tunnel mode
Tunnel source/destination
address
Tunnel interface
address type
Manually
configured tunnel
IPv6 manual tunneling
The source/destination IP address
is a manually configured IPv4
address.
IPv6 address
IPv6-over-IPv4 GRE
tunneling
The source/destination IP address
is a manually configured IPv4
address.
IPv6 address
6to4 tunneling
The source IP address is a
manually configured IPv4
address. The destination IP
address need not be configured.
6to4 address, in the
format of
2002:IPv4-source-addr
ess::/48