R3721-F3210-F3171-HP High-End Firewalls VPN Configuration Guide-6PW101

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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 t
yp
e
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
Intra-site automatic
tunnel addressing
protocol (ISATAP)
tunneling
The source IP address is a manually
configured IPv4 address. The
destination IP address need not be
configured.
ISATAP address, in the
format of
Prefix:0:5EFE:IPv4-sour
ce-address/64
According to the way an IPv6 packet is encapsulated, IPv6 over IPv4 tunnels are divided into the
following modes:
• IPv6 manual tunneling
A manually configured tunnel is a point-to-point link. Each link is a separate tunnel. IPv6 manual tunnels
are mainly used to provide stable connections for regular secure communication between border routers
or between border routers and hosts for access to remote IPv6 networks.
• IPv6-over-IPv4 GRE tunneling
IPv6 packets can be carried over IPv6-over-IPv4 GRE tunnels to pass through an IPv4 network. Like an
IPv6 manually configured tunnel, an IPv6-over-IPv4 GRE tunnel is a point-to-point link. IPv6-over-IPv4 GRE
tunnels are mainly used to provide stable connections for secure communication between border routers