H3C Technologies H3C S10500 Series Switches - Manual (Page 160)

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Tunnel type Tunnel mode
Tunnel source/destination
address
Tunnel interface
address type
6to4 tunneling
The source IP address is a
manually configured IPv4
address. The destination IP
address does not need to be
configured.
6to4 address, in the
format of
2002:IPv4-source-addr
ess::/48
Automatic tunnel
Intra-site automatic tunnel
addressing protocol
(ISATAP) tunneling
The source IP address is a
manually configured IPv4
address. The destination IP
address does not need to be
configured.
ISATAP address, in the
format of
Prefix:0:5EFE:IPv4-sour
ce-address/64
1. 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.
2. 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
or between host and border router. For more information about related configurations, see the chapter
“GRE configuration.”
3. 6to4 tunneling
An automatic 6to4 tunnel is a point-to-multipoint tunnel and is used to connect multiple isolated IPv6
networks over an IPv4 network to remote IPv6 networks. The embedded IPv4 address in an IPv6 address
is used to automatically acquire the destination IPv4 address of the tunnel.
The automatic 6to4 tunnel adopts 6to4 addresses. The address format is 2002:abcd:efgh:subnet
number::interface ID/64, where 2002 represents the fixed IPv6 address prefix, and abcd:efgh
represents the 32-bit globally unique source IPv4 address of the 6to4 tunnel, in hexadecimal notation. For
example, 1.1.1.1 can be represented by 0101:0101. The part that follows 2002:abcd:efgh uniquely
identifies a host in a 6to4 network. The tunnel destination is automatically determined by the embedded
IPv4 address, which makes it easy to create a 6to4 tunnel.
The tunnel can forward IPv6 packets because the 16-bit subnet number of the 64-bit address prefix in
6to4 addresses can be customized and the first 48 bits in the address prefix are fixed to a permanent
value and the IPv4 address of the tunnel source or destination.
4. ISATAP tunneling
An ISATAP tunnel is a point-to-multipoint automatic tunnel. The destination of a tunnel can automatically
be acquired from the embedded IPv4 address in the destination address of an IPv6 packet.
When an ISATAP tunnel is used, the destination address of an IPv6 packet and the IPv6 address of a
tunnel interface both adopt special ISATAP addresses. The ISATAP address format is
prefix(64bit):0:5EFE:abcd:efgh. The 64-bit prefix is the prefix of a valid IPv6 unicast address, but
abcd:efgh is a 32-bit source IPv4 address in hexadecimal, which might not be globally unique. Through
the embedded IPv4 address, an ISATAP tunnel can be automatically created to transfer IPv6 packets.
The ISATAP tunnel is mainly used for communication between IPv6 routers or between a host and an IPv6
router over an IPv4 network.