Chapter 3 Ipv6 Tunnel Configuration; Figure 3-4 Principles Of A 6To4 Tunnel - Zte ZXR10 5900E Configuration Manual

header encapsulation. During the encapsulation, the source and destination
addresses of the IPv4 header are manually configured by the user.
encapsulated packet is then sent according to the IPv4 packet sending process.
Decapsulation: The process is just contrary to the encapsulation process. If the
à
protocol number in the IPv4 header of the received IPv4 packet is 41, the host or
router proceeds to the 6in4 decapsulation process and searches for the matched
tunnel number according to the source and destination addresses of the packet.
If the tunnel number is found, the host or router removes the IPv4 header added
during tunnel encapsulation and delivers the remaining IPv6 packet to the IPv6
packet receiving process for further handling.
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6to4 Tunnel
Figure 3-4

Figure 3-4 Principles of a 6to4 Tunnel

A 6to4 tunnel is a point-to-multipoint auto tunnel used to connect multiple isolated IPv6
sites through an IPv4 network to an IPv6 network. It makes possible the automatic
acquisition of the IPv4 address at the termination point of the tunnel by embedding an
IPv4 address in the destination address of an IPv6 packet.
The
2002:abcd:efgh:Subnet ID::InterfaceID/64. Of the address, 2002 is a fixed IPv6
address prefix, abcd:efgh is a globally unique 32-bit IPv4 source address of the 6to4
tunnel in hexadecimal system (e.g. 1.1.1.1 can be expressed as 0101:0101), and
the rest portion uniquely identifies the position of a host in a 6to4 network. As the
termination point of the tunnel can be automatically determined by this embedded
IPv4 address, tunnel establishment becomes very convenient.
Because the 16-bit subnet ID in the 64-bit address prefix of the 6to4 address can be
user-defined whereas the first 48 bits of the prefix are a fixed number or determined by
the IPv4 address of the device at the start or termination point of a tunnel, it becomes
possible to forward IPv6 packets over the tunnel. The 6to4 tunnel makes possible the
interconnection of two IPv6 networks through an IPv4 network and thus conquers the
limitations of automatic IPv4-compatible IPv6 tunnels in practical use.
The 6to4 tunnel involves a tunnel encapsulation and decapsulation process.
SJ-20150114102049-011|2015-01-15 (R1.0)
shows the operating principles of a 6to4 tunnel.
6to4 tunnel assumes

Chapter 3 IPv6 Tunnel Configuration

a special 6to4 address
3-3
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in the format of