ZyXEL Communications P-660H-61 User Manual page 346

Appendix E IPv6
On the ZyXEL Device, you can either set up a configured tunnel or an automatic 6to4 tunnel. The
following describes each method.
Configured Tunnel
A configured tunnel is a point-to-point tunnelling mechanism that encapsulates an IPv6 address
with an IPv4 address. Routers (A and B) on both IPv6 networks (1 and 2) each must have an
interface that connects to the IPv4 network (with an IPv4 address). This allows the router to send
and receive IPv6 data over the IPv4 network.
In this case, you must specify B's public IPv4 address on A (similarly, specify A's public IPv4
address on B) in order for packets to arrive at the intended destination through the IPv4 network.
Figure 215 Configured Tunnel Example
6to4 Tunnel
A 6to4 tunnel is an automatic tunnelling mechanism that provides connection between IPv6
networks across an IPv4 network. To transmit IPv6 packets over an IPv4 network, the IPv6 packets
are encapsulated inside IPv4 packets.
The following figure shows a network example.
Figure 216 6to4 Relay Router Network Example
In a 6to4 tunnel, 6to4 routers (A and B in the example network) forward these packets between
IPv6 networks (1 and 2) over the IPv4 Internet. A 6to4 relay router (C) connects to both an IPv6
and IPv4 network. A 6to4 relay router is used to forward packets between 6to4 routers in an IPv4
Internet and an IPv6 device (Z) on the IPv6 Internet.
To transmit packets, a 6to4 address is used with a special IPv6 prefix of 2002:: to encode a given
IPv4 address. A 6to4 address has the following format:
2002:IPv4 address:subnet ID:host ID/64
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ADSL Router Series User's Guide