8.1. Types of tunnels

8.1.1. Static point-to-point tunneling: 6bone

A point-to-point tunnel is a dedicated tunnel to an endpoint, which knows about your IPv6 network (for backward routing) and the IPv4 address of your tunnel endpoint and defined in RFC 2893 / Transition Mechanisms for IPv6 Hosts and Routers. Requirements:

• IPv4 address of your local tunnel endpoint must be static, global unique and reachable from the foreign tunnel endpoint

• A global IPv6 prefix assigned to you (see 6bone registry)

• A foreign tunnel endpoint which is capable to route your IPv6 prefix to your local tunnel endpoint (mostly remote manual configuration required)

8.1.2. Automatically tunneling

Automatic tunneling occurs, when a node directly connects another node gotten the IPv4 address of the other node before.

8.1.3. 6to4-Tunneling

6to4 tunneling (RFC 3056 / Connection of IPv6 Domains via IPv4 Clouds) uses a simple mechanism to create automatic tunnels. Each node with a global unique IPv4 address is able to be a 6to4 tunnel endpoint (if no IPv4 firewall prohibits traffic). 6to4 tunneling is mostly not a one-to-one tunnel. This case of tunneling can be divided into upstream and downstream tunneling. Also, a special IPv6 address indicates that this node will use 6to4 tunneling for connecting the world-wide IPv6 network

|   3+13   |    32     |    16  |            64 bits             | 
+---+------+-----------+--------+--------------------------------+ 
|  FP+TLA  |  V4ADDR   | SLA ID |           Interface ID         | 
|  0x2002  |           |        |                                | 
+---+------+-----------+--------+--------------------------------+