6to4 Information 6to4 Information28 October 2004
The "6to4" transition mechanism provides a way to connect IPv6 end-site networks by automatically tunnelling over the intervening IPv4 Internet. A special IPv6 routing prefix (2002::/16) is used to indicate that the remaining 32-bits of the external routing prefix contain the IPv4 end-point address of a boundary IPv6 router for that site that will respond to IPv6 in IPv4 encapsulation. Thus another "6to4" end-site can automatically discover this tunnel endpoint by dint of DNS lookups for any host on that network.
This page will hopefully provide sufficient information to understand this concept as well as helping to operationally setup the facility for an end-site and operationally use "6to4".
An overview of the "6to4" concept can be found in the Cisco Internet Protocol Journal, Volume 3, Number 1, March 2000, Routing IPv6 over IPv4
The "6to4" Proposed Standard, RFC 3056 [Connection of IPv6 Domains via IPv4 Clouds]
The "6to4-Anycast" Proposed Standard, RFC 3068 [An Anycast Prefix for 6to4 Relay Routers]
Hubert Feyrer's 6to4 Explained (or: Flogging a dead horse)The Microsoft Research IPv6 folk also have some "6to4" information
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