DTCP (Dynamic Tunnel Configuration Protocol)

Hajimu UMEMOTO / ume@mahoroba.org

About DTCP

Since an IPv6 over IPv4 tunnel is established by specifying an IPv4 address of each other, basically, we can use an IPv6 over IPv4 tunnel only when we have a statically assigned IPv4 address.

To solve this problem, Trumpet Software International Pty Ltd. offers DTCP (Dynamic Tunnel Configuration Protocol).

The DTCP is a protocol which uses an IPv4 TCP. A server configures a tunnel per connection request from a client, dynamically. DTCP uses APOP for authentication.

Note: basically, an IPv6 over IPv4 tunnel cannot traverse a NAT. The DTCP is a protocol to solve this limitation.

There are following three kind of a tunnel type in the DTCP:

host
Connecting one host. One IPv6 address is assigned to a client.
tunnelonly
Only IPv6 over IPv4 tunnel is established. You need to configure routes and an IPv6 address separately from the DTCP.
network
Connecting a network. An IPv6 prefix is assigned to a client.
With network tunnel type, you can do a prefix delegation.

Following sites provide a service using network tunnel type:

Feel6
WIDE X6-Bone
IMASY

I'll assume to use network tunnel type in further description.

You can find the implementations of DTCP for BSD from this site.
It seems that USAGI has another implementation of a DTCP client:

http://www.linux-ipv6.org/cvsweb/usagi/src/mkdtcp/

All Rights Reserved, Copyright (C) 2004-2006 Hajimu UMEMOTO
Last Modified Apr 3, 2006
ume@mahoroba.org