IPv6 Tunnel Broker
RFC 3053

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Network Working Group                                          A. Durand
Request for Comments: 3053                         SUN Microsystems, Inc
Category: Informational                                        P. Fasano
                                                             I. Guardini
                                                            CSELT S.p.A.
                                                                D. Lento
                                                                     TIM
                                                            January 2001

                           IPv6 Tunnel Broker

Status of this Memo

   This memo provides information for the Internet community.  It does
   not specify an Internet standard of any kind.  Distribution of this
   memo is unlimited.

Copyright Notice

   Copyright (C) The Internet Society (2001).  All Rights Reserved.

Abstract

   The IPv6 global Internet as of today uses a lot of tunnels over the
   existing IPv4 infrastructure.  Those tunnels are difficult to
   configure and maintain in a large scale environment.  The 6bone has
   proven that large sites and Internet Service Providers (ISPs) can do
   it, but this process is too complex for the isolated end user who
   already has an IPv4 connection and would like to enter the IPv6
   world.  The motivation for the development of the tunnel broker model
   is to help early IPv6 adopters to hook up to an existing IPv6 network
   (e.g., the 6bone) and to get stable, permanent IPv6 addresses and DNS
   names.  The concept of the tunnel broker was first presented at
   Orlando's IETF in December 1998.  Two implementations were
   demonstrated during the Grenoble IPng & NGtrans interim meeting in
   February 1999.

1. Introduction

   The growth of IPv6 networks started mainly using the transport
   facilities offered by the current Internet.  This led to the
   development of several techniques to manage IPv6 over IPv4 tunnels.
   At present most of the 6bone network is built using manually
   configured tunnels over the Internet.  The main drawback of this
   approach is the overwhelming management load for network
   administrators, who have to perform extensive manual configuration
   for each tunnel.  Several attempts to reduce this management overhead

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RFC 3053                   IPv6 Tunnel Broker               January 2001

   have already been proposed and each of them presents interesting
   advantages but also solves different problems than the Tunnel Broker,
   or poses drawbacks not present in the Tunnel Broker:

      -  the use of automatic tunnels with IPv4 compatible addresses [1]
         is a simple mechanism to establish early IPv6 connectivity
         among isolated dual-stack hosts and/or routers.  The problem
         with this approach is that it does not solve the address
         exhaustion problem of IPv4.  Also there is a great fear to
         include the complete IPv4 routing table into the IPv6 world
         because this would worsen the routing table size problem
         multiplying it by 5;

      -  6over4 [2] is a site local transition mechanism based on the
         use of IPv4 multicast as a virtual link layer.  It does not
         solve the problem of connecting an isolated user to the global
         IPv6 Internet;

      -  6to4 [3] has been designed to allow isolated IPv6 domains,
         attached to a wide area network with no native IPv6 support
         (e.g., the IPv4 Internet), to communicate with other such IPv6
         domains with minimal manual configuration.  The idea is to
         embed IPv4 tunnel addresses into the IPv6 prefixes so that any
         domain border router can automatically discover tunnel
         endpoints for outbound IPv6 traffic.

   The Tunnel Broker idea is an alternative approach based on the
   provision of dedicated servers, called Tunnel Brokers, to
   automatically manage tunnel requests coming from the users.  This
   approach is expected to be useful to stimulate the growth of IPv6
   interconnected hosts and to allow early IPv6 network providers to
   provide easy access to their IPv6 networks.

   The main difference between the Tunnel Broker and the 6to4 mechanisms
   is that the they serve a different segment of the IPv6 community:

      -  the Tunnel Broker fits well for small isolated IPv6 sites, and
         especially isolated IPv6 hosts on the IPv4 Internet, that want
         to easily connect to an existing IPv6 network;

      -  the 6to4 approach has been designed to allow isolated IPv6
         sites to easily connect together without having to wait for
         their IPv4 ISPs to deliver native IPv6 services.  This is very
         well suited for extranet and virtual private networks.  Using
         6to4 relays, 6to4 sites can also reach sites on the IPv6
         Internet.

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