RFC 3053 (rfc3053) - Page 2 of 13

IPv6 Tunnel Broker

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.





Durand, et al.               Informational