Network Working Group C. Huitema Request for Comments: 3068 Microsoft Category: Standards Track June 2001 An Anycast Prefix for 6to4 Relay Routers Status of this Memo This document specifies an Internet standards track protocol for the Internet community, and requests discussion and suggestions for improvements. Please refer to the current edition of the "Internet Official Protocol Standards" (STD 1) for the standardization state and status of this protocol. Distribution of this memo is unlimited. Copyright Notice Copyright (C) The Internet Society (2001). All Rights Reserved.
AbstractThis memo introduces a "6to4 anycast address" in order to simplify the configuration of 6to4 routers. It also defines how this address will be used by 6to4 relay routers, how the corresponding "6to4 anycast prefix" will be advertised in the IGP and in the EGP. The memo documents the reservation by IANA (Internet Assigned Numbers Authority) of the "6to4 relay anycast prefix." RFC3056], there are two deployment options for a 6to4 routing domain, depending on whether or not the domain is using an IPv6 exterior routing protocol. If a routing protocol is used, then the 6to4 routers acquire routes to all existing IPv6 networks through the combination of EGP and IGP. If no IPv6 exterior routing protocol is used, the 6to4 routers using a given relay router each have a default IPv6 route pointing to the relay router. This second case is typically used by small networks; for these networks, finding and configuring the default route is in practice a significant hurdle. In addition, even when the managers of these networks find an available route, this route often points to a router on the other side of the Internet, leading to very poor performance. The operation of 6to4 routers requires either that the routers participate in IPv6 inter-domain routing, or that the routers be provisioned with a default route. This memo proposes a standard method to define the default route. It introduces the IANA assigned "6to4 Relay anycast prefix" from which 6to4 packets will be
automatically routed to the nearest available router. It allows the managers of the 6to4 relay routers to control the sources authorized to use their resource. It makes it easy to set up a large number of 6to4 relay routers, thus enabling scalability. RFC3056], in particular the definition of a 6to4 router and a 6to4 Relay Router. It adds the definition of the 6to4 Relay anycast prefix, 6to4 Relay anycast address, 6to4 IPv6 relay anycast address, and Equivalent IPv4 unicast address.
The 6to4 relay routers that advertise the 6to4 anycast prefix will receive packets bound to the 6to4 anycast address. They will relay these packets to the IPv6 Internet, as specified in [RFC3056]. Each 6to4 relay router that advertise the 6to4 anycast prefix MUST also provide an equivalent IPv4 unicast address. Packets sent to that unicast address will follow the same processing path as packets sent to the anycast address, i.e., be relayed to the IPv6 Internet.
to be retrieved from the IGP tables. If the service is obtained through a peering agreement with another domain, the information will be retrieved from the EGP data, e.g., the BGP path attributes. The second step is obviously to perform connectivity tests using the equivalent unicast IPv4 address.
RADB]. Further analysis has shown that this was not required for practical operation.
A condition for easy migration out of the "tunnelling" state is that it be easy to have connectivity to the "real" IPv6 network; this means that people trust that opting for a real IPv6 address will not somehow result in lower performances. So the anycast proposal actually ensures that we don't stay in a perpetual transition. RFC3056]. The anycast technique introduces an additional risk, that a rogue router or a rogue AS would introduce a bogus route to the 6to4 anycast prefix, and thus divert the traffic. IPv4 network managers have to guarantee the integrity of their routing to the 6to4 anycast prefix in much the same way that they guarantee the integrity of the generic v4 routing. RFC 2026 [Bradner, 1996], Section 10.4, and describes the position of the IETF concerning intellectual property claims made against this document.
The IETF takes no position regarding the validity or scope of any intellectual property or other rights that might be claimed to pertain to the implementation or use other technology described in this document or the extent to which any license under such rights might or might not be available; neither does it represent that it has made any effort to identify any such rights. Information on the IETF's procedures with respect to rights in standards-track and standards-related documentation can be found in BCP-11. Copies of claims of rights made available for publication and any assurances of licenses to be made available, or the result of an attempt made to obtain a general license or permission for the use of such proprietary rights by implementers or users of this specification can be obtained from the IETF Secretariat. The IETF invites any interested party to bring to its attention any copyrights, patents or patent applications, or other proprietary rights which may cover technology that may be required to practice this standard. Please address the information to the IETF Executive Director. [RFC3056] Carpenter, B. and K. Moore "Connection of IPv6 Domains via IPv4 Clouds", RFC 3056, February 2001. [RADB] Introducing the RADB. Merit Networks, http://www.radb.net/docs/intro.html.
Acknowledgement Funding for the RFC Editor function is currently provided by the Internet Society.