Network Working Group R. Bush Internet-Draft Internet Initiative Japan Obsoletes: 2526 (if approved) July 4, 2011 Intended status: Standards Track Expires: January 5, 2012 IPv6 Subnet Anycast Deprecated draft-ymbk-no-subnet-anycast-00 Abstract IPv6 Subnet Anycast is not used operationally, complicates implementations, and complicates protocol specifications. The form of anycast actually used in the Internet is routing-based, and is essentilly the same as that of IPv4 anycast. Therefore, this document deprecates IPv6 Subnet Anycast. This is an early draft and will require non-trivial fill-in and details. Status of this Memo This Internet-Draft is submitted in full conformance with the provisions of BCP 78 and BCP 79. This document may not be modified, and derivative works of it may not be created, and it may not be published except as an Internet-Draft. Internet-Drafts are working documents of the Internet Engineering Task Force (IETF). Note that other groups may also distribute working documents as Internet-Drafts. The list of current Internet- Drafts is at http://datatracker.ietf.org/drafts/current/. Internet-Drafts are draft documents valid for a maximum of six months and may be updated, replaced, or obsoleted by other documents at any time. It is inappropriate to use Internet-Drafts as reference material or to cite them other than as "work in progress." This Internet-Draft will expire on January 5, 2012. Copyright Notice Copyright (c) 2011 IETF Trust and the persons identified as the document authors. All rights reserved. This document is subject to BCP 78 and the IETF Trust's Legal Provisions Relating to IETF Documents (http://trustee.ietf.org/license-info) in effect on the date of Bush Expires January 5, 2012 [Page 1] Internet-Draft IPv6 Subnet Anycast Deprecated July 2011 publication of this document. Please review these documents carefully, as they describe your rights and restrictions with respect to this document. Code Components extracted from this document must include Simplified BSD License text as described in Section 4.e of the Trust Legal Provisions and are provided without warranty as described in the Simplified BSD License. Table of Contents 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 3 2. Security Considerations . . . . . . . . . . . . . . . . . . . . 3 3. IANA Considerations . . . . . . . . . . . . . . . . . . . . . . 3 4. Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . . 3 5. References . . . . . . . . . . . . . . . . . . . . . . . . . . 4 5.1. Normative References . . . . . . . . . . . . . . . . . . . 4 5.2. Informative References . . . . . . . . . . . . . . . . . . 4 Author's Address . . . . . . . . . . . . . . . . . . . . . . . . . 4 Bush Expires January 5, 2012 [Page 2] Internet-Draft IPv6 Subnet Anycast Deprecated July 2011 1. Introduction The form of anycast which is used in the operational internet is described in [RFC4786]. This is used widely in IPv4 and IPv6. To quote, "To distribute a service using anycast, the service is first associated with a stable set of IP addresses, and reachability to those addresses is advertised in a routing system from multiple, independent service nodes." IPv6 subnet anycast, as defined in [RFC2526], complicates host and router stacks. It also makes address assignment needlessly complex, see [RFC6164]. IPv6 Subnet Anycast is not actually used or deployed. In this case, it is fairly certain that implementations are not even debugged. As IPv6 becomes more widely deployed, having special unused code in the critical code path is unnecessary, unwise, and invites bugs and inefficiency. There is no need for reserved subnet anycast addresses, because any address can be an anycast address. Only the node where an anycast address is configured needs to know that it is an anycast address. That is, there is no need to be able to recognise such an address from its format. The use of IPv4 anycast has not been impeded by the inability to tell an anycast address from an ordinary address. Therefore, this document deprecates IPv6 Subnet Anycast addresses and removes the relevance conformance requirements from host and router implementations. 2. Security Considerations There are no known security implications for this document. It probably reduces vulnerabilities. 3. IANA Considerations This document asks nothing of the IANA. 4. Acknowledgments The author wishes to thank Karl Auer. Bush Expires January 5, 2012 [Page 3] Internet-Draft IPv6 Subnet Anycast Deprecated July 2011 5. References 5.1. Normative References [RFC2526] Johnson, D. and S. Deering, "Reserved IPv6 Subnet Anycast Addresses", RFC 2526, March 1999. 5.2. Informative References [RFC4786] Abley, J. and K. Lindqvist, "Operation of Anycast Services", BCP 126, RFC 4786, December 2006. [RFC6164] Kohno, M., Nitzan, B., Bush, R., Matsuzaki, Y., Colitti, L., and T. Narten, "Using 127-Bit IPv6 Prefixes on Inter- Router Links", RFC 6164, April 2011. Author's Address Randy Bush Internet Initiative Japan 5147 Crystal Springs Bainbridge Island, Washington 98110 US Phone: +1 206 780 0431 x1 Email: randy@psg.com Bush Expires January 5, 2012 [Page 4]