Deprecating Anycast Prefix for 6to4 Relay Routers

The information below is for an old version of the document
Document Type Active Internet-Draft (v6ops WG)
Authors Ole Trøan  , Brian Carpenter 
Last updated 2015-01-04
Replaces draft-troan-v6ops-6to4-to-historic
Stream IETF
Intended RFC status Informational
Formats pdf htmlized (tools) htmlized bibtex
Stream WG state Adopted by a WG
Document shepherd Fred Baker
IESG IESG state I-D Exists (IESG: Dead)
Consensus Boilerplate Unknown
Telechat date
Responsible AD Ron Bonica
IESG note The document shepherd is Fred Baker (
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v6ops WG                                                        O. Troan
Internet-Draft                                                     Cisco
Obsoletes: 3068, 6732 (if approved)                    B. Carpenter, Ed.
Intended status: Best Current Practice                 Univ. of Auckland
Expires: July 8, 2015                                    January 4, 2015

           Deprecating Anycast Prefix for 6to4 Relay Routers


   Experience with the "Connection of IPv6 Domains via IPv4 Clouds
   (6to4)" IPv6 transition mechanism defined in RFC 3056 has shown that
   when used in its anycast mode, the mechanism is unsuitable for
   widespread deployment and use in the Internet.  This document
   therefore requests that RFC 3068, "An Anycast Prefix for 6to4 Relay
   Routers", be made obsolete and moved to historic status.  It also
   obsoletes RFC 6732 "6to4 Provider Managed Tunnels".  It recommends
   that future products should not support 6to4 anycast and that
   existing deployments should be reviewed.  This complements the
   guidelines in RFC 6343.

Status of This Memo

   This Internet-Draft is submitted in full conformance with the
   provisions of BCP 78 and BCP 79.

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   This Internet-Draft will expire on July 8, 2015.

Copyright Notice

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   document authors.  All rights reserved.

   This document is subject to BCP 78 and the IETF Trust's Legal
   Provisions Relating to IETF Documents
   ( in effect on the date of

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   publication of this document.  Please review these documents
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1.  Introduction

   The original form of the 6to4 transition mechanism [RFC3056] relies
   on unicast addressing.  However, its extension specified in "An
   Anycast Prefix for 6to4 Relay Routers" [RFC3068] has been shown to
   have severe practical problems when used in the Internet.  This
   document requests that RFC 3068 and RFC 6732 be moved to Historic
   status as defined in section 4.2.4 of [RFC2026].  It complements the
   deployment guidelines in [RFC6343].

   6to4 was designed to help transition the Internet from IPv4 to IPv6.
   It has been a good mechanism for experimenting with IPv6, but because
   of the high failure rates seen with anycast 6to4 [HUSTON], end users
   may end up disabling IPv6 on hosts as a result, and some content
   providers have been reluctant to make content available over IPv6.

   [RFC6343] analyses the known operational issues in detail and
   describes a set of suggestions to improve 6to4 reliability, given the
   widespread presence of hosts and customer premises equipment that
   support it.  The advice to disable 6to4 by default has been widely
   adopted in recent operating systems, and the failure modes have been
   widely hidden from users by many browsers adopting the "Happy
   Eyeballs" approach [RFC6555].

   Nevertheless, a substantial amount of 6to4 traffic is still observed
   by IPv6 content providers.  The remaining successful users of anycast
   6to4 are likely to be on hosts using the obsolete policy table
   [RFC3484], which prefers 6to4 above IPv4, and running without Happy
   Eyeballs.  Furthermore, they must have a route to an operational
   anycast relay and they must be accessing an IPv6 host that has a
   route to an operational return relay.

   However, experience shows that operational failures caused by anycast
   6to4 have continued, despite the advice in RFC 6343 being available.

1.1.  Related Work

   IPv6 Rapid Deployment on IPv4 Infrastructures (6rd) [RFC5969]
   explicitly builds on the 6to4 mechanism, using a service provider
   prefix instead of 2002::/16.  However, the deployment model is based

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   on service provider support, such that 6rd avoids the problems
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