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 2014-12-10
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: June 13, 2015                                 December 10, 2014

           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

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   provisions of BCP 78 and BCP 79.

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   This Internet-Draft will expire on June 13, 2015.

Copyright Notice

   Copyright (c) 2014 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
   ( in effect on the date of

Troan & Carpenter         Expires June 13, 2015                 [Page 1]
Internet-Draft          Deprecating 6to4 Anycast           December 2014

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   described in the Simplified BSD License.

1.  Introduction

   There would appear to be little evidence of substantial active use of
   the original form of 6to4 described in [RFC3056].  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.  However, experience shows that operational failures have
   continued despite this advice being available.  Fortunately the
   advice to disable 6to4 by default has been widely adopted in recent
   operating systems, and the failure modes have been largely hidden
   from users by many browsers adopting the "Happy Eyeballs" approach
   [RFC6555].  Nevertheless, a substantial amount of 6to4 traffic is
   still observed and the operational problems caused by 6to4 still

   Although facts are hard to obtain, the remaining successful users of
   anycast 6to4 are likely to be on hosts using the obsolete policy
   table [RFC3484] (which prefers 6to4 above IPv4), without Happy
   Eyeballs, with a route to an operational anycast relay, and accessing
   sites that have a route to an operational return relay.

   IPv6 Rapid Deployment on IPv4 Infrastructures (6rd) [RFC5969]
   explicitly builds on the 6to4 mechanism, and could be viewed as a
   superset of 6to4, using a service provider prefix instead of
   2002::/16.  However, the deployment model is based on service povider
   support, such that 6rd can avoid the problems described here.  In
   this sense, 6rd can be viewed as superseding 6to4 as described in
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