v6ops WG
Internet Engineering Task Force (IETF)                          O. Troan
Internet-Draft
Request for Comments: 7526                                         Cisco
Obsoletes: 3068, 6732 (if approved)
BCP: 196                                               B. Carpenter, Ed.
Intended status: Best Current Practice
Obsoletes: 3068, 6732                                  Univ. of Auckland
Expires: August 1, 2015                                 January 28,
Category: Best Current Practice                               April 2015
ISSN: 2070-1721

         Deprecating the Anycast Prefix for 6to4 Relay Routers
                draft-ietf-v6ops-6to4-to-historic-11.txt

Abstract

   Experience with the "Connection of IPv6 Domains via IPv4 Clouds
   (6to4)" IPv6 6to4 transition mechanism defined in RFC 3056
   ("Connection of IPv6 Domains via IPv4 Clouds") has shown that
   when used in its anycast mode, the
   mechanism is unsuitable for widespread deployment and use in the Internet.  This
   Internet when used in its anycast mode.  Therefore, this document
   therefore
   requests that RFC 3068, "An 3068 ("An Anycast Prefix for 6to4 Relay
   Routers", Routers")
   and RFC 6732 ("6to4 Provider Managed Tunnels") be made obsolete and
   moved to historic 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.

   Internet-Drafts are working memo documents an Internet Best Current Practice.

   This document is a product of the Internet Engineering Task Force
   (IETF).  Note that other groups may also distribute
   working documents as Internet-Drafts.  The list  It represents the consensus of current Internet-
   Drafts is at http://datatracker.ietf.org/drafts/current/.

   Internet-Drafts are draft documents valid the IETF community.  It has
   received public review and has been approved for a maximum publication by the
   Internet Engineering Steering Group (IESG).  Further information on
   BCPs is available in Section 2 of six months RFC 5741.

   Information about the current status of this document, any errata,
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   material or to cite them other than as "work in progress."

   This Internet-Draft will expire on August 1, 2015.
   http://www.rfc-editor.org/info/rfc7526.

Copyright Notice

   Copyright (c) 2015 IETF Trust and the persons identified as the
   document authors.  All rights reserved.

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Table of Contents

   1.  Introduction  . . . . . . . . . . . . . . . . . . . . . . . .   2
     1.1.  Related Work  . . . . . . . . . . . . . . . . . . . . . .   3
   2.  Conventions . . . . . . . . . . . . . . . . . . . . . . . . .   3
   3.  6to4 operational problems Operational Problems . . . . . . . . . . . . . . . . . .   3
   4.  Deprecation . . . . . . . . . . . . . . . . . . . . . . . . .   4
   5.  Implementation Recommendations  . . . . . . . . . . . . . . .   5
   6.  Operational Recommendations . . . . . . . . . . . . . . . . .   5
   7.  IANA Considerations . . . . . . . . . . . . . . . . . . . . .   6
   8.  Security Considerations . . . . . . . . . . . . . . . . . . .   6
   9.  Acknowledgements  References  . . . . . . . . . . . . . . . . . . . . . . . . .   6
   10.
     9.1.  Normative References  . . . . . . . . . . . . . . . . . .   6
     9.2.  Informative References  . . . . . . .   7
     10.1.  Normative References . . . . . . . . . . .   7
   Acknowledgements  . . . . . . .   7
     10.2.  Informative References . . . . . . . . . . . . . . . . .   8   9
   Authors' Addresses  . . . . . . . . . . . . . . . . . . . . . . .   8   9

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 RFCs 3068 and RFC 6732 be moved to Historic
   status
   status, as defined in section 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 hosts; this has resulted in the past some content
   providers were being reluctant to make content available over IPv6
   for this reason. in the
   past.

   [RFC6343] analyses analyzes 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 measurable 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
   [RFC3484] (which prefers 6to4 above IPv4, 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, continued despite the advice in RFC 6343 being available.

1.1.  Related Work

   IPv6

   "IPv6 Rapid Deployment on IPv4 Infrastructures (6rd) -- Protocol
   Specification" [RFC5969] explicitly builds on the 6to4 mechanism,
   using a service provider prefix instead of 2002::/16.  However, the
   deployment model is based on service provider support, support such that 6rd
   avoids the problems observed with anycast 6to4.

   The framework for 6to4 "6to4 Provider Managed Tunnels Tunnels" [RFC6732] is
   intended to help a service provider manage 6to4 anycast tunnels.
   This framework only exists because of the problems observed with
   anycast 6to4.

2.  Conventions

   The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
   "SHOULD", "SHOULD NOT", "RECOMMENDED", "NOT RECOMMENDED", "MAY", and
   "OPTIONAL" in this document are to be interpreted as described in RFC
   2119 [RFC2119].

   The

   In this document, the word "deprecate" and its derivatives are used
   only in their generic sense of "criticize or express disapproval" and
   do not have any specific normative meaning.  A deprecated function
   might exist in the Internet for many years to allow backwards
   compatibility.

3.  6to4 operational problems Operational Problems

   6to4 is a mechanism designed to allow isolated IPv6 islands to reach
   each other using IPv6 over IPv4 IPv6-over-IPv4 automatic tunneling.  To reach the
   native IPv6 Internet Internet, the mechanism uses relay routers both in both the
   forward and reverse direction.  The mechanism is supported in many
   IPv6 implementations.  With the increased deployment of IPv6, the
   mechanism has been shown to have a number of shortcomings.

   In the forward direction direction, a 6to4 node will send IPv4 encapsulated IPv4-encapsulated
   IPv6 traffic to a 6to4 relay, relay that is connected both to both the 6to4 cloud
   and
   to native IPv6.  In the reverse direction direction, a 2002::/16 route is
   injected into the native IPv6 routing domain to attract traffic from
   native IPv6 nodes to a 6to4 relay router.  It is expected that
   traffic will use different relays in the forward and reverse
   direction.

   One model of 6to4 deployment, described in section Section 5.2 of RFC 3056,
   suggests that a 6to4 router should have a set of managed connections
   (via BGP connections) to a set of 6to4 relay routers.  While this
   makes the forward path more controlled, it does not guarantee a
   functional reverse path.  In any case case, this model has the same
   operational burden as manually configured tunnels and has seen no
   deployment in the public Internet.

   RFC 3068 adds an extension that allows the use of a well known well-known IPv4
   anycast address to reach the nearest 6to4 relay in the forward
   direction.  However, this anycast mechanism has a number of
   operational issues and problems, which are described in detail in
   Section 3 of [RFC6343].  This document is intended to deprecate the
   anycast mechanism.

   Peer-to-peer usage of the 6to4 mechanism exists in the Internet,
   likely unknown to many operators.  This usage is harmless to third
   parties and is not dependent on the anycast 6to4 mechanism that this
   document deprecates.

4.  Deprecation

   This document formally deprecates the anycast 6to4 transition
   mechanism defined in [RFC3068] and the associated anycast IPv4
   address 192.88.99.1.  It is no longer considered to be a useful
   service of last resort.

   The prefix 192.88.99.0/24 MUST NOT be reassigned for other use except
   by a future IETF standards action. Standards Action.

   The basic unicast 6to4 mechanism defined in [RFC3056] and the
   associated 6to4 IPv6 prefix 2002::/16 are not deprecated.  The
   default address selection rules specified in [RFC6724] are not
   modified.

   In the absence of 6to4 anycast, 6to4 "6to4 Provider Managed Tunnels Tunnels"
   [RFC6732] will no longer be necessary, so they are also deprecated by
   this document.

   Incidental references to 6to4 should be reviewed and possibly removed
   from other IETF documents if and when they are updated.  These
   documents include RFC3162, RFC3178, RFC3790, RFC4191, RFC4213,
   RFC4389, RFC4779, RFC4852, RFC4891, RFC4903, RFC5157, RFC5245,
   RFC5375, RFC5971, RFC6071 RFC 3162, RFC 3178, RFC 3790, RFC 4191, RFC 4213,
   RFC 4389, RFC 4779, RFC 4852, RFC 4891, RFC 4903, RFC 5157, RFC 5245,
   RFC 5375, RFC 5971, RFC 6071, and RFC6890. RFC 6890.

5.  Implementation Recommendations

   It is NOT RECOMMENDED to include the anycast 6to4 transition
   mechanism in new implementations.  If included in any
   implementations, the anycast 6to4 mechanism MUST be disabled by
   default.

   In host implementations, unicast 6to4 MUST also be disabled by
   default.  All hosts using 6to4 MUST support the IPv6 address IPv6-address-
   selection policy described in [RFC6724].

   In router implementations, 6to4 MUST be disabled by default.  In
   particular, enabling IPv6 forwarding on a device MUST NOT
   automatically enable 6to4.

6.  Operational Recommendations

   This document does not imply a recommendation for the generalized
   filtering of traffic or routes for 6to4 or even anycast 6to4.  It
   simply recommends against further deployment of the anycast 6to4
   mechanism, calls for current 6to4 deployments to evaluate the
   efficacy of continued use of the anycast 6to4 mechanism, and makes
   recommendations intended to prevent any use of 6to4 from hampering
   broader deployment and use of native IPv6 on the Internet as a whole.

   Networks SHOULD NOT filter out packets whose source address is
   192.88.99.1, because this is normal 6to4 traffic from a 6to4 return
   relay somewhere in the Internet.  This includes ensuring that traffic
   from a local 6to4 return relay with a source address of 192.88.99.1
   is allowed through anti-spoofing filters such (such as those described in
   [RFC2827] and [RFC3704] [RFC3704]) or through Unicast Reverse-Path-Forwarding Reverse Path Forwarding
   (uRPF) checks [RFC5635].

   The guidelines in Section 4 of [RFC6343] remain valid for those who
   choose to continue operating Anycast anycast 6to4 despite its deprecation.

   Current operators of an anycast 6to4 relay with the IPv4 address
   192.88.99.1 SHOULD review the information in [RFC6343] and the
   present document, and then consider carefully whether the anycast
   relay can be discontinued as traffic diminishes.  Internet service
   providers that do not operate an anycast relay but do provide their
   customers with a route to 192.88.99.1 SHOULD verify that it does in
   fact lead to an operational anycast relay, as discussed in
   Section 4.2.1 of [RFC6343].  Furthermore, Internet service providers
   and other network providers MUST NOT originate a route to
   192.88.99.1, unless they actively operate and monitor an anycast 6to4
   relay service as detailed in Section 4.2.1 of [RFC6343].

   Operators of a 6to4 return relay responding to the IPv6 prefix
   2002::/16 SHOULD review the information in [RFC6343] and the present
   document, and then consider carefully whether the return relay can be
   discontinued as traffic diminishes.  To avoid confusion, note that
   nothing in the design of 6to4 assumes or requires that return packets
   are handled by the same relay as outbound packets.  As discussed in
   Section 4.5 of RFC 6343, content providers might choose to continue
   operating a return relay for the benefit of their own residual 6to4
   clients.  Internet service providers SHOULD announce the IPv6 prefix
   2002::/16 to their own customers if and only if it leads to a
   correctly operating return relay as described in RFC 6343.  IPv6-only
   service providers, including those operating a NAT64 service
   [RFC6146], are advised that their own customers need a route to such
   a relay in case a residual 6to4 user served by a different service
   provider attempts to communicate with them.

   Operators of 6to4 "6to4 Provider Managed Tunnels Tunnels" [RFC6732] SHOULD
   carefully consider when this service can be discontinued as traffic
   diminishes.

7.  IANA Considerations

   The document creating the IANA "IANA IPv4 Special-Purpose Address Registry
   Registry" [RFC6890] included the 6to4 relay anycast Relay Anycast prefix
   (192.88.99.0/24) as Table 10.  Instead,  Per this document, IANA is requested to mark has marked the
   192.88.99.0/24 prefix originally (originally defined by [RFC3068] [RFC3068]) as
   "Deprecated (6to4 Relay
   Anycast)", pointing Anycast)" and added a reference to this RFC.
   The Boolean values for the present document. address block 192.88.99.0/24 have been
   removed.  Redelegation of this prefix for any usage use requires
   justification via an IETF Standards Action [RFC5226].

8.  Security Considerations

   There are no new security considerations pertaining to this document.
   General security issues with tunnels are listed in [RFC6169] and more
   specifically to 6to4 in [RFC3964] and [RFC6324].

10.

9.  References

10.1.

9.1.  Normative References

   [RFC2026]  Bradner, S., "The Internet Standards Process -- Revision
              3", BCP 9, RFC 2026, October 1996. 1996,
              <http://www.rfc-editor.org/info/rfc2026>.

   [RFC2119]  Bradner, S., "Key words for use in RFCs to Indicate
              Requirement Levels", BCP 14, RFC 2119, March 1997. 1997,
              <http://www.rfc-editor.org/info/rfc2119>.

   [RFC2827]  Ferguson, P. and D. Senie, "Network Ingress Filtering:
              Defeating Denial of Service Attacks which employ IP Source
              Address Spoofing", BCP 38, RFC 2827, May 2000. 2000,
              <http://www.rfc-editor.org/info/rfc2827>.

   [RFC3056]  Carpenter, B. and K. Moore, "Connection of IPv6 Domains
              via IPv4 Clouds", RFC 3056, February 2001. 2001,
              <http://www.rfc-editor.org/info/rfc3056>.

   [RFC3068]  Huitema, C., "An Anycast Prefix for 6to4 Relay Routers",
              RFC 3068, June 2001. 2001,
              <http://www.rfc-editor.org/info/rfc3068>.

   [RFC3704]  Baker, F. and P. Savola, "Ingress Filtering for Multihomed
              Networks", BCP 84, RFC 3704, March 2004. 2004,
              <http://www.rfc-editor.org/info/rfc3704>.

   [RFC5226]  Narten, T. and H. Alvestrand, "Guidelines for Writing an
              IANA Considerations Section in RFCs", BCP 26, RFC 5226,
              May 2008. 2008, <http://www.rfc-editor.org/info/rfc5226>.

   [RFC6146]  Bagnulo, M., Matthews, P., and I. van Beijnum, "Stateful
              NAT64: Network Address and Protocol Translation from IPv6
              Clients to IPv4 Servers", RFC 6146, April 2011. 2011,
              <http://www.rfc-editor.org/info/rfc6146>.

   [RFC6724]  Thaler, D., Ed., Draves, R., Matsumoto, A., and T. Chown,
              "Default Address Selection for Internet Protocol Version 6
              (IPv6)", RFC 6724, September 2012. 2012,
              <http://www.rfc-editor.org/info/rfc6724>.

   [RFC6890]  Cotton, M., Vegoda, L., Bonica, R., Ed., and B. Haberman,
              "Special-Purpose IP Address Registries", BCP 153, RFC
              6890, April 2013.

10.2. 2013,
              <http://www.rfc-editor.org/info/rfc6890>.

9.2.  Informative References

   [HUSTON]   Huston, , G., "Flailing IPv6", The ISP Column, December
              2010,
              <http://www.potaroo.net/ispcol/2010-12/6to4fail.html>.

   [RFC3484]  Draves, R., "Default Address Selection for Internet
              Protocol version 6 (IPv6)", RFC 3484, February 2003. 2003,
              <http://www.rfc-editor.org/info/rfc3484>.

   [RFC3964]  Savola, P. and C. Patel, "Security Considerations for
              6to4", RFC 3964, December 2004. 2004,
              <http://www.rfc-editor.org/info/rfc3964>.

   [RFC5635]  Kumari, W. and D. McPherson, "Remote Triggered Black Hole
              Filtering with Unicast Reverse Path Forwarding (uRPF)",
              RFC 5635, August 2009. 2009,
              <http://www.rfc-editor.org/info/rfc5635>.

   [RFC5969]  Townsley, W. and O. Troan, "IPv6 Rapid Deployment on IPv4
              Infrastructures (6rd) -- Protocol Specification", RFC
              5969, August 2010. 2010,
              <http://www.rfc-editor.org/info/rfc5969>.

   [RFC6169]  Krishnan, S., Thaler, D., and J. Hoagland, "Security
              Concerns with IP Tunneling", RFC 6169, April 2011. 2011,
              <http://www.rfc-editor.org/info/rfc6169>.

   [RFC6324]  Nakibly, G. and F. Templin, "Routing Loop Attack Using
              IPv6 Automatic Tunnels: Problem Statement and Proposed
              Mitigations", RFC 6324, August 2011. 2011,
              <http://www.rfc-editor.org/info/rfc6324>.

   [RFC6343]  Carpenter, B., "Advisory Guidelines for 6to4 Deployment",
              RFC 6343, August 2011. 2011,
              <http://www.rfc-editor.org/info/rfc6343>.

   [RFC6555]  Wing, D. and A. Yourtchenko, "Happy Eyeballs: Success with
              Dual-Stack Hosts", RFC 6555, April 2012. 2012,
              <http://www.rfc-editor.org/info/rfc6555>.

   [RFC6732]  Kuarsingh, V., Ed., Lee, Y., and O. Vautrin, "6to4
              Provider Managed Tunnels", RFC 6732, September 2012.

9. 2012,
              <http://www.rfc-editor.org/info/rfc6732>.

Acknowledgements

   The authors would like to acknowledge Tore Anderson, Mark Andrews,
   Dmitry Anipko, Jack Bates, Cameron Byrne, Ben Campbell, Lorenzo
   Colitti, Gert Doering, Nick Hilliard, Philip Homburg, Ray Hunter,
   Joel Jaeggli, Victor Kuarsingh, Kurt Erik Lindqvist, Jason Livingood,
   Jeroen Massar, Keith Moore, Tom Petch, Daniel Roesen, Mark Townsley Townsley,
   and James Woodyatt for their contributions and discussions on this
   topic.

   Special thanks go to Fred Baker, David Farmer, Wes George, and Geoff
   Huston for their significant contributions.

   Many thanks to Gunter Van de Velde for documenting the harm caused by
   non-managed tunnels and stimulating the creation of this document.

Authors' Addresses

   Ole Troan
   Cisco
   Oslo
   Norway

   Email:

   EMail: ot@cisco.com

   Brian Carpenter (editor)
   Department of Computer Science
   University of Auckland
   PB 92019
   Auckland  1142
   New Zealand

   Email:

   EMail: brian.e.carpenter@gmail.com