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Internet Engineering Task Force                                W. George
Internet-Draft                                                 L. Howard
Intended status: Best Current Practice                 Time Warner Cable
Expires: April 3, 2015                                September 30, 2014

                     IPv6 Support Within IETF work


   This document recommends that the IETF formally require its standards
   work to be IP version agnostic or to explicitly include support for
   IPv6, with some exceptions, to ensure that it is possible to operate
   without dependencies on IPv4.

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 documents of the Internet Engineering
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   This Internet-Draft will expire on April 3, 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
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Table of Contents

   1.  Introduction  . . . . . . . . . . . . . . . . . . . . . . . .   2
     1.1.  Requirements Language . . . . . . . . . . . . . . . . . .   3
   2.  IPv6-only operation . . . . . . . . . . . . . . . . . . . . .   3
     2.1.  Functional Parity with IPv4 . . . . . . . . . . . . . . .   3
     2.2.  IPv4 Sunset . . . . . . . . . . . . . . . . . . . . . . .   3
   3.  Requirements and Recommendations  . . . . . . . . . . . . . .   4
   4.  Acknowledgements  . . . . . . . . . . . . . . . . . . . . . .   5
   5.  IANA Considerations . . . . . . . . . . . . . . . . . . . . .   5
   6.  Security Considerations . . . . . . . . . . . . . . . . . . .   5
   7.  References  . . . . . . . . . . . . . . . . . . . . . . . . .   5
     7.1.  Normative References  . . . . . . . . . . . . . . . . . .   5
     7.2.  Informative References  . . . . . . . . . . . . . . . . .   5
   Authors' Addresses  . . . . . . . . . . . . . . . . . . . . . . .   5

1.  Introduction

   [RFC6540] gives guidance to implementers that in order to ensure
   interoperability and proper function after IPv4 exhaustion, IP-
   capable devices need to support IPv6, and cannot be reliant on IPv4,
   because global IPv4 exhaustion creates many circumstances where the
   use of IPv6 will no longer be optional.  Since this is an IETF Best
   Current Practice recommendation, it is imperative that the results of
   IETF efforts enable implementers to follow that recommendation.  This
   document provides recommendations and guidance as to how IETF itself
   should handle future work as it relates to Internet Protocol

   When considering support for IPv4 vs IPv6 within IETF work, the
   general goal is to provide tools that enable networks and
   applications to operate seamlessly in any combination of IPv4-only,
   dual-stack, or IPv6-only as their needs dictate.  However, as the
   IPv4 to IPv6 transition continues, it will become increasingly
   difficult to ensure interoperability and backward compatibility with
   IPv4-only networks and applications.  As IPv6 deployment grows, IETF
   will naturally focus on features and protocols that enhance and
   extend IPv6, along with continuing work on items that are IP version
   agnostic.  New features and protocols will not typically be
   introduced for use as IPv4-only.  However, as of this document's
   writing, there is no formal requirement for all IETF work to support
   IPv6, either implicitly by being network-layer agnostic or explicitly
   by having an IPv6-specific implementation.

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1.1.  Requirements Language

   The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
   document are to be interpreted as described in RFC 2119 [RFC2119].

2.  IPv6-only operation

   At this document's writing, IPv6 has seen significant deployment.
   Most of these deployments are dual-stack, with IPv4 and IPv6
   coexisting on the same networks.  However, dual-stack is a waypoint
   in the transition from IPv4 to IPv6.  The eventual end state is
   networks and end points that are IPv6-only.  Some operators may take
   a long time to turn off IPv4, if they ever do, but the IETF MUST
   ensure that its standards can be deployed by even the first operators
   to turn off IPv4.  Problems (and solutions) need to be identified
   before they are encountered by the earliest adopters.

2.1.  Functional Parity with IPv4

   In order for IPv6-only operation to be realistic, IPv6 MUST have at
   least functional parity with IPv4.  "Functional parity" means that
   any function that IPv4 enables MUST also be enabled by IPv6.  This
   does not mean that every feature that exists in IPv4 will exist in
   IPv6; different features may enable the same function.  For instance,
   IPv4 supports some features that are no longer in use.  In some cases
   it has not been practical to remove them in IPv4, or even to declare
   them historic, but it is unnecessary to carry them forward into IPv6.
   IPv6 also eliminates the need for some features that exist in IPv4;
   no effort to create unneeded features is required.  Functional parity
   does not mean that all functions in IPv6 must also be possible in
   IPv4.  Indeed, with IPv6 becoming the predominant protocol, new
   functionality should be developed in IPv6, and IETF effort SHOULD NOT
   be spent retrofitting features into the legacy protocol.

2.2.  IPv4 Sunset

   Somewhat distinct from identifying the needed features for IPv6-only
   functional parity is the effort to identify what is necessary to
   disable or sunset IPv4 in a given network.  Since many of the
   protocols in use today were designed to be fault-tolerant and very
   robust, actually removing them from a network once they are no longer
   needed is sometimes complex.  Many implementations may not even have
   "off switches" because the assumption was that they would never be
   switched off in a normal network implementation.  The Sunset4 Working
   Group was chartered to address these issues:

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   "The Working Group will point out specific areas of concern, provide
   recommendations, and standardize protocols that facilitate the
   graceful "sunsetting" of the IPv4 Internet in areas where IPv6 has
   been deployed.  This includes the act of shutting down IPv4 itself,
   as well as the ability of IPv6-only portions of the Internet to
   continue to connect with portions of the Internet that remain
   IPv4-only. ...  Disabling IPv4 in applications, hosts, and networks
   is new territory for much of the Internet today, and it is expected
   that problems will be uncovered including those related to basic IPv4
   functionality, interoperability, as well as potential security
   concerns.  The working group will report on common issues, provide
   recommendations, and, when necessary, protocol extensions in order to
   facilitate disabling IPv4 in networks where IPv6 has been deployed."

3.  Requirements and Recommendations

   Ongoing focus is required to ensure that future IETF work is capable
   of IPv6-only operation.  This attention may take the form of IESG
   evaluation, individual document reviews, or future WG charters.  Due
   to the existing operational base of IPv4, it is not realistic to
   completely bar further work on IPv4 within the IETF at this time, nor
   to formally declare it historic.  Until the time when IPv4 is no
   longer in wide use and/or declared historic, the IETF needs to
   continue to update IPv4-only protocols and features for vital
   operational or security issues.  Similarly, the IETF needs to
   complete the work related to IPv4-to-IPv6 transition tools for
   migrating more traffic to IPv6.  As the transition to IPv6-capable
   networks accelerates, it is also likely that some changes may be
   necessary in IPv4 protocols to facilitate decommissioning IPv4 in a
   way that does not create unacceptable impact to applications or
   users.  These sorts of IPv4-focused activities, in support of
   security, transition, and decommissioning, should continue,
   accompanied by problem statements based on operational experience.
   Generally the focus should move away from IPv4-only work.

      The IESG SHOULD review working group charters to ensure that work
      will be capable of operating without IPv4, except in cases of IPv4
      security, transition, and decommissioning work.

      IETF SHOULD make updates to IPv4 protocols and features to
      facilitate IPv4 decommissioning

      IETF work SHOULD explicitly support IPv6 or SHOULD be IP version
      agnostic (because it is implemented above the network layer),
      except IPv4-specific transition or address-sharing technologies.

      IETF SHOULD NOT initiate new IPv4 extension technology

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      IETF work SHOULD function completely on IPv6-only nodes and
      networks, unless consensus exists that it is unnecessary to use a
      given feature or protocol on IPv6-only networks.

      IETF SHOULD identify and update IPv4-only protocols and
      applications to support IPv6 unless consensus exists that it is
      unnecessary for a given feature or protocol.

4.  Acknowledgements

   Thanks to the following people for their comments: Jari Arkko, Ralph
   Droms, Scott Brim, Margaret Wasserman, Brian Haberman.  Thanks also
   to Randy Bush, Mark Townsley, and Dan Wing for their discussion in
   IntArea WG at IETF 81 in Taipei, TW regarding transition
   technologies, IPv4 life extension, and IPv6 support.

5.  IANA Considerations

   This memo includes no request to IANA.

6.  Security Considerations

   This document generates no new security considerations because it is
   not defining a new protocol.  As existing work is analyzed for its
   ability to operate properly on IPv6-only networks, new security
   issues may be identified.

7.  References

7.1.  Normative References

   [RFC2119]  Bradner, S., "Key words for use in RFCs to Indicate
              Requirement Levels", BCP 14, RFC 2119, March 1997.

7.2.  Informative References

   [RFC6540]  George, W., Donley, C., Liljenstolpe, C., and L. Howard,
              "IPv6 Support Required for All IP-Capable Nodes", BCP 177,
              RFC 6540, April 2012.

Authors' Addresses

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   Wesley George
   Time Warner Cable
   13820 Sunrise Valley Drive
   Herndon, VA  20171

   Phone: +1 703-561-2540
   Email: wesley.george@twcable.com

   Lee Howard
   Time Warner Cable
   13820 Sunrise Valley Drive
   Herndon, VA  20171

   Phone: +1-703-345-3513
   Email: lee.howard@twcable.com

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