





Network Working Group                                          J. Curran
Request for Comments: 5211                                     July 2008
Category: Informational


                      An Internet Transition Plan

Status of This Memo

   This memo provides information for the Internet community.  It does
   not specify an Internet standard of any kind.  Distribution of this
   memo is unlimited.

IESG Note

   This RFC is not a candidate for any level of Internet Standard.  The
   IETF disclaims any knowledge of the fitness of this RFC for any
   purpose and notes that the decision to publish is not based on IETF
   review apart from IESG review for conflict with IETF work.  RFC
   Editor has chosen to publish this document at its discretion.  See
   RFC 3932 for more information.

Abstract

   This memo provides one possible plan for transitioning the Internet
   from a predominantly IPv4-based connectivity model to a predominantly
   IPv6-based connectivity model.

Table of Contents

   1. Introduction ....................................................2
      1.1. Requirements Language ......................................2
   2. A Phased Transition Model .......................................2
      2.1. Preparation Phase - Present to December 2009 ...............3
      2.2. Transition Phase - January 2010 to December 2011 ...........4
      2.3. Post-Transition Phase - January 2012 to the Future .........4
   3. Summary .........................................................5
   4. Security Considerations .........................................5
   5. IANA Considerations .............................................5
   6. Acknowledgments .................................................6
   7. References ......................................................6
      7.1. Normative References .......................................6
      7.2. Informative References .....................................6








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1.  Introduction

   This memo provides one possible plan for transitioning the Internet
   from a predominantly IPv4-based connectivity model to a predominantly
   IPv6-based connectivity model.

   Other transition plans are possible and this purely informational
   document does not create an obligation on any party to undertake any
   of the actions specified herein, and the use of requirements language
   per RFC 2119 is only for the purpose of clearly describing the
   proposed transition plan in unambiguous terms.

   The motivation for an Internet-wide transition plan is to facilitate
   coordination of expectations among innumerable, highly decentralized
   entities during a period of significant change, thus reducing risk to
   the defining Internet property of universal connectivity.

   The purpose of specifying this particular transition plan is to allow
   for overall assessment of the challenges of accomplishing the desired
   transition and to continue the discussion of Internet-wide transition
   plans in general.

1.1.  Requirements Language

   The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
   "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this
   document are to be interpreted as described in RFC 2119 [RFC2119].
   RFC 2119 defines the use of these key words to help make the intent
   of Standards Track documents as clear as possible.  While not a
   Standards Track document, the same key words are used in this
   document only for sake of clarity in describing the proposed
   transition plan.

2.  A Phased Transition Model

   It is not reasonable to specify the changes that each and every
   system connected to the Internet must undergo in order to achieve the
   desired transition, as the number of connected systems precludes
   creating one plan that contains such a level of detail.  Further,
   while there are common scenarios that may be specified for
   transitioning individual networks (refer to [RFC3750] and [RFC4057]
   for examples), the specific timeline and mechanisms utilized for a
   given network will be unique.  Despite these challenges, it is
   necessary to coordinate expectations on an overall basis so that
   Internet-wide connectivity is maintained throughout the transition.






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   This document specifies a three-phase transition plan that includes
   preparation, transition, and post-transition phases, and delineates
   the necessary activities within each phase based on the role that an
   organization plays in the provision and use of Internet services.

   An important distinction made in this transition plan is identifying
   the explicit requirement for existing end-site organizations to add
   IPv6-based connectivity to their public-facing servers during a
   transition phase.  An accelerated adoption of IPv6 for public-facing
   servers enables new organizations in the post-transition phase to be
   connected to the Internet only via IPv6 and still have access to a
   substantial representative base of publicly available servers.

   For nearly every organization, the task of IPv6-enabling their
   public-facing servers is far easier than undertaking an
   organization-wide adoption of IPv6.  Still, the requirement for
   existing Internet-connected organizations to add IPv6 connectivity
   (even to a small number of systems) will be a significant hurdle and
   require a level of effort that may not be achievable given the lack
   of compelling additional benefits to these organizations [RFC1669].
   This transition plan presumes that "connectivity is its own reward"
   [RFC1958] and that there still exists a sufficient level of
   cooperation among Internet participants to make this evolution
   possible.

   The three proposed phases are: Preparation Phase, Transition Phase,
   and Post-Transition Phase.  The timeline for the phases has been set
   to allow entry to the Post-Transition Phase prior to the projected
   IPv4 address pool exhaustion date [IPUSAGE].

2.1.  Preparation Phase - Present to December 2009

   In the Preparation Phase, Service Providers pilot test their IPv6
   network services, and end-site organizations prepare to provide
   Internet-facing services via IPv6-based connectivity while continuing
   to provide Internet-facing services via IPv4 connectivity.

   During the Preparation Phase, the following principles apply:

   PREP1: Service Providers SHOULD offer pilot IPv6-based Internet
          Service to their Internet customers.  IPv6-based Internet
          Service MAY be provided via IPv6 transition mechanisms (such
          as those described in [RFC4213], for example) or via native
          IPv6 network service.







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   PREP2: Organizations SHOULD arrange for IPv6-based Internet
          connectivity for any Internet-facing servers (e.g., web,
          email, and domain name servers).  Internet-facing IPv6 servers
          in this phase SHOULD use separate service names per [RFC4472]
          to avoid impact to production IPv4-based services unless the
          organization supports production IPv6 connectivity.

   PREP3: Organizations MAY provide IPv6-based Internet connectivity to
          internal user communities.

2.2.  Transition Phase - January 2010 to December 2011

   In the Transition Phase, Service Providers offer production IPv6 and
   IPv4 services to their Internet customers.  End-site organizations
   provide Internet-facing services in a production manner via IPv6-
   based connectivity in addition to IPv4-based connectivity.

   During the Transition Phase, the following principles apply:

   TRANS1: Service Providers MUST offer IPv6-based Internet Service to
           their Internet customers.  IPv6-based Internet Service SHOULD
           be via native IPv6 network service but MAY be via IPv6
           transition mechanisms if necessary.

   TRANS2: Organizations MUST arrange for IPv6-based Internet
           connectivity for any Internet-facing servers (e.g., web,
           email, and domain name servers).  Internet-facing IPv6
           servers SHOULD be treated as production by the organization,
           and SHOULD be treated as production by other Internet
           organizations.

   TRANS3: Organizations SHOULD provide IPv6-based Internet connectivity
           to their internal user communities, and provide IPv6 internal
           supporting servers (e.g., DNS, DHCP).  IPv6-based Internet
           connectivity MAY be via native IPv6 network service or MAY be
           via IPv6 transition mechanisms.

2.3.  Post-Transition Phase - January 2012 to the Future

   In the Post-Transition Phase, end-site organizations provide all
   Internet-facing services via IPv6-based connectivity, thus allowing
   for new Internet customers connected solely by IPv6.

   During the Post-Transition Phase, the following principles apply:

   POST1: Service Providers MUST offer IPv6-based Internet Service to
          their Internet customers.  IPv6-based Internet Service SHOULD
          be via native IPv6 network service.



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   POST2: Organizations MUST arrange for IPv6-based Internet
          connectivity for any Internet-facing servers (e.g., web,
          email, and domain name servers).  Internet-facing IPv6 servers
          MUST be treated as production by the organization, and SHOULD
          be treated as production by other Internet organizations.

   POST3: Organizations SHOULD provide IPv6-based Internet connectivity
          to internal user communities, and provide IPv6 internal
          supporting infrastructure (e.g., routers, DNS, DHCP, etc).
          IPv6-based Internet connectivity SHOULD be via native IPv6
          network service or MAY be via IPv6 transition mechanisms.

   POST4: Service Providers MAY continue to offer IPv4-based Internet
          connectivity to their Internet customers.  Organizations MAY
          continue to use IPv4-based Internet connectivity.

3.  Summary

   In order to facilitate full Internet-wide connectivity during the
   transition from IPv4-based connectivity to IPv6-based connectivity, a
   transition plan which provides clear guidance to organizations
   regarding expectations is necessary.  As the specific expectations
   change over time, and vary greatly by organization, a phased approach
   is specified in this document, with the timeline for each phase set
   with the intention of allowing enough time for the necessary planning
   and deployment steps which each organization much undertake.  This
   Internet Transition Plan provides for transition to predominantly
   IPv6-connectivity by January 2012 which, with careful management, may
   meet the overall requirements of allowing the Internet to scale as
   specified in "The Recommendation for the IP Next Generation Protocol"
   [RFC1752].

4.  Security Considerations

   This memo describes the transition of the Internet from IPv4-based
   connectivity to predominantly IPv6-based connectivity.  This change
   inherently has security implications due to the widespread deployment
   of a new version of the Internet Protocol but these are beyond the
   scope of this document and are covered in [RFC4942].  This document
   raises no new security issues itself.

5.  IANA Considerations

   While no new name or identifier space is created by this document,
   the policies for management of Internet Protocol version 4 (IPv4)
   address space may not provide for IPv4 availability through the
   Transition Phase as intended by this plan.  The IANA should work with




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   all parties to develop policies per [RFC2050] which allow continued
   general availability of IPv4 address resources sufficiently long for
   any transition plan that receives widespread community support.

6.  Acknowledgments

   This document would not have been possible without the abundant
   suggestions made by members of the Internet community at large, but
   specific thanks go to Fred Baker, Jim Bound, Scott Bradner, Bob
   Braden, Randy Bush, David Divins, Geoff Huston, Chris Morrow, Jordi
   Palet, Ken Shores, James Woodyatt, and the members of the IETF V6
   Operations Working Group for their review and insightful suggestions
   for improvement.

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.

   [RFC4213]  Nordmark, E. and R. Gilligan, "Basic Transition Mechanisms
              for IPv6 Hosts and Routers", RFC 4213, October 2005.

   [RFC4472]  Durand, A., Ihren, J., and P. Savola, "Operational
              Considerations and Issues with IPv6 DNS", RFC 4472, April
              2006.

   [RFC1752]  Bradner, S. and A. Mankin, "The Recommendation for the IP
              Next Generation Protocol", RFC 1752, January 1995.

7.2.  Informative References

   [RFC1958]  Carpenter, B., Ed., "Architectural Principles of the
              Internet", RFC 1958, June 1996.

   [RFC1669]  Curran, J., "Market Viability as a IPng Criteria", RFC
              1669, August 1994.

   [IPUSAGE]  Huston, G., IPv4 Address Report, February 2008,
              <http://www.potaroo.net/tools/ipv4/index.html>.

   [RFC4057]  Bound, J., Ed., "IPv6 Enterprise Network Scenarios", RFC
              4057, June 2005.

   [RFC3750]  Huitema, C., Austein, R., Satapati, S., and R. van der
              Pol, "Unmanaged Networks IPv6 Transition Scenarios", RFC
              3750, April 2004.



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   [RFC2050]  Hubbard, K., Kosters, M., Conrad, D., Karrenberg, D., and
              J. Postel, "Internet Registry IP Allocation Guidelines",
              BCP 12, RFC 2050, November 1996.

   [RFC4942]  Davies, E., Krishnan, S., and P. Savola, "IPv6
              Transition/Co-existence Security Considerations", RFC
              4942, September 2007.

Author's Address

   John Curran
   99 Otis Street
   Cambridge, MA USA 20190

   EMail: jcurran@istaff.org




































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