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Network Working Group                                          J. CurranRequest for Comments: 5211                                     July 2008Category: InformationalAn Internet Transition PlanStatus 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.  SeeRFC 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 Contents1. Introduction ....................................................21.1. Requirements Language ......................................22. A Phased Transition Model .......................................22.1. Preparation Phase - Present to December 2009 ...............32.2. Transition Phase - January 2010 to December 2011 ...........42.3. Post-Transition Phase - January 2012 to the Future .........43. Summary .........................................................54. Security Considerations .........................................55. IANA Considerations .............................................56. Acknowledgments .................................................67. References ......................................................67.1. Normative References .......................................67.2. Informative References .....................................6Curran                       Informational                      [Page 1]

RFC 5211              An Internet Transition Plan              July 20081.  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   perRFC 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 inRFC 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.Curran                       Informational                      [Page 2]

RFC 5211              An Internet Transition Plan              July 2008   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.Curran                       Informational                      [Page 3]

RFC 5211              An Internet Transition Plan              July 2008   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.Curran                       Informational                      [Page 4]

RFC 5211              An Internet Transition Plan              July 2008   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 withCurran                       Informational                      [Page 5]

RFC 5211              An Internet Transition Plan              July 2008   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.  References7.1.  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",RFC1669, 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",RFC4057, June 2005.   [RFC3750]  Huitema, C., Austein, R., Satapati, S., and R. van der              Pol, "Unmanaged Networks IPv6 Transition Scenarios",RFC3750, April 2004.Curran                       Informational                      [Page 6]

RFC 5211              An Internet Transition Plan              July 2008   [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",RFC4942, September 2007.Author's Address   John Curran   99 Otis Street   Cambridge, MA USA 20190   EMail: jcurran@istaff.orgCurran                       Informational                      [Page 7]

RFC 5211              An Internet Transition Plan              July 2008Full Copyright Statement   Copyright (C) The IETF Trust (2008).   This document is subject to the rights, licenses and restrictions   contained inBCP 78 and athttp://www.rfc-editor.org/copyright.html,   and except as set forth therein, the authors retain all their rights.   This document and the information contained herein are provided on an   "AS IS" basis and THE CONTRIBUTOR, THE ORGANIZATION HE/SHE REPRESENTS   OR IS SPONSORED BY (IF ANY), THE INTERNET SOCIETY, THE IETF TRUST AND   THE INTERNET ENGINEERING TASK FORCE DISCLAIM ALL WARRANTIES, EXPRESS   OR IMPLIED, INCLUDING BUT NOT LIMITED TO ANY WARRANTY THAT THE USE OF   THE INFORMATION HEREIN WILL NOT INFRINGE ANY RIGHTS OR ANY IMPLIED   WARRANTIES OF MERCHANTABILITY OR FITNESS FOR A PARTICULAR PURPOSE.Intellectual Property   The IETF takes no position regarding the validity or scope of any   Intellectual Property Rights or other rights that might be claimed to   pertain to the implementation or use of the technology described in   this document or the extent to which any license under such rights   might or might not be available; nor does it represent that it has   made any independent effort to identify any such rights.  Information   on the procedures with respect to rights in RFC documents can be   found inBCP 78 andBCP 79.   Copies of IPR disclosures made to the IETF Secretariat and any   assurances of licenses to be made available, or the result of an   attempt made to obtain a general license or permission for the use of   such proprietary rights by implementers or users of this   specification can be obtained from the IETF on-line IPR repository athttp://www.ietf.org/ipr.   The IETF invites any interested party to bring to its attention any   copyrights, patents or patent applications, or other proprietary   rights that may cover technology that may be required to implement   this standard.  Please address the information to the IETF at   ietf-ipr@ietf.org.Curran                       Informational                      [Page 8]