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Versions: (draft-dionne-sunset4-v4gapanalysis) 00 01 02 03 04

Network Working Group                                         JP. Dionne
Internet-Draft                                              S. Perreault
Intended status: Informational                                  Viagenie
Expires: February 7, 2013                                        T. Tsou
                                               Huawei Technologies (USA)
                                                          August 6, 2012


                      Gap Analysis for IPv4 Sunset
                   draft-ietf-sunset4-gapanalysis-00

Abstract

   Sunsetting IPv4 refers to the process of turning off IPv4
   definitively.  It can be seen as the final phase of the migration to
   IPv6.  This memo analyses difficulties arising when sunsetting IPv4,
   and identifies the gaps resulting in additional work.

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
   Task Force (IETF).  Note that other groups may also distribute
   working documents as Internet-Drafts.  The list of current Internet-
   Drafts is at http://datatracker.ietf.org/drafts/current/.

   Internet-Drafts are draft documents valid for a maximum of six months
   and may be updated, replaced, or obsoleted by other documents at any
   time.  It is inappropriate to use Internet-Drafts as reference
   material or to cite them other than as "work in progress."

   This Internet-Draft will expire on February 7, 2013.

Copyright Notice

   Copyright (c) 2012 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
   (http://trustee.ietf.org/license-info) in effect on the date of
   publication of this document.  Please review these documents
   carefully, as they describe your rights and restrictions with respect
   to this document.  Code Components extracted from this document must
   include Simplified BSD License text as described in Section 4.e of
   the Trust Legal Provisions and are provided without warranty as



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   described in the Simplified BSD License.


Table of Contents

   1.  Introduction  . . . . . . . . . . . . . . . . . . . . . . . . . 3
   2.  Related Work  . . . . . . . . . . . . . . . . . . . . . . . . . 3
   3.  Remotely Disabling IPv4 . . . . . . . . . . . . . . . . . . . . 3
     3.1.  Indicating that IPv4 connectivity is unavailable  . . . . . 3
     3.2.  Disabling IPv4 in the LAN . . . . . . . . . . . . . . . . . 3
   4.  Client Connection Establishment Behavior  . . . . . . . . . . . 4
   5.  Disabling IPv4 in Operating System and Applications . . . . . . 5
   6.  IANA Considerations . . . . . . . . . . . . . . . . . . . . . . 5
   7.  Security Considerations . . . . . . . . . . . . . . . . . . . . 5
   8.  Acknowledgements  . . . . . . . . . . . . . . . . . . . . . . . 5
   9.  Informative References  . . . . . . . . . . . . . . . . . . . . 5
   Authors' Addresses  . . . . . . . . . . . . . . . . . . . . . . . . 7


































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1.  Introduction

   The final phase of the migration to IPv6 is the sunset of IPv4, that
   is turning off IPv4 definitively on the attached networks and on the
   upstream networks.

   Some current implementations behavior make it hard to sunset IPv4.
   Additionally, some new features could be added to IPv4 to make its
   sunsetting easier.  This document analyzes the current situation and
   proposes new work in this area.


2.  Related Work

   [RFC3789], [RFC3790],[RFC3791], [RFC3792], [RFC3793], [RFC3794],
   [RFC3795] and [RFC3796] contain surveys of IETF protocols with their
   IPv4 dependencies.


3.  Remotely Disabling IPv4

3.1.  Indicating that IPv4 connectivity is unavailable

   PROBLEM 1:  When an IPv4 node boots and requests an IPv4 address
               (e.g., using DHCP), it typically interprets the absence
               of a response as a failure condition even when it is not.

   PROBLEM 2:  Home router devices often identify themselves as default
               routers in DHCP responses that they send to requests
               coming from the LAN, even in the absence of IPv4
               connectivity on the WAN.

   One way to address these issues is to send a signal to an dual-stack
   node that IPv4 connectivity is unavailable.  Given that IPv4 shall be
   off, the message must be delivered through IPv6.

3.2.  Disabling IPv4 in the LAN

   PROBLEM 3:  IPv4-enabled hosts inside an IPv6-only LAN can auto-
               configure IPv4 addresses [RFC3927] and enable various
               protocols over IPv4 such as mDNS
               [I-D.cheshire-dnsext-multicastdns] and LLMNR [RFC4795].
               This can be undesirable for operational or security
               reasons, since in the absence of IPv4, no monitoring or
               logging of IPv4 will be in place.






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   PROBLEM 4:  IPv4 can be completely disabled on a link by filtering it
               on the L2 switching device.  However, this may not be
               possible in all cases or complex to deploy.  For example,
               an ISP is often not able to control the L2 switching
               device in the subscriber home network.

   One way to address these issues is to send a signal to an dual-stack
   node that auto-configuration of IPv4 addresses is undesirable, or
   that direct IPv4 communications between nodes on the same link should
   not take place.

   This problem was described in [RFC2563], which standardized a DHCP
   option to disable IPv4 address auto-configuration.  However, using
   this option requires running an IPv4 DHCP server, which is contrary
   to the goal of IPv4 sunsetting.  An equivalent way of signalling this
   over IPv6 is necessary,, using either Router Advertisements or
   DHCPv6.

   Furthermore, it could be useful to have L2 switches snoop this
   signalling and automatically start filtering IPv4 traffic as a
   consequence.

   Finally, it could be useful to publish guidelines on how to safely
   block IPv4 on an L2 switch.


4.  Client Connection Establishment Behavior

   PROBLEM 5:  Happy Eyeballs [RFC6555] refers to the multiple
               approaches to dual-stack client implementations that try
               to reduce connection setup delays by trying both IPv4 and
               IPv6 paths simultaneously.  Some implementations
               introduce delays which provide an advantage to IPv6,
               while others do not [Huston2012].  The latter will pick
               the fastest path, no matter whether it is over IPv4 or
               IPv6, directing more traffic over IPv4 than the other
               kind of implementations.  This can prove problematic in
               the context of IPv4 sunsetting, especially for Carrier-
               Grade NAT phasing out.

   PROBLEM 6:  getaddrinfo() [RFC3493] sends DNS queries for both A and
               AAAA records regardless of the state of IPv4 or IPv6
               availability.  The AI_ADDRCONFIG flag can be used to
               change this behavior, but it relies on programmers using
               the getaddrinfo() function to always pass this flag to
               the function.  The current situation is that in an IPv6-
               only environment, many useless A queries are made.




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   Recommendations on client connection establishment behavior that
   would facilitate IPv4 sunsetting is therefore appropriate.


5.  Disabling IPv4 in Operating System and Applications

   PROBLEM 7:  Completely disabling IPv4 at runtime often reveals
               implementation bugs.  Hard-coded dependencies on IPv4
               abound, such as on the 127.0.0.1 address assigned to the
               loopback interface.  It is therefore often operationally
               impossible to completely disable IPv4 on individual
               nodes.

   PROBLEM 8:  In an IPv6-only world, legacy IPv4 code in operating
               systems and applications incurs a maintenance overhead
               and can present security risks.

   It is possible to completely remove IPv4 support from an operating
   system as has been shown by the work of Bjoern Zeeb on FreeBSD.
   [Zeeb] Removing IPv4 support in the kernel revealed many IPv4
   dependencies in libraries and applications.

   It would be useful for the IETF to provide guidelines to programmers
   on how to avoid creating dependencies on IPv4, how to discover
   existing dependencies, and how to eliminate them.  Having programs
   and operating systems that behave well in an IPv6-only environment is
   a prerequisite for IPv4 sunsetting.


6.  IANA Considerations

   None.


7.  Security Considerations

   TODO


8.  Acknowledgements

   TODO


9.  Informative References

   [Huston2012]
              Huston, G. and G. Michaelson, "RIPE 64: Analysing Dual



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              Stack Behaviour and IPv6 Quality", April 2012.

   [I-D.cheshire-dnsext-multicastdns]
              Cheshire, S. and M. Krochmal, "Multicast DNS",
              draft-cheshire-dnsext-multicastdns-15 (work in progress),
              December 2011.

   [RFC2563]  Troll, R., "DHCP Option to Disable Stateless Auto-
              Configuration in IPv4 Clients", RFC 2563, May 1999.

   [RFC3493]  Gilligan, R., Thomson, S., Bound, J., McCann, J., and W.
              Stevens, "Basic Socket Interface Extensions for IPv6",
              RFC 3493, February 2003.

   [RFC3789]  Nesser, P. and A. Bergstrom, "Introduction to the Survey
              of IPv4 Addresses in Currently Deployed IETF Standards
              Track and Experimental Documents", RFC 3789, June 2004.

   [RFC3790]  Mickles, C. and P. Nesser, "Survey of IPv4 Addresses in
              Currently Deployed IETF Internet Area Standards Track and
              Experimental Documents", RFC 3790, June 2004.

   [RFC3791]  Olvera, C. and P. Nesser, "Survey of IPv4 Addresses in
              Currently Deployed IETF Routing Area Standards Track and
              Experimental Documents", RFC 3791, June 2004.

   [RFC3792]  Nesser, P. and A. Bergstrom, "Survey of IPv4 Addresses in
              Currently Deployed IETF Security Area Standards Track and
              Experimental Documents", RFC 3792, June 2004.

   [RFC3793]  Nesser, P. and A. Bergstrom, "Survey of IPv4 Addresses in
              Currently Deployed IETF Sub-IP Area Standards Track and
              Experimental Documents", RFC 3793, June 2004.

   [RFC3794]  Nesser, P. and A. Bergstrom, "Survey of IPv4 Addresses in
              Currently Deployed IETF Transport Area Standards Track and
              Experimental Documents", RFC 3794, June 2004.

   [RFC3795]  Sofia, R. and P. Nesser, "Survey of IPv4 Addresses in
              Currently Deployed IETF Application Area Standards Track
              and Experimental Documents", RFC 3795, June 2004.

   [RFC3796]  Nesser, P. and A. Bergstrom, "Survey of IPv4 Addresses in
              Currently Deployed IETF Operations & Management Area
              Standards Track and Experimental Documents", RFC 3796,
              June 2004.

   [RFC3927]  Cheshire, S., Aboba, B., and E. Guttman, "Dynamic



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              Configuration of IPv4 Link-Local Addresses", RFC 3927,
              May 2005.

   [RFC4795]  Aboba, B., Thaler, D., and L. Esibov, "Link-local
              Multicast Name Resolution (LLMNR)", RFC 4795,
              January 2007.

   [RFC6555]  Wing, D. and A. Yourtchenko, "Happy Eyeballs: Success with
              Dual-Stack Hosts", RFC 6555, April 2012.

   [Zeeb]     "FreeBSD Snapshots without IPv4 support",
              <http://wiki.freebsd.org/IPv6Only>.


Authors' Addresses

   Jean-Philippe Dionne
   Viagenie
   246 Aberdeen
   Quebec, QC  G1R 2E1
   Canada

   Phone: +1 418 656 9254
   Email: jean-philippe.dionne@viagenie.ca
   URI:   http://viagenie.ca


   Simon Perreault
   Viagenie
   246 Aberdeen
   Quebec, QC  G1R 2E1
   Canada

   Phone: +1 418 656 9254
   Email: simon.perreault@viagenie.ca
   URI:   http://viagenie.ca


   Tina Tsou
   Huawei Technologies (USA)
   2330 Central Expressway
   Santa Clara, CA  95050
   USA

   Phone: +1 408 330 4424
   Email: tina.tsou.zouting@huawei.com





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