IAB Thoughts on IPv6 Network Address Translation
RFC 5902

Document Type RFC - Informational (July 2010; No errata)
Last updated 2015-11-11
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Internet Architecture Board (IAB)                              D. Thaler
Request for Comments: 5902                                      L. Zhang
Category: Informational                                      G. Lebovitz
ISSN: 2070-1721                                                July 2010

            IAB Thoughts on IPv6 Network Address Translation

Abstract

   There has been much recent discussion on the topic of whether the
   IETF should develop standards for IPv6 Network Address Translators
   (NATs).  This document articulates the architectural issues raised by
   IPv6 NATs, the pros and cons of having IPv6 NATs, and provides the
   IAB's thoughts on the current open issues and the solution space.

Status of This Memo

   This document is not an Internet Standards Track specification; it is
   published for informational purposes.

   This document is a product of the Internet Architecture Board (IAB)
   and represents information that the IAB has deemed valuable to
   provide for permanent record.  Documents approved for publication by
   the IAB are not a candidate for any level of Internet Standard; see
   Section 2 of RFC 5741.

   Information about the current status of this document, any errata,
   and how to provide feedback on it may be obtained at
   http://www.rfc-editor.org/info/rfc5902.

Copyright Notice

   Copyright (c) 2010 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.

Thaler, et al.                Informational                     [Page 1]
RFC 5902                 IPv6 NAT Considerations               July 2010

Table of Contents

   1.  Introduction . . . . . . . . . . . . . . . . . . . . . . . . .  2
   2.  What is the problem? . . . . . . . . . . . . . . . . . . . . .  3
     2.1.  Avoiding Renumbering . . . . . . . . . . . . . . . . . . .  3
     2.2.  Site Multihoming . . . . . . . . . . . . . . . . . . . . .  4
     2.3.  Homogenous Edge Network Configurations . . . . . . . . . .  4
     2.4.  Network Obfuscation  . . . . . . . . . . . . . . . . . . .  5
       2.4.1.  Hiding Hosts . . . . . . . . . . . . . . . . . . . . .  5
       2.4.2.  Topology Hiding  . . . . . . . . . . . . . . . . . . .  8
       2.4.3.  Summary Regarding NAT as a Tool for Network
               Obfuscation  . . . . . . . . . . . . . . . . . . . . .  8
     2.5.  Simple Security  . . . . . . . . . . . . . . . . . . . . .  9
     2.6.  Discussion . . . . . . . . . . . . . . . . . . . . . . . .  9
   3.  Architectural Considerations of IPv6 NAT . . . . . . . . . . .  9
   4.  Solution Space . . . . . . . . . . . . . . . . . . . . . . . . 11
     4.1.  Discussion . . . . . . . . . . . . . . . . . . . . . . . . 12
   5.  Security Considerations  . . . . . . . . . . . . . . . . . . . 13
   6.  IAB Members at the Time of Approval  . . . . . . . . . . . . . 13
   7.  Informative References . . . . . . . . . . . . . . . . . . . . 14

1.  Introduction

   In the past, the IAB has published a number of documents relating to
   Internet transparency and the end-to-end principle, and other IETF
   documents have also touched on these issues as well.  These documents
   articulate the general principles on which the Internet architecture
   is based, as well as the core values that the Internet community
   seeks to protect going forward.  Most recently, RFC 4924 [RFC4924]
   reaffirms these principles and provides a review of the various
   documents in this area.

   Facing imminent IPv4 address space exhaustion, recently there have
   been increased efforts in IPv6 deployment.  However, since late 2008
   there have also been increased discussions about whether the IETF
   should standardize network address translation within IPv6.  People
   who are against standardizing IPv6 NAT argue that there is no
   fundamental need for IPv6 NAT, and that as IPv6 continues to roll
   out, the Internet should converge towards reinstallation of the end-
   to-end reachability that has been a key factor in the Internet's
   success.  On the other hand, people who are for IPv6 NAT believe that
   NAT vendors would provide IPv6 NAT implementations anyway as NAT can
   be a solution to a number of problems, and that the IETF should avoid
   repeating the same mistake as with IPv4 NAT, where the lack of
   protocol standards led to different IPv4 NAT implementations, making
   NAT traversal difficult.

Thaler, et al.                Informational                     [Page 2]
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