Analysis of Solution Proposals for Hosts to Learn NAT64 Prefix
RFC 7051

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Internet Engineering Task Force (IETF)                  J. Korhonen, Ed.
Request for Comments: 7051                                      Broadcom
Category: Informational                               T. Savolainen, Ed.
ISSN: 2070-1721                                                    Nokia
                                                           November 2013

     Analysis of Solution Proposals for Hosts to Learn NAT64 Prefix

Abstract

   Hosts and applications may benefit from learning if an IPv6 address
   is synthesized and if NAT64 and DNS64 are present in a network.  This
   document analyzes all proposed solutions (known at the time of
   writing) for communicating whether the synthesis is taking place,
   what address format was used, and what IPv6 prefix was used by the
   NAT64 and DNS64.  These solutions enable both NAT64 avoidance and
   local IPv6 address synthesis.  The document concludes by recommending
   the standardization of the approach based on heuristic discovery.

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 Engineering Task Force
   (IETF).  It represents the consensus of the IETF community.  It has
   received public review and has been approved for publication by the
   Internet Engineering Steering Group (IESG).  Not all documents
   approved by the IESG are 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/rfc7051.

Korhonen & Savolainen         Informational                     [Page 1]
RFC 7051                  Learning NAT64 Prefix            November 2013

Copyright Notice

   Copyright (c) 2013 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
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   include Simplified BSD License text as described in Section 4.e of
   the Trust Legal Provisions and are provided without warranty as
   described in the Simplified BSD License.

Table of Contents

   1. Introduction ....................................................3
   2. Terminology .....................................................4
   3. Issues ..........................................................5
   4. Background ......................................................6
   5. Proposed Solutions to Learn about Synthesis and
      Network-Specific Prefix .........................................7
      5.1. DNS Query for a Well-Known Name ............................7
           5.1.1. Solution Description ................................7
           5.1.2. Analysis and Discussion .............................7
           5.1.3. Summary .............................................8
      5.2. EDNS0 Option Indicating AAAA Record Synthesis and Format ...8
           5.2.1. Solution Description ................................8
           5.2.2. Analysis and Discussion .............................9
           5.2.3. Summary ............................................10
      5.3. EDNS0 Flags Indicating AAAA Record Synthesis and Format ...10
           5.3.1. Solution Description ...............................10
           5.3.2. Analysis and Discussion ............................10
           5.3.3. Summary ............................................11
      5.4. DNS Resource Record for IPv4-Embedded IPv6 Address ........11
           5.4.1. Solution Description ...............................11
           5.4.2. Analysis and Discussion ............................12
           5.4.3. Summary ............................................12
      5.5. Learning the IPv6 Prefix of a Network's NAT64 Using DNS ...13
           5.5.1. Solution Description ...............................13
           5.5.2. Analysis and Discussion ............................13
           5.5.3. Summary ............................................14
      5.6. Learning the IPv6 Prefix of a Network's NAT64
           Using DHCPv6 ..............................................14
           5.6.1. Solution Description ...............................14
           5.6.2. Analysis and Discussion ............................15
           5.6.3. Summary ............................................15

Korhonen & Savolainen         Informational                     [Page 2]
RFC 7051                  Learning NAT64 Prefix            November 2013

      5.7. Learning the IPv6 Prefix of a Network's NAT64