Softwire Problem Statement
RFC 4925

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• 03

Network Working Group                                         X. Li, Ed.
Request for Comments: 4925                                        CERNET
Category: Informational                                  S. Dawkins, Ed.
                                                                  Huawei
                                                            D. Ward, Ed.
                                                           Cisco Systems
                                                          A. Durand, Ed.
                                                                 Comcast
                                                               July 2007

                       Softwire Problem Statement

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.

Copyright Notice

   Copyright (C) The IETF Trust (2007).

Abstract

   This document captures the problem statement for the Softwires
   Working Group, which is developing standards for the discovery,
   control, and encapsulation methods for connecting IPv4 networks
   across IPv6-only networks as well as IPv6 networks across IPv4-only
   networks.  The standards will encourage multiple, inter-operable
   vendor implementations by identifying, and extending where necessary,
   existing standard protocols to resolve a selected set of "IPv4/IPv6"
   and "IPv6/IPv4" transition problems.  This document describes the
   specific problems ("Hubs and Spokes" and "Mesh") that will be solved
   by the standards developed by the Softwires Working Group.  Some
   requirements (and non-requirements) are also identified to better
   describe the specific problem scope.

Li, et al.                   Informational                      [Page 1]
RFC 4925               Softwire Problem Statement              July 2007

Table of Contents

   1.  Introduction . . . . . . . . . . . . . . . . . . . . . . . . .  3
     1.1.  Terminology  . . . . . . . . . . . . . . . . . . . . . . .  4
   2.  Hubs and Spokes Problem  . . . . . . . . . . . . . . . . . . .  6
     2.1.  Description  . . . . . . . . . . . . . . . . . . . . . . .  8
     2.2.  Non-Upgradable CPE Router  . . . . . . . . . . . . . . . .  9
     2.3.  Network Address Translation (NAT) and Port Address
           Translation (PAT)  . . . . . . . . . . . . . . . . . . . . 10
     2.4.  Static Prefix Delegation . . . . . . . . . . . . . . . . . 10
     2.5.  Softwire Initiator . . . . . . . . . . . . . . . . . . . . 11
     2.6.  Softwire Concentrator  . . . . . . . . . . . . . . . . . . 11
     2.7.  Softwire Concentrator Discovery  . . . . . . . . . . . . . 12
     2.8.  Scaling  . . . . . . . . . . . . . . . . . . . . . . . . . 12
     2.9.  Routing  . . . . . . . . . . . . . . . . . . . . . . . . . 12
     2.10. Multicast  . . . . . . . . . . . . . . . . . . . . . . . . 12
     2.11. Security . . . . . . . . . . . . . . . . . . . . . . . . . 12
       2.11.1.  Authentication, Authorization, and Accounting
                (AAA) . . . . . . . . . . . . . . . . . . . . . . . . 12
       2.11.2.  Privacy, Integrity, and Replay Protection . . . . . . 13
     2.12. Operations and Management (OAM)  . . . . . . . . . . . . . 13
     2.13. Encapsulations . . . . . . . . . . . . . . . . . . . . . . 13
   3.  Mesh Problem . . . . . . . . . . . . . . . . . . . . . . . . . 14
     3.1.  Description  . . . . . . . . . . . . . . . . . . . . . . . 14
     3.2.  Scaling  . . . . . . . . . . . . . . . . . . . . . . . . . 16
     3.3.  Persistence, Discovery, and Setup Time . . . . . . . . . . 16
     3.4.  Multicast  . . . . . . . . . . . . . . . . . . . . . . . . 17
     3.5.  Softwire Encapsulation . . . . . . . . . . . . . . . . . . 17
     3.6.  Security . . . . . . . . . . . . . . . . . . . . . . . . . 17
   4.  Security Considerations  . . . . . . . . . . . . . . . . . . . 18
   5.  Principal Authors  . . . . . . . . . . . . . . . . . . . . . . 18
   6.  Contributors . . . . . . . . . . . . . . . . . . . . . . . . . 19
   7.  References . . . . . . . . . . . . . . . . . . . . . . . . . . 20
     7.1.  Normative References . . . . . . . . . . . . . . . . . . . 20
     7.2.  Informative References . . . . . . . . . . . . . . . . . . 20

Li, et al.                   Informational                      [Page 2]
RFC 4925               Softwire Problem Statement              July 2007

1.  Introduction

   The Softwires Working Group is specifying the standardization of
   discovery, control, and encapsulation methods for connecting IPv4
   networks across IPv6-only networks and IPv6 networks across IPv4-only
   networks in a way that will encourage multiple, inter-operable vendor
   implementations.  This document describes the specific problems
   ("Hubs and Spokes" and "Mesh") that will be solved by the standards
   developed by the Softwires Working Group.  Some requirements (and