Softwire Mesh Framework
RFC 5565

Network Working Group                                              J. Wu
Request for Comments: 5565                                        Y. Cui
Category: Standards Track                            Tsinghua University
                                                                 C. Metz
                                                                E. Rosen
                                                     Cisco Systems, Inc.
                                                               June 2009

                        Softwire Mesh Framework

Status of This Memo

   This document specifies an Internet standards track protocol for the
   Internet community, and requests discussion and suggestions for
   improvements.  Please refer to the current edition of the "Internet
   Official Protocol Standards" (STD 1) for the standardization state
   and status of this protocol.  Distribution of this memo is unlimited.

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Wu, et al.                  Standards Track                     [Page 1]
RFC 5565                Softwire Mesh Framework                June 2009

Abstract

   The Internet needs to be able to handle both IPv4 and IPv6 packets.
   However, it is expected that some constituent networks of the
   Internet will be "single-protocol" networks.  One kind of single-
   protocol network can parse only IPv4 packets and can process only
   IPv4 routing information; another kind can parse only IPv6 packets
   and can process only IPv6 routing information.  It is nevertheless
   required that either kind of single-protocol network be able to
   provide transit service for the "other" protocol.  This is done by
   passing the "other kind" of routing information from one edge of the
   single-protocol network to the other, and by tunneling the "other
   kind" of data packet from one edge to the other.  The tunnels are
   known as "softwires".  This framework document explains how the
   routing information and the data packets of one protocol are passed
   through a single-protocol network of the other protocol.  The
   document is careful to specify when this can be done with existing
   technology and when it requires the development of new or modified
   technology.

Table of Contents

   1. Introduction ....................................................3
   2. Specification of Requirements ...................................6
   3. Scenarios of Interest ...........................................7
      3.1. IPv6-over-IPv4 Scenario ....................................7
      3.2. IPv4-over-IPv6 Scenario ....................................9
   4. General Principles of the Solution .............................10
      4.1. E-IP and I-IP .............................................10
      4.2. Routing ...................................................10
      4.3. Tunneled Forwarding .......................................11
   5. Distribution of Inter-AFBR Routing Information .................11
   6. Softwire Signaling .............................................13
   7. Choosing to Forward through a Softwire .........................15
   8. Selecting a Tunneling Technology ...............................15
   9. Selecting the Softwire for a Given Packet ......................16
   10. Softwire OAM and MIBs .........................................17
      10.1. Operations and Maintenance (OAM) .........................17
      10.2. MIBs .....................................................18
   11. Softwire Multicast ............................................18
      11.1. One-to-One Mappings ......................................18