4over6 Transit Solution Using IP Encapsulation and MP-BGP Extensions
RFC 5747

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Independent Submission                                             J. Wu
Request for Comments: 5747                                        Y. Cui
Category: Experimental                                             X. Li
ISSN: 2070-1721                                                    M. Xu
                                                     Tsinghua University
                                                                 C. Metz
                                                     Cisco Systems, Inc.
                                                              March 2010

  4over6 Transit Solution Using IP Encapsulation and MP-BGP Extensions

Abstract

   The emerging and growing deployment of IPv6 networks will introduce
   cases where connectivity with IPv4 networks crossing IPv6 transit
   backbones is desired.  This document describes a mechanism for
   automatic discovery and creation of IPv4-over-IPv6 tunnels via
   extensions to multiprotocol BGP.  It is targeted at connecting
   islands of IPv4 networks across an IPv6-only backbone without the
   need for a manually configured overlay of tunnels.  The mechanisms
   described in this document have been implemented, tested, and
   deployed on the large research IPv6 network in China.

Status of This Memo

   This document is not an Internet Standards Track specification; it is
   published for examination, experimental implementation, and
   evaluation.

   This document defines an Experimental Protocol for the Internet
   community.  This is a contribution to the RFC Series, independently
   of any other RFC stream.  The RFC Editor has chosen to publish this
   document at its discretion and makes no statement about its value for
   implementation or deployment.  Documents approved for publication by
   the RFC Editor 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/rfc5747.

IESG Note

   The mechanisms and techniques described in this document are related
   to specifications developed by the IETF softwire working group and
   published as Standards Track documents by the IETF, but the
   relationship does not prevent publication of this document.

Wu, et al.                    Experimental                      [Page 1]
RFC 5747                         4over6                       March 2010

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.

Table of Contents

   1. Introduction ....................................................3
   2. 4over6 Framework Overview .......................................3
   3. Prototype Implementation ........................................5
      3.1. 4over6 Packet Forwarding ...................................5
      3.2. Encapsulation Table ........................................6
      3.3. MP-BGP 4over6 Protocol Extensions ..........................7
           3.3.1. Receiving Routing Information from Local CE .........8
           3.3.2. Receiving 4over6 Routing Information from a
                  Remote 4over6 PE ....................................8
   4. 4over6 Deployment Experience ....................................9
      4.1. CNGI-CERNET2 ...............................................9
      4.2. 4over6 Testbed on the CNGI-CERNET2 IPv6 Network ............9
      4.3. Deployment Experiences ....................................10
   5. Ongoing Experiment .............................................11
   6. Relationship to Softwire Mesh Effort ...........................12
   7. IANA Considerations ............................................12
   8. Security Considerations ........................................13
   9. Conclusion .....................................................13
   10. Acknowledgements ..............................................13
   11. Normative References ..........................................14

Wu, et al.                    Experimental                      [Page 2]
RFC 5747                         4over6                       March 2010

1.  Introduction

   Due to the lack of IPv4 address space, more and more IPv6 networks
   have been deployed not only on edge networks but also on backbone
   networks.  However, there are still a large number of legacy IPv4
   hosts and applications.  As a result, IPv6 networks and IPv4
   applications/hosts will have to coexist for a long period of time.

   The emerging and growing deployment of IPv6 networks will introduce