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Connecting IPv6 Islands over IPv4 MPLS Using IPv6 Provider Edge Routers (6PE)
RFC 4798

Network Working Group                                       J. De Clercq
Request for Comments: 4798                                Alcatel-Lucent
Category: Standards Track                                        D. Ooms
                                                              OneSparrow
                                                              S. Prevost
                                                                      BT
                                                          F. Le Faucheur
                                                                   Cisco
                                                           February 2007

             Connecting IPv6 Islands over IPv4 MPLS Using
                    IPv6 Provider Edge Routers (6PE)

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.

Copyright Notice

   Copyright (C) The IETF Trust (2007).

Abstract

   This document explains how to interconnect IPv6 islands over a
   Multiprotocol Label Switching (MPLS)-enabled IPv4 cloud.  This
   approach relies on IPv6 Provider Edge routers (6PE), which are Dual
   Stack in order to connect to IPv6 islands and to the MPLS core, which
   is only required to run IPv4 MPLS.  The 6PE routers exchange the IPv6
   reachability information transparently over the core using the
   Multiprotocol Border Gateway Protocol (MP-BGP) over IPv4.  In doing
   so, the BGP Next Hop field is used to convey the IPv4 address of the
   6PE router so that dynamically established IPv4-signaled MPLS Label
   Switched Paths (LSPs) can be used without explicit tunnel
   configuration.

De Clercq, et al.           Standards Track                     [Page 1]
RFC 4798                          6PE                      February 2007

Table of Contents

   1. Introduction ....................................................2
      1.1. Requirements Language ......................................4
   2. Protocol Overview ...............................................4
   3. Transport over IPv4-signaled LSPs and IPv6 Label Binding ........5
   4. Crossing Multiple IPv4 Autonomous Systems .......................7
   5. Security Considerations ........................................10
   6. Acknowledgements ...............................................10
   7. References .....................................................11
      7.1. Normative References ......................................11
      7.2. Informative References ....................................11

1.  Introduction

   There are several approaches for providing IPv6 connectivity over an
   MPLS core network [RFC4029] including (i) requiring that MPLS
   networks support setting up IPv6-signaled Label Switched Paths (LSPs)
   and establish IPv6 connectivity by using those LSPs, (ii) use
   configured tunneling over IPv4-signaled LSPs, or (iii) use the IPv6
   Provider Edge (6PE) approach defined in this document.

   The 6PE approach is required as an alternative to the use of standard
   tunnels.  It provides a solution for an MPLS environment where all
   tunnels are established dynamically, thereby addressing environments
   where the effort to configure and maintain explicitly configured
   tunnels is not acceptable.

   This document specifies operations of the 6PE approach for
   interconnection of IPv6 islands over an IPv4 MPLS cloud.  The
   approach requires that the edge routers connected to IPv6 islands be
   Dual Stack Multiprotocol-BGP-speaking routers [RFC4760], while the
   core routers are only required to run IPv4 MPLS.  The approach uses
   MP-BGP over IPv4, relies on identification of the 6PE routers by
   their IPv4 address, and uses IPv4-signaled MPLS LSPs that do not
   require any explicit tunnel configuration.

   Throughout this document, the terminology of [RFC2460] and [RFC4364]
   is used.

   In this document an 'IPv6 island' is a network running native IPv6 as
   per [RFC2460].  A typical example of an IPv6 island would be a
   customer's IPv6 site connected via its IPv6 Customer Edge (CE) router
   to one (or more) Dual Stack Provider Edge router(s) of a Service
   Provider.  These IPv6 Provider Edge routers (6PE) are connected to an
   IPv4 MPLS core network.

De Clercq, et al.           Standards Track                     [Page 2]
RFC 4798                          6PE                      February 2007

            +--------+
            |site A  CE---+  +-----------------+

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