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---+ +-----------------+
+--------+ | | | +--------+
6PE-+ IPv4 MPLS core +-6PE--CE site C |
+--------+ | | | +--------+
|site B CE---+ +-----------------+
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