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rfc:rfc4798

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---+  +-----------------+
          +--------+
           IPv6 islands          IPv4 cloud       IPv6 island
          <-------------><---------------------><-------------->
                                Figure 1
 The interconnection method described in this document typically
 applies to an Internet Service Provider (ISP) that has an IPv4 MPLS
 network, that is familiar with BGP (possibly already offering
 BGP/MPLS VPN services), and that wants to offer IPv6 services to some
 of its customers.  However, the ISP may not (yet) want to upgrade its
 network core to IPv6, nor use only IPv6-over-IPv4 tunneling.  With
 the 6PE approach described here, the provider only has to upgrade
 some Provider Edge (PE) routers to Dual Stack operations so that they
 behave as 6PE routers (and route reflectors if those are used for the
 exchange of IPv6 reachability among 6PE routers) while leaving the
 IPv4 MPLS core routers untouched.  These 6PE routers provide
 connectivity to IPv6 islands.  They may also provide other services
 simultaneously (IPv4 connectivity, IPv4 L3VPN services, L2VPN
 services, etc.).  Also with the 6PE approach, no tunnels need to be
 explicitly configured, and no IPv4 headers need to be inserted in
 front of the IPv6 packets between the customer and provider edge.
 The ISP obtains IPv6 connectivity to its peers and upstreams using
 means outside of the scope of this document, and its 6PE routers
 readvertise it over the IPv4 MPLS core with MP-BGP.
 The interface between the edge router of the IPv6 island (Customer
 Edge (CE) router) and the 6PE router is a native IPv6 interface which
 can be physical or logical.  A routing protocol (IGP or EGP) may run
 between the CE router and the 6PE router for the distribution of IPv6
 reachability information.  Alternatively, static routes and/or a
 default route may be used on the 6PE router and the CE router to
 control reachability.  An IPv6 island may connect to the provider
 network over more than one interface.
 The 6PE approach described in this document can be used for customers
 that already have an IPv4 service from the network provider and
 additionally require an IPv6 service, as well as for customers that
 require only IPv6 connectivity.

De Clercq, et al. Standards Track [Page 3] RFC 4798 6PE February 2007

 The scenario is also described in [RFC4029].
 Note that the 6PE approach specified in this document provides global
 IPv6 reachability.  Support of IPv6 VPNs is not within the scope of
 this document and is addressed in [RFC4659].
 Deployment of the 6PE approach over an existing IPv4 MPLS cloud does
 not require an introduction of new mechanisms in the core (other than
 potentially those described at the end of Section 3 for dealing with
 dynamic MTU discovery).  Configuration and operations of the 6PE
 approach have a lot of similarities with the configuration and
 operations of an IPv4 VPN service ([RFC4364]) or IPv6 VPN service
 ([RFC4659]) over an IPv4 MPLS core because they all use MP-BGP to
 distribute non-IPv4 reachability information for transport over an
 IPv4 MPLS Core.  However, the configuration and operations of the 6PE
 approach is somewhat simpler, since it does not involve all the VPN
 concepts such as Virtual Routing and Forwarding (VRFs) tables.

1.1. Requirements Language

 The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
 "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this
 document are to be interpreted as described in RFC 2119 [RFC2119].

2. Protocol Overview

 Each IPv6 site is connected to at least one Provider Edge router that
 is located on the border of the IPv4 MPLS cloud.  We call such a
 router a 6PE router.  The 6PE router MUST be dual stack IPv4 and
 IPv6.  The 6PE router MUST be configured with at least one IPv4
 address on the IPv4 side and at least one IPv6 address on the IPv6
 side.  The configured IPv4 address needs to be routable in the IPv4
 cloud, and there needs to be a label bound via an IPv4 label
 distribution protocol to this IPv4 route.
 As a result of this, every considered 6PE router knows which MPLS
 label to use to send packets to any other 6PE router.  Note that an
 MPLS network offering BGP/MPLS IP VPN services already fulfills these
 requirements.
 No extra routes need to be injected in the IPv4 cloud.
 We call the 6PE router receiving IPv6 packets from an IPv6 site an
 ingress 6PE router (relative to these IPv6 packets).  We call a 6PE
 router forwarding IPv6 packets to an IPv6 site an egress 6PE router
 (relative to these IPv6 packets).

De Clercq, et al. Standards Track [Page 4] RFC 4798 6PE February 2007

 Interconnecting IPv6 islands over an IPv4 MPLS cloud takes place
 through the following steps:
 1. Exchange IPv6 reachability information among 6PE routers with MP-
    BGP [RFC2545]:
    The 6PE routers MUST exchange the IPv6 prefixes over MP-BGP
    sessions as per [RFC2545] running over IPv4.  The MP-BGP Address
    Family Identifier (AFI) used MUST be IPv6 (value 2).  In doing so,
    the 6PE routers convey their IPv4 address as the BGP Next Hop for
    the advertised IPv6 prefixes.  The IPv4 address of the egress 6PE
    router MUST be encoded as an IPv4-mapped IPv6 address in the BGP
    Next Hop field.  This encoding is consistent with the definition
    of an IPv4-mapped IPv6 address in [RFC4291] as an "address type
    used to represent the address of IPv4 nodes as IPv6 addresses".
    In addition, the 6PE MUST bind a label to the IPv6 prefix as per
    [RFC3107].  The Subsequence Address Family Identifier (SAFI) used
    in MP-BGP MUST be the "label" SAFI (value 4) as defined in
    [RFC3107].  Rationale for this and label allocation policies are
    discussed in Section 3.
 2. Transport IPv6 packets from the ingress 6PE router to the egress
    6PE router over IPv4-signaled LSPs:
    The ingress 6PE router MUST forward IPv6 data over the IPv4-
    signaled LSP towards the egress 6PE router identified by the IPv4
    address advertised in the IPv4-mapped IPv6 address of the BGP Next
    Hop for the corresponding IPv6 prefix.
 As required by the BGP specification [RFC4271], PE routers form a
 full peering mesh unless Route Reflectors are used.

3. Transport over IPv4-signaled LSPs and IPv6 Label Binding

 In this approach, the IPv4-mapped IPv6 addresses allow a 6PE router
 that has to forward an IPv6 packet to automatically determine the
 IPv4-signaled LSP to use for a particular IPv6 destination by looking
 at the MP-BGP routing information.
 The IPv4-signaled LSPs can be established using any existing
 technique for label setup [RFC3031] (LDP, RSVP-TE, etc.).
 To ensure interoperability among systems that implement the 6PE
 approach described in this document, all such systems MUST support
 tunneling using IPv4-signaled MPLS LSPs established by LDP [RFC3036].
 When tunneling IPv6 packets over the IPv4 MPLS backbone, rather than
 successively prepend an IPv4 header and then perform label imposition

De Clercq, et al. Standards Track [Page 5] RFC 4798 6PE February 2007

 based on the IPv4 header, the ingress 6PE Router MUST directly
 perform label imposition of the IPv6 header without prepending any
 IPv4 header.  The (outer) label imposed MUST correspond to the IPv4-
 signaled LSP starting on the ingress 6PE Router and ending on the
 egress 6PE Router.
 While this approach could theoretically operate in some situations
 using a single level of labels, there are significant advantages in
 using a second level of labels that are bound to IPv6 prefixes via
 MP-BGP advertisements in accordance with [RFC3107].
 For instance, the use of a second level label allows Penultimate Hop
 Popping (PHP) on the IPv4 Label Switch Router (LSR) upstream of the
 egress 6PE router, without any IPv6 capabilities/upgrades on the
 penultimate router; this is because it still transmits MPLS packets
 even after the PHP (instead of having to transmit IPv6 packets and
 encapsulate them appropriately).
 Also, an existing IPv4-signaled LSP that is using "IPv4 Explicit NULL
 label" over the last hop (e.g., because that LSP is already being
 used to transport IPv4 traffic with the Pipe Diff-Serv Tunneling
 Model as defined in [RFC3270]) could not be used to carry IPv6 with a
 single label since the "IPv4 Explicit NULL label" cannot be used to
 carry native IPv6 traffic (see [RFC3032]), while it could be used to
 carry labeled IPv6 traffic (see [RFC4182]).
 This is why a second label MUST be used with the 6PE approach.
 The label bound by MP-BGP to the IPv6 prefix indicates to the egress
 6PE Router that the packet is an IPv6 packet.  This label advertised
 by the egress 6PE Router with MP-BGP MAY be an arbitrary label value,
 which identifies an IPv6 routing context or outgoing interface to
 send the packet to, or MAY be the IPv6 Explicit Null Label.  An
 ingress 6PE Router MUST be able to accept any such advertised label.
 [RFC2460] requires that every link in the IPv6 Internet have an MTU
 of 1280 octets or larger.  Therefore, on MPLS links that are used for
 transport of IPv6, as per the 6PE approach, and that do not support
 link-specific fragmentation and reassembly, the MTU must be
 configured to at least 1280 octets plus the encapsulation overhead.
 Some IPv6 hosts might be sending packets larger than the MTU
 available in the IPv4 MPLS core and rely on Path MTU discovery to
 learn about those links.  To simplify MTU discovery operations, one
 option is for the network administrator to engineer the MTU on the
 core facing interfaces of the ingress 6PE consistent with the core
 MTU.  ICMP 'Packet Too Big' messages can then be sent back by the
 ingress 6PE without the corresponding packets ever entering the MPLS

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

 core.  Otherwise, routers in the IPv4 MPLS network have the option to
 generate an ICMP "Packet Too Big" message using mechanisms as
 described in Section 2.3.2, "Tunneling Private Addresses through a
 Public Backbone" of [RFC3032].
 Note that in the above case, should a core router with an outgoing
 link with an MTU smaller than 1280 receive an encapsulated IPv6
 packet larger than 1280, then the mechanisms of [RFC3032] may result
 in the "Packet Too Big" message never reaching the sender.  This is
 because, according to [RFC4443], the core router will build an ICMP
 "Packet Too Big" message filled with the invoking packet up to 1280
 bytes, and when forwarding downstream towards the egress PE as per
 [RFC3032], the MTU of the outgoing link will cause the packet to be
 dropped.  This may cause significant operational problems; the
 originator of the packets will notice that his data is not getting
 through, without knowing why and where they are discarded.  This
 issue would only occur if the above recommendation (to configure MTU
 on MPLS links of at least 1280 octets plus encapsulation overhead) is
 not adhered to (perhaps by misconfiguration).

4. Crossing Multiple IPv4 Autonomous Systems

 This section discusses the case where two IPv6 islands are connected
 to different Autonomous Systems (ASes).
 Like in the case of multi-AS backbone operations for IPv4 VPNs
 described in Section 10 of [RFC4364], three main approaches can be
 distinguished:
 a. eBGP redistribution of IPv6 routes from AS to neighboring AS
    This approach is the equivalent for exchange of IPv6 routes to
    procedure (a) described in Section 10 of [RFC4364] for the
    exchange of VPN-IPv4 routes.
    In this approach, the 6PE routers use IBGP (according to [RFC2545]
    and [RFC3107] and as described in this document for the single-AS
    situation) to redistribute labeled IPv6 routes either to an
    Autonomous System Border Router (ASBR) 6PE router, or to a route
    reflector of which an ASBR 6PE router is a client.  The ASBR then
    uses eBGP to redistribute the (non-labeled) IPv6 routes to an ASBR
    in another AS, which in turn distributes them to the 6PE routers
    in that AS as described earlier in this specification, or perhaps
    to another ASBR, which in turn distributes them etc.

De Clercq, et al. Standards Track [Page 7] RFC 4798 6PE February 2007

    There may be one, or multiple, ASBR interconnection(s) across any
    two ASes.  IPv6 needs to be activated on the inter-ASBR links and
    each ASBR 6PE router has at least one IPv6 address on the
    interface to that link.
    No inter-AS LSPs are used.  There is effectively a separate mesh
    of LSPs across the 6PE routers within each AS.
    In this approach, the ASBR exchanging IPv6 routes may peer over
    IPv6 or IPv4.  The exchange of IPv6 routes MUST be carried out as
    per [RFC2545].
    Note that the peering ASBR in the neighboring AS to which the IPv6
    routes were distributed with eBGP, should in its turn redistribute
    these routes to the 6PEs in its AS using IBGP and encoding its own
    IPv4 address as the IPv4-mapped IPv6 BGP Next Hop.
 b. eBGP redistribution of labeled IPv6 routes from AS to neighboring
    AS
    This approach is the equivalent for exchange of IPv6 routes to
    procedure (b) described in Section 10 of [RFC4364] for the
    exchange of VPN-IPv4 routes.
    In this approach, the 6PE routers use IBGP (as described earlier
    in this document for the single-AS situation) to redistribute
    labeled IPv6 routes either to an Autonomous System Border Router
    (ASBR) 6PE router, or to a route reflector of which an ASBR 6PE
    router is a client.  The ASBR then uses eBGP to redistribute the
    labeled IPv6 routes to an ASBR in another AS, which in turn
    distributes them to the 6PE routers in that AS as described
    earlier in this specification, or perhaps to another ASBR, which
    in turn distributes them, etc.
    There may be one, or multiple, ASBR interconnection(s) across any
    two ASes.  IPv6 may or may not be activated on the inter-ASBR
    links.
    This approach requires that there be label switched paths
    established across ASes.  Hence the corresponding considerations
    described for procedure (b) in Section 10 of [RFC4364] apply
    equally to this approach for IPv6.
    In this approach, the ASBR exchanging IPv6 routes may peer over
    IPv4 or IPv6 (in which case IPv6 obviously needs to be activated
    on the inter-ASBR link).  When peering over IPv6, the exchange of
    labeled IPv6 routes MUST be carried out as per [RFC2545] and
    [RFC3107].  When peering over IPv4, the exchange of labeled IPv6

De Clercq, et al. Standards Track [Page 8] RFC 4798 6PE February 2007

    routes MUST be carried out as per [RFC2545] and [RFC3107] with
    encoding of the IPv4 address of the ASBR as an IPv4-mapped IPv6
    address in the BGP Next Hop field.
 c. Multi-hop eBGP redistribution of labeled IPv6 routes between
    source and destination ASes, with eBGP redistribution of labeled
    IPv4 routes from AS to neighboring AS.
    This approach is the equivalent for exchange of IPv6 routes to
    procedure (c) described in Section 10 of [RFC4364] for exchange of
    VPN-IPv4 routes.
    In this approach, IPv6 routes are neither maintained nor
    distributed by the ASBR routers.  The ASBR routers need not be
    dual stack, but may be IPv4/MPLS-only routers.  An ASBR needs to
    maintain labeled IPv4 /32 routes to the 6PE routers within its AS.
    It uses eBGP to distribute these routes to other ASes.  ASBRs in
    any transit ASes will also have to use eBGP to pass along the
    labeled IPv4 /32 routes.  This results in the creation of an IPv4
    label switched path from the ingress 6PE router to the egress 6PE
    router.  Now 6PE routers in different ASes can establish multi-hop
    eBGP connections to each other over IPv4, and can exchange labeled
    IPv6 routes (with an IPv4-mapped IPv6 BGP Next Hop) over those
    connections.
    IPv6 need not be activated on the inter-ASBR links.
    The considerations described for procedure (c) in Section 10 of
    [RFC4364] with respect to possible use of multi-hop eBGP
    connections via route-reflectors in different ASes, as well as
    with respect to the use of a third label in case the IPv4 /32
    routes for the PE routers are NOT made known to the P routers,
    apply equally to this approach for IPv6.
    This approach requires that there be IPv4 label switched paths
    established across the ASes leading from a packet's ingress 6PE
    router to its egress 6PE router.  Hence the considerations
    described for procedure (c) in Section 10 of [RFC4364], with
    respect to LSPs spanning multiple ASes, apply equally to this
    approach for IPv6.
    Note also that the exchange of IPv6 routes can only start after
    BGP has created IPv4 connectivity between the ASes.

De Clercq, et al. Standards Track [Page 9] RFC 4798 6PE February 2007

5. Security Considerations

 The extensions defined in this document allow BGP to propagate
 reachability information about IPv6 routes over an MPLS IPv4 core
 network.  As such, no new security issues are raised beyond those
 that already exist in BGP-4 and use of MP-BGP for IPv6.
 The security features of BGP and corresponding security policy
 defined in the ISP domain are applicable.
 For the inter-AS distribution of IPv6 routes according to case (a) of
 Section 4 of this document, no new security issues are raised beyond
 those that already exist in the use of eBGP for IPv6 [RFC2545].
 For the inter-AS distribution of IPv6 routes according to case (b)
 and (c) of Section 4 of this document, the procedures require that
 there be label switched paths established across the AS boundaries.
 Hence the appropriate trust relationships must exist between and
 among the set of ASes along the path.  Care must be taken to avoid
 "label spoofing".  To this end an ASBR 6PE SHOULD only accept labeled
 packets from its peer ASBR 6PE if the topmost label is a label that
 it has explicitly signaled to that peer ASBR 6PE.
 Note that for the inter-AS distribution of IPv6 routes, according to
 case (c) of Section 4 of this document, label spoofing may be more
 difficult to prevent.  Indeed, the MPLS label distributed with the
 IPv6 routes via multi-hop eBGP is directly sent from the egress 6PE
 to ingress 6PEs in another AS (or through route reflectors).  This
 label is advertised transparently through the AS boundaries.  When
 the egress 6PE that sent the labeled IPv6 routes receives a data
 packet that has this particular label on top of its stack, it may not
 be able to verify whether the label was pushed on the stack by an
 ingress 6PE that is allowed to do so.  As such, one AS may be
 vulnerable to label spoofing in a different AS.  The same issue
 equally applies to the option (c) of Section 10 of [RFC4364].  Just
 as it is the case for [RFC4364], addressing this particular security
 issue is for further study.

6. Acknowledgements

 We wish to thank Gerard Gastaud and Eric Levy-Abegnoli who
 contributed to this document.  We also wish to thank Tri T. Nguyen,
 who initiated this document, but unfortunately passed away much too
 soon.  We also thank Pekka Savola for his valuable comments and
 suggestions.

De Clercq, et al. Standards Track [Page 10] RFC 4798 6PE February 2007

7. References

7.1. Normative References

 [RFC2119]  Bradner, S., "Key words for use in RFCs to Indicate
            Requirement Levels", BCP 14, RFC 2119, March 1997.
 [RFC2460]  Deering, S. and R. Hinden, "Internet Protocol, Version 6
            (IPv6) Specification", RFC 2460, December 1998.
 [RFC2545]  Marques, P. and F. Dupont, "Use of BGP-4 Multiprotocol
            Extensions for IPv6 Inter-Domain Routing", RFC 2545, March
            1999.
 [RFC3032]  Rosen, E., Tappan, D., Fedorkow, G., Rekhter, Y.,
            Farinacci, D., Li, T., and A. Conta, "MPLS Label Stack
            Encoding", RFC 3032, January 2001.
 [RFC3036]  Andersson, L., Doolan, P., Feldman, N., Fredette, A., and
            B. Thomas, "LDP Specification", RFC 3036, January 2001.
 [RFC3107]  Rekhter, Y. and E. Rosen, "Carrying Label Information in
            BGP-4", RFC 3107, May 2001.
 [RFC4291]  Hinden, R. and S. Deering, "IP Version 6 Addressing
            Architecture", RFC 4291, February 2006.
 [RFC4760]  Bates, T., Chandra, R., Katz, D., and Y. Rekhter,
            "Multiprotocol Extensions for BGP-4", RFC 4760, January
            2007.

7.2. Informative References

 [RFC3031]  Rosen, E., Viswanathan, A., and R. Callon, "Multiprotocol
            Label Switching Architecture", RFC 3031, January 2001.
 [RFC3270]  Le Faucheur, F., Wu, L., Davie, B., Davari, S., Vaananen,
            P., Krishnan, R., Cheval, P., and J. Heinanen, "Multi-
            Protocol Label Switching (MPLS) Support of Differentiated
            Services", RFC 3270, May 2002.
 [RFC4029]  Lind, M., Ksinant, V., Park, S., Baudot, A., and P.
            Savola, "Scenarios and Analysis for Introducing IPv6 into
            ISP Networks", RFC 4029, March 2005.
 [RFC4182]  Rosen, E., "Removing a Restriction on the use of MPLS
            Explicit NULL", RFC 4182, September 2005.

De Clercq, et al. Standards Track [Page 11] RFC 4798 6PE February 2007

 [RFC4271]  Rekhter, Y., Li, T., and S. Hares, "A Border Gateway
            Protocol 4 (BGP-4)", RFC 4271, January 2006.
 [RFC4364]  Rosen, E. and Y. Rekhter, "BGP/MPLS IP Virtual Private
            Networks (VPNs)", RFC 4364, February 2006.
 [RFC4443]  Conta, A., Deering, S., and M. Gupta, "Internet Control
            Message Protocol (ICMPv6) for the Internet Protocol
            Version 6 (IPv6) Specification", RFC 4443, March 2006.
 [RFC4659]  De Clercq, J., Ooms, D., Carugi, M., and F. Le Faucheur,
            "BGP-MPLS IP Virtual Private Network (VPN) Extension for
            IPv6 VPN", RFC 4659, September 2006.

De Clercq, et al. Standards Track [Page 12] RFC 4798 6PE February 2007

Authors' Addresses

 Jeremy De Clercq
 Alcatel-Lucent
 Copernicuslaan 50
 Antwerpen  2018
 Belgium
 EMail: jeremy.de_clercq@alcatel-lucent.be
 Dirk Ooms
 OneSparrow
 Belegstraat 13
 Antwerpen  2018
 Belgium
 EMail: dirk@onesparrow.com
 Stuart Prevost
 BT
 Room 136 Polaris House, Adastral Park, Martlesham Heath
 Ipswich Suffolk IP5 3RE
 England
 EMail: stuart.prevost@bt.com
 Francois Le Faucheur
 Cisco
 Domaine Green Side, 400 Avenue de Roumanille
 Biot, Sophia Antipolis  06410
 France
 EMail: flefauch@cisco.com

De Clercq, et al. Standards Track [Page 13] RFC 4798 6PE February 2007

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 contained in BCP 78, and except as set forth therein, the authors
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De Clercq, et al. Standards Track [Page 14]

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