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Using Multipoint LDP When the Backbone Has No Route to the Root
RFC 6512

Internet Engineering Task Force (IETF)                      IJ. Wijnands
Request for Comments: 6512                                      E. Rosen
Category: Standards Track                                  Cisco Systems
ISSN: 2070-1721                                             M. Napierala
                                                                    AT&T
                                                              N. Leymann
                                                        Deutsche Telekom
                                                           February 2012

    Using Multipoint LDP When the Backbone Has No Route to the Root

Abstract

   The control protocol used for constructing Point-to-Multipoint and
   Multipoint-to-Multipoint Label Switched Paths ("MP LSPs") contains a
   field that identifies the address of a "root node".  Intermediate
   nodes are expected to be able to look up that address in their
   routing tables.  However, this is not possible if the route to the
   root node is a BGP route and the intermediate nodes are part of a
   BGP-free core.  This document specifies procedures that enable an MP
   LSP to be constructed through a BGP-free core.  In these procedures,
   the root node address is temporarily replaced by an address that is
   known to the intermediate nodes and is on the path to the true root
   node.

Status of This Memo

   This is an Internet Standards Track document.

   This document is a product of the Internet Engineering Task Force
   (IETF).  It represents the consensus of the IETF community.  It has
   received public review and has been approved for publication by the
   Internet Engineering Steering Group (IESG).  Further information on
   Internet Standards is available in 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/rfc6512.

Copyright Notice

   Copyright (c) 2012 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

Wijnands, et al.             Standards Track                    [Page 1]
RFC 6512         Using mLDP with Recursive Opaque Values   February 2012

   publication of this document.  Please review these documents
   carefully, as they describe your rights and restrictions with respect
   to this document.  Code Components extracted from this document must
   include Simplified BSD License text as described in Section 4.e of
   the Trust Legal Provisions and are provided without warranty as
   described in the Simplified BSD License.

Table of Contents

   1. Introduction ....................................................3
   2. The Recursive Opaque Value ......................................5
      2.1. Encoding ...................................................5
      2.2. Procedures .................................................5
   3. The VPN-Recursive Opaque Value ..................................6
      3.1. Encoding ...................................................6
      3.2. Procedures .................................................7
           3.2.1. Non-Segmented Inter-AS P-Tunnels ....................7
           3.2.2. Limited Carrier's Carrier Function ..................9
   4. IANA Considerations ............................................10
   5. Security Considerations ........................................10
   6. Acknowledgments ................................................10
   7. References .....................................................11
      7.1. Normative References ......................................11
      7.2. Informative References ....................................11

Wijnands, et al.             Standards Track                    [Page 2]
RFC 6512         Using mLDP with Recursive Opaque Values   February 2012

1.  Introduction

   The document [mLDP] extends LDP [LDP] to support multipoint Label
   Switched Paths.  These extensions are known as "Multipoint LDP", or
   more simply, as "mLDP".  [mLDP] defines several LDP Forwarding
   Equivalence Class (FEC) element encodings: "Point-to-Multipoint"
   (P2MP), "Multipoint-to-Multipoint (MP2MP) Upstream", and "MP2MP
   Downstream".

   The encoding for these three FEC elements, as defined in [mLDP], is
   shown in Figure 1.

       0                   1                   2                   3
       0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

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