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Network Working Group                                      J.-L. Le Roux 
Internet Draft                                                  T. Morin 
Category: Informational                                   France Telecom 
Expires: January 2006                                    
                                                         Vincent Parfait 
                                                                  Equant 
                                                         
                                                             Luyuan Fang 
                                                                    AT&T 
                                                         
                                                                Lei Wang 
                                                                 Telenor 
                                                         
                                                             Yuji Kamite 
                                                      NTT Communications 
                                                                         
                                                            Shane Amante 
                                                  Level 3 Communications 
                                                                         
                                                               July 2005 
                                                                         
 
            Requirements for point-to-multipoint extensions to  
                     the Label Distribution Protocol  
 
                     draft-leroux-mpls-mp-ldp-reqs-01.txt 
 
 
Status of this Memo 
 
   By submitting this Internet-Draft, each author represents that any 
   applicable patent or other IPR claims of which he or she is aware 
   have been or will be disclosed, and any of which he or she becomes 
   aware will be disclosed, in accordance with Section 6 of BCP 79. 
    
   This document is an Internet-Draft and is in full conformance with 
   all provisions of Section 10 of RFC2026. Internet-Drafts are working 
   documents of the Internet Engineering Task Force (IETF), its areas, 
   and its working groups. Note that other groups may also distribute 
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   Internet-Drafts are draft documents valid for a maximum of six months 
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   time. It is inappropriate to use Internet- Drafts as reference 
   material or to cite them other than as "work in progress." 
    
   The list of current Internet-Drafts can be accessed at 
   http://www.ietf.org/ietf/1id-abstracts.txt. 
    
   The list of Internet-Draft Shadow Directories can be accessed at 
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Abstract 
    
   This document lists a set of functional requirements for Label 
   Distribution Protocol (LDP) extensions for setting up point-to-
   multipoint (P2MP) Label Switched Paths (LSP), in order to deliver 
   point-to-multipoint applications over a Multi Protocol Label 
   Switching (MPLS) infrastructure. It is intended that solutions that 
   specify LDP procedures for setting up P2MP LSP satisfy these 
   requirements. 
 
Conventions used in this document 
 
   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. 
 
Table of Contents 
    
   1.      Terminology.................................................3 
   2.      Introduction................................................4 
   3.      Problem Statement and Requirements Overview.................5 
   3.1.    Problem Statement...........................................5 
   3.2.    Requirements overview.......................................6 
   4.      Application scenarios.......................................6 
   5.      Detailed Requirements.......................................6 
   5.1.    P2MP LSPs...................................................6 
   5.2.    P2MP LSP FEC................................................6 
   5.3.    Setting up, tearing down and modifying P2MP LSPs............7 
   5.4.    Label Advertisement.........................................7 
   5.5.    Data Duplication............................................8 
   5.6.    Avoiding loops..............................................8 
   5.7.    P2MP LSP routing............................................8 
   5.8.    P2MP LSP Re-routing.........................................8 
   5.8.1.  Rerouting on a Better Path..................................8 
   5.8.2.  Rerouting upon Network Failure..............................9 
   5.8.3.  Rerouting upon Planned Maintenance..........................9 
   5.9.    Support for LAN interfaces..................................9 
   5.10.   Support for encapsulation in P2P and P2MP TE tunnels........9 
   5.11.   Label spaces................................................9 
   5.12.   IPv4/IPv6 support..........................................10 
   5.13.   Multi-Area LSPs............................................10 
   5.14.   OAM........................................................10 
   5.15.   Graceful Restart and Fault Recovery........................10 
   5.16.   Robustness.................................................10 
   5.17.   Scalability................................................11 
   5.17.1.  Orders of magnitude of the expected numbers of P2MP 
             LSPs and leaves per LSP in operational networks..........11 
   5.18.   Backward Compatibility.....................................11 
   6.      Shared Trees...............................................11 
   7.      Evaluation criteria........................................12 
   7.1.    Performances...............................................12 
 
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   7.2.    Complexity and Risks.......................................12 
   8.      Security Considerations....................................12 
   9.      Acknowledgments............................................12 
   10.     References.................................................12 
   11.     Authors' Addresses:........................................14 
   12.     Intellectual Property Statement............................15 
    
 
1. Terminology 
    
      LSR: Label Switching Router 
    
      LSP: MPLS Label Switched Path 
    
      Ingress LSR: Router acting as a sender of an LSP 
    
      Egress LSR: Router acting as a receiver of an LSP 
     
      P2P LSP: A LSP that has one unique Ingress LSR and one unique  
               Egress LSR 
 
      MP2P LSP: A LSP that has one or more Ingress LSRs and one unique  
                Egress LSR 
       
      P2MP LSP: A LSP that has one unique Ingress LSR and one or more  
                Egress LSRs    
   
      Leaf LSR: Egress LSR of a P2MP LSP  
       
      Transit LSR: A LSR of a P2MP LSP that has one or more downstream  
                   LSRs 
 
      Branch LSR: A LSR of a P2MP LSP that has more than one downstream  
                  LSRs 
       
      Bud LSR: A LSR of a P2MP LSP that is an egress but also has one or  
               more directly connected downstream LSRs 
 
       
 
 
 
 
 
 
 
 
 
 
 
 
 
 
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2. Introduction 
 
   Many operators have deployed LDP [LDP] for setting up point-to-point 
   (P2P) and multipoint-to-point (MP2P) LSPs, in order to offer point-to 
   -point services in MPLS backbones. 
    
   There are emerging requirements for supporting delivery of point-to-
   multipoint applications in MPLS backbones, such as those defined in 
   [L3VPN-MCAST-REQ] and [L2VPN-MCAST-REQ].  
    
   An interesting and useful approach for operators who want to support 
   point-to-multipoint traffic delivery on an MPLS backbone and have 
   already deployed LDP for P2P traffic would be to rely on LDP 
   extensions in order to setup point-to-multipoint (P2MP) LSPs. This 
   would bring consistency with P2P MPLS applications and would ease the 
   delivery of point-to-multipoint applications in an MPLS backbone. 
    
   This document lists a set of requirements for LDP extensions, for 
   setting up P2MP LSPs, so as to deliver P2MP traffic over a MPLS 
   infrastructure.  
   It is intended that solutions that specify LDP procedures for P2MP 
   LSP setup, satisfy these requirements. 
    
   Note that generic requirements for P2MP extensions to MPLS are out of 
   the scope of this document. Rather this document describes solution 
   specific requirements related to LDP extensions in order to set up 
   P2MP LSPs. 
    
   Other mechanisms could be used for setting up P2MP LSPs, such as for 
   instance PIM extensions, but these are out of the scope of this 
   document. The objective is not to compare these mechanisms but rather 
   to focus on the requirements for an LDP extension approach. 
    
   Section 3 points out the problem statement. Section 4 illustrates 
   application scenarios. Finally section 5 addresses detailed 
   requirements. 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
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3. Problem Statement and Requirements Overview 
    
3.1. Problem Statement 
    
   Many operators have deployed LDP [LDP] for setting up P2P and MP2P 
   MPLS LSPs as PE-to-PE tunnels so as to carry point-to-point traffic 
   essentially in Layer 3 and Layer 2 VPN networks. 
   There are emerging requirements for supporting multicast traffic 
   delivery within these VPN infrastructures ([L3VPN-MCAST-REQ] and 
   [L2VPN-MCAST-REQ]).  
   For various reasons, including consistency with P2P applications, and 
   taking full advantages of MPLS network infrastructure, it would be 
   highly desirable to use MPLS LSPs for the delivery of multicast 
   traffic. 
   This could be implemented by setting up a group of P2P or MP2P LSPs, 
   but such an approach may be sub-optimal since it would result in data 
   replication at the ingress LSR, and bandwidth inefficiency (duplicate 
   data traffic within the network). 
   Hence new mechanisms are required that would allow traffic from an 
   Ingress LSR to be efficiently delivered to a number of Egress LSRs in 
   an MPLS backbone, avoiding duplicate copies of a packet on a given 
   link.  
    
   Such efficient traffic delivery requires setting up P2MP LSPs. A P2MP 
   LSPs is an LSP starting at an Ingress LSR, and ending on a set of one 
   or more Egress LSRs. Traffic sent by the Ingress LSR is replicated on 
   one or more Branch LSRs down to Egress LSRs. 
 
   RSVP-TE extensions for setting up P2MP TE LSPs, which meet 
   requirements expressed in [P2MP-TE-REQ], have been defined in [P2MP-
   TE-RSVP]. This approach is useful, in network environments where 
   Traffic Engineering capabilities are required.  
   However, for operators that deployed LDP for setting up PE-to-PE 
   unicast MPLS LSPs, and without the need of traffic engineering, an 
   interesting approach would be using LDP extensions for setting up 
   P2MP LSPs.  
 
   Note that there are other alternatives for setting up P2MP (e.g. PIM 
   extensions defined in [PIM-MPLS]), that could be useful in various 
   situations. These are out of the scope of this document. 
    
   This document focuses on the LDP approach for setting up P2MP LSPs.  
   The following gives a set of guidelines that a specification of LDP 
   extensions for setting up P2MP LSPs should follow.  
    
    
    
    
    
    
    
 
 
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3.2. Requirements overview 
 
   The P2MP LDP mechanism MUST support setting up P2MP LSPs, i.e. LSPs 
   with one Ingress LSR and one or more egress LSRs, with traffic 
   replication at some Branch LSRs.  
    
   The P2MP LDP mechanism MUST allow the arbitrary addition or removal 
   of leaves associated with a P2MP LSP. 
     
   The P2MP LDP mechanism MUST interoperate seamlessly with existing P2P  
   and MP2P LDP mechanisms.  
   It is of paramount importance that the P2MP LDP mechanism MUST NOT  
   impede the operation of existing P2P/MP2P LSPs. 
    
   Note that the P2MP LDP mechanism MAY also allow setting up 
   multipoint-to-multipoint (MP2MP) LSPs connecting a group of Leaf LSRs 
   acting indifferently as Ingress LSR or Egress LSR. This may allow 
   reducing the amount of LDP state to be maintained by a LSR. Detailed 
   requirements for MP2MP LSPs are left for further study. 
   
4. Application scenarios 
 
To be completed in next revision 
 
 
5. Detailed Requirements 
 
5.1. P2MP LSPs 
    
   The P2MP LDP mechanism MUST support setting up P2MP LSPs.  
    
   A P2MP LSP has one Ingress LSR and one or more Egress LSRs. Traffic 
   sent by the Ingress LSR is received by all Egress LSRs. The specific 
   aspects related to P2MP LSP is the action required at 
   a Branch LSR, where data replication occurs. Incoming labelled data 
   is appropriately replicated to several outgoing interfaces which may 
   use different labels. Only one copy of a packet MUST be sent on a 
   given link of a P2MP LSP.  
 
   A P2MP LSP MUST be identified by a constant and unique identifier    
   within the whole LDP domain, whatever the number of leaves, which   
   may vary dynamically. 
   This identifier will be used so as to add/remove leaves to/from the 
   P2MP tree.  
      
5.2. P2MP LSP FEC 
    
   As with P2P MPLS technology [LDP], traffic MUST be classified into a 
   FEC in this P2MP extension. All packets which belong to a particular 
   P2MP FEC and which travel from a particular node MUST use the same 
   P2MP LSP.  
     
 
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   As such, a solution MUST specify a FEC that is suitable for P2MP 
   forwarding. Such P2MP FEC MUST be distinguished clearly from the 
   exiting P2P/MP2P FEC. 
 
5.3. Setting up, tearing down and modifying P2MP LSPs 
 
   The P2MP LDP mechanism MUST support the establishment, maintenance 
   and teardown of P2MP LSPs in a scalable manner. This MUST include 
   both the existence of a large amount of P2MP LSPs within a single 
   network and a large amount of leaf LSRs for a single P2MP LSP. 
    
   In order to scale well with a large number of leaves it is 
   RECOMMENDED to follow a leaf-initiated MP LSP setup approach. For 
   that purpose, leaves will have to be aware of the P2MP LSP 
   identifier. The way a Leaf LSR discovers P2MP LSPs identifiers SHOULD 
   not be part of P2MP LDP extensions. Instead this SHOULD be part of 
   the applications that will use P2MP LSPs, and it is out of the scope 
   of this document. 
    
   The P2MP LDP mechanism MUST allow the dynamic addition and removal of 
   leaves to and from a P2MP LSP. It is RECOMMENDED that these 
   operations be leaf-initiated. 
   It is RECOMMENDED that these operations do not cause any additional 
   processing except on the path from the Branch LSR to the added or 
   removed Leaf LSR. 
 
5.4. Label Advertisement 
 
   The P2MP LDP mechanism SHOULD support downstream unsolicited label 
   advertisement mode. This is well suited to a leaf-initiated approach 
   and is consistent with P2P/MP2P LDP operations. 
    
   In order to follow a leaf initiated LSP setup approach, the P2MP LDP 
   mechanism SHOULD support the Ordered label distribution control mode. 
   Note that the Independent control mode is not relevant in a P2MP 
   context, because the upstream LSRs cannot distribute labels 
   independently like P2P/MP2P LDP, they must wait for label 
   distribution from downstream LSRs. 
 
   Upstream label allocation ([MPLS-UPSTREAM]) may be particularly 
   useful to avoid packet replication on LAN interfaces of a P2MP LSP, 
   or when encapsulating the P2MP LSP into a P2MP TE tunnel. 
    
   Hence the P2MP LDP mechanism SHOULD also support upstream solicited 
   label advertisement mode, where the solicitation is made by the 
   downstream LSR, but the label is assigned by the upstream LSR.  
   Note that the existing base LDP specification [RFC3036] does not 
   specify upstream solicited label advertisement. Hence specific 
   extensions SHOULD be defined.  
    


 
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5.5. Data Duplication 
 
   Data duplication refers to the receipt of multiple copies of a packet 
   by any leaf. Although this may be a marginal situation, it may also 
   be detrimental for certain applications. Hence, data duplication 
   SHOULD be avoided as much as possible, and limited to (hopefully 
   rare) transitory conditions. 
 
   Note, in particular, that data duplication might occur if P2MP LSP 
   rerouting is being performed (See also section 5.6). 
    
5.6. Avoiding loops 
    
   The P2MP LDP mechanism SHOULD have a mechanism to avoid routing loops 
   even during transient events. Furthermore, the P2MP LDP mechanism 
   MUST avoid routing loops that may trigger unexpected non-localized 
   exponential growth of traffic. Note that any loop-avoidance mechanism 
   MUST respect scalability requirements. 
    
5.7. P2MP LSP routing 
    
   As with P2P and MP2P LDP LSPs, the P2MP LDP mechanism MUST support 
   hop-by-hop LSP routing. P2MP LSP LDP-based routing SHOULD rely upon 
   the information maintained in LSR Routing Information Bases (RIB). 
   For instance, P2MP LSP routing could rely upon a shortest path to the 
   Ingress LSR. Note that unlike P2P/MP2P LDP routing, Equal Cost Multi 
   Path (ECMP) MUST be avoided with P2MP LDP routing. 
 
5.8. P2MP LSP Re-routing 
 
   The P2MP LDP mechanism MUST support the rerouting of a P2MP LSP in 
   the following cases: 
        -A better path exists (e.g. new link, metric change) 
        -Network failure (link or node) 
        -Planned maintenance 
    
5.8.1. Rerouting on a Better Path 
 
   The P2MP LDP mechanism MUST allow for rerouting of a P2MP LSP in case 
   a better path is created in the network, for instance as a result of 
   a metric change, or the addition of links or nodes. 
   Traffic disruption MUST be minimized during such rerouting. It is 
   RECOMMENDED that devices perform make-before-break for traffic on 
   P2MP LSP’s to minimize traffic disruption. 
   It SHOULD be feasible to avoid packet loss during such rerouting. 
   Unnecessary data duplication during such rerouting MUST also be 
   minimized. 
    
    
    
    
    
 
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5.8.2. Rerouting upon Network Failure 
    
   The P2MP LDP mechanism MUST allow for rerouting of a P2MP LSP in case 
   of link or node failure(s). The rerouting time SHOULD be minimized as 
   much as possible so as to reduce traffic disruption. 
    
   A mechanism MUST be defined to prevent constant P2MP LSP teardown and 
   rebuild which may be caused by the instability of a specific 
   link/node in the network.  
 
5.8.3. Rerouting upon Planned Maintenance 
 
   The P2MP LDP mechanism MUST support planned maintenance operations. 
   It SHOULD be possible to reroute a P2MP LSP before a link/node is 
   deactivated for maintenance purposes. Traffic disruption MUST be 
   minimized during such rerouting. It SHOULD be feasible to avoid 
   packet loss during such rerouting.  
   Unnecessary traffic duplication during such rerouting MUST also be 
   minimized. 
 
5.9. Support for LAN interfaces 
 
   The P2MP LDP mechanism MUST provide a way for a Branch LSR to send a 
   single copy of the data onto an Ethernet LAN interface and reach 
   multiple adjacent downstream nodes. This requires that the same label 
   be negotiated will all downstream LSRs for the LSP. In order to ease 
   such negotiation an upstream label allocation approach may be used. 
 
5.10. Support for encapsulation in P2P and P2MP TE tunnels 
 
   The P2MP LDP mechanism MUST support nesting P2MP LSPs into P2P and 
   P2MP TE tunnels.  
   The P2MP LDP mechanism MUST provide a way for a Branch LSR of a P2MP 
   LPS, which is also a Head End LSR of a P2MP TE tunnel, to send a 
   single copy of the data onto the tunnel and reach all downstream LSRs 
   on the P2MP LSP, which are also Egress LSRs of the tunnel. As with 
   LAN interfaces, this requires that the same LDP label be negotiated 
   with all downstream LSRs for the P2MP LDP LSP. In order to ease such 
   negotiation, an upstream label allocation approach may be used. 
 
5.11. Label spaces 
 
   Labels for P2MP LSPs and P2P/MP2P LSPs MAY be assigned from shared or 
   dedicated label spaces.  
   MPLS Context Specific Label Spaces ([UPSTREAM-LABEL]) and 
   particularly Upstream label spaces and Tunnel label spaces MAY be 
   required to support upstream label allocation so as to avoid packet 
   replication on LAN or P2MP TE Tunnel interfaces. 
    
   Note that dedicated label spaces will require the establishment of 
   separate P2MP LDP sessions. 
    
 
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5.12. IPv4/IPv6 support 
    
   The P2MP LDP mechanism MUST be equally applicable to IPv4 and IPv6 
   traffic. Likewise, it SHOULD be possible to convey both kinds of 
   traffic in a given P2MP LSP facility. 
    
   Also the P2MP LDP mechanism MUST support the establishment of LDP 
   sessions over both IPv4 and IPv6 control planes. 
    
5.13. Multi-Area LSPs 
    
   The P2MP LDP mechanism MUST support the establishment of multi-area 
   P2MP LSPs, i.e. LSPs whose leaves do not all reside in the same IGP 
   area. This SHOULD be possible without requiring the advertisement of 
   Leaf LSRs' addresses across IGP areas. 
    
5.14. OAM 
 
   LDP management tools ([LDP-MIB]…) MUST be enhanced to support P2MP 
   LDP extensions. This may yield a new MIB module, which may possibly 
   be inherited from the LDP MIB. 
    
   In order to facilitate correct management, P2MP LDP LSPs MUST have 
   unique identifiers, otherwise it is impossible to determine which LSP 
   is being managed. 
   OAM facilities will have special demands in P2MP MPLS environments 
   especially within the context of tracing the paths and determining 
   the connectivity of P2MP LSPs. Further and precise requirements and 
   mechanisms for OAM purpose are out of the scope of this document and 
   are addressed in [P2MP-OAM-REQ]. 
    
5.15. Graceful Restart and Fault Recovery 
 
   LDP Graceful Restart mechanisms [LDP-GR] and Fault Recovery [LDP-FT] 
   mechanisms SHOULD be enhanced to support P2MP LDP LSPs. 
    
   Particularly [LDP-GR] applies only to downstream unsolicited label 
   distribution. Hence new mechanisms are required to account for 
   upstream label assignment, particularly in multi segment LANs. 
    
5.16. Robustness 
 
   A solution SHOULD avoid whatever single points of failures or propose 
   some technical solutions for a failover mechanism. 
 
 
 
 
 
 
 
 
 
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5.17. Scalability 
    
   Scalability is a key requirement for the P2MP LDP mechanism.  
   It MUST be designed to scale well with an increase in the number of 
   any of the following: 
      - number of Leaf LSRs per P2MP LSP 
      - number of Branch LSRs per P2MP LSP 
      - number of P2MP LSPs per LSR 
 
   In order to scale well with an increase in the number of leaves, it 
   is RECOMMENDED that the size of a P2MP LSP state on a LSR, for one 
   particular LSP, depend only on the number of adjacent LSRs on the 
   LSP. 
    
5.17.1. Orders of magnitude of the expected numbers of P2MP LSPs and 
       leaves per LSP in operational networks 
    
   To be completed in next revision 
    
5.18. Backward Compatibility 
    
   In order to allow for a smooth migration, the P2MP LDP mechanism 
   SHOULD offer as much backward compatibility as possible. In 
   particular, the solution SHOULD allow the setup of a P2MP LSP along 
   non Branch Transit LSRs that do not support P2MP LDP extensions. 
 
   Also, the P2MP LDP solution MUST interoperate seamlessly with current 
   LDP mechanisms and inherit its capability sets from [LDP]. The P2MP 
   LDP solution MUST not impede the operation of P2P/MP2P LSPs. A P2MP 
   LDP solution MUST be designed in such a way that it allows P2P/MP2P 
   and P2MP LSPs to be signalled on the same interface. 
    
6. Shared Trees 
    
   For traffic delivery between a group of N LSRs which are acting  
   indifferently as Ingress or Egress LSR, it may be useful to  
   setup a multipoint-to-multipoint (MP2MP) LSP connecting all these 
   LSRs, instead of having N P2MP LSPs. This would reduce the amount of 
   state that has to be maintained on a given LSR.  
    
   Hence the P2MP LDP mechanism MAY also allow setting up MP2MP LSPs. 
   Detailed requirements for MP2MP LSPs are left for further study 
    
   Note that the setup of such shared trees, with as objective to reduce 
   the amount of state, could also rely on the application protocols 
   that uses LDP LSPs, rather than on LDP itself. For instance with 
   Multicast L3 VPN applications, it would be possible to build a shared 
   tree that relies on a set of unicast LDP LSPs, from each PE of the 
   group to a particular PE, acting as tree root, and one P2MP LDP LSP 
   from the root to all PEs of the group (see [2547-MCAST]).  
    
 
 
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7. Evaluation criteria 
 
7.1. Performances 
 
      The solution will be evaluated with respect to the following 
      criteria: 
    
      (1) Time (in msec) to add or remove a Leaf LSR; 
      (2) Time (in msec) to repair a P2MP LSP in case of link or node  
          failure; 
      (3) Scalability (state size, number of messages, message size). 
    
   Particularly, the P2MP LDP mechanism SHOULD be designed so that 
   convergence times in case of link or node failure are minimized, in 
   order to limit traffic disruption.  
 
7.2. Complexity and Risks 
    
   The proposed solution SHOULD not introduce complexity to the current 
   LDP operations to such a degree that it would affect the stability 
   and diminish the benefits of deploying such P2MP LDP solution. 
    
8. Security Considerations 
    
   This document does not introduce any new security issue beyond those 
   inherent to LDP, and a P2MP LDP solution may rely on the security 
   mechanisms defined in [LDP] (e.g. TCP MD-5). 
    
9. Acknowledgments 
 
   We would like to thank Christian Jacquenet (France Telecom),   
   Hitoshi Fukuda (NTT Communications), Ina Minei (Juniper) and Dean  
   Cheng (Cisco Systems) for their highly useful comments and  
   suggestions. 
 
   We would also like to thank authors of [P2MP-TE-REQ] from which some 
   text of this document has been inspired. 
 
10. References 
    
   [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate 
   Requirement Levels", BCP 14, RFC 2119, March 1997. 
    
   [RFC3667] Bradner, S., "IETF Rights in Contributions", BCP 78, RFC 
   3667, February 2004. 
 
   [BCP79] Bradner, S., "Intellectual Property Rights in IETF 
   Technology", RFC 3979, March 2005. 
    
   [LDP] L. Andersson, P. Doolan, N. Feldman, A. Fredette, B. Thomas, 
   "LDP Specification", RFC 3036, January 2001 
    
 
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   [L3VPN-MCAST-REQ] T. Morin, Ed., "Requirements for Multicast in L3 
   Provider-Provisioned VPNs", draft-ietf-l3vpn-ppvpn-mcast-reqts-
   01.txt, work in progress.  
    
   [L2VPN-MCAST-REQ]  Y. Kamite et al. " Requirements for Multicast 
   Support in Virtual Private LAN Services", draft-kamite-l2vpn-vpls-
   mcast-reqts-00.txt, work in progress 
 
   [P2MP-TE-REQ] S. Yasukawa, et. al., "Requirements for Point-to-
   Multipoint capability extension to MPLS", draft-ietf-mpls-p2mp-sig-
   requirement-03.txt, work in progress. 
 
   [P2MP-TE-RSVP] R. Aggarwal, D. Papadimitriou, S. Yasukawa, et. al.., 
   "Extensions to RSVP-TE for Point to Multipoint TE LSPs", draft-ietf-
   mpls-rsvp-te-p2mp-02.txt, work in progress. 
 
   [PIM-MPLS] D. Farinacci, Y. Rekhter, E. Rosen, T. Qian, " Using PIM 
   to Distribute MPLS Labels for Multicast Routes", draft-farinacci-
   mpls-multicast-03.txt. 
    
   [MPLS-UPSTREAM-LABEL] R. Aggarwal, Y. Rekhter, E. Rosen, "MPLS 
   Upstream Label Assignment and Context Specific Label Space", draft-
   raggarwa-mpls-upstream-label-00.txt, work in progress. 
    
   [LDP-MIB] J. Cuchiarra et al. " Definitions of Managed Objects for 
   the Multiprotocol Label Switching (MPLS), Label Distribution Protocol 
   (LDP)", RFC3815, June 2004. 
 
   [LDP-GR] M. Leelanivas, Y. Rekhter, R. Aggarwal, " Graceful Restart 
   Mechanism for Label Distribution Protocol" RFC3478, February 2003. 
    
   [LDP-FT] A. Farrel, " Fault Tolerance for the Label Distribution 
   Protocol (LDP)", RFC3479, February 2003. 
    
   [2547-MCAST] E. Rosen, R. Aggarwal, et. al., "Multicast in MPLS/BGP 
   IP VPNs", draft-ietf-l3vpn-2547bis-mcast, work in progress. 
    
   [P2MP-OAM-REQ] S. Yasukawa, A. Farrel, D. King, T. Nadeau, "OAM 
   Requirements for Point-To-Multipoint MPLS Networks", draft-yasukawa-
   mpls-p2mp-oam-reqs-00.txt, work in progress. 
    
    
    
    
    
    
    
    
    
    
    
 
 
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11. Authors' Addresses:  
     
   Jean-Louis Le Roux  
   France Telecom  
   2, avenue Pierre-Marzin  
   22307 Lannion Cedex  
   FRANCE 
   Email: jeanlouis.leroux@francetelecom.com 
     
   Thomas Morin  
   France Telecom  
   2, avenue Pierre-Marzin  
   22307 Lannion Cedex  
   FRANCE 
   Email: thomas.morin@francetelecom.com 
 
   Vincent Parfait 
   EQUANT 
   1041 Route des Dolines 
   Sophia Antipolis 
   06560 Valbonne  
   FRANCE 
   Email: vincent.parfait@equant.com 
 
   Luyuan Fang 
   AT&T 
   200 Laurel Avenue 
   Middletown, NJ  07748 
   USA 
   Email: luyuanfang@att.com 
 
   Lei Wang 
   Telenor 
   Snaroyveien 30 
   Fornebu  1331 
   NORWAY 
   Email: lei.wang@telenor.com 
 
   Yuji Kamite 
   NTT Communications Corporation 
   Tokyo Opera City Tower 
   3-20-2 Nishi Shinjuku, Shinjuku-ku, 
   Tokyo 163-1421, 
   JAPAN 
   Email: y.kamite@ntt.com 
    
   Shane Amante 
   Level 3 Communications, LLC 
   1025 Eldorado Blvd 
   Broomfield, CO 80021 
   USA 
   Email: shane@level3.net 
 
Le Roux et al.      Reqs for P2MP extensions to LDP          [Page 14] 
  
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