Network Working Group                             Seisho Yasukawa (NTT)
Internet Draft                                                   Editor
Category: Standards Track Informational

Expiration Date: August December 2004                                  March                                July 2004

       Requirements for Point to Multipoint extension to RSVP-TE
               <draft-ietf-mpls-p2mp-requirement-02.txt> Traffic Engineered MPLS LSPs
               <draft-ietf-mpls-p2mp-requirement-03.txt>

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Abstract

    This document presents a basic set of requirements for Point-to-
   Multipoint(P2MP)
    Point-to-Multipoint(P2MP) Traffic Engineering Engineered (TE) extensions to Multiprotocol
    Label Switching (MPLS). (MPLS) Label Switched Paths (LSPs). It specifies
    functional requirements for
   RSVP-TE solutions in order to deliver P2MP
    applications over a MPLS TE infrastructure. It is intended that
    solutions that specify RSVP-TE procedures for P2MP TE LSP setup satisfy
    these requirements.

    There is no intent to either specify solution specific details in
    this document. document or application specific requirements.
    It is intended that the requirements presented in this document are
    not limited to the requirements of packet switched networks, but
    also encompass the requirements of L2SC, TDM, lambda and port
    switching networks managed by Generalized MPLS (GMPLS) protocols.
    Protocol solutions developed to meet the requirements set out in
    this document must attempt to be equally applicable to MPLS and
    GMPLS.

    Table of Contents
    1. Introduction .................................................. 4 ................................................. 04
    2. Definitions ................................................... 5 .................................................. 05
       2.1 Acronyms .................................................. 5 ................................................. 05
       2.2 Terminology ............................................... 5 .............................................. 06
       2.3 Conventions ............................................... 7 .............................................. 07
    3. Problem statements Statement ............................................ 7 07
       3.1 Motivation ................................................ 7 ............................................... 07
       3.2 Requirements overview ..................................... 8 Overview .................................... 08
    4. Application Specific Requirements .............................10 Examples of candidate applications that may require
       P2MP TE LSP ...................................................10
       4.1  P2MP tunnel TE LSP for IP multicast data .........................10 ....................... 10
       4.2  P2MP TE backbone network for IP multicast network .........11 ....... 11
       4.3  Layer 2 Multicast Over MPLS ...............................12 ............................. 13
       4.4  VPN multicast network .....................................13 ................................... 13
       4.5  GMPLS network .............................................14 Networks .......................................... 14
    5. Detailed requirements for P2MP TE extensions ..................14 ................. 15
       5.1  P2MP LSP tunnels ..........................................14 ........................................ 15
       5.2  P2MP explicit routing .....................................15 ................................... 15
       5.3  Explicit Path Loose Hops and Widely Scoped Abstract Nodes .16 Nodes.17
       5.4  P2MP TE LSP establishment, teardown, and modification
            mechanisms ................................................17 .............................................. 17
       5.5  Fragmentation ........................................... 18
       5.6  Failure Reporting and Error Recovery ......................17
      5.6 .................... 18
       5.7  Record route of P2MP TE LSP tunnels .......................18
      5.7 ..................... 19
       5.8  Call Admission Control (CAC) and QoS control Control mechanism
          of P2MP TE LSP tunnels ....................................18
      5.8 .. 19
       5.9  Reoptimization of P2MP TE LSP .............................19
      5.9 ........................... 20
       5.10 IPv4/IPv6 support .........................................19
      5.10 ....................................... 20
       5.11 P2MP MPLS Label ..........................................20
      5.11 ......................................... 21
       5.12 Routing advertisement of P2MP capability .................20
      5.12 ................ 21
       5.13 Multi-Area/AS LSP ........................................20
      5.13 ....................................... 21
       5.14 P2MP MPLS OAM ............................................20
      5.14 Scalability ..............................................21 ........................................... 21
       5.15 Scalability ............................................. 22
       5.16 Backwards Compatibility ..................................21
      5.16 GMPLS ....................................................22 ................................. 22
       5.17 GMPLS ................................................... 23
       5.18 Requirements for Hierarchical P2MP TE LSPs ...............22
      5.18 .............. 24
       5.19 P2MP Crankback routing ...................................23 .................................. 24
    6. Security Considerations........................................23 Considerations ...................................... 24
    7. Acknowledgements ..............................................23 ............................................. 25
    8. References ....................................................23 ................................................... 25
       8.1 Normative References ......................................23 ..................................... 25
       8.2 Informational References ..................................24 ................................. 26
    9. Editor's Address ..............................................26 ............................................. 27
    10. Authors' Addresses ............................................26 .......................................... 27
    11. Intellectual Property Consideration ...........................27 ......................... 29
       11.1 IPR Disclosure Acknowledgement ...........................28 .......................... 29
    12. Full Copyright Statement ......................................28 .................................... 29

1. Introduction

    Existing MPLS Traffic Engineering (MPLS-TE) allows for strict QoS
    guarantees, resources optimization, and fast failure recovery, but
    is limited to P2P applications. There are P2MP applications like
    Content Distribution, Interactive Multimedia and VPN multicast that
    would also benefit from these TE capabilities. This clearly
    motivates enhancements of the base MPLS-TE tool box in order to
    support P2MP applications.

    This document presents a set of requirements for Point-to-Multipoint
   (P2MP)
    Point-to-Multipoint(P2MP) Traffic Engineering (TE) extensions to
    Multiprotocol Label Switching (MPLS). It specifies functional
    requirements for solutions to deliver P2MP TE LSPs. For the sake of
    illustration, RSVP-TE [RFC3209] in order is one possible candidate to provide
    such a solution so as to deliver P2MP applications over a MPLS TE. TE LSPs.

    It is intended that solutions, solutions that specify RSVP-TE procedures and extensions for
    P2MP TE LSP setup, setup satisfy these requirements. It There is not intended no intent to
    either specify solution specific details in this document. document or
    application specific requirements.

    It is intended that the requirements presented in this document are
    not limited to the requirements of packet switched networks, but
    also encompass the requirements of TDM, lambda and port switching
    networks managed by Generalized MPLS (GMPLS) protocols. Protocol
    solutions developed to meet the requirements set out in this
    document must attempt to be equally applicable to MPLS and GMPLS.

    Content Distribution (CD), Interactive multi-media (IMM), and VPN
    multicast are applications that are best supported with multicast
    capabilities. For some of them , there is a requirement to use P2MP
    TE LSPs. One possible way to map P2MP flows onto LSPs in a MPLS
    network is to setup multiple P2P TE LSPs, one to each of the
    required egress LSRs. This requires replicating incoming packets to
    all the P2P LSPs at the ingress LSR to accommodate multipoint
    communication. This is sub-optimal. It sub-optimal as it places the replication
    burden on the ingress LSR and hence has very poor scaling
    characteristics. It also wastes bandwidth resources, memory and
    MPLS (e.g. label) resources in the network.

    Hence, to provide TE for a P2MP application in an efficient manner
    (that is, with scalable impact on signaling and protocol state) in
    a large-scale environment, P2MP TE mechanisms are required
    specifically to support P2MP TE LSPs. Existing As of now, existing MPLS TE
    mechanisms such as [RFC3209] do not support P2MP TE LSPs so new
    mechanisms must be developed.

    This should be achieved without running requiring the use of a multicast
    routing protocol in the network core, and with maximum re-use of the
    existing MPLS protocols: in particular, MPLS Traffic
    Engineering.

   A P2MP That is, the separation between routing and signaling
    that exists in the P2P TE LSP will network should be set up with maintained within the
    P2MP TE constraints network, and will allow
   efficient packet or data replication at various branching points in the network. RSVP-TE construction of the TEDB from which P2MP TE
    LSP paths are computed should not be constrained to use a multicast
    protocol.

    A P2MP TE LSP will be set up with TE constraints and will allow
    efficient packet or data replication at various branching points in
    the network. Note that the notion of "efficient" packet replication
    is relative and may have different meanings depending on the
    objectives (see section 5.2).

    For instance, RSVP-TE could be used for setting up a P2MP TE LSP
    with enhancements to existing P2P TE LSP procedures. The

    P2MP TE LSP setup
   mechanism will mechanisms MUST include the ability to add/remove
    receivers to/from an existing P2MP TE LSP.

   Moreover,

    Note that with existing multicast routing mechanisms, multicast
    traffic cannot currently benefit from P2P TE LSPs. Hence, CAC Call
    Admission Control for P2P TE LSP cannot take into account the
    bandwidth used for multicast traffic. P2MP TE will allow the
    bandwidth used by both the unicast and multicast traffic traffics to be
    counted by means of CAC.

    This document is organized as follows: Section 2 provides a set of
    definitions used throughout the document. The problem statement is
    then discussed in Section 3. This for the sake of illustration, this
    document discusses lists various applications that can could make use P2MP TE
    LSP. Detailed application-specific requirements as far as
    P2MP TE LSP is concerned are out of the scope of this document.
    Detailed requirements for the setup support of a applications that require
    P2MP MPLS TE LSP using
   RSVP-TE LSPs are described. Application specific requirements described in section 4.

    The requirement for Multipoint-to-Point and Multipoint-to-Multipoint
    TE LSPs are also
   described. outside of the scope of this document.

2. Definitions

2.1 Acronyms

    P2P:

       Point-to-point

    P2MP:

       Point-to-multipoint

2.2 Terminology

    The reader is assumed to be familiar with the terminology in
    [RFC3031] and [RFC3209].

    P2MP TE LSP:

       A traffic engineered label switched path that has one unique
       ingress LSR (also referred to as the root) and more than one or more
       egress LSR LSRs (also referred to as the leaf).

    P2MP tree:

       The ordered set of LSRs and links that comprise the path of a
       P2MP TE LSP from its ingress LSR to all of its egress LSRs.

    sub-P2MP tree:

       A sub-P2MP tree is a portion of a P2MP tree starting at
       a particular LSR that is a member of the P2MP tree and includes
       ALL downstream LSRs that are also members of the P2MP tree.

    P2P sub-LSP:

       The path from the ingress LSR to a particular egress LSR.

    ingress LSR:

       The LSR that is responsible for initiating the signaling
       messages that set up the P2MP TE LSP.

    egress LSR:

       One of potentially many destinations of the P2MP TE LSP.
       Egress LSRs may also be referred to as leaf nodes or leaves.

    bud LSR:

      An LSR that is an egress, but also has one or more directly
      connected downstream LSRs.

   branch LSR:

       An LSR that has more than one directly connected downstream LSR.

    graft LSR:

       An LSR that is already a member of the P2MP tree and is in
       process of signaling a new sub-P2MP tree.

    prune LSR:

       An LSR that is already a member of the P2MP tree and is in
       process of tearing down an existing sub-P2MP tree.

    P2MP-ID (Pid):

       The ID that can be used to map a set of P2P sub- LSPs sub-LSPs to a
       particular P2MP LSP.

2.3 Conventions

    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 [RFC2119].

3. Problem Statement

3.1 Motivation

    Content Distribution (CD), Interactive multi-media (IMM), and VPN
    multicast are applications that are best supported with multicast
    capabilities.

    IP Multicast provides P2MP communication. However, there are no
    Traffic Engineering (TE) capabilities or QoS guarantees with
    existing IP multicast protocols. Note that Diff-serv
    (see [RFC2475],[RFC2597] and [RFC3246]) combined with IP multicast
    routing may not be sufficient for P2MP applications for many of the
    same reasons that it is not sufficient for unicast applications.
    Note also that multicast tree trees provided by existing IP multicast
    routing protocols are not optimal, optimal from a bandwidth usage
    perspective, which may lead to significant bandwidth wasting.

    TE and Constraint Based Routing, including Call Admission Control
   (CAC),
    Control(CAC), explicit source routing and bandwidth reservation, is
    required to enable efficient resource optimization, usage and strict QoS guarantees, and
   fast recovery around network failures.
    guarantees.

    Furthermore there are no existing P2MP mechanisms for carrying layer
    2 or SONET/SDH multicast traffic over MPLS. TE capabilities are
    desirable for both these applications. applications; the related set of application
    requirements are outside of the scope of this document and might
    require special pseudowire encapsulation.

    One possible solution would be to setup multiple P2P TE LSPs, one to
    each of the required egress LSRs. This requires replicating incoming
    traffic to all the P2P LSPs at the ingress LSR to accommodate
    multipoint communication. This is clearly sub-optimal. It sub-optimal as it places
    the replication burden on the ingress LSR and hence has very poor
    scaling characteristics. It also wastes bandwidth resources, memory
    and MPLS
   (e.g. MPLS(e.g. label) resources in the network.

    Hence, to provide MPLS TE [RFC2702] for a P2MP application in an
    efficient manner (that is, with scalable impact on signaling and
    protocol state) in a large scale environment, P2MP TE mechanisms
    are required. Existing MPLS P2P TE mechanisms have to be enhanced
    to support P2MP TE LSP.

3.2. Requirements Overview

    This document states basic requirements for the setup of P2MP TE
   LSPs. This should be achieved
    LSPs and a solution SHOULD satisfy them without running requiring that a
    multicast routing protocol in is used, although such a protocol
    MUST NOT be prohibited. It is desirable to maximize the network core and with maximum re-use of the
    existing MPLS TE techniques and protocols. Note that the use of
    MPLS forwarding to carry the multicast traffic may also be useful
    in the context of some network
   design designs where it is being might be desired to
    avoid running some multicast routing protocol like PIM [PIM-SM] or
    BGP (which might be required for the use of PIM).

    A P2MP TE LSP path will be set up with TE constraints and will computed taking into account various
    constraints such as bandwidth, affinities, required level of
    protection and so on. The solution MUST allow
   efficient MPLS packet replication at for the computation
    of P2MP TE LSP paths satisfying constraints with the objective of
    supporting various branching points optimization criteria such as delays, bandwidth
    consumption in the
   network. RSVP-TE will be network, or any other combinations.

    This document does not restrict the choice of signaling protocol
    used for setting to set up a P2MP TE LSP with
   enhancements LSP, but it should be noted that [RFC3468]
    states
      ... the consensus reached by the Multiprotocol Label Switching
    (MPLS) Working Group within the IETF to existing P2P TE LSP procedures. focus its
    efforts on "Resource Reservation Protocol (RSVP)-TE: Extensions to
    RSVP for Label-Switched Paths (LSP) Tunnels" (RFC 3209) as the MPLS
    signaling protocol for traffic engineering applications...

    The P2MP TE LSP setup mechanism will MUST include the ability to
    add/remove egress LSRs to/from an existing P2MP TE LSP and should MUST allow
    for the support of  all the TE LSP management procedures already
    defined for P2P TE LSP
   (like such as the non disruptive rerouting - the (the so
    called "Make before break" procedure).

    The computation of P2MP TE trees is implementation dependent and is
    beyond the scope of the solutions that are built with this document
    as a guideline.

    A separate document(s) will specify how to build P2MP TE LSPs.
    The usage of those solutions will be application dependent and is
    out of the scope of this document. However, it is a requirement that
    those solutions attempt to be applicable to GMPLS as well as to MPLS
    so that only a single set of solutions are developed.

    Consider the following figure.

                          Source 1 (S1)
                                |
                              I-LSR1
                              |   |
                              |   |
             R2----E-LSR3--LSR1   LSR2---E-LSR2--Receiver 1 (R1)
                              |   :
                   R3----E-LSR4   E-LSR5
                              |   :
                              |   :
                             R4   R5

                            Figure 1

    Figure 1 shows a single ingress (I-LSR1), and four egresses
   (E-LSR2, egresses(E-LSR2,
    E-LSR3, E-LSR4 and E-LSR5). I-LSR1 is attached to a traffic source
    that is generating traffic for a P2MP application.
    Receivers R1, R2, R3 and R4 are attached to E-LSR2, E-LSR3 and
    E-LSR4.

    The following are the objectives of P2MP LSP establishment and use.

       a) A P2MP TE LSP tree which satisfies various constraints is pre-
         determined
          pre-determined and supplied to ingress I-LSR1.

          Note that no assumption is made on whether the tree is provided
          to I-LSR1 or computed by I-LSR1. Note that the solution SHOULD
          also allow for the support of partial path by means of loose
          routing.

          Typical constraints are bandwidth requirements, resource class
          affinities, fast rerouting, preemption. preemption, to mention a few of
          them. There should not be any restriction on the possibility
          to support the set of constraints already defined for point to
          point TE LSPs. A new constraint may specify which LSRs should
          be used as branch points for the P2MP LSR in order to take
          into account some LSR capabilities or network constraints.

       b) A P2MP TE LSP is set up by means of RSVP-TE from I-LSR1 to E-LSR2, E-LSR3 and
          E-LSR4 using the tree information.

       c) In this case, the branch LSR1 should replicate incoming
          packets or data and send them to E-LSR3 and E-LSR4.

       d) If a new receiver (R5) expresses an interest in receiving
          traffic, a new tree is determined and a sub-P2MP tree from
          LSR2 to E-LSR5 is grafted onto the P2MP tree. LSR2 becomes a
          branch LSR.

4. Application Specific Requirements Examples of candidate applications that may require P2MP TE LSP

    This section describes some of the candidate applications that P2MP
    MPLS TE is applicable to along with application specific requirements. to.

    The purpose of this section is not to mandate how P2MP TE LSPs must
    be used in certain application scenarios. Rather it is to illustrate
    some of the potential application scenarios so as to highlight the
    features and functions that any P2MP solution must provide in order
    to be of wide use and applicability. This section is not meant to be
    exhaustive, and P2MP is not limited to the described applications.

4.1 P2MP TE LSP for IP multicast data

    One typical scenario is to use P2MP TE LSPs as P2MP tunnels carrying
    multicast data traffic (e.g. IP mcast). In this scenario, a P2MP TE
    LSP is established between an ingress LSR which supports IP
    multicast source and several egress LSRs which support several IP
    multicast receivers. Instead of using an IP multicast routing
   protocol in the network core, a A P2MP TE LSP is established over the network
    and IP multicast data are tunneled from an ingress LSR node to
    multiple egress leaf LSRs with data replication at the branch LSRs
    in the network core. Figure 2 shows an example.

    Note that a P2MP TE LSP can be established over multiple areas/ASs
    and that the egress LSRs may deliver data into an IP multicast
    network.

                              Mcast Source
                                   |
                +---------------I-LSR0----------------+
                |                  |                  |
                |                LSR0            +----E-LSR2---R2
                |               /    \          /     |
      R1---E-LSR1---LSR2-----LSR1     LSR3----LSR4----E-LSR3---R3
                |             /        \        \     |
                |            /          \        +----E-LSR4---R4
                +-------B-LSR1---------B-LSR2---------+
                +-------- / ------++------ \ ---------+
                |         |       ||                  |
      R5---E-LSR5--------LSR5     || IPmcast Network  |
                |       /  \      ||                  |
                +-E-LSR6---E-LSR7-++----MR0--MR1------+
                    |        |           |    |
                    R6       R7          R8   R9

                               Figure 2

4.2  P2MP TE backbone network for IP multicast network

    P2MP TE LSPs are applicable in a backbone network to construct or
    support a multicast network(e.g. IPmcast network).

    The IP multicast access networks are interconnected by P2MP TE LSPs.
    A P2MP TE LSP is established from an ingress LSR which accommodates
    an IP multicast network that has a multicast source to multiple
    egress LSRs which each accommodate an IP multicast network.

    In this scenario, ingress/egress LSRs placed at the edge of
    multicast network must handle an IP multicast routing protocol.
    This means that the ingress/egress LSRs exchange IP multicast
    routing messages as
   neighbour neighbor routers. Figure 3 shows a network
    example of this scenario.

    A P2MP TE LSP is established from a I-LSR1 to E-LSR2, E-LSR3, E-LSR4
    and the ingress/egress LSR exchanges the multicast routing messages
    with each other.

    As specified in the section on related to the problem statement it
    should be possible for a solution to add/remove egress LSRs to/from
    the P2MP MPLS TE LSP. IP multicast group membership distribution
    between the egress LSRs may change frequently. This in turn may
    require a potential P2MP MPLS TE solution, that is suitable for IP
    multicast, to handle additions/deletions of egress LSRs with an
    appropriate reactiveness.

    It is recommended to support a message exchange mechanism on top of
    P2MP LSP setup mechanism to support multicast (S, G) Join/Leave.

    Though several schemes exist to handle this scenario, these are out
    of scope of this document. This document only describes requirements
    to setup a P2MP TE LSP.

                              Mcast Source
                                   |
                            +-----MR-----+
                            |      |     |
                            |     MR     |
                            +------|-----+
                +---------------I-LSR1----------------+
                |              // ||| \\              |
                |             //  |||  \\             |
                |            //  |LSR|  \\            |
                |        ___//____/|_____\\____       |
                |       /  //     |||     \\   \      |
                |       | //      |||      \\  |      |
                +-----E-LSR2----E-LSR3-----E-LSR4-----+
                +---- / ---++------|------++--- \ ----+
                |    |     ||      |      ||    |     |
           R1---MR---MR    ||      MR     ||    MR__  |
                |   /  \   ||     /  \    ||   /  \ \MR---R8
                +--MR--MR--++----MR--MR---++--MR--MR--+
                   |    |        |    |       |    |
                   R2   R3       R4   R5      R6   R7

                                 Figure 3

4.3  Layer 2 Multicast Over MPLS

    Existing layer 2 networks offer multicast video services. These are
    typically carried using layer 2 NBMA technology such as ATM or
    layer 2 Broadcast Access technology such as Ethernet. It may be
    desirable to deliver these layer 2 multicast services over
    a converged MPLS infrastructure where P2MP TE LSPs are used instead.

    For instance, several SPs provision P2MP ATM VCs for TV/ADSL
    services. These P2MP VCs are setup between a video server and a set
    of ATM DSLAMs. Each channel is carried in a distinct P2MP VC. These
    VC maybe be routed independently, or may all be nested into a unique
    PVC, connecting the video sever to all DSLAMs.

    Such service could benefit from a P2MP MPLS-TE control plane. An
    option is to setup a permanent P2MP TE LSP between the video server
    and all DSLAMs, that would correspond to a PVC carrying all channel
    VCs. In this case each DSLAM receives all channels, even if there
    are no receivers that are registered for a given channel.
    This ensure fast zapping, but lead to significant bandwidth wasting.

    A second option is to setup a distinct P2MP TE LSP per channel. If a
    client, behind a DSLAM, zaps to a new channel, then the DSLAM has
    to be added to the P2MP TE LSP carrying this channel using a P2MP TE
    grafting procedure. procedure, if it is not already egress LSR for that LSP.
    Pruning procedure has to be used to remove a DSLAM from the P2MP TE
    LSP if it when there is not already egress LSR for that
   LSP because all the clients, no longer any client behind the DSLAM, stop watching
    the channel.

4.4 VPN multicast network

    In this scenario, P2MP TE LSPs are could be utilized to construct a
    provider network which can deliver VPN multicast service(s) to its
    customers.

    A P2MP TE LSP is established between all the PE routers which
    accommodate the customer private network(s) that handle the IP
    multicast packets. Each PE router must handle a VPN instance.

    For example, in Layer3 VPNs like BGP/MPLS based IP VPNs
    [BGPMPLS-VPN], this means that each PE router must handle both
    private multicast VRF tables and common multicast routing and
    forwarding table.  And each PE router exchanges private multicast
    routing information between the corresponding PE routers. It is
   desirable that In case
    of high rate source, the need for P2MP MPLS TE LSP can be used envisaged for
    Layer3 VPN data transmission.

    Another example is a Layer2 VPN that supports multipoint LAN
    connectivity service. In an Ethernet network environment, IP
    multicast data is flooded to the appropriate Ethernet port(s).

    An Ethernet multipoint Layer2 VPN service provided by MPLS, this
    function is achieved by switching MPLS encapsulated frames towards
    the relevant PE nodes. But if existing P2P TE LSPs are used as
    tunnels between PEs, any ingress PE must duplicate the frames and
    send them to the corresponding PEs. This means the data stream is
    flooded just from the ingress PE, which will waste the provider's
    network resources.

    So, for Layer 2 VPNs that are required to support multicast traffic,
    it is might be desirable that P2MP MPLS TE LSPs are used for data
    transmission with an appropriate layer 2 encapsulation technique
    (for example, pseudo wire) instead of P2P MPLS TE LSPs, contributing
    in turn to savings of network resources.

    This document does not set requirements for how multicast VPNs are
    provided, but it does set requirements for the function that must be
    available in P2MP MPLS solutions. Therefore, it is not a requirement
    that multicast VPNs utilize P2MP MPLS, TE LSPs, but it is a requirement
    that P2MP MPLS solutions should be capable of supporting multicast
    VPNs.

    As already pointed out, application-specific requirements are out of
    the scope of this document.

4.5 GMPLS Networks

    GMPLS currently supports only P2P TE-LSPs just like MPLS. GMPLS
    enhances MPLS to support four new classes of interfaces: Layer-2
    Switch Capable (L2SC), Time-Division Multiplex (TDM), Lambda Switch
    Capable (LSC) and Fiber-Switch Capable (FSC) in addition to Packet
    Switch Capable (PSC) already supported by MPLS. All of these
    interface classes have so far been limited to P2P TE LSPs
    (see [RFC 3473] [RFC3473] and [RFC 3471]).

    The requirement for P2MP services for non-packet switch interfaces
    is similar to that for PSC interfaces. In particular, cable
    distribution services such as video distribution are prime
    candidates to use P2MP features. Therefore, it is a requirement that
    reasonable attempts must be made to make all the features/mechanisms
    (and protocol extensions) that will be defined to provide MPLS P2MP
    TE LSPs will be equally applicable to P2MP PSC and non-PSC TE-LSPs.

5. Detailed If the
    requirements for P2MP of non-PSC networks over-complicate the PSC solution a
    decision may be taken to separate the solutions. This decision must
    be taken in full consultation with the MPLS and CCAMP working
    groups.

5. Detailed requirements for P2MP TE extensions

5.1 P2MP LSP tunnels

    The P2MP RSVP-TE TE extensions MUST be applicable to the signaling of LSPs
    of different traffic types. For example, it MUST be possible to
    signal a P2MP TE LSP to carry any kind of payload being packet or
    non-packet based (including frame, cell, TDM un/structured, etc.)
    Carrying IP multicast or Ethernet traffic within a P2MP tunnel are
    typical examples.

    As with P2P MPLS technology [RFC3031], traffic is classified with a
    FEC in this extension. All packets which belong to a particular FEC
    and which travel from a particular node MUST follow the same P2MP
    tree.

    In order to scale to a large number of branches, P2MP TE LSPs SHOULD
    be identified by a unique identifier (the P2MP ID or Pid) that is
    constant for the whole LSP regardless of the number of branches
    and/or leaves. Therefore, the identification of the P2MP session by
    its destination addresses is not adequate.

5.2 P2MP explicit routing

    Various optimizations in P2MP tree formation need to be applied to
    meet various QoS requirements and operational constraints.

    Some P2MP applications may request a bandwidth guaranteed P2MP tree
    which satisfies end-to-end delay requirements. And some operators
    may want to set up a cost minimum P2MP tree by specifying branch LSRs
    explicitly.

    The P2MP TE solution therefore MUST provide a means of establishing
    arbitrary P2MP trees under the control of an external tree
    computation process or path configuration process or dynamic tree
    computation process located on the ingress LSR. Figure 4 shows two
    typical examples.

                 A                                      A
                 |                                    /   \
                 B                                   B     C
                 |                                  / \   / \
                 C                                 D   E  F   G
                 |                                / \ / \/ \ / \
     D--E*-F*-G*-H*-I*-J*-K*--L                  H  I J KL M N  O

          Steiner P2MP tree                        SPF P2MP tree

                 Figure 4 Examples of P2MP TE LSP topology

    One example is the Steiner P2MP tree (Cost minimum P2MP tree)
    [STEINER]. This P2MP tree is suitable for constructing a cost
    minimum P2MP tree. tree so as to minimize the bandwidth consumption in
    the core. To realize this P2MP tree, several intermediate LSRs must
    be both MPLS data terminating LSRs and transit LSRs (LSRs E, F, G,
    H, I, J and K in the figure 4). This means that the LSRs must
    perform both label swapping and popping at the same time. Therefore,
    the P2MP TE solution MUST support a mechanism that can setup this
    kind of bud LSR between an ingress LSR and egress LSRs. Note that
    this includes constrained Steiner trees that allow for the
    computation of a minimal cost trees with some other constraints such
    as a bounded delay between the source and every receiver.

    Another example is a CSPF (Constraint Shortest Path Fast) First) P2MP
    tree. By some metric (which can be set upon any specific criteria
    like the delay, bandwidth, a combination of those), one can
    calculate a cost
   minimum shortest path P2MP tree. This P2MP tree is suitable for
    carrying real time traffic.

    The solution MUST allow the operator to make use of any tree
    computation technique. In the former case an efficient/optimal tree
    is defined as a minimal cost tree (Steiner tree) whereas in the
    later case it is defined as the tree that provides shortest path
    between the source and any receiver.

    To support explicit setup of any reasonable P2MP tree shape, a P2MP
    TE solution MUST support some form of explicit source-based control
    of the P2MP tree which can explicitly include particular LSRs as
    branch nodes. This can be used by the ingress LSR to setup the P2MP
    TE LSP. Being implementation specific (more precisely dependent on
   the data structure specific representation and its processing), the
   detailed method for controlling the P2MP TE LSP topology depends on
   how the control plane represents the P2MP TE LSP data plane entity.  For instance, a P2MP TE LSP can be simply represented as a
    whole tree or by its individual branches.

   Here the effectiveness of the potential solutions is left outside
   the scope of this document. In any case, it is expected that this
   control must be driven by the ingress LSR.

5.3 Explicit Path Loose Hops and Widely Scoped Abstract Nodes

    A P2MP tree is completely specified if all of the required branches
    and hops between a sender and leaf LSR are indicated.

    A P2MP tree is partially specified if only a subset of intermediate
    branches and hops are indicated. This may be achieved using loose
    hops in the explicit path, or using widely scoped abstract nodes
    such as IPv4 prefixes shorter than 32 bits, or AS numbers.
    A partially specified P2MP tree may might be particularly useful in
    inter-area and inter-AS situations. situations although P2MP requirements for
    inter-area and inter-AS are beyond the scope of this document.

    Protocol solutions SHOULD include a way to specify loose hops and
    widely scoped abstract nodes in the explicit source-
   based source-based control
    of the P2MP tree as defined in the previous section. Where this
    support is provided, protocol solutions MUST allow downstream LSRs
    to apply further explicit control to the P2MP tree to resolve a
    partially specified tree into a (more) completely specified tree.

    Protocol solutions MUST allow the P2MP tree to be completely
    specified at the ingress where sufficient information exists to
    allow the full tree to be computed.

    In all cases, the egress nodes of the P2MP TE LSP must be fully
    specified.

    In case of a tree being computed by some downstream LSRs (e.g. the
    case of hops specified as loose hops), the solution MUST provide
    the ability for the ingress LSR of the P2MP TE LSP to learn the full
    P2MP tree. Note that this requirement MAY be relaxed in some
    environments (e.g. Inter-AS) where confidentiality must be preserved.

5.4 P2MP TE LSP establishment, teardown, and modification mechanisms

    The P2MP TE solution MUST support large scale establishment, maintenance and
    teardown of P2MP TE LSPs
   establishment and teardown in a scalable manner. This MUST include
    both the existence of very many LSPs at once, and the existence of
    very many destinations for a single P2MP LSP.

    In addition to P2MP TE LSP establishment and teardown mechanism, it
    SHOULD implement partial P2MP tree modification mechanism.

    For the purpose of adding sub-P2MP TE LSPs to an existing P2MP TE
    LSP, the extensions SHOULD support a grafting mechanism. For the
    purpose of deleting a sub-P2MP TE LSPs from an existing P2MP TE LSP,
    the extensions SHOULD support a pruning mechanism.

    It is RECOMMENDED that these grafting and pruning operations do not
    cause any additional processing in nodes except along the path to
    the grafting and pruning node and its downstream nodes. Moreover,
    both grafting and pruning operations MUST not be traffic disruptive
    for the traffic currently forwarded along the P2MP tree.

5.5 Fragmentation

   The P2MP TE solution MUST handle the situation where a single
   protocol message cannot contain all of the information necessary to
   signal the establishment of the P2MP LSP. It MUST be possible to
   establish the LSP in these circumstances.

   This situation may arrise in either of the following circumstances.
     a. The ingress LSR cannot signal the whole tree in a single
        message.
     b. The information in a message expands to be too large (or is
        discovered to be too large) at some transit node. This may
        occur because of some increase in the information that needs
        to be signaled or because of a reduction in the size of
        signaling message that is supported.

5.6 Failure Reporting and Error Recovery

    Failure events may cause egress nodes or sub-P2MP LSPs to become
    detached from the P2MP TE LSP. These events MUST be reported
    upstream as for a P2P LSP.

    The solution SHOULD provide recovery techniques such as protection
    and restoration allowing recovery of any impacted sub-P2MP TE
    LSPs. In particular, a solution MUST provide fast protection
    mechanisms applicable to P2MP TE LSP similar to the solutions
    specified in [FRR] for P2P TE LSPs. Note also that no assumption is
    made on whether backup paths for P2MP TE LSPs should or should not
    be shared with P2P TE LSPs backup paths. paths.

    Note that other application-specific requirement documents may
    introduce even more stringent requirement such as non packet loss,
    at the cost of some increased bandwidth consumption.

    The solution SHOULD also support the ability to meet other network
    recovery requirements such as bandwidth protection and bounded
    propagation delay increase along the backup path during failure.

    A P2MP TE solution MUST support P2MP fast protection mechanism to
    handle P2MP applications sensitive to traffic disruption.

    The report of the failure of delivery to fewer than all of the
    egress nodes SHOULD NOT cause automatic teardown of the P2MP TE LSP.

    That is, while some egress nodes remain connected to the P2MP tree
    it should be a matter of local policy at the ingress whether the
    P2MP LSP is retained.

    When all egress nodes downstreams downstream of a branch node have become
    disconnected from the P2MP tree, and the some branch node is unable
    to restore connectivity to any of them through by means of some recovery or
    protection mechanisms, the branch node MAY remove itself from the
    P2MP tree. tree provided that it is not also an egress LSR. Since the
    faults that severed the various downstream egress nodes from the
    P2MP tree may be disparate, the branch node MUST report all such
    errors to its upstream neighbor. The ingress node can then decide
    to re-compute the path to those particular egress nodes, around the
    failure point.

    Solutions MAY include the facility for transit LSRs and particularly
    branch nodes to recompute sub-P2MP trees to restore them after
    failures. In the event of successful repair, error notifications
    SHOULD NOT be reported to upstream nodes, but the new paths are
    reported if route recording is in use. Crankback requirements are
    discussed in Section 5.18.

5.6

5.7 Record route of P2MP TE LSP tunnels

    Being able to identify the established topology of P2MP TE LSP is
    very important for various purposes such as management and operation
    of some local recovery mechanisms like Fast Reroute [FRR]. A network
    operator uses this information to manage P2MP TE LSPs. Therefore,
    topology information MUST be collected and updated after P2MP TE LSP
    establishment and modification process.

   For this purpose, the conventional Record Route mechanism is useful.
   As with other conventional mechanism, this information should be
   forwarded upstream towards the sender node.

    The P2MP TE solution MUST support a mechanism which can collect and
    update P2MP tree topology information after P2MP LSP establishment
    and modification process. For example, the P2P MPLS TE mechanism of
    route recording could be extended and used if RSVP-TE was used as
    the P2MP signaling protocol.

    It is RECOMMENDED that the information is collected in a data format
    by which the sender node can recognize the P2MP tree topology
    without involving some complicated data calculation process.

    The solution MUST support the recording of both outgoing interfaces
    and node-id [NODE-ID].

5.7

5.8 Call Admission Control (CAC) and QoS Control mechanism
     of P2MP TE LSP tunnels LSPs

    P2MP TE LSPs may share network resource with P2P TE LSPs. Therefore
    it is important to use CAC and QoS in the same way as P2P TE LSPs
    for easy and scalable operation.

    In particular, it should be highlighted that because Multicast
    traffic cannot make use of P2P TE LSP, multicast traffic cannot be
    easily taken into account by P2P TE LSPs when performing CAC.

    The use of P2MP TE LSP will now allow for an accounting of the
    unicast and multicast traffic for bandwidth reservation.

    P2MP TE solutions MUST support both FF resource sharing and SE reservation styles. exclusive
    resource utilization to facilitate co-existence with other LSPs to
    the same destination(s).

    P2MP TE solution MUST be applicable to Diffserv-enabled DiffServ-enabled networks
    that can provide consistent QoS control in P2MP LSP traffic.

    Any solution SHOULD also satisfy the DS-TE requirements [RFC3564]
    and interoperate smoothly with current P2P DS-TE protocol
    specifications.

    Note that this requirement document does not make any assumption on
    the type of bandwidth pool used for P2MP TE LSPs which can either be
    shared with P2P TE LSP or be dedicated for P2MP use.

5.8

5.9 Reoptimization of P2MP TE LSP

    The detection of a more optimal path (for example, one with a lower
    overall cost) is an example of a situation where P2MP TE LSP
    re-routing may be required. While re-routing is in progress, an
    important requirement is avoiding double bandwidth reservation
    (over the common parts between the old and new LSP) thorough the use
    of resource sharing.

    Make-before-break
   (see [RFC3209]) delivers simultaneously a solution to these
   requirements.

   Make-before-break MUST be supported for a P2MP TE LSP to ensure that
    there is no traffic disruption when the P2MP TE LSP is re-routed.
    For example, the P2P MPLS TE make-before-break mechanism could be
    extended and used if RSVP-TE was used as the P2MP signaling protocol.

    It is possibile possible to achieve make-before-break that only applies to a
    sub-P2MP tree without impacting the data on all of the other parts
    of the P2MP tree.

    The solution SHOULD allow for make-before-break reoptimization of a
    sub-tree with no impact on the rest of the tree (no label
    reallocation, no change in identifiers, etc.).

    The solution SHOULD also provide the ability for the ingress LSR to
    have a strict control on the reoptimization process.
    Such reoptimization MAY be initiated by the sub-tree root branch
    node (that is, the branch node MAY setup a new sub-tree, then splice
    traffic on the new subtree and delete the former sub-tree).

5.9

5.10 IPv4/IPv6 support

    Any P2MP TE solution MUST be equally applicable to IPv4 and IPv6.

5.10

5.11 P2MP MPLS Label

    A P2MP TE solution MUST support establishment of both P2P and P2MP
    TE LSPs and MUST NOT impede the operation of P2P TE LSPs within the
    same network. A P2MP TE solution MUST be specified in such a way
    that it allows P2MP and P2P TE LSPs to be signaled on the same
    interface. Labels for P2MP TE LSPs and P2P TE LSPs MAY be assigned
    from shared or dedicated label space(s). Label space shareability is
    implementation specific.

5.11

5.12 Routing advertisement of P2MP capability

    Several high-level requirements have been identified to determine
    the capabilities of LSRs within a P2MP network. This The aim of such
    information is to facilitate the computation of P2MP trees using TE
    constraints within a network that contains LSRs that do not all have
    the same capabilities levels with respect to P2MP signaling and data
    forwarding.

    These capabilities include, but are not limited to:

    - the ability of an LSR to support branching.
    - the ability of an LSR to act as an egress and a branch for the
      same LSP.
    - the ability of an LSR to support P2MP MPLS-TE signalling.

    It is expected that it may be appropriate to gather this information
    through extensions to TE IGPs (see [RFC3630] and [IS-IS-TE]), but
    the precise requirements and mechanisms are out of the scope of this
    document. It is expected that a separate document will cover this
    requirement.

5.12

5.13 Multi-Area/AS LSP

    P2MP TE solutions SHOULD support multi-area/AS P2MP TE LSPs.

    The precise requirements in support of multi-area/AS P2MP TE LSPs is
    out of the scope of this document. It is expected that a separate
    document will cover this requirement.

5.13

5.14 P2MP MPLS OAM

    Management of P2MP LSPs is as important as the management of P2P
    LSPs.

    The MPLS and GMPLS MIB modules MUST be enhanced to provide P2MP TE
    LSP management.

    In order to facilitate correct management, P2MP TE LSPs MUST have
    unique identifiers.

    OAM facilities will have special demands in P2MP environments
    especially within the context of tracing the paths and connectivity
    of P2MP TE LSPs. The precise requirements and mechanisms for OAM are
    out of the scope of this document. It is expected that a separate
    document will cover these requirements.

5.14

5.15 Scalability

    Scalability is a key requirement in P2MP MPLS systems. Solutions
    MUST be designed to scale well with an increase in the number of any
    of the following:

    - the number of recipients
    - the number of branch points
    - the number of branches.

    Both scalability of performance and operation MUST be considered.

    Key considerations SHOULD include:
    - the amount of refresh processing associated with maintaining
      a P2MP TE LSP.
    - the amount of protocol state that must be maintained by ingress
      and transit LSRs along a P2MP tree.
    - the number of protocol messages required to set up or tear down a
      P2MP LSP as a function of the number of egress LSRs.
    - the number of protocol messages required to repair a P2MP LSP
      after failure or perform make-before-break.
    - the amount of protocol information transmitted to manage
      a P2MP TE LSP (i.e. the message size).
    - the amount of potential routing extensions.
    - the amount of control plane processing required by the ingress,
      transit and egress LSRs to add/delete a branch LSP to/from an
      existing P2MP LSP.

5.15

    It is expected that the applicability of each solution will be
    evaluated with regards to the aforementioned scalability criteria.

5.16 Backwards Compatibility

    It SHOULD be an aim of any P2MP solution to offer as much backward
    compatibility as possible. An ideal which is probably impossible to

    achieve would be to offer P2MP services across legacy MPLS networks
    without any change to any LSR in the network.

    If this ideal cannot be achieved, the aim SHOULD be to use legacy
    nodes as both transit non-branch LSRs and egress LSRs.

    It is a further requirement of all protocol solutions for the solution that any LSR that
    implements the solution SHALL NOT be prohibited by that act from
    supporting P2P TE LSPs using existing signaling mechanisms. That is,
    unless administratively prohibited, P2P TE LSPs MUST be supported
    through a P2MP network.

5.16

    Also, it is a requirement that P2MP TE LSPs MUST be able to co-exist
    with IP unicast and IP multicast networks.

5.17 GMPLS

    Solutions for MPLS P2MP TE-LSPs when applied to GMPLS P2MP PSC or
    non-PSC TE-LSPs MUST be backward and forward compatible with the
    other features of GMPLS including:

    - control and data plane separation (IF_ID RSVP_HOP and IF_ID
      ERROR_SPEC),
    - full support of numbered and unnumbered TE links (see [RFC 3477]
      and [GMPLS-ROUTE]),
    - use of the GENERALIZED_LABEL_REQUEST and GENERALIZED_LABEL_REQUEST, the GENERALIZED_LABEL
      (C-Type 2 and 3) 3), the SUGGESTED_LABEL and the RECOVERY_LABEL,
      in conjunction with the LABEL_SET and the ACCEPTABLE_LABEL_SET
      object,
    - processing of the ADMIN_STATUS object,
    - processing of the PROTECTION object,
    - support of Explicit Label Control,
    - processing of the Path_State_Removed Flag,
    - handling of Graceful Deletion procedures.
    - E2E and Segment Recovery procedures.

    In addition, since non-PSC TE-LSPs may have to be processed in
    environments where the "P2MP capability" could be limited, specific
    constraints may also apply during the P2MP TE Path computation.
    Being technology specific, these constraints are outside the scope
    of this document. However, technology independent constraints
    (i.e. constraints that are applicable independently of the LSP
    class) SHOULD be allowed during P2MP TE LSP message processing.
    It has to be emphasized that path computation and management
    techniques shall be as close as possible to those being used for
    PSC P2P TE LSPs and P2MP TE LSPs.

   Finally, note that bi-directional TE LSPs are not applicable to
   multicast traffic. Although many leaf nodes may be considered as
   senders in a multicast group, a P2MP TE LSP models a single
   distribution tree from a sender to multiple recipients. If such
   a tree were made bi-directional it would be a multipoint-to-point
   tree in the reverse direction.

5.17

5.18 Requirements for Hierarchical P2MP TE LSPs

    [LSP-HIER] defines concepts and procedures for P2P LSP hierarchy.

    These procedures SHOULD be extended to support P2MP LSP hierarchy.

    The P2MP MPLS-TE solution SHOULD support the concept of region and
    region hierarchy (PSC1<PSC2<PSC3<PSC4<L2SC<TDM<LSC<FSC).

    Particularly it SHOULD allow a Region i P2MP TE LSP to be nested
    into a region j P2MP TE LSP or multiple region j P2P TE LSPs,
    providing that i<j.

    The precise requirements and mechanisms for this function are out of
    the scope of this document. It is expected that a separate document
    will cover these requirements.

5.18

5.19 P2MP Crankback routing

    P2MP solutions SHOULD support cranckback crankback requirements as defined in
    [CRANKBACK]. In particular, they SHOULD provide sufficient
    information to a branch LSR from downstream LSRs to allow the branch
    LSR to re-route a sub-tree around any failures or problems in the
    network.

6. Security Considerations

    This requirements document does not define any protocol extensions
    and does not, therefore, make any changes to any security models.

    It should be noted that P2MP signaling mechanisms built on P2P
    RSVP-TE signaling are likely to inherit all of the security
    techniques and problems associated with RSVP-TE. These problems may
    be exacerbated in P2MP situations where security relationships may
    need to maintained between an ingress and multiple egresses. Such
    issues are similar to security issues for IP multicast.

    It is a requirement that documents offering solutions for P2MP LSPs
    MUST have detailed security sections.

7. Acknowledgements

    The authors would like to thank George Swallow, Ichiro Inoue and Inoue, Dean Cheng
    Cheng, and Eric Rosen for their review and suggestions on an earlier draft of
   this document. suggestions.

8. References

8.1 Normative References

    [RFC2119]     Bradner, S., "Key words for use in RFCs to Indicate
                  Requirement Levels", BCP 14, RFC 2119, March 1997.

    [RFC2475]     Blake, S., Black, D., Carlson, M., Davies, E., Wang, Z.
                  and W. Weiss,  "An Architecture for Differentiated
                  Services", RFC 2475, December 1998.

    [RFC2597]     Heinanen, J., Baker, F., Weiss, W. and J. Wroclawski,
                  "Assured Forwarding PHB Group", RFC 2597, June 1999.

    [RFC2702]     D. Awduche, J. Malcolm, J. Agogbua, M. O'Dell, J.
                  McManus, "Requirements for Traffic Engineering Over
                  MPLS", RFC2702, September 1999.

    [RFC3031]     Rosen, E., Viswanathan, A. and R. Callon,
                  "Multiprotocol Label Switching Architecture", RFC 3031,
                  January 2001.

    [RFC3209]     Awduche, D., Berger, L., Gan, D., Li, T., Srinivasan,
                  V. and G. Swallow, "RSVP-TE: Extensions to RSVP for LSP
                  Tunnels", RFC 3209, December 2001.

    [RFC3246]     Davie, B., Charny, A., Bennet, J.C.R., Benson, K., Le
                  Boudec, J.Y., Davari, S., Courtney, W., Firioiu, V. and
                  D. Stiliadis, "An Expedited Forwarding PHB (Per-Hop
                  Behavior)", RFC 3246, March 2002.

    [RFC3667]     Bradner, S., "IETF Rights in Contributions", BCP 78,
                  RFC 3667, February 2004.

    [RFC3668]     Bradner, S., Ed., "Intellectual Property Rights in IETF
                  Technology", BCP 79, RFC 3668, February 2004.

8.2 Informational References

    [RFC3471]     Berger, L., Editor, "Generalized Multi-Protocol Label
                  Switching (GMPLS) Signaling Functional Description",
                  RFC 3471, January 2003.

    [RFC3473]     Berger, L., Editor, "Generalized Multi-Protocol Label
                  Switching (GMPLS) Signaling - Resource ReserVation
                  Protocol-Traffic Engineering (RSVP-TE) Extensions",
                  RFC 3473, January 2003.

    [RFC3477]     K. Kompella, Y. Rekhter, "Signalling Unnumbered Links
                  in Resource ReSerVation Protocol -Traffic Engineering
                  (RSVP-TE)", RFC3477, January 2003.

    [RFC3564]     F. Le Faucheur, W. Lai, "Requirements for Support of
                  Differentiated Services-aware MPLS Traffic
                  Engineering", RFC 3564, July 2003.

    [RFC3630]     D. Katz, D. Yeung, K. Kompella, "Traffic Engineering
                  Extensions to OSPF Version 2", RFC 3630, September
                  2003.

    [PIM-SM]      B. Fenner, M. Hadley, H. Holbrook, I. Kouvelas,
                  "Protocol Independent Multicast - Sparse Mode (PIM-SM):
                  Protocol Specification (Revised)", draft-ietf-pim-sm-
                  v2-new-08.txt, October 2003.

    [BGPMPLS-VPN] E. Rosen, Y.Rekhter, Editor, "BGP/MPLS IP VPNs",
                  draft-ietf-l3vpn-rfc2547bis-01.txt, September 2003.

    [GMPLS-ROUTE] K. Kompella, Y. Rekhter,  Editor, "Routing Extensions
                  in Support of Generalized Multi-Protocol Label
                  Switching", draft-ietf-ccamp-gmpls-routing-08.txt,
                  October 2003.

    [STEINER]     H. Salama, et al., "Evaluation of Multicast Routing
                  Algorithm for Real-Time Communication on High-Speed
                  Networks," IEEE Journal on Selected Area in
                  Communications, pp.332-345, 1997.

    [FRR]         P. Pan, D. Gan, G. Swallow, J. P. Vasseur, D. Cooper,
                  A. Atlas, M. Jork,"Fast Reroute Extensions to RSVP-TE
                  for LSP Tunnels", draft-ietf-mpls-rsvp-lsp-fastreroute-
                 03.txt,
                  draft-ietf-mpls-rsvp-lsp-fastreroute-03.txt, July
                  2003.

    [IS-IS-TE]    Henk Smit, Tony Li, "IS-IS extensions for Traffic
                  Engineering", draft-ietf-isis-traffic-04.txt, December
                  2002.

    [CRANKBACK]   A. Farrel, A. Satyanarayana, A. Iwata, N. Fujita, G.
                  Ash, S. Marshall, "Crankback Signaling Extensions for
                  MPLS Signaling", draft-ietf-ccamp-crankback-01.txt,
                  January 2004.

    [LSP-HIER]    K. Kompella, Y. Rekhter, "LSP Hierarchy with
                  Generalized MPLS TE", draft-ietf-mpls-lsp-hierarchy-
                  08.txt, September 2002.

    [NODE-ID]     Vasseur, Ali and Sivabalan, "Definition of an RRO node-
                  id subobject", draft-ietf-mpls-nodeid-subobject-01.txt,
                  June 2003.

9. Editor's Address

    Seisho Yasukawa
    NTT Corporation
    9-11, Midori-Cho 3-Chome
    Musashino-Shi, Tokyo 180-8585,
    Japan
    Phone: +81 422 59 4769
    Email: yasukawa.seisho@lab.ntt.co.jp

10. Authors' Addresses

    Dimitri Papadimitriou
    Alcatel
    Francis Wellensplein 1,
    B-2018 Antwerpen,
    Belgium
    Phone : +32 3 240 8491
    Email: dimitri.papadimitriou@alcatel.be

    JP Vasseur
    Cisco Systems, Inc.
    300 Beaver Brook Road
    Boxborough, MA 01719,
    USA
    Email: jpv@cisco.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
    Rahul Aggarwal
    Juniper Networks
    1194 North Mathilda Ave.
    Sunnyvale, CA 94089
    Email: rahul@juniper.net

    Alan Kullberg
    Motorola Computer Group
    120 Turnpike Rd.
    Southborough, MA 01772
    Email: alan.kullberg@motorola.com

    Adrian Farrel
    Old Dog Consulting
    Phone: +44 (0) 1978 860944
    Email: adrian@olddog.co.uk

    Markus Jork
    Avici Systems
    101 Billerica Avenue
    N. Billerica, MA 01862
    Phone: +1 978 964 2142
    Email: mjork@avici.com

    Andrew G. Malis
    Tellabs
    2730 Orchard Parkway
    San Jose, CA 95134
    Phone: +1 408 383 7223
    Email: andy.malis@tellabs.com

    Jean-Louis Le Roux
    France Telecom
    2, avenue Pierre-Marzin
    22307 Lannion Cedex
    France
    Email: jeanlouis.leroux@francetelecom.com

11. Intellectual Property Consideration

    The IETF takes no position regarding the validity or scope of any
    Intellectual Property Rights or other rights that might be claimed
    to pertain to the implementation or use of the technology
    described in this document or the extent to which any license
    under such rights might or might not be available; nor does it
    represent that it has made any independent effort to identify any
    such rights.  Information on the procedures with respect to rights
    in RFC documents can be found in BCP 78 and BCP 79.

    Copies of IPR disclosures made to the IETF Secretariat and any
    assurances of licenses to be made available, or the result of an
    attempt made to obtain a general license or permission for the use
    of such proprietary rights by implementers or users of this
    specification can be obtained from the IETF on-line IPR repository
    at http://www.ietf.org/ipr.

    The IETF invites any interested party to bring to its attention
    any copyrights, patents or patent applications, or other
    proprietary rights that may cover technology that may be required
    to implement this standard.  Please address the information to the
    IETF at ietf-ipr@ietf.org.

11.1 IPR Disclosure Acknowledgement

    By submitting this Internet-Draft, I certify that any applicable
    patent or other IPR claims of which I am aware have been disclosed,
    and any of which I become aware will be disclosed, in accordance
    with RFC 3668.

12. Full Copyright Statement

    Copyright (C) The Internet Society (2004).  This document is
    subject to the rights, licenses and restrictions contained in BCP
    78, and except as set forth therein, the authors retain all their
    rights.

    This document and the information contained herein are provided
    on an "AS IS" basis and THE CONTRIBUTOR, THE ORGANIZATION HE/SHE
    REPRESENTS OR IS SPONSORED BY (IF ANY), THE INTERNET SOCIETY AND
    THE INTERNET ENGINEERING TASK FORCE DISCLAIM ALL WARRANTIES,
    EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO ANY WARRANTY THAT
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    ANY IMPLIED WARRANTIES OF MERCHANTABILITY OR FITNESS FOR A
    PARTICULAR PURPOSE.