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rfc:rfc6006

Internet Engineering Task Force (IETF) Q. Zhao, Ed. Request for Comments: 6006 Huawei Technology Category: Standards Track D. King, Ed. ISSN: 2070-1721 Old Dog Consulting

                                                          F. Verhaeghe
                                           Thales Communication France
                                                             T. Takeda
                                                       NTT Corporation
                                                                Z. Ali
                                                   Cisco Systems, Inc.
                                                             J. Meuric
                                                        France Telecom
                                                        September 2010
                           Extensions to
     the Path Computation Element Communication Protocol (PCEP)
  for Point-to-Multipoint Traffic Engineering Label Switched Paths

Abstract

 Point-to-point Multiprotocol Label Switching (MPLS) and Generalized
 MPLS (GMPLS) Traffic Engineering Label Switched Paths (TE LSPs) may
 be established using signaling techniques, but their paths may first
 need to be determined.  The Path Computation Element (PCE) has been
 identified as an appropriate technology for the determination of the
 paths of point-to-multipoint (P2MP) TE LSPs.
 This document describes extensions to the PCE communication Protocol
 (PCEP) to handle requests and responses for the computation of paths
 for P2MP TE LSPs.

Status of This Memo

 This is an Internet Standards Track document.
 This document is a product of the Internet Engineering Task Force
 (IETF).  It represents the consensus of the IETF community.  It has
 received public review and has been approved for publication by the
 Internet Engineering Steering Group (IESG).  Further information on
 Internet Standards is available in Section 2 of RFC 5741.
 Information about the current status of this document, any errata,
 and how to provide feedback on it may be obtained at
 http://www.rfc-editor.org/info/rfc6006.

Zhao, et al. Standards Track [Page 1] RFC 6006 Extensions to PCEP for P2MP TE LSPs September 2010

Copyright Notice

 Copyright (c) 2010 IETF Trust and the persons identified as the
 document authors.  All rights reserved.
 This document is subject to BCP 78 and the IETF Trust's Legal
 Provisions Relating to IETF Documents
 (http://trustee.ietf.org/license-info) in effect on the date of
 publication of this document.  Please review these documents
 carefully, as they describe your rights and restrictions with respect
 to this document.  Code Components extracted from this document must
 include Simplified BSD License text as described in Section 4.e of
 the Trust Legal Provisions and are provided without warranty as
 described in the Simplified BSD License.
 This document may contain material from IETF Documents or IETF
 Contributions published or made publicly available before November
 10, 2008.  The person(s) controlling the copyright in some of this
 material may not have granted the IETF Trust the right to allow
 modifications of such material outside the IETF Standards Process.
 Without obtaining an adequate license from the person(s) controlling
 the copyright in such materials, this document may not be modified
 outside the IETF Standards Process, and derivative works of it may
 not be created outside the IETF Standards Process, except to format
 it for publication as an RFC or to translate it into languages other
 than English.

Table of Contents

 1. Introduction ....................................................3
    1.1. Terminology ................................................4
    1.2. Requirements Language ......................................5
 2. PCC-PCE Communication Requirements ..............................5
 3. Protocol Procedures and Extensions ..............................6
    3.1. P2MP Capability Advertisement ..............................6
         3.1.1. P2MP Computation TLV in the Existing PCE
                Discovery Protocol ..................................6
         3.1.2. Open Message Extension ..............................7
    3.2. Efficient Presentation of P2MP LSPs ........................7
    3.3. P2MP Path Computation Request/Reply Message Extensions .....8
         3.3.1. The Extension of the RP Object ......................8
         3.3.2. The New P2MP END-POINTS Object ......................9
    3.4. Request Message Format ....................................12
    3.5. Reply Message Format ......................................12
    3.6. P2MP Objective Functions and Metric Types .................13
         3.6.1. New Objective Functions ............................13
         3.6.2. New Metric Object Types ............................14
    3.7. Non-Support of P2MP Path Computation ......................14

Zhao, et al. Standards Track [Page 2] RFC 6006 Extensions to PCEP for P2MP TE LSPs September 2010

    3.8. Non-Support by Back-Level PCE Implementations .............15
    3.9. P2MP TE Path Reoptimization Request .......................15
    3.10. Adding and Pruning Leaves to/from the P2MP Tree ..........16
    3.11. Discovering Branch Nodes .................................19
         3.11.1. Branch Node Object ................................19
    3.12. Synchronization of P2MP TE Path Computation Requests .....19
    3.13. Request and Response Fragmentation .......................20
         3.13.1. Request Fragmentation Procedure ...................21
         3.13.2. Response Fragmentation Procedure ..................21
         3.13.3. Fragmentation Examples ............................21
    3.14. UNREACH-DESTINATION Object ...............................22
    3.15. P2MP PCEP-ERROR Objects and Types ........................23
    3.16. PCEP NO-PATH Indicator ...................................24
 4. Manageability Considerations ...................................25
    4.1. Control of Function and Policy ............................25
    4.2. Information and Data Models ...............................25
    4.3. Liveness Detection and Monitoring .........................25
    4.4. Verifying Correct Operation ...............................25
    4.5. Requirements for Other Protocols and Functional
         Components ................................................26
    4.6. Impact on Network Operation ...............................26
 5. Security Considerations ........................................26
 6. IANA Considerations ............................................27
    6.1. PCEP TLV Type Indicators ..................................27
    6.2. Request Parameter Bit Flags ...............................27
    6.3. Objective Functions .......................................27
    6.4. Metric Object Types .......................................27
    6.5. PCEP Objects ..............................................28
    6.6. PCEP-ERROR Objects and Types ..............................29
    6.7. PCEP NO-PATH Indicator ....................................30
    6.8. SVEC Object Flag ..........................................30
    6.9. OSPF PCE Capability Flag ..................................30
 7. Acknowledgements ...............................................30
 8. References .....................................................30
    8.1. Normative References ......................................30
    8.2. Informative References ....................................32

1. Introduction

 The Path Computation Element (PCE) defined in [RFC4655] is an entity
 that is capable of computing a network path or route based on a
 network graph, and applying computational constraints.  A Path
 Computation Client (PCC) may make requests to a PCE for paths to be
 computed.
 [RFC4875] describes how to set up point-to-multipoint (P2MP) Traffic
 Engineering Label Switched Paths (TE LSPs) for use in Multiprotocol
 Label Switching (MPLS) and Generalized MPLS (GMPLS) networks.

Zhao, et al. Standards Track [Page 3] RFC 6006 Extensions to PCEP for P2MP TE LSPs September 2010

 The PCE has been identified as a suitable application for the
 computation of paths for P2MP TE LSPs [RFC5671].
 The PCE communication Protocol (PCEP) is designed as a communication
 protocol between PCCs and PCEs for point-to-point (P2P) path
 computations and is defined in [RFC5440].  However, that
 specification does not provide a mechanism to request path
 computation of P2MP TE LSPs.
 A P2MP LSP is comprised of multiple source-to-leaf (S2L) sub-LSPs.
 These S2L sub-LSPs are set up between ingress and egress Label
 Switching Routers (LSRs) and are appropriately overlaid to construct
 a P2MP TE LSP.  During path computation, the P2MP TE LSP may be
 determined as a set of S2L sub-LSPs that are computed separately and
 combined to give the path of the P2MP LSP, or the entire P2MP TE LSP
 may be determined as a P2MP tree in a single computation.
 This document relies on the mechanisms of PCEP to request path
 computation for P2MP TE LSPs.  One path computation request message
 from a PCC may request the computation of the whole P2MP TE LSP, or
 the request may be limited to a sub-set of the S2L sub-LSPs.  In the
 extreme case, the PCC may request the S2L sub-LSPs to be computed
 individually with it being the PCC's responsibility to decide whether
 to signal individual S2L sub-LSPs or combine the computation results
 to signal the entire P2MP TE LSP.  Hence the PCC may use one path
 computation request message or may split the request across multiple
 path computation messages.

1.1. Terminology

 Terminology used in this document:
    TE LSP: Traffic Engineering Label Switched Path.
    LSR: Label Switching Router.
    OF: Objective Function: A set of one or more optimization criteria
    used for the computation of a single path (e.g., path cost
    minimization), or for the synchronized computation of a set of
    paths (e.g., aggregate bandwidth consumption minimization).
    P2MP: Point-to-Multipoint.
    P2P: Point-to-Point.
 This document also uses the terminology defined in [RFC4655],
 [RFC4875], and [RFC5440].

Zhao, et al. Standards Track [Page 4] RFC 6006 Extensions to PCEP for P2MP TE LSPs September 2010

1.2. Requirements Language

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

2. PCC-PCE Communication Requirements

 This section summarizes the PCC-PCE communication requirements for
 P2MP MPLS-TE LSPs described in [RFC5862].  The numbering system
 corresponds to the requirement numbers used in [RFC5862].
 1.  The PCC MUST be able to specify that the request is a P2MP path
     computation request.
 2.  The PCC MUST be able to specify that objective functions are to
     be applied to the P2MP path computation request.
 3.  The PCE MUST have the capability to reject a P2MP path request
     and indicate non-support of P2MP path computation.
 4.  The PCE MUST provide an indication of non-support of P2MP path
     computation by back-level PCE implementations.
 5.  A P2MP path computation request MUST be able to list multiple
     destinations.
 6.  A P2MP path computation response MUST be able to carry the path
     of a P2MP LSP.
 7.  By default, the path returned by the PCE SHOULD use the
     compressed format.
 8.  It MUST be possible for a single P2MP path computation request or
     response to be conveyed by a sequence of messages.
 9.  It MUST NOT be possible for a single P2MP path computation
     request to specify a set of different constraints, traffic
     parameters, or quality-of-service requirements for different
     destinations of a P2MP LSP.
 10. P2MP path modification and P2MP path diversity MUST be supported.
 11. It MUST be possible to reoptimize existing P2MP TE LSPs.
 12. It MUST be possible to add and remove P2MP destinations from
     existing paths.

Zhao, et al. Standards Track [Page 5] RFC 6006 Extensions to PCEP for P2MP TE LSPs September 2010

 13. It MUST be possible to specify a list of applicable branch nodes
     to use when computing the P2MP path.
 14. It MUST be possible for a PCC to discover P2MP path computation
     capability.
 15. The PCC MUST be able to request diverse paths when requesting a
     P2MP path.

3. Protocol Procedures and Extensions

 The following section describes the protocol extensions required to
 satisfy the requirements specified in Section 2 ("PCC-PCE
 Communication Requirements") of this document.

3.1. P2MP Capability Advertisement

3.1.1. P2MP Computation TLV in the Existing PCE Discovery Protocol

 [RFC5088] defines a PCE Discovery (PCED) TLV carried in an OSPF
 Router Information Link State Advertisement (LSA) defined in
 [RFC4970] to facilitate PCE discovery using OSPF.  [RFC5088]
 specifies that no new sub-TLVs may be added to the PCED TLV.  This
 document defines a new flag in the OSPF PCE Capability Flags to
 indicate the capability of P2MP computation.
 Similarly, [RFC5089] defines the PCED sub-TLV for use in PCE
 Discovery using IS-IS.  This document will use the same flag
 requested for the OSPF PCE Capability Flags sub-TLV to allow IS-IS to
 indicate the capability of P2MP computation.
 The IANA assignment for a shared OSPF and IS-IS P2MP Capability Flag
 is documented in Section 6.9 ("OSPF PCE Capability Flag") of this
 document.
 PCEs wishing to advertise that they support P2MP path computation
 would set the bit (10) accordingly.  PCCs that do not understand this
 bit will ignore it (per [RFC5088] and [RFC5089]).  PCEs that do not
 support P2MP will leave the bit clear (per the default behavior
 defined in [RFC5088] and [RFC5089]).
 PCEs that set the bit to indicate support of P2MP path computation
 MUST follow the procedures in Section 3.3.2 ("The New P2MP END-POINTS
 Object") to further qualify the level of support.

Zhao, et al. Standards Track [Page 6] RFC 6006 Extensions to PCEP for P2MP TE LSPs September 2010

3.1.2. Open Message Extension

 Based on the Capabilities Exchange requirement described in
 [RFC5862], if a PCE does not advertise its P2MP capability during
 discovery, PCEP should be used to allow a PCC to discover, during the
 Open Message Exchange, which PCEs are capable of supporting P2MP path
 computation.
 To satisfy this requirement, we extend the PCEP OPEN object by
 defining a new optional TLV to indicate the PCE's capability to
 perform P2MP path computations.
 IANA has allocated value 6 from the "PCEP TLV Type Indicators" sub-
 registry, as documented in Section 6.1 ("PCEP TLV Type Indicators").
 The description is "P2MP capable", and the length value is 2 bytes.
 The value field is set to default value 0.
 The inclusion of this TLV in an OPEN object indicates that the sender
 can perform P2MP path computations.
 The capability TLV is meaningful only for a PCE, so it will typically
 appear only in one of the two Open messages during PCE session
 establishment.  However, in case of PCE cooperation (e.g.,
 inter-domain), when a PCE behaving as a PCC initiates a PCE session
 it SHOULD also indicate its path computation capabilities.

3.2. Efficient Presentation of P2MP LSPs

 When specifying additional leaves, or optimizing existing P2MP TE
 LSPs as specified in [RFC5862], it may be necessary to pass existing
 P2MP LSP route information between the PCC and PCE in the request and
 reply messages.  In each of these scenarios, we need new path objects
 for efficiently passing the existing P2MP LSP between the PCE and
 PCC.
 We specify the use of the Resource Reservation Protocol Traffic
 Engineering (RSVP-TE) extensions Explicit Route Object (ERO) to
 encode the explicit route of a TE LSP through the network.  PCEP ERO
 sub-object types correspond to RSVP-TE ERO sub-object types.  The
 format and content of the ERO object are defined in [RFC3209] and
 [RFC3473].
 The Secondary Explicit Route Object (SERO) is used to specify the
 explicit route of a S2L sub-LSP.  The path of each subsequent S2L
 sub-LSP is encoded in a P2MP_SECONDARY_EXPLICIT_ROUTE object SERO.
 The format of the SERO is the same as an ERO defined in [RFC3209] and
 [RFC3473].

Zhao, et al. Standards Track [Page 7] RFC 6006 Extensions to PCEP for P2MP TE LSPs September 2010

 The Secondary Record Route Object (SRRO) is used to record the
 explicit route of the S2L sub-LSP.  The class of the P2MP SRRO is the
 same as the SRRO defined in [RFC4873].
 The SERO and SRRO are used to report the route of an existing TE LSP
 for which a reoptimization is desired.  The format and content of the
 SERO and SRRO are defined in [RFC4875].
 A new PCEP object class and type are requested for SERO and SRRO.
 Object-Class Value    29
 Name                  SERO
 Object-Type           1: SERO
                       2-15: Unassigned
 Reference             RFC 6006
 Object-Class Value    30
 Name                  SRRO
 Object-Type           1: SRRO
                       2-15: Unassigned
 Reference             RFC 6006
 The IANA assignment is documented in Section 6.5 ("PCEP Objects").
 Since the explicit path is available for immediate signaling by the
 MPLS or GMPLS control plane, the meanings of all of the sub-objects
 and fields in this object are identical to those defined for the ERO.

3.3. P2MP Path Computation Request/Reply Message Extensions

 This document extends the existing P2P RP (Request Parameters) object
 so that a PCC can signal a P2MP path computation request to the PCE
 receiving the PCEP request.  The END-POINTS object is also extended
 to improve the efficiency of the message exchange between PCC and PCE
 in the case of P2MP path computation.

3.3.1. The Extension of the RP Object

 The PCE path computation request and reply messages will need the
 following additional parameters to indicate to the receiving PCE that
 the request and reply messages have been fragmented across multiple
 messages, that they have been requested for a P2MP path, and whether
 the route is represented in the compressed or uncompressed format.
 This document adds the following flags to the RP Object:

Zhao, et al. Standards Track [Page 8] RFC 6006 Extensions to PCEP for P2MP TE LSPs September 2010

 The F-bit is added to the flag bits of the RP object to indicate to
 the receiver that the request is part of a fragmented request, or is
 not a fragmented request.
 o  F (RP fragmentation bit - 1 bit):
    0: This indicates that the RP is not fragmented or it is the last
       piece of the fragmented RP.
    1: This indicates that the RP is fragmented and this is not the
       last piece of the fragmented RP.  The receiver needs to wait
       for additional fragments until it receives an RP with the same
       RP-ID and with the F-bit set to 0.
 The N-bit is added in the flag bits field of the RP object to signal
 the receiver of the message that the request/reply is for P2MP or is
 not for P2MP.
 o  N (P2MP bit - 1 bit):
    0: This indicates that this is not a PCReq or PCRep message for
       P2MP.
    1: This indicates that this is a PCReq or PCRep message for P2MP.
 The E-bit is added in the flag bits field of the RP object to signal
 the receiver of the message that the route is in the compressed
 format or is not in the compressed format.  By default, the path
 returned by the PCE SHOULD use the compressed format.
 o  E (ERO-compression bit - 1 bit):
    0: This indicates that the route is not in the compressed format.
    1: This indicates that the route is in the compressed format.
 The IANA assignment is documented in Section 6.2 ("Request Parameter
 Bit Flags") of this document.

3.3.2. The New P2MP END-POINTS Object

 The END-POINTS object is used in a PCReq message to specify the
 source IP address and the destination IP address of the path for
 which a path computation is requested.  To represent the end points
 for a P2MP path efficiently, we define two new types of END-POINTS
 objects for the P2MP path:

Zhao, et al. Standards Track [Page 9] RFC 6006 Extensions to PCEP for P2MP TE LSPs September 2010

 o  Old leaves whose path can be modified/reoptimized;
 o  Old leaves whose path must be left unchanged.
 With the new END-POINTS object, the PCE path computation request
 message is expanded in a way that allows a single request message to
 list multiple destinations.
 In total, there are now 4 possible types of leaves in a P2MP request:
 o  New leaves to add (leaf type = 1)
 o  Old leaves to remove (leaf type = 2)
 o  Old leaves whose path can be modified/reoptimized (leaf type = 3)
 o  Old leaves whose path must be left unchanged (leaf type = 4)
 A given END-POINTS object gathers the leaves of a given type.  The
 type of leaf in a given END-POINTS object is identified by the END-
 POINTS object leaf type field.
 Using the new END-POINTS object, the END-POINTS portion of a request
 message for the multiple destinations can be reduced by up to 50% for
 a P2MP path where a single source address has a very large number of
 destinations.
 Note that a P2MP path computation request can mix the different types
 of leaves by including several END-POINTS objects per RP object as
 shown in the PCReq Routing Backus-Naur Form (RBNF) [RFC5511] format
 in Section 3.4 ("Request Message Format").

Zhao, et al. Standards Track [Page 10] RFC 6006 Extensions to PCEP for P2MP TE LSPs September 2010

 The format of the new END-POINTS object body for IPv4 (Object-Type 3)
 is as follows:
   0                   1                   2                   3
   0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
  +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
  |                          Leaf type                            |
  +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
  |                     Source IPv4 address                       |
  +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
  |                  Destination IPv4 address                     |
  +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
  ~                           ...                                 ~
  +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
  |                  Destination IPv4 address                     |
  +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
    Figure 1.  The New P2MP END-POINTS Object Body Format for IPv4
 The format of the END-POINTS object body for IPv6 (Object-Type 4) is
 as follows:
   0                   1                   2                   3
   0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
  +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
  |                          Leaf type                            |
  +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
  |                                                               |
  |                Source IPv6 address (16 bytes)                 |
  |                                                               |
  +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
  |                                                               |
  |              Destination IPv6 address (16 bytes)              |
  |                                                               |
  +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
  ~                           ...                                 ~
  +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
  |                                                               |
  |              Destination IPv6 address (16 bytes)              |
  |                                                               |
  +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
    Figure 2.  The New P2MP END-POINTS Object Body Format for IPv6
 The END-POINTS object body has a variable length.  These are
 multiples of 4 bytes for IPv4, and multiples of 16 bytes, plus 4
 bytes, for IPv6.

Zhao, et al. Standards Track [Page 11] RFC 6006 Extensions to PCEP for P2MP TE LSPs September 2010

3.4. Request Message Format

 The PCReq message is encoded as follows using RBNF as defined in
 [RFC5511].
 Below is the message format for the request message:
         <PCReq Message>::= <Common Header>
                               <request>
      where:
              <request>::= <RP>
                              <end-point-rro-pair-list>
                              [<OF>]
                              [<LSPA>]
                              [<BANDWIDTH>]
                              [<metric-list>]
                              [<IRO>]
                              [<LOAD-BALANCING>]
      where:
              <end-point-rro-pair-list>::=
                                 <END-POINTS>[<RRO-List>][<BANDWIDTH>]
                                 [<end-point-rro-pair-list>]
              <RRO-List>::=<RRO>[<BANDWIDTH>][<RRO-List>]
              <metric-list>::=<METRIC>[<metric-list>]
         Figure 3.  The Message Format for the Request Message
 Note that we preserve compatibility with the [RFC5440] definition of
 <request>.  At least one instance of <endpoints> MUST be present in
 this message.
 We have documented the IANA assignment of additional END-POINTS
 Object-Types in Section 6.5 ("PCEP Objects") of this document.

3.5. Reply Message Format

 The PCRep message is encoded as follows using RBNF as defined in
 [RFC5511].

Zhao, et al. Standards Track [Page 12] RFC 6006 Extensions to PCEP for P2MP TE LSPs September 2010

 Below is the message format for the reply message:
        <PCRep Message>::= <Common Header>
                              <response>
        <response>::=<RP>
                        [<end-point-path-pair-list>]
                        [<NO-PATH>]
                        [<attribute-list>]
      where:
         <end-point-path-pair-list>::=
                 [<END-POINTS>]<path>[<end-point-path-pair-list>]
        <path> ::= (<ERO>|<SERO>) [<path>]
        <attribute-list>::=[<OF>]
                             [<LSPA>]
                             [<BANDWIDTH>]
                             [<metric-list>]
                             [<IRO>]
          Figure 4.  The Message Format for the Reply Message
 The optional END-POINTS object in the reply message is used to
 specify which paths are removed, changed, not changed, or added for
 the request.  The path is only needed for the end points that are
 added or changed.
 If the E-bit (ERO-Compress bit) was set to 1 in the request, then the
 path will be formed by an ERO followed by a list of SEROs.
 Note that we preserve compatibility with the [RFC5440] definition of
 <response> and the optional <end-point-path-pair-list> and <path>.

3.6. P2MP Objective Functions and Metric Types

3.6.1. New Objective Functions

 Six objective functions have been defined in [RFC5541] for P2P path
 computation.
 This document defines two additional objective functions -- namely,
 SPT (Shortest Path Tree) and MCT (Minimum Cost Tree) that apply to
 P2MP path computation.  Hence two new objective function codes have
 to be defined.
 The description of the two new objective functions is as follows.

Zhao, et al. Standards Track [Page 13] RFC 6006 Extensions to PCEP for P2MP TE LSPs September 2010

 Objective Function Code: 7
    Name: Shortest Path Tree (SPT)
    Description: Minimize the maximum source-to-leaf cost with respect
    to a specific metric or to the TE metric used as the default
    metric when the metric is not specified (e.g., TE or IGP metric).
 Objective Function Code: 8
    Name: Minimum Cost Tree (MCT)
    Description: Minimize the total cost of the tree, that is the sum
    of the costs of tree links, with respect to a specific metric or
    to the TE metric used as the default metric when the metric is not
    specified.
 Processing these two new objective functions is subject to the rules
 defined in [RFC5541].

3.6.2. New Metric Object Types

 There are three types defined for the <METRIC> object in [RFC5440] --
 namely, the IGP metric, the TE metric, and the hop count metric.
 This document defines three additional types for the <METRIC> object:
 the P2MP IGP metric, the P2MP TE metric, and the P2MP hop count
 metric.  They encode the sum of the metrics of all links of the tree.
 We propose the following values for these new metric types:
 o  P2MP IGP metric: T=8
 o  P2MP TE metric: T=9
 o  P2MP hop count metric: T=10

3.7. Non-Support of P2MP Path Computation

 o  If a PCE receives a P2MP path request and it understands the P2MP
    flag in the RP object, but the PCE is not capable of P2MP
    computation, the PCE MUST send a PCErr message with a PCEP-ERROR
    object and corresponding Error-Value.  The request MUST then be
    cancelled at the PCC.  New Error-Types and Error-Values are
    requested in Section 6 ("IANA Considerations") of this document.
 o  If the PCE does not understand the P2MP flag in the RP object,
    then the PCE MUST send a PCErr message with Error-value=2
    (capability not supported).

Zhao, et al. Standards Track [Page 14] RFC 6006 Extensions to PCEP for P2MP TE LSPs September 2010

3.8. Non-Support by Back-Level PCE Implementations

 If a PCE receives a P2MP request and the PCE does not understand the
 P2MP flag in the RP object, and therefore the PCEP P2MP extensions,
 then the PCE SHOULD reject the request.

3.9. P2MP TE Path Reoptimization Request

 A reoptimization request for a P2MP TE path is specified by the use
 of the R-bit within the RP object as defined in [RFC5440] and is
 similar to the reoptimization request for a P2P TE path.  The only
 difference is that the user MUST insert the list of RROs and SRROs
 after each type of END-POINTS in the PCReq message, as described in
 the "Request Message Format" section (Section 3.4) of this document.
 An example of a reoptimization request and subsequent PCReq message
 is described below:
         Common Header
         RP with P2MP flag/R-bit set
         END-POINTS for leaf type 3
           RRO list
         OF (optional)
          Figure 5.  PCReq Message Example 1 for Optimization
 In this example, we request reoptimization of the path to all leaves
 without adding or pruning leaves.  The reoptimization request would
 use an END-POINT type 3.  The RRO list would represent the P2MP LSP
 before the optimization, and the modifiable path leaves would be
 indicated in the END-POINTS object.
 It is also possible to specify distinct leaves whose path cannot be
 modified.  An example of the PCReq message in this scenario would be:
         Common Header
         RP with P2MP flag/R-bit set
         END-POINTS for leaf type 3
           RRO list
         END-POINTS for leaf type 4
           RRO list
         OF (optional)
          Figure 6.  PCReq Message Example 2 for Optimization

Zhao, et al. Standards Track [Page 15] RFC 6006 Extensions to PCEP for P2MP TE LSPs September 2010

3.10. Adding and Pruning Leaves to/from the P2MP Tree

 When adding new leaves to or removing old leaves from the existing
 P2MP tree, by supplying a list of existing leaves, it SHOULD be
 possible to optimize the existing P2MP tree.  This section explains
 the methods for adding new leaves to or removing old leaves from the
 existing P2MP tree.
 To add new leaves, the user MUST build a P2MP request using END-
 POINTS with leaf type 1.
 To remove old leaves, the user must build a P2MP request using END-
 POINTS with leaf type 2.  If no type-2 END-POINTS exist, then the PCE
 MUST send an error type 17, value=1: The PCE is not capable of
 satisfying the request due to no END-POINTS with leaf type 2.
 When adding new leaves to or removing old leaves from the existing
 P2MP tree, the PCC must also provide the list of old leaves, if any,
 including END-POINTS with leaf type 3, leaf type 4, or both.  New
 PCEP-ERROR objects and types are necessary for reporting when certain
 conditions are not satisfied (i.e., when there are no END-POINTS with
 leaf type 3 or 4, or in the presence of END-POINTS with leaf type 1
 or 2).  A generic "Inconsistent END-POINT" error will be used if a
 PCC receives a request that has an inconsistent END-POINT (i.e., if a
 leaf specified as type 1 already exists).  These IANA assignments are
 documented in Section 6.6 ("PCEP-ERROR Objects and Types") of this
 document.
 For old leaves, the user MUST provide the old path as a list of RROs
 that immediately follows each END-POINTS object.  This document
 specifies error values when specific conditions are not satisfied.
 The following examples demonstrate full and partial reoptimization of
 existing P2MP LSPs:
 Case 1: Adding leaves with full reoptimization of existing paths
         Common Header
         RP with P2MP flag/R-bit set
         END-POINTS for leaf type 1
           RRO list
         END-POINTS for leaf type 3
           RRO list
         OF (optional)

Zhao, et al. Standards Track [Page 16] RFC 6006 Extensions to PCEP for P2MP TE LSPs September 2010

 Case 2: Adding leaves with partial reoptimization of existing paths
         Common Header
         RP with P2MP flag/R-bit set
         END-POINTS for leaf type 1
         END-POINTS for leaf type 3
           RRO list
         END-POINTS for leaf type 4
           RRO list
         OF (optional)
 Case 3: Adding leaves without reoptimization of existing paths
         Common Header
         RP with P2MP flag/R-bit set
         END-POINTS for leaf type 1
           RRO list
         END-POINTS for leaf type 4
           RRO list
         OF (optional)
 Case 4: Pruning Leaves with full reoptimization of existing paths
         Common Header
         RP with P2MP flag/R-bit set
         END-POINTS for leaf type 2
           RRO list
         END-POINTS for leaf type 3
           RRO list
         OF (optional)
 Case 5: Pruning leaves with partial reoptimization of existing paths
         Common Header
         RP with P2MP flag/R-bit set
         END-POINTS for leaf type 2
           RRO list
         END-POINTS for leaf type 3
           RRO list
         END-POINTS for leaf type 4
           RRO list
         OF (optional)

Zhao, et al. Standards Track [Page 17] RFC 6006 Extensions to PCEP for P2MP TE LSPs September 2010

 Case 6: Pruning leaves without reoptimization of existing paths
         Common Header
         RP with P2MP flag/R-bit set
         END-POINTS for leaf type 2
           RRO list
         END-POINTS for leaf type 4
           RRO list
         OF (optional)
 Case 7: Adding and pruning leaves with full reoptimization of
 existing paths
         Common Header
         RP with P2MP flag/R-bit set
         END-POINTS for leaf type 1
         END-POINTS for leaf type 2
           RRO list
         END-POINTS for leaf type 3
           RRO list
         OF (optional)
 Case 8: Adding and pruning leaves with partial reoptimization of
 existing paths
         Common Header
         RP with P2MP flag/R-bit set
         END-POINTS for leaf type 1
         END-POINTS for leaf type 2
           RRO list
         END-POINTS for leaf type 3
           RRO list
         END-POINTS for leaf type 4
           RRO list
         OF (optional)
 Case 9: Adding and pruning leaves without reoptimization of existing
 paths
         Common Header
         RP with P2MP flag/R-bit set
         END-POINTS for leaf type 1
         END-POINTS for leaf type 2
           RRO list
         END-POINTS for leaf type 4
           RRO list
         OF (optional)

Zhao, et al. Standards Track [Page 18] RFC 6006 Extensions to PCEP for P2MP TE LSPs September 2010

3.11. Discovering Branch Nodes

 Before computing the P2MP path, a PCE may need to be provided means
 to know which nodes in the network are capable of acting as branch
 LSRs.  A PCE can discover such capabilities by using the mechanisms
 defined in [RFC5073].

3.11.1. Branch Node Object

 The PCC can specify a list of nodes that can be used as branch nodes
 or a list of nodes that cannot be used as branch nodes by using the
 Branch Node Capability (BNC) Object.  The BNC Object has the same
 format as the Include Route Object (IRO) defined in [RFC5440], except
 that it only supports IPv4 and IPv6 prefix sub-objects.  Two Object-
 types are also defined:
 o  Branch node list: List of nodes that can be used as branch nodes.
 o  Non-branch node list: List of nodes that cannot be used as branch
    nodes.
 The object can only be carried in a PCReq message.  A Path Request
 may carry at most one Branch Node Object.
 The Object-Class and Object-types have been allocated by IANA.  The
 IANA assignment is documented in Section 6.5 ("PCEP Objects").

3.12. Synchronization of P2MP TE Path Computation Requests

 There are cases when multiple P2MP LSPs' computations need to be
 synchronized.  For example, one P2MP LSP is the designated backup of
 another P2MP LSP.  In this case, path diversity for these dependent
 LSPs may need to be considered during the path computation.
 The synchronization can be done by using the existing Synchronization
 VECtor (SVEC) functionality defined in [RFC5440].

Zhao, et al. Standards Track [Page 19] RFC 6006 Extensions to PCEP for P2MP TE LSPs September 2010

 An example of synchronizing two P2MP LSPs, each having two leaves for
 Path Computation Request Messages, is illustrated below:
         Common Header
         SVEC for sync of LSP1 and LSP2
         OF (optional)
         END-POINTS1 for P2MP
           RRO1 list
         END-POINTS2 for P2MP
           RRO2 list
         Figure 7.  PCReq Message Example for Synchronization
 This specification also defines two new flags to the SVEC Object Flag
 Field for P2MP path dependent computation requests.  The first new
 flag is to allow the PCC to request that the PCE should compute a
 secondary P2MP path tree with partial path diversity for specific
 leaves or a specific S2L sub-path to the primary P2MP path tree.  The
 second flag, would allow the PCC to request that partial paths should
 be link direction diverse.
 The following flags are added to the SVEC object body in this
 document:
 o  P (Partial Path Diverse bit - 1 bit):
    When set, this would indicate a request for path diversity for a
    specific leaf, a set of leaves, or all leaves.
 o  D (Link Direction Diverse bit - 1 bit):
    When set, this would indicate a request that a partial path or
    paths should be link direction diverse.
 The IANA assignment is referenced in Section 6.8 of this document.

3.13. Request and Response Fragmentation

 The total PCEP message length, including the common header, is
 16 bytes.  In certain scenarios the P2MP computation request may not
 fit into a single request or response message.  For example, if a
 tree has many hundreds or thousands of leaves, then the request or
 response may need to be fragmented into multiple messages.

Zhao, et al. Standards Track [Page 20] RFC 6006 Extensions to PCEP for P2MP TE LSPs September 2010

 The F-bit has been outlined in "The Extension of the RP Object"
 (Section 3.3.1) of this document.  The F-bit is used in the RP object
 header to signal that the initial request or response was too large
 to fit into a single message and will be fragmented into multiple
 messages.  In order to identify the single request or response, each
 message will use the same request ID.

3.13.1. Request Fragmentation Procedure

 If the initial request is too large to fit into a single request
 message, the PCC will split the request over multiple messages.  Each
 message sent to the PCE, except the last one, will have the F-bit set
 in the RP object to signify that the request has been fragmented into
 multiple messages.  In order to identify that a series of request
 messages represents a single request, each message will use the same
 request ID.
 The assumption is that request messages are reliably delivered and in
 sequence, since PCEP relies on TCP.

3.13.2. Response Fragmentation Procedure

 Once the PCE computes a path based on the initial request, a response
 is sent back to the PCC.  If the response is too large to fit into a
 single response message, the PCE will split the response over
 multiple messages.  Each message sent to the PCE, except the last
 one, will have the F-bit set in the RP object to signify that the
 response has been fragmented into multiple messages.  In order to
 identify that a series of response messages represents a single
 response, each message will use the same response ID.
 Again, the assumption is that response messages are reliably
 delivered and in sequence, since PCEP relies on TCP.

3.13.3. Fragmentation Examples

 The following example illustrates the PCC sending a request message
 with Req-ID1 to the PCE, in order to add one leaf to an existing tree
 with 1200 leaves.  The assumption used for this example is that one
 request message can hold up to 800 leaves.  In this scenario, the
 original single message needs to be fragmented and sent using two
 smaller messages, which have the Req-ID1 specified in the RP object,
 and with the F-bit set on the first message, and cleared on the
 second message.

Zhao, et al. Standards Track [Page 21] RFC 6006 Extensions to PCEP for P2MP TE LSPs September 2010

         Common Header
         RP1 with Req-ID1 and P2MP=1 and F-bit=1
         OF (optional)
         END-POINTS1 for P2MP
           RRO1 list
         Common Header
         RP2 with Req-ID1 and P2MP=1 and F-bit=0
         OF (optional)
         END-POINTS1 for P2MP
           RRO1 list
            Figure 8.  PCReq Message Fragmentation Example
 To handle a scenario where the last fragmented message piece is lost,
 the receiver side of the fragmented message may start a timer once it
 receives the first piece of the fragmented message.  When the timer
 expires and it has not received the last piece of the fragmented
 message, it should send an error message to the sender to signal that
 it has received an incomplete message.  The relevant error message is
 documented in Section 3.15 ("P2MP PCEP-ERROR Objects and Types").

3.14. UNREACH-DESTINATION Object

 The PCE path computation request may fail because all or a subset of
 the destinations are unreachable.
 In such a case, the UNREACH-DESTINATION object allows the PCE to
 optionally specify the list of unreachable destinations.
 This object can be present in PCRep messages.  There can be up to one
 such object per RP.
 The following UNREACH-DESTINATION objects will be required:
 UNREACH-DESTINATION Object-Class is 28.
 UNREACH-DESTINATION Object-Type for IPv4 is 1.
 UNREACH-DESTINATION Object-Type for IPv6 is 2.

Zhao, et al. Standards Track [Page 22] RFC 6006 Extensions to PCEP for P2MP TE LSPs September 2010

 The format of the UNREACH-DESTINATION object body for IPv4 (Object-
 Type=1) is as follows:
     0                   1                   2                   3
     0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
    +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
    |                  Destination IPv4 address                     |
    +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
    ~                           ...                                 ~
    +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
    |                  Destination IPv4 address                     |
    +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
          Figure 9.  UNREACH-DESTINATION Object Body for IPv4
 The format of the UNREACH-DESTINATION object body for IPv6 (Object-
 Type=2) is as follows:
     0                   1                   2                   3
     0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
    +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
    |                                                               |
    |            Destination IPv6 address (16 bytes)                |
    |                                                               |
    |                                                               |
    +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
    ~                          ...                                  ~
    +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
    |                                                               |
    |              Destination IPv6 address (16 bytes)              |
    |                                                               |
    |                                                               |
    +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
         Figure 10.  UNREACH-DESTINATION Object Body for IPv6

3.15. P2MP PCEP-ERROR Objects and Types

 To indicate an error associated with policy violation, a new error
 value "P2MP Path computation not allowed" should be added to the
 existing error code for policy violation (Error-Type=5) as defined in
 [RFC5440]:

Zhao, et al. Standards Track [Page 23] RFC 6006 Extensions to PCEP for P2MP TE LSPs September 2010

 Error-Type=5; Error-Value=7: if a PCE receives a P2MP path
 computation request that is not compliant with administrative
 privileges (i.e., "The PCE policy does not support P2MP path
 computation"), the PCE MUST send a PCErr message with a PCEP-ERROR
 object (Error-Type=5) and an Error-Value (Error-Value=7).  The
 corresponding P2MP path computation request MUST also be cancelled.
 To indicate capability errors associated with the P2MP path request,
 a new Error-Type (16) and subsequent error-values are defined as
 follows for inclusion in the PCEP-ERROR object:
 Error-Type=16; Error-Value=1: if a PCE receives a P2MP path request
 and the PCE is not capable of satisfying the request due to
 insufficient memory, the PCE MUST send a PCErr message with a PCEP-
 ERROR object (Error-Type=16) and an Error-Value (Error-Value=1).  The
 corresponding P2MP path computation request MUST also be cancelled.
 Error-Type=16; Error-Value=2: if a PCE receives a P2MP path request
 and the PCE is not capable of P2MP computation, the PCE MUST send a
 PCErr message with a PCEP-ERROR object (Error-Type=16) and an Error-
 Value (Error-Value=2).  The corresponding P2MP path computation
 request MUST also be cancelled.
 To indicate P2MP message fragmentation errors associated with a P2MP
 path request, a new Error-Type (17) and subsequent error-values are
 defined as follows for inclusion in the PCEP-ERROR object:
 Error-Type=18; Error-Value=1: if a PCE has not received the last
 piece of the fragmented message, it should send an error message to
 the sender to signal that it has received an incomplete message
 (i.e., "Fragmented request failure").  The PCE MUST send a PCErr
 message with a PCEP-ERROR object (Error-Type=18) and an Error-Value
 (Error-Value=1).

3.16. PCEP NO-PATH Indicator

 To communicate the reasons for not being able to find P2MP path
 computation, the NO-PATH object can be used in the PCRep message.
 One new bit is defined in the NO-PATH-VECTOR TLV carried in the
 NO-PATH Object:
 bit 24: when set, the PCE indicates that there is a reachability
 problem with all or a subset of the P2MP destinations.  Optionally,
 the PCE can specify the destination or list of destinations that are
 not reachable using the new UNREACH-DESTINATION object defined in
 Section 3.14.

Zhao, et al. Standards Track [Page 24] RFC 6006 Extensions to PCEP for P2MP TE LSPs September 2010

4. Manageability Considerations

 [RFC5862] describes various manageability requirements in support of
 P2MP path computation when applying PCEP.  This section describes how
 manageability requirements mentioned in [RFC5862] are supported in
 the context of PCEP extensions specified in this document.
 Note that [RFC5440] describes various manageability considerations in
 PCEP, and most of the manageability requirements mentioned in
 [RFC5862] are already covered there.

4.1. Control of Function and Policy

 In addition to PCE configuration parameters listed in [RFC5440], the
 following additional parameters might be required:
 o  The ability to enable or disable P2MP path computations on the
    PCE.
 o  The PCE may be configured to enable or disable the advertisement
    of its P2MP path computation capability.  A PCE can advertise its
    P2MP capability via the IGP discovery mechanism discussed in
    Section 3.1.1 ("P2MP Computation TLV in the Existing PCE Discovery
    Protocol"), or during the Open Message Exchange discussed in
    Section 3.1.2 ("Open Message Extension").

4.2. Information and Data Models

 A number of MIB objects have been defined for general PCEP control
 and monitoring of P2P computations in [PCEP-MIB].  [RFC5862]
 specifies that MIB objects will be required to support the control
 and monitoring of the protocol extensions defined in this document.
 A new document will be required to define MIB objects for PCEP
 control and monitoring of P2MP computations.

4.3. Liveness Detection and Monitoring

 There are no additional considerations beyond those expressed in
 [RFC5440], since [RFC5862] does not address any additional
 requirements.

4.4. Verifying Correct Operation

 There are no additional requirements beyond those expressed in
 [RFC4657] for verifying the correct operation of the PCEP sessions.
 It is expected that future MIB objects will facilitate verification
 of correct operation and reporting of P2MP PCEP requests, responses,
 and errors.

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4.5. Requirements for Other Protocols and Functional Components

 The method for the PCE to obtain information about a PCE capable of
 P2MP path computations via OSPF and IS-IS is discussed in
 Section 3.1.1 ("P2MP Computation TLV in the Existing PCE Discovery
 Protocol") of this document.
 The subsequent IANA assignments are documented in Section 6.9 ("OSPF
 PCE Capability Flag") of this document.

4.6. Impact on Network Operation

 It is expected that the use of PCEP extensions specified in this
 document will not significantly increase the level of operational
 traffic.  However, computing a P2MP tree may require more PCE state
 compared to a P2P computation.  In the event of a major network
 failure and multiple recovery P2MP tree computation requests being
 sent to the PCE, the load on the PCE may also be significantly
 increased.

5. Security Considerations

 As described in [RFC5862], P2MP path computation requests are more
 CPU-intensive and also utilize more link bandwidth.  In the event of
 an unauthorized P2MP path computation request, or a denial of service
 attack, the subsequent PCEP requests and processing may be disruptive
 to the network.  Consequently, it is important that implementations
 conform to the relevant security requirements of [RFC5440] that
 specifically help to minimize or negate unauthorized P2MP path
 computation requests and denial of service attacks.  These mechanisms
 include:
 o  Securing the PCEP session requests and responses using TCP
    security techniques (Section 10.2 of [RFC5440]).
 o  Authenticating the PCEP requests and responses to ensure the
    message is intact and sent from an authorized node (Section 10.3
    of [RFC5440]).
 o  Providing policy control by explicitly defining which PCCs, via IP
    access-lists, are allowed to send P2MP path requests to the PCE
    (Section 10.6 of [RFC5440]).
 PCEP operates over TCP, so it is also important to secure the PCE and
 PCC against TCP denial of service attacks.  Section 10.7.1 of
 [RFC5440] outlines a number of mechanisms for minimizing the risk of
 TCP based denial of service attacks against PCEs and PCCs.

Zhao, et al. Standards Track [Page 26] RFC 6006 Extensions to PCEP for P2MP TE LSPs September 2010

 PCEP implementations SHOULD consider the additional security provided
 by the TCP Authentication Option (TCP-AO) [RFC5925].

6. IANA Considerations

 IANA maintains a registry of PCEP parameters.  A number of IANA
 considerations have been highlighted in previous sections of this
 document.  IANA has made the following allocations.

6.1. PCEP TLV Type Indicators

 As described in Section 3.1.2., the newly defined P2MP capability TLV
 allows the PCE to advertise its P2MP path computation capability.
 IANA has made the following allocation from the "PCEP TLV Type
 Indicators" sub-registry.
    Value       Description          Reference
    6           P2MP capable         RFC 6006

6.2. Request Parameter Bit Flags

 As described in Section 3.3.1, three new RP Object Flags have been
 defined.  IANA has made the following allocations from the PCEP "RP
 Object Flag Field" sub-registry:
    Bit      Description                         Reference
    18       Fragmentation (F-bit)               RFC 6006
    19       P2MP (N-bit)                        RFC 6006
    20       ERO-compression (E-bit)             RFC 6006

6.3. Objective Functions

 As described in Section 3.6.1, two new Objective Functions have been
 defined.  IANA has made the following allocations from the PCEP
 "Objective Function" sub-registry:
    Code Point        Name        Reference
    7                 SPT         RFC 6006
    8                 MCT         RFC 6006

6.4. Metric Object Types

 As described in Section 3.6.2, three new metric object T fields have
 been defined.  IANA has made the following allocations from the PCEP
 "METRIC Object T Field" sub-registry:

Zhao, et al. Standards Track [Page 27] RFC 6006 Extensions to PCEP for P2MP TE LSPs September 2010

    Value           Description               Reference
    8               P2MP IGP metric           RFC 6006
    9               P2MP TE metric            RFC 6006
    10              P2MP hop count metric     RFC 6006

6.5. PCEP Objects

 As discussed in Section 3.3.2, two new END-POINTS Object-Types are
 defined.  IANA has made the following Object-Type allocations from
 the "PCEP Objects" sub-registry:
    Object-Class Value    4
    Name                  END-POINTS
    Object-Type           3: IPv4
                          4: IPv6
                          5-15: Unassigned
    Reference             RFC 6006
 As described in Section 3.2, Section 3.11.1, and Section 3.14, four
 PCEP Object-Classes and six PCEP Object-Types have been defined.
 IANA has made the following allocations from the "PCEP Objects" sub-
 registry:
    Object-Class Value    28
    Name                  UNREACH-DESTINATION
    Object-Type           1: IPv4
                          2: IPv6
                          3-15: Unassigned
    Reference             RFC 6006
    Object-Class Value    29
    Name                  SERO
    Object-Type           1: SERO
                          2-15: Unassigned
    Reference             RFC 6006
    Object-Class Value    30
    Name                  SRRO
    Object-Type           1: SRRO
                          2-15: Unassigned
    Reference             RFC 6006

Zhao, et al. Standards Track [Page 28] RFC 6006 Extensions to PCEP for P2MP TE LSPs September 2010

    Object-Class Value    31
    Name                  Branch Node Capability Object
    Object-Type           1: Branch node list
                          2: Non-branch node list
                          3-15: Unassigned
    Reference             RFC 6006

6.6. PCEP-ERROR Objects and Types

 As described in Section 3.15, a number of new PCEP-ERROR Object Error
 Types and Values have been defined.  IANA has made the following
 allocations from the PCEP "PCEP-ERROR Object Error Types and Values"
 sub-registry:
    Error
    Type  Meaning                                            Reference
    5     Policy violation
            Error-value=7:                                   RFC 6006
              P2MP Path computation is not allowed
    16    P2MP Capability Error
            Error-Value=0: Unassigned                        RFC 6006
            Error-Value=1:                                   RFC 6006
              The PCE is not capable to satisfy the request
              due to insufficient memory
            Error-Value=2:                                   RFC 6006
              The PCE is not capable of P2MP computation
    17    P2MP END-POINTS Error
            Error-Value=0: Unassigned                        RFC 6006
            Error-Value=1:                                   RFC 6006
              The PCE is not capable to satisfy the request
              due to no END-POINTS with leaf type 2
            Error-Value=2:                                   RFC 6006
              The PCE is not capable to satisfy the request
              due to no END-POINTS with leaf type 3
            Error-Value=3:                                   RFC 6006
              The PCE is not capable to satisfy the request
              due to no END-POINTS with leaf type 4
            Error-Value=4:                                   RFC 6006
              The PCE is not capable to satisfy the request
              due to inconsistent END-POINTS
    18    P2MP Fragmentation Error
            Error-Value=0: Unassigned                        RFC 6006
            Error-Value=1:                                   RFC 6006
              Fragmented request failure

Zhao, et al. Standards Track [Page 29] RFC 6006 Extensions to PCEP for P2MP TE LSPs September 2010

6.7. PCEP NO-PATH Indicator

 As discussed in Section 3.16, a new NO-PATH-VECTOR TLV Flag Field has
 been defined.  IANA has made the following allocation from the PCEP
 "NO-PATH-VECTOR TLV Flag Field" sub-registry:
    Bit    Description                               Reference
    24     P2MP Reachability Problem                 RFC 6006

6.8. SVEC Object Flag

 As discussed in Section 3.12, two new SVEC Object Flags are defined.
 IANA has made the following allocation from the PCEP "SVEC Object
 Flag Field" sub-registry:
    Bit      Description                              Reference
    19       Partial Path Diverse                     RFC 6006
    20       Link Direction Diverse                   RFC 6006

6.9. OSPF PCE Capability Flag

 As discussed in Section 3.1.1, a new OSPF Capability Flag is defined
 to indicate P2MP path computation capability.  IANA has made the
 following assignment from the OSPF Parameters "Path Computation
 Element (PCE) Capability Flags" registry:
    Bit      Description                              Reference
    10       P2MP path computation                    RFC 6006

7. Acknowledgements

 The authors would like to thank Adrian Farrel, Young Lee, Dan Tappan,
 Autumn Liu, Huaimo Chen, Eiji Okim, Nick Neate, Suresh Babu K, Dhruv
 Dhody, Udayasree Palle, Gaurav Agrawal, Vishwas Manral, Dan
 Romascanu, Tim Polk, Stewart Bryant, David Harrington, and Sean
 Turner for their valuable comments and input on this document.

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.

Zhao, et al. Standards Track [Page 30] RFC 6006 Extensions to PCEP for P2MP TE LSPs September 2010

 [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.
 [RFC3473]   Berger, L., Ed., "Generalized Multi-Protocol Label
             Switching (GMPLS) Signaling Resource ReserVation
             Protocol-Traffic Engineering (RSVP-TE) Extensions",
             RFC 3473, January 2003.
 [RFC4873]   Berger, L., Bryskin, I., Papadimitriou, D., and A.
             Farrel, "GMPLS Segment Recovery", RFC 4873, May 2007.
 [RFC4875]   Aggarwal, R., Ed., Papadimitriou, D., Ed., and S.
             Yasukawa, Ed., "Extensions to Resource Reservation
             Protocol - Traffic Engineering (RSVP-TE) for Point-to-
             Multipoint TE Label Switched Paths (LSPs)", RFC 4875, May
             2007.
 [RFC4970]   Lindem, A., Ed., Shen, N., Vasseur, JP., Aggarwal, R.,
             and S. Shaffer, "Extensions to OSPF for Advertising
             Optional Router Capabilities", RFC 4970, July 2007.
 [RFC5073]   Vasseur, J., Ed., and J. Le Roux, Ed., "IGP Routing
             Protocol Extensions for Discovery of Traffic Engineering
             Node Capabilities", RFC 5073, December 2007.
 [RFC5088]   Le Roux, JL., Ed., Vasseur, JP., Ed., Ikejiri, Y., and R.
             Zhang, "OSPF Protocol Extensions for Path Computation
             Element (PCE) Discovery", RFC 5088, January 2008.
 [RFC5089]   Le Roux, JL., Ed., Vasseur, JP., Ed., Ikejiri, Y., and R.
             Zhang, "IS-IS Protocol Extensions for Path Computation
             Element (PCE) Discovery", RFC 5089, January 2008.
 [RFC5511]   Farrel, A., "Routing Backus-Naur Form (RBNF): A Syntax
             Used to Form Encoding Rules in Various Routing Protocol
             Specifications", RFC 5511, April 2009.
 [RFC5440]   Vasseur, JP., Ed., and JL. Le Roux, Ed., "Path
             Computation Element (PCE) Communication Protocol (PCEP)",
             RFC 5440, March 2009.
 [RFC5541]   Le Roux, JL., Vasseur, JP., and Y. Lee, "Encoding of
             Objective Functions in the Path Computation Element
             Communication Protocol (PCEP)", RFC 5541, June 2009.

Zhao, et al. Standards Track [Page 31] RFC 6006 Extensions to PCEP for P2MP TE LSPs September 2010

8.2. Informative References

 [RFC4655]   Farrel, A., Vasseur, J.-P., and J. Ash, "A Path
             Computation Element (PCE)-Based Architecture", RFC 4655,
             August 2006.
 [RFC4657]   Ash, J., Ed., and J. Le Roux, Ed., "Path Computation
             Element (PCE) Communication Protocol Generic
             Requirements", RFC 4657, September 2006.
 [RFC5671]   Yasukawa, S. and A. Farrel, Ed., "Applicability of the
             Path Computation Element (PCE) to Point-to-Multipoint
             (P2MP) MPLS and GMPLS Traffic Engineering (TE)",
             RFC 5671, October 2009.
 [RFC5862]   Yasukawa, S. and A. Farrel, "Path Computation Clients
             (PCC) - Path Computation Element (PCE) Requirements for
             Point-to-Multipoint MPLS-TE", RFC 5862, June 2010.
 [RFC5925]   Touch, J., Mankin, A., and R. Bonica, "The TCP
             Authentication Option", RFC 5925, June 2010.
 [PCEP-MIB]  Koushik, K., Stephan, E., Zhao, Q., and D. King, "PCE
             communication protocol (PCEP) Management Information
             Base", Work in Progress, July 2010.

Contributors

 Jean-Louis Le Roux
 France Telecom
 2, Avenue Pierre-Marzin
 22307 Lannion Cedex
 France
 EMail: jeanlouis.leroux@orange-ftgroup.com
 Mohamad Chaitou
 France
 EMail: mohamad.chaitou@gmail.com

Zhao, et al. Standards Track [Page 32] RFC 6006 Extensions to PCEP for P2MP TE LSPs September 2010

Authors' Addresses

 Quintin Zhao (editor)
 Huawei Technology
 125 Nagog Technology Park
 Acton, MA  01719
 US
 EMail: qzhao@huawei.com
 Daniel King (editor)
 Old Dog Consulting
 UK
 EMail: daniel@olddog.co.uk
 Fabien Verhaeghe
 Thales Communication France
 160 Bd Valmy 92700 Colombes
 France
 EMail: fabien.verhaeghe@gmail.com
 Tomonori Takeda
 NTT Corporation
 3-9-11, Midori-Cho
 Musashino-Shi, Tokyo 180-8585
 Japan
 EMail: takeda.tomonori@lab.ntt.co.jp
 Zafar Ali
 Cisco Systems, Inc.
 2000 Innovation Drive
 Kanata, Ontario  K2K 3E8
 Canada
 EMail: zali@cisco.com
 Julien Meuric
 France Telecom
 2, Avenue Pierre-Marzin
 22307 Lannion Cedex
 France
 EMail: julien.meuric@orange-ftgroup.com

Zhao, et al. Standards Track [Page 33]

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