Internet DRAFT - draft-many-pce-pcep-bcp

draft-many-pce-pcep-bcp







PCE Working Group                                       R. Casellas, Ed.
Internet-Draft                                                      CTTC
Intended status: Best Current Practice          O. Gonzalez de Dios, Ed.
Expires: October 29, 2015                                 Telefonica I+D
                                                          A. Farrel, Ed.
                                                      Old Dog Consulting
                                                             C. Margaria
                                                        Juniper Networks
                                                                D. Dhody
                                                                X. Zhang
                                                     Huawei Technologies
                                                          April 27, 2015


      PCEP Best Current Practices - Message formats and extensions
                       draft-many-pce-pcep-bcp-02

Abstract

   A core standards track RFC defines the main underlying mechanisms,
   basic object format and message structure of the Path Computation
   Element (PCE) Communications Protocol (PCEP).  PCEP has been later
   extended in several RFCs, focusing on specific functionalities.  The
   proliferation of such companion RFCs may cause ambiguity when
   implementing a PCE based solution.  This document aims at documenting
   best current practices and at providing a reference RBNF grammar for
   PCEP messages, including object ordering and precedence rules.

Status of This Memo

   This Internet-Draft is submitted in full conformance with the
   provisions of BCP 78 and BCP 79.

   Internet-Drafts are working documents of the Internet Engineering
   Task Force (IETF).  Note that other groups may also distribute
   working documents as Internet-Drafts.  The list of current Internet-
   Drafts is at http://datatracker.ietf.org/drafts/current/.

   Internet-Drafts are draft documents valid for a maximum of six months
   and may be updated, replaced, or obsoleted by other documents at any
   time.  It is inappropriate to use Internet-Drafts as reference
   material or to cite them other than as "work in progress."

   This Internet-Draft will expire on October 29, 2015.







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Copyright Notice

   Copyright (c) 2015 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.

Table of Contents

   1.  Introduction and Motivation . . . . . . . . . . . . . . . . .   3
     1.1.  Object Ordering Issues and Inconsistencies  . . . . . . .   4
     1.2.  Inconsistent Naming . . . . . . . . . . . . . . . . . . .   5
     1.3.  Semantics and Exclusive Rules . . . . . . . . . . . . . .   6
   2.  Initial Considerations  . . . . . . . . . . . . . . . . . . .   7
   3.  Requirements Language . . . . . . . . . . . . . . . . . . . .   7
   4.  RBNF Grammars . . . . . . . . . . . . . . . . . . . . . . . .   7
     4.1.  Common Constructs . . . . . . . . . . . . . . . . . . . .   7
       4.1.1.  Object Sequences  . . . . . . . . . . . . . . . . . .   7
       4.1.2.  Synchronized Vectors  . . . . . . . . . . . . . . . .   8
       4.1.3.  Monitoring Metrics  . . . . . . . . . . . . . . . . .   8
       4.1.4.  Monitoring Requests and Responses . . . . . . . . . .   9
       4.1.5.  Attributes  . . . . . . . . . . . . . . . . . . . . .   9
       4.1.6.  Paths . . . . . . . . . . . . . . . . . . . . . . . .  11
     4.2.  PCEP Messages . . . . . . . . . . . . . . . . . . . . . .  11
       4.2.1.  PCEP Open Message . . . . . . . . . . . . . . . . . .  11
       4.2.2.  PCEP Keep Alive (KeepAlive) Message . . . . . . . . .  11
       4.2.3.  PCEP Request (PCReq) Message  . . . . . . . . . . . .  11
       4.2.4.  PCEP Reply (PCRep) Message  . . . . . . . . . . . . .  12
       4.2.5.  PCEP Monitoring Request (PCMonReq) Message  . . . . .  13
       4.2.6.  PCEP Monitoring Reply (PCMonRep) Message  . . . . . .  13
       4.2.7.  PCEP Notify (PCNtf) Message . . . . . . . . . . . . .  14
       4.2.8.  PCEP Error (PCErr) Message  . . . . . . . . . . . . .  14
       4.2.9.  PCEP Report (PCRpt) Message . . . . . . . . . . . . .  15
       4.2.10. PCEP Update (PCUpd) Message . . . . . . . . . . . . .  16
       4.2.11. PCEP Initiate (PCInitiate) Message  . . . . . . . . .  16
   5.  Management Considerations . . . . . . . . . . . . . . . . . .  17
   6.  Security Considerations . . . . . . . . . . . . . . . . . . .  17
   7.  Contributing Authors  . . . . . . . . . . . . . . . . . . . .  17
   8.  Acknowledgments . . . . . . . . . . . . . . . . . . . . . . .  18
   9.  Normative References  . . . . . . . . . . . . . . . . . . . .  18



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   Authors' Addresses  . . . . . . . . . . . . . . . . . . . . . . .  20

1.  Introduction and Motivation

   The RBNF notation, defined in [RFC5511], is used to specify the
   message format for the Path Computation Element communication
   Protocol (PCEP).  The core of PCEP has been defined in [RFC5440] and
   later extended, notably, in [RFC7150] to support Vendor Extensions;
   in [RFC5455], adding a CLASSTYPE object to support Diffserv-aware
   Traffic Engineering (DS-TE); in [RFC5520], for topology
   confidentiality by means of Path-Keys; in [RFC5521], in support of
   exclusions; in [RFC5541] to convey specific Objective Functions; in
   [RFC5557], for Global Concurrent Optimization, in [RFC5886], for
   monitoring and in [RFC6006] for point-to-multipoint (P2MP)
   computation.

   At the time of writing, several I.-D. are also addressing specific
   aspects, such as PCEP extensions for GMPLS networks
   [I-D.ietf-pce-gmpls-pcep-extensions], for hierarchical PCE
   [I-D.ietf-pce-hierarchy-extensions] or for multi-layer, multi-region
   networks [I-D.ietf-pce-inter-layer-ext].  Stateful PCE capabilites
   are also being defined in [I-D.ietf-pce-stateful-pce], including the
   case where a PCE is able to initiate the establishment and release of
   LSPs in [I-D.ietf-pce-pce-initiated-lsp].

   Most PCEP RFCs describe specific protocol extensions and, as such,
   they focus on their constructs extending some base RFCs.  Although it
   is not the intention of each individual draft or RFC to provide the
   latest and most complete/full definition of the protocol messages, in
   practice combining all the extensions as defined in the respective
   RFCs is complex, and open to interpretation.

   Message rules are sometimes provided within the text, resulting in
   ambiguity.  Moreover, the fact that extensions may be defined in
   parallel may be a problem.  The canonical example is the case where
   RFC X defines construct p ::= A and subsequent RFC Y extends RFC X
   stating that object C MUST follow object A and RFC Z also extends RFC
   X stating that object D MUST follow object A.

   This document describes current practice when implementing existing
   PCEP RFCs.  This involves extending the existing RBNF notations using
   more verbose constructs where appropiate, while being semantically
   equivalent, in order to avoid ambiguity and to facilitate message
   validation.







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1.1.  Object Ordering Issues and Inconsistencies

   The use of RBNF [RFC5511] states that the ordering of objects and
   constructs in an assignment is explicit, and protocol specifications
   MAY opt to state that ordering is only RECOMMENDED (the elements of a
   list of objects and constructs MAY be received in any order).

   The core PCEP document [RFC5440] states in Section 6 that an
   implementation MUST form the PCEP messages using the object ordering
   specified in [RFC5440].

   [RFC5886] equally states that "An implementation MUST form the PCEP
   messages using the object ordering specified in this document."

   [RFC5521] only states that "the XRO is OPTIONAL and MAY be carried
   within Path Computation Request (PCReq) and Path Computation Reply
   (PCRep) messages." and no ordering is provided.  For example, it does
   not mention SVEC objects or rules.

   [RFC5541] specifies that "the OF object MAY be carried within a PCReq
   message.  If an objective function is to be applied to a set of
   synchronized path computation requests, the OF object MUST be carried
   just after the corresponding SVEC (Synchronization VECtor) object and
   MUST NOT be repeated for each elementary request.  Similarly, if a
   metric is to be applied to a set of synchronized requests, the METRIC
   object MUST follow the SVEC object and MUST NOT be repeated for each
   elementary request. (...) An OF object specifying an objective
   function that applies to an individual path computation request (non-
   synchronized case) MUST follow the RP object for which it applies".
   It should be understood that this last sentence introduces ambiguity
   and if interpreted as the OF object MUST strictly follow (right
   after) the RP object, it contradicts [RFC5440] where the RP object is
   followed by the ENDPOINTS object.

   RFCs that extend the core PCEP protocol are not consistent with the
   object ordering.

   [RFC5541] in section 3.2 is not consistent with the ordering of OF
   and metric-list:












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   <svec-list>      ::= <SVEC>
                        [<OF>]
                        [<metric-list>]

   <request>        ::= <RP>
                        (snip)
                        [<metric-list>]
                        [<OF>]

   <attribute-list> ::= [<OF>]
                        [<LSPA>]
                        [<BANDWIDTH>]
                        [<metric-list>]

   In view of the above considerations, this document aims at providing
   an object ordering for PCEP messages so implementations can
   interoperate.

1.2.  Inconsistent Naming

   PCEP RFCs may use inconsistent or ambiguous naming.  For example
   [RFC5440] defines the Open message as having a common header and an
   OPEN object, and later uses Open to refer to the object that may
   appear in a PCErr message.

   <Open Message>  ::= <Common Header>
                       <OPEN>

   <PCErr Message> ::= <Common Header>
                       (<error-obj-list> [<Open>]) | <error>
                       [<error-list>]

   It is common that a sequence or repetition of an object OBJ is noted
   as obj-list.  It may happen that in extensions to core documents, the
   naming is kept although it no longer applies to such a sequence.  For
   example, [RFC5886] states:

   <svec-list> ::= <SVEC>
                   [<OF>]
                   [<svec-list>]

   and later

   <svec-list> ::= <SVEC>
                   [<svec-list>]






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1.3.  Semantics and Exclusive Rules

   The current RBNF notation does not capture the semantics/intent of
   the messages; notably, when two options are mutually exclusive and at
   least one is mandatory.  In most cases, this is noted as both options
   being optional.  For example [RFC5440] states:

   <response>::=<RP>
               [<NO-PATH>]
               [<attribute-list>]
               [<path-list>]

   with this example, a message that contains a response of the form
   <RP><NO-PATH><ERO><..> (that is, a NO-PATH object followed by a path)
   is correct and successfully parsed.  Likewise, a response with just
   an RP object is valid.  Although the actual text within the RFC may
   state the intention and disambiguate the grammar, the RBNF notation
   can be improved to better capture the semantics, message structure
   and original intent.  Such enhancements allow the automated
   validation of message elements.

   Similarly, if the intent is to specific a rule such as metric-pce
   which includes a PCE-ID object followed by a PROC-TIME object and/or
   an OVERLOAD object, the syntax:

   <metric-pce> ::= <PCE-ID> [<PROC-TIME>] [<OVERLOAD>]

   allows, amongst other combinations, that neither PROC-TIME nor
   OVERLOAD appears, which is not the intended behavior (there should be
   at least one metric).  The alternative

   <metric-pce> ::= <PCE-ID> <metric-argument-list>
   <metric-argument-list> ::= <metric-argument> [<metric-argument-list>]
   <metric-argument> ::= <PROC-TIME> | <OVERLOAD>

   or equivalently

   <metric-pce> ::= <PCE-ID> (<metric-argument>...)
   <metric-argument> ::= <PROC-TIME> | <OVERLOAD>


   does not reflect that each metric-argument should appear at most
   once.  This can be addressed verbosely:








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   <metric-pce> ::= <PCE-ID>
                   ( <PROC-TIME> | <OVERLOAD> | <PROC-TIME><OVERLOAD> )

   <metric-pce> ::= <PCE-ID>
                   ( <PROC-TIME>[<OVERLOAD>] | [<PROC-TIME>]<OVERLOAD> )

   Here the semantic is that we require any object of the set {PROC-
   TIME, OVERLOAD} to be present, and there should be at least one.
   Note that currently there are only a few cases where the "non-empty
   set" case arises.

2.  Initial Considerations

   This document does not modify the content of defined PCEP objects and
   TLVs.

   This document is not normative, the normative definition is included
   in the existing specs.  This does not preclude integration with a
   future revision of such documents.

3.  Requirements Language

   This draft does not provide any new extensions to PCEP, but it
   includes requirements specified by existing RFCs for illustrative
   purpose.

   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].

4.  RBNF Grammars

   This section provides the proposed RBNF notation for the PCEP
   messages.  Specific constructs or grammar rules that appear in
   several messages or deserve special considerations are described
   first.

4.1.  Common Constructs

4.1.1.  Object Sequences











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   <of-list>              ::= <OF> [<of-list>]

   <metric-list>          ::= <METRIC> [<metric-list>]

   <vendor-info-list>     ::= <VENDOR-INFORMATION> [<vendor-info-list>]

   <pce-id-list>          ::= <PCE-ID> [<pce-id-list>]
         -- (note: named pce-list in original)

4.1.2.  Synchronized Vectors

   SVEC tuple:
         A svec-tuple is a construct that associates a SVEC object with
         one or more constraining objects.  The selected order follows
         the relative order of having OF and metric-list after the SVEC
         object, and the name svec-list has been changed since it no
         longer means a list of SVEC objects.

   <svec-tuple> ::= <SVEC>
                    [<OF>]
                    [<metric-list>]
                    [<vendor-info-list>]
                    [<GC>]
                    [<XRO>]

   <svec-tuple-list> ::= <svec-tuple> [<svec-tuple-list>]

   Note that, again, as an example [RFC7150] defines:

   <svec-list> ::= <SVEC>
                    [<OF>]
                    [<GC>]
                    [<XRO>]
                    [<metric-list>]
                    [<vendor-info-list>]
                    [<svec-list>]

   There are two problems, ordering and naming.  So, we use the afore
   defined svec-tuple-list.  The construct is updated to reflect the new
   name and to have the same relative order in the attributes that
   constrain a individual request

4.1.3.  Monitoring Metrics

   A metric-pce-id is a rule that associates a PCE identified by its
   PCE-ID to a list of metric arguments.





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   <metric-pce-id> ::= <PCE-ID>
                      (<PROC-TIME> [<OVERLOAD>] |
                      [<PROC-TIME>] <OVERLOAD> )

   <metric-pce-id-list> ::= <metric-pce-id> [<metric-pce-id-list>]

4.1.4.  Monitoring Requests and Responses

   See [RFC5886] for the definition of specific/general and in-band/out-
   of-band.


   <monitoring> ::= <MONITORING> <PCC-ID-REQ>

   <monitoring-request> ::= <monitoring> [<pce-id-list>]

   <monitoring-response> ::= <monitoring>
             (<specific-monitoring-metrics-list> |
              <general-monitoring-metrics-list>)

   <specific-monitoring-metrics-list> ::=
             <specific-monitoring-metrics>
             [<specific-monitoring-metrics-list>]

   <general-monitoring-metrics-list>  ::=
             <general-monitoring-metrics>
             [<general-monitoring-metrics-list>]

   <specific-monitoring-metrics> ::=
             <RP> <monitoring-metrics>

   <general-monitoring-metrics>  ::=
             <monitoring-metrics>

   <monitoring-metrics> ::=
             <metric-pce-id-list>

4.1.5.  Attributes

   Attributes are used to constrain a request, or to qualify a path
   (defined later in this document).  However, it is not straightforward
   to define an attributes construct, since it may change for P2P or
   P2MP paths, and some objects (e.g.  BANDWIDTH) may appear multiple
   times, with different semantics:

      In [RFC5440] the BANDWIDTH object can optionally appear as a path
      attribute or as a request constraint.




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      In [RFC5440] the RRO object is only used in requests "The RRO is
      exclusively carried within a PCReq message" for reoptimization.
      In such contexts, the RRO and an optional BANDWIDTH objects are
      bound together, in the so called rro-bw-pair construct which is
      also an attribute.

      In some contexts (stateful) paths are defined as having an
      optional RRO object, outside the PCEP attributes construct.

      In P2MP paths, multiple RRO objects may appear.


         -- Note: it is expected that each attribute may appear
         -- just once, even if the RBNF grammar allows it. If an
         -- object is allowed to repeat a list is used (e.g.
         -- metric-list

         -- Note: the ordering is implied by the notation below.

   -- For P2P reoptimizations
   <rro-bw-pair>     ::= <RRO> [<BANDWIDTH>]

   -- For P2MP reoptimizations
   <rro-list-bw>     ::= <rro-list>[<BANDWIDTH>]

   -- Some attributes only apply to P2MP computations
   <attribute>      ::=
             <CLASSTYPE> |
             <LSPA> |
             <OF> |
             <BANDWIDTH> |
             <metric-list> |
             <vendor-info-list> |
             <IRO> |
             <BNC> |             -- Only in P2MP
             <XRO> |
             <RRO> |             -- Used in Reports
             <rro-bw-pair> |     -- Only in P2P
             <rro-list-bw> |     -- Only in P2MP
             <LOAD-BALANCING> |
             <INTER-LAYER> |
             <SWITCH-LAYER> |
             <REQ-ADAP-CAP>

   <attributes> ::= <attribute> [<attributes>]






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4.1.6.  Paths

   A path is defined consistently as a qualified ERO (or ERO/SERO for
   P2MP).  Similar path constructs appear, notably, in PCEP responses,
   in solicited/unsolicited state reports and in update requests.  The
   following remarks apply:

   The <path> construct is then defined as:


   <ero-sero-list> ::= (<ERO> | <SERO>) [<ero-sero-list>]

   <path>      ::= <ERO> [<attributes>]

   <p2mp-path> ::= <ero-sero-list> [<attributes>]

   <path-list> ::= <path>|<p2mp-path> [<path-list>]


4.2.  PCEP Messages

4.2.1.  PCEP Open Message

   <Open Message> ::= <Common Header>
                      <OPEN>

4.2.2.  PCEP Keep Alive (KeepAlive) Message

   <KeepAlive Message>::= <Common Header>

4.2.3.  PCEP Request (PCReq) Message

   Note that the actual parsing depends on the content (flags) of the
   Request Parameters (RP) object, notably expansion and P2MP.  In some
   cases, this may be considered redundant, e.g. the presence of a
   PATH_KEY object and the corresponding flag.

   [Editor's note: from a notation perspective, we lack a way to express
   "if object a field x has value v then include object b, else include
   object c".  RNBF extensions can be considered in future revisions of
   the PCEP protocol, e.g. defining new constructs :

   (<a with x=v> <b>) | (<a with x!=v> <c>)

   this issue is still open.]

   The PCReq message contains a possibly monitored list of requests,
   some of which may be grouped by SVEC tuples.



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   <PCReq Message>::= <Common Header>
                      [<monitoring-request>]
                      [<svec-tuple-list>]
                      <request-list>

   where:

   <request-list>     ::= <request> [<request-list>]

   -- A request is either an expansion, a P2P request or a P2MP request

   <request>          ::= <expansion> |
                          <p2p_computation> |
                          <p2mp_computation>

   <expansion>        ::= <RP><PATH-KEY>

   <p2p_computation>  ::= <RP><ENDPOINTS>
                         [<LSP>]
                         [<attributes>]

   <p2mp_computation> ::= <RP><tree-list>
                          [<attributes>]

   -- For a P2P computation
   -- in RFC6006 there is a bw per tree,
   -- it is intended to be an optimization for an RRO list

   <tree>          ::= <ENDPOINTS>(<rro-bw-pair>|<rro-list-bw>)

   <tree-list> ::= <tree> [<tree-list>]

   <tree> ::= <ENDPOINTS> <rro-bw-pair>


4.2.4.  PCEP Reply (PCRep) Message















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   <PCRep Message> ::= <Common Header>
                       [<svec-tuple-list>]
                       <response-list>

   -- Note: should clarify the use of SVEC tuple list

   where

   <response-list> ::= <response> [<response-list>]

   -- An individual response may include monitoring info

   <response>  ::= <RP> [<monitoring>] [<LSP>]
                  (<success> | <failure>) [<monitoring-metrics>]


   -- Note: should clarify P2MP attributes. P2MP response
   -- also includes endpoint-path-pair-list. TBD

   <success>   ::= <path-list>

   <failure>   ::= <NO-PATH> [<attributes>]


4.2.5.  PCEP Monitoring Request (PCMonReq) Message

      The PCMonReq message is defined in [RFC5886] for out-of-band
      monitoring requests.

      [RFC5886] specifies that there is one mandatory object but the
      grammar also includes PCC-ID-REQ as mandatory.

      [Ed note:does it make sense to include a pce-id-list and a svec-
      list/request-list at the same time?]

   <PCMonReq Message>    ::= <Common Header>
                             <monitoring-request>
                             [[<svec-tuple-list>] <request-list>]


4.2.6.  PCEP Monitoring Reply (PCMonRep) Message

      The PCMonRep message is defined in [RFC5886] for out-of-band
      monitoring responses.

      [RFC5886] specifies that there is one mandatory object but the
      grammar also includes PCC-ID-REQ as mandatory.




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      [RFC5886] does not allow bundling several specific monitoring
      responses.  A PCMonReq message causes N PCMonRep messages.

   <PCMonRep Message> ::= <Common Header>
                          <monitoring-response>

4.2.7.  PCEP Notify (PCNtf) Message

   <PCNtf Message> ::= <Common Header>
                       ( <solicited-notify> | <unsolicited-notify> )

   where

   <solicited-notify>   ::= <request-id-list> <notification-list>

   <unsolicited-notify> ::= <notification-list>

   <request-id-list>    ::= <RP> [<request-id-list>]

   <notification-list>  ::= <NOTIFICATION> [<notification-list>]

4.2.8.  PCEP Error (PCErr) Message

      Errors can occur during PCEP handshake, or bound to one or more
      requests.

      An error during handshake is never solicited, i.e., not associated
      to a list of requests.

      A solicited error binds one or more Requests (RPs) to one or more
      PCEP-ERROR objects.




















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   <PCErr Message> ::=
                 <Common Header>
               ( <solicited-error> | <unsolicited-error> )

   where

   -- Solicited error is bound to a Request Paramters (RP) list or
   -- to a Stateful Request Parameters (SRP) list

   <solicited-error> ::= <request-id-list> | <stateful-request-id-list>

   -- Unsolicited Error can be due to handshake or asynchronous

   <unsolicited-error> ::= <handshake-error> | <pcep-error-list>

   -- Handshake Error is bound to an OPEN object

   <handshake-error>   ::= <pcep-error-list> <OPEN>


   <request-id-list>   ::= <RP> [<request-id-list>]

   <stateful-request-id-list> ::= <SRP>[<stateful-request-id-list>]

   <pcep-error-list>   ::= <PCEP-ERROR> [<pcep-error-list>]

4.2.9.  PCEP Report (PCRpt) Message

   The PCRpt format is defined in [I-D.ietf-pce-stateful-pce].  Note,
   however, that the end-of-sync, solicited-report and unsolicited-
   report are introduced for convenience, and that the RRO object is
   already part of the attributes construct.



















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   <PCRpt Message> ::= <Common Header>
                        <state-report-list>
   Where:

   <state-report-list> ::= <state-report> [<state-report-list>]

   <state-report> ::=
       <end-of-sync> |
       <solicited-report> |
       <unsolicited-report>

   -- LSP flags signal end of synchronization

   <end-of-sync> ::= <LSP>

   <solicited-report>   ::= <SRP> <LSP> <path>

   <unsolicited-report> ::= <LSP> <path>


4.2.10.  PCEP Update (PCUpd) Message

   As [I-D.ietf-pce-stateful-pce].

   <PCUpd Message> ::= <Common Header>
                       <udpate-request-list>

   Where:

   <update-request-list> ::= <update-request>[<update-request-list>]

   <update-request> ::= <SRP>
                        <LSP>
                        <path>

4.2.11.  PCEP Initiate (PCInitiate) Message

   As [I-D.ietf-pce-pce-initiated-lsp].  Note that the <path> construct
   is used here.












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   <PCInitiate Message> ::= <Common Header>
                            <PCE-initiated-lsp-request-list>
   Where:

   <PCE-initiated-lsp-request-list> ::= <PCE-initiated-lsp-request>
       [<PCE-initiated-lsp-request-list>]

   -- A request can be an instantiation or a deletion. SRP / LSP
   -- flags are used to select
   <PCE-initiated-lsp-request> ::=
       <PCE-initiated-lsp-instantiation> |
       <PCE-initiated-lsp-deletion>)

   <PCE-initiated-lsp-instantiation> ::= <SRP>
                                         <LSP>
                                         <ENDPOINTS>
                                         <path>

   <PCE-initiated-lsp-deletion> ::= <SRP>
                                    <LSP>




5.  Management Considerations

   This document does not define additional management considerations.

6.  Security Considerations

   This document does not define additional security considerations.

7.  Contributing Authors

      Robert Varga
      Pantheon
      robert.varga@pantheon.sk


      Jonathan Harwick
      Metaswitch
      Jonathan.Hardwick@metaswitch.com


      Olivier Dugeon
      Orange
      olivier.dugeon@orange.com




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      Julien Meuric
      Orange
      julien.meuric@orange.com


      Ina Minei
      Google
      inaminei@google.com


8.  Acknowledgments

   This work was supported in part by the PACE Support Action
   (http://ict-pace.net/) project under grant agreement number 619712.

9.  Normative References

   [I-D.ietf-pce-gmpls-pcep-extensions]
              Margaria, C., Dios, O., and F. Zhang, "PCEP extensions for
              GMPLS", draft-ietf-pce-gmpls-pcep-extensions-09 (work in
              progress), February 2014.

   [I-D.ietf-pce-hierarchy-extensions]
              Zhang, F., Zhao, Q., Dios, O., Casellas, R., and D. King,
              "Extensions to Path Computation Element Communication
              Protocol (PCEP) for Hierarchical Path Computation Elements
              (PCE)", draft-ietf-pce-hierarchy-extensions-01 (work in
              progress), February 2014.

   [I-D.ietf-pce-inter-layer-ext]
              Oki, E., Takeda, T., Farrel, A., and F. Zhang, "Extensions
              to the Path Computation Element communication Protocol
              (PCEP) for Inter-Layer MPLS and GMPLS Traffic
              Engineering", draft-ietf-pce-inter-layer-ext-08 (work in
              progress), January 2014.

   [I-D.ietf-pce-pce-initiated-lsp]
              Crabbe, E., Minei, I., Sivabalan, S., and R. Varga, "PCEP
              Extensions for PCE-initiated LSP Setup in a Stateful PCE
              Model", draft-ietf-pce-pce-initiated-lsp-01 (work in
              progress), June 2014.

   [I-D.ietf-pce-stateful-pce]
              Crabbe, E., Minei, I., Medved, J., and R. Varga, "PCEP
              Extensions for Stateful PCE", draft-ietf-pce-stateful-
              pce-09 (work in progress), June 2014.





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

   [RFC5440]  Vasseur, JP. and JL. Le Roux, "Path Computation Element
              (PCE) Communication Protocol (PCEP)", RFC 5440, March
              2009.

   [RFC5455]  Sivabalan, S., Parker, J., Boutros, S., and K. Kumaki,
              "Diffserv-Aware Class-Type Object for the Path Computation
              Element Communication Protocol", RFC 5455, March 2009.

   [RFC5511]  Farrel, A., "Routing Backus-Naur Form (RBNF): A Syntax
              Used to Form Encoding Rules in Various Routing Protocol
              Specifications", RFC 5511, April 2009.

   [RFC5520]  Bradford, R., Vasseur, JP., and A. Farrel, "Preserving
              Topology Confidentiality in Inter-Domain Path Computation
              Using a Path-Key-Based Mechanism", RFC 5520, April 2009.

   [RFC5521]  Oki, E., Takeda, T., and A. Farrel, "Extensions to the
              Path Computation Element Communication Protocol (PCEP) for
              Route Exclusions", RFC 5521, April 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.

   [RFC5557]  Lee, Y., Le Roux, JL., King, D., and E. Oki, "Path
              Computation Element Communication Protocol (PCEP)
              Requirements and Protocol Extensions in Support of Global
              Concurrent Optimization", RFC 5557, July 2009.

   [RFC5886]  Vasseur, JP., Le Roux, JL., and Y. Ikejiri, "A Set of
              Monitoring Tools for Path Computation Element (PCE)-Based
              Architecture", RFC 5886, June 2010.

   [RFC6006]  Zhao, Q., King, D., Verhaeghe, F., Takeda, T., Ali, Z.,
              and J. Meuric, "Extensions to the Path Computation Element
              Communication Protocol (PCEP) for Point-to-Multipoint
              Traffic Engineering Label Switched Paths", RFC 6006,
              September 2010.

   [RFC7150]  Zhang, F. and A. Farrel, "Conveying Vendor-Specific
              Constraints in the Path Computation Element Communication
              Protocol", RFC 7150, March 2014.






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Authors' Addresses

   Ramon Casellas (editor)
   CTTC
   Av. Carl Friedrich Gauss n.7
   Castelldefels  08860 Barcelona
   Spain

   Phone: +34 93 645 29 00
   Email: ramon.casellas@cttc.es


   Oscar Gonzalez de Dios (editor)
   Telefonica I+D
   Don Ramon de la Cruz 82-84
   Madrid  28045
   Spain

   Phone: +34913128832
   Email: oscar.gonzalezdedios@telefonica.com


   Adrian Farrel (editor)
   Old Dog Consulting

   Email: adrian@olddog.co.uk


   Cyril Margaria
   Juniper Networks
   88 Centennial Ave, Piscataway Township
   New Jersey
   US

   Email: cmargaria@juniper.net


   Dhruv Dhody
   Huawei Technologies
   Leela Palace
   Bangalore, Karnataka  560008
   INDIA

   Email: dhruv.dhody@huawei.com







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   Xian Zhang
   Huawei Technologies

   Email: zhang.xian@huawei.com















































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