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Versions: 00 01 02 03 04 05 draft-ietf-pce-wson-routing-wavelength

Network Working Group                                          Y. Lee
Internet Draft                                                 Huawei
Intended status: Standard Track                            G. Bernstein
Expires: May 2008                                    Grotto Networking
                                                      October 29, 2007


    Path Computation Element Communication Protocol (PCEP) Requirements
       and Extensions for the Support of Wavelength Switched Optical
                                 Networks
               draft-lee-pce-wson-routing-wavelength-00.txt


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Copyright Notice

   Copyright (C) The IETF Trust (2007).

Abstract




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   This memo provides application-specific PCEP requirements and
   protocol enhancements for the support of Wavelength Switched Optical
   Networks (WSON).  Lightpath provisioning in WSONs requires a routing
   and wavelength assignment (RWA) process.  Different computational
   architectures for the RWA process are given and the PCEP extensions
   needed to support these architectures are defined.





Conventions used in this document

   The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
   "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this
   document are to be interpreted as described in RFC-2119 0.

Table of Contents


   1. Terminology.................................................3
   2. Introduction................................................4
   3. Background: RWA Computation Architectures....................4
   4. PCECP Requirements..........................................5
      4.1. RWA Computation Options.................................6
      4.2. Timeliness Characteristics of lightpath.................7
      4.3. Duration of lightpath...................................7
      4.4. Optimization Degree.....................................8
      4.5. Wavelength Selection Preference.........................8
      4.6. Wavelength Assignment and Wavelength Set Information.....9
      4.7. Lightpath Route Parameters..............................9
   5. Protocol extensions for support of WSON Routing and Wavelength
   Assignment (RWA)...............................................9
      5.1. RWA Computation Options.................................9
      5.2. Lightpath Route Parameter TLV..........................11
      5.3. Wavelength Selection Preferences.......................12
      5.4. Wavelength Suggestion/Restriction TLV..................14
      5.5. Error Indicator........................................14
      5.6. NO-PATH Indicator......................................14
   6. Manageability Considerations................................15
      6.1. Control of Function and Policy.........................15
      6.2. Information and Data Models, e.g. MIB module...........16
      6.3. Liveness Detection and Monitoring......................16
      6.4. Verifying Correct Operation............................16
      6.5. Requirements on Other Protocols and Functional Components16
      6.6. Impact on Network Operation............................16
   7. Security Considerations.....................................17


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   8. IANA Considerations........................................17
   9. Acknowledgments............................................17
   10. References................................................17
      10.1. Normative References..................................17
      10.2. Informative References................................18
   Author's Addresses............................................18
   Intellectual Property Statement................................19
   Disclaimer of Validity........................................19

1. Terminology

   The terminology explained herein complies with [RFC4655].

   PCC: Path Computation Client: Any client application requesting a
   path computation to be performed by a Path Computation Element.

   PCE: Path Computation Element: An entity (component, application or
   network node) that is capable of computing a network path or route
   based on a network graph and applying computational constraints.

   TED: Traffic Engineering Database which contains the topology and
   resource information of the domain.  The TED may be fed by IGP
   extensions or potentially by other means.

   PCECP: The PCE Communication Protocol: PCECP is the generic abstract
   idea of a protocol that is used to communicate path computation
   requests a PCC to a PCE, and to return computed paths from the PCE to
   the PCC.  The PCECP can also be used between cooperating PCEs.

   PCEP: The PCE communication Protocol: PCEP is the actual protocol
   that implements the PCECP idea.

   RWA: Routing and Wavelength Assignment

   WSON: Wavelength Switched Optical Networks: WDM based optical
   networks in which switching is performed selectively based on the
   center wavelength of an optical signal.

   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].

   These terms are also used in the parts of this document that specify
   requirements for clarity of specification of those requirements.





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2. Introduction

   [RFC4655] defines the PCE based Architecture and explains how a Path
   Computation Element (PCE) may compute Label Switched Paths (LSP) in
   Multiprotocol Label Switching Traffic Engineering (MPLS-TE) and
   Generalized MPLS (GMPLS) networks at the request of PCCs.  A PCC is
   shown to be any network component that makes such a request and may
   be for instance an Optical Switching Element with a WDM network.  The
   PCE, itself, can be located anywhere within the network, and may be
   within an optical switching element, an NMS or Operational Support
   System (OSS), or may be an independent network server.

   The PCECP is the communication protocol used between PCC and PCE, and
   may also be used between cooperating PCEs.  [RFC4657] sets out the
   common protocol requirements for the PCECP.  Additional application-
   specific requirements for PCECP are deferred to separate documents.

   This document provides a set of application-specific PCECP
   requirements and protocol enhancements for support of path
   computation in Wavelength Switched Optical Network (WSON).  WSON
   refers to Wavelength Division Mulitiplexing (WDM) based optical
   networks in which switching is performed selectively based on the
   wavelength of an optical signal.  The path in WSON is referred to as
   a lightpath.  In order to provision a light path, both routing and
   wavelength assignment (RWA) are required.



3. Background: RWA Computation Architectures

   The WSON framework [WSON Frame] document defines the following RWA
   computation architectures.

   o Combined RWA --- Both routing and wavelength assignment are
      performed at a single computational entity.  This choice assumes
      that computational entity has sufficient WSON network link/nodal
      and topology information to be able to compute RWA.

   o Separate Routing and WA --- Separate entities perform routing and
      wavelength assignment.  The path obtained from the routing
      computational entity must be furnished to the entity performing
      wavelength assignment.

   o Routing with Distributed WA --- Routing is performed at a
      computational entity while wavelength assignment is performed in a
      distributed fashion across the nodes along the path.



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   For the Combined RWA architecture, there are two possible computing
   entities: (i) the NE is the computational entity -- in this case,
   there is no separate PCE as the NE assumes PCE function; (ii) a
   separate PCE is the computational entity.  This document is only
   concerned with case (ii). In this case, the PCE should perform both
   routing (R) and wavelength assignment (WA) upon request of the PCC.

   For the Separate Routing and Wavelength architecture, there can be
   two variations:


   o A separate PCE will perform only wavelength assignment (WA) while
      the NE performs the route calculation based on its local knowledge.
      In this case, the NE should furnish the route list to the PCE so
      that the PCE would be able to assign wavelength to the route.

   o One PCE performs the routing (R) function while another PCE
      performs the Wavelength Assignment (WA) function in a tandem
      fashion.  The fact that two PCEs are involved (one for Routing and
      one for Wavelength Assignment (WA)) could be invisible to the
      original PCC.


   For the Routing with Distributed WA architecture, the PCE is only
   responsible for routing (i.e., path computation), not for exact
   wavelength assignment. The exact assignment of wavelength would be
   performed at the NEs along the path in a distributed fashion. However,
   the PCE may choose to limit the wavelengths that can be used (i.e.,
   suggesting the wavelength set to the NEs)



4. PCECP Requirements

   This section provides the PCECP requirements to support WSON routing
   and wavelength assignment (RWA) application.  The requirements
   specified in this section are detailed requirements based on high-
   level specification in the WSON Framework draft [WSON FRAME].  The
   requirements specified here should be regarded as application-
   specific requirements and are justifiable based on the extensibility
   clause found in section 6.1.14 of [RFC4657]:

   The PCECP MUST support the requirements specified in the application-
   specific requirements documents.  The PCECP MUST also allow
   extensions as more PCE applications will be introduced in the future.



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   The PCEP SHOULD support the following capabilities either via
   creation of new objects and/or modification of existing object where
   applicable.



    4.1. RWA Computation Options

   The following RWA computation options should be conveyed in the PC
   Request:

   o The request is for Wavelength Assignment (WA) only.  This case may
      arise when the NE is capable of route calculation at the node
      level (e.g., via an IGP-TE) but with no wavelength information
      available at the node level, or when two PCEs work in tandem with
      one performing the routing (R) function and another wavelength
      assignment (WA).  In either case, the calculated route list at one
      computing entity should be supplied in the request message to the
      other computing entity where WA is applied.

   o The request is for both Routing and Wavelength Assignment (R+WA).
      This case may arise when the NE is not capable of both route
      calculation and wavelength assignment at the node level or a more
      optimal RWA is desired.

   o The request is for Routing (R) only.  This case may arise when the
      NE is not capable of route calculation at the node level while
      wavelength assignment is done at the node level in a distributed
      fashion.

   o The request is for Routing (R) with the suggested/restricted
      wavelength set. This is a variation from the Routing only option.
      With this option, the PCE computes the route and the candidate
      wavelengths associated with the route. In this case, the exact
      wavelength assignment is to be performed at the NE level.


   The corresponding PC Reply message should include the following
   information:

   o An indicator that conveys the original request was for (i) WA only;
      (ii) R+WA; (iii) R only; (iv) R with the suggested/restricted
      wavelength set






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   o The route list and the recommended wavelength(s) to be used for
      the route. The encoding of this requirement can be fulfilled with
      the ERO object and ERO Label subobject within the ERO as defined
      in [RFC3471]. See section 4.6 for details of wavelength label
      assignment.

   o In the case of failure to find a proper route or wavelength
      assigned to the route, proper reasons for the failure should be
      conveyed: (i) route not found; (ii) wavelength not found (i.e.,
      wavelength blocking); (iii) both route and wavelength not found.



    4.2. Timeliness Characteristics of lightpath

   The request may indicate specific timeliness lightpath
   characteristics associated with the request:

   o Time Critical: this type of request is useful for those lightpath
      establishment requests used for restoration of service or other
      high priority real time services.

   o Soft Time Bounds: this type of request is a more typical new
      connection request.  While expected to be responsive, there should
      be more time to take into account network optimization.

   o Scheduled: this type of request is useful when the requested
      lightpath connections are not time critical (i.e., the request is
      significantly ahead of their intended "in-service" time.  It is to
      be noted that we will not explicitly deal with scheduled case in
      this document but the optimization can be handled via [PCE-GCO].

   The reply should indicate the original timeliness characteristics of
   the lightpath request with path computation results.



    4.3. Duration of lightpath

   The request may indicate specific lightpath duration information
   associated with the request. This may be useful to the PCE since it
   is not worthwhile to optimize lightpaths with relatively short
   duration as compared to pseudo-static paths.






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    4.4. Optimization Degree

   The PC Request Message should indicate the degree of optimization
   associated with lightpath computation.


   o Concurrent Optimization: multiple lightpaths requested at one time.

   o Lightpath(s) and backup lightpath(s) requested at one time.

   o Sequential Optimization: single lightpath requested at a time.

   The PC Reply Message should include the original optimization degree
   associated with the request when replying the path computation
   results.


    4.5. Wavelength Selection Preference

   The PC Request may indicate the Wavelength Selection Preference to
   which a path computation request is applied.

   The Wavelength Selection Preference to be supported at the minimum is:

   o Random

   o First Fit

   o Most Used

   o Least Loaded

   o Don't care: default

   Note that the objective functions to be supported for a single LSP
   request are listed in [PCEP] and [PCE-OF] and that the objective
   functions to be supported for a concurrent LSP request are listed in
   [PCE-GCO] and [PCE-OF].

   The PC Reply should indicate which wavelength selection preference
   has actually been applied.







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    4.6. Wavelength Assignment and Wavelength Set Information

   The PCE MUST specify the wavelength assignment and/or wavelength set
   information in response to the wavelength assignment/wavelength set
   Request made by the PCC in the PCReq message.

   If the original request is either for both Routing and Wavelength
   Assignment or for Wavelength Assignment only, the exact wavelength
   assignment result can be conveyed to PCC using the ERO object and ERO
   Label subobject within the ERO. Note that this is not a new
   requirement. Current PCEP allows this mechanism which is defined as
   the Label Set mechanism in [RFC3471].

   If the original request is for Routing with wavelength
   suggested/restricted wavelength set, then the Wavelength Set
   information must be provided to the PCC.



    4.7. Lightpath Route Parameters

   The following Lightpath Route Parameters should be indicated:

   o Bidirectional Assignment of wavelengths for a bidirectional LSP
      request.

   o Possible simultaneous assignment of the same wavelength to primary
      and backup paths.

   The PC Reply Message should include the original lightpath route
   parameter associated with the request when replying the path
   computation results.


5. Protocol extensions for support of WSON Routing and Wavelength
   Assignment (RWA)



    5.1. RWA Computation Options

   The PCE has to include the RWA computation option in the PCReq
   message in order to convey a particular computation option.  To
   support such indication a new flag, the RC flag, is defined in the RP
   (Request Parameter) Object.  The PCE also has to include the
   Directionality of Wavelength Assignment indicator when the request is


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   for a bidirectional TE LSP.  To support such indication a new flag, I
   flag, is defined in the RP Object.


   The RC flag and I flag are defined in the RP (Request Parameter)
   object 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
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |       Reserved    |            Flags   |I|RC|D|M|F|O|B|R| Pri |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |                        Request-ID-number                      |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |                                                               |
   //                      Optional TLV(s)                        //
   |                                                               |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+


       Figure 1            RP object body format in the PCReq Message


   RC bits (Routing wavelength Computation bits - 2 bits):

   o 11: Request is for both R (Routing) and Wavelength Assignment (WA).

   o 01: Request is for Wavelength Assignment (WA) only.

   o 10: Request is for Routing (R) with suggested/restricted
      Wavelength Set

   o 00: Request is for Routing (R) only.

   When RC bit is set to 11 in a PCReq message, the requesting PCC
   requires the PCE to provide in the PCRep message the assigned
   wavelength associated with the computed path.  This request is for
   both Routing (R) and Wavelength Assignment (WA).

   When RC bit is set to 01 in a PCReq message, the requesting PCC
   requires the PCE only to provide wavelength assignment (WA).  In such
   case, the PCC must provide the already computed route (as indicated
   by the ERO and the Bandwidth Object following the RP object) to which
   the PCE would assign the wavelengths.  Note that this option is to
   fulfill one of the RWA computational architectures, namely, the
   Separate Routing and WA option.


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   When RC bit is set to 10, then the PCE is expected to provide some
   suggestive or restrictive wavelength information associated with the
   route.

   When RC bit is set to either 11, 01 or 10, then additional parameters
   associated with the requested lightpath should be provided in
   optional lightpath Route Parameter TLV (as specified in Section 4.7)
   within the RP object. See Section 5.2 for the encoding of Lightpath
   Route Parameter TLV.

   When B bit is set in the RP object in a PCReq message, this indicates
   that the path computation request relates to a bidirectional TE LSP
   [PCEP].  In such case, a new flag, I flag, should be defined in the
   RP object should be defined in order to indicate that a bidirectional
   assignment of wavelength be required for the bidirectional TE LSP.

   I bit (dIrectionality bit - 1 bit): When set, the request is a
   bidirectional wavelength assignment.  Otherwise, the request is a
   unidirectional wavelength assignment.

   The RP object in the PC Reply message should properly indicate the
   original request for the RWA Computation (RC) bit and I bit that have
   actually been applied by the PCE. The actual route list and
   wavelength assignment is to be found in the ERO object and within an
   ERO an ERO Label subobject. An ERO Label subobject can be used to
   indicate the wavelength to be used at a particular node. Note that
   current GMPLS signaling supports an explicit route object (ERO) and
   within an ERO an ERO Label subobject.



    5.2. Lightpath Route Parameter TLV

   When the RC bit is set to either 11, 01 or 10 in the RP object
   associated with PC Req message, then the following TLV should be
   included as part of the RP object within the PC Request message.

   The format of the Lightpath Route Parameter TLV is as follows:










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   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
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |     Type      |    Length     |                               |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |         Bidirectional Assignment of wavelengths               |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |         Same wavelength to primary and backup paths           |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+


              Type     To be defined by IANA (suggested value = )
              Length   Variable
              Value    Bidirectional Assignment of wavelengths (0 or 1)
                      Same Wavelength to primary and backup (0 or 1)


   Figure 2    The Lightpath Route Parameter TLV in the RP object in the
                              PC Rep Message



    5.3. Wavelength Selection Preferences

   When the RC (RWA Computation) option is associated with computing
   wavelength assignment in the RP object of the PC Request message,
   then the following Wavelength Selection Preference TLV may be
   included in the RP object as an optional TLV.

   The format of the Wavelength Selection Preference TLV is as follows:


















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   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
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |     Type      |    Length     |                               |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |                Wavelength Selection Preference                |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |                           TDB                                 |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

              Type     To be defined by IANA (suggested value = )
              Length   Variable
              Value    Wavelength Selection Preference

     Figure 3    The Wavelength Selection/Assignment Preferences TLV in
                    the RP object in the PC Rep Message


   Five wavelength selection preferences are defined in this document
   and their identifier should be assigned by IANA (suggested value)

   Function
   Code            Description

   1               Random

   2               First Fit

   3               Most Used

   4               Least Loaded

   5              Don't Care


   The Wavelength Selection Preference TLV should also be included in
   the RP object in the PC Reply message to indicate which wavelength
   selection preference has actually been applied by the PCE in its
   wavelength assignment procedure.








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    5.4. Wavelength Suggestion/Restriction TLV

   With the Routing with Distributed Wavelength Assignment option, the
   PC Reply should specify the wavelength set information in response to
   the wavelength assignment/wavelength set Request made by the PCC in
   the PCReq message if so requested by the setting of the RC bit in the
   RP object in the PCReq message.

   We refer to this information as wavelength restriction TLV.

   The encoding of wavelength Suggestion/Restriction TLV is to be
   provided in the next version.


    5.5. Error Indicator

   To indicate errors associated with the RWA request, a new Error-Type
   (15) and subsequent error-values are defined as follows for inclusion
   in the PCEP-ERROR object:

   A new Error-Type (15) and subsequent error-values are defined as
   follows:

   Error-Type=15 and Error-Value=1: if a PCE receives a RWA computation
   request and the PCE is not capable of RWA, the PCE MUST send a PCErr
   message with a PCEP ERROR object (Error-Type=15) and an Error-Value
   (Error-Value=1).  The corresponding RWA computation request MUST be
   cancelled.

   To indicate an error associated with policy violation, a new error
   value "RWA not allowed" should be added to an existing error code for
   policy violation (Error-Type=6) as defined in [PCEP].

   Error-Type=6; Error-Value=3: if a PCE receives a RWA computation
   request which is not compliant with administrative privileges (i.e.,
   the PCE policy does not support RWA), the PCE sends a PCErr message
   with a PCEP-ERROR Object (Error-Type=6) and an Error-Value (Error-
   Value=3).  The corresponding RWA computation MUST be cancelled.

    5.6. NO-PATH Indicator

   To communicate the reason(s) for not being able to find RWA
   computation, the NO-PATH object can be used in the PCRep message.

   The format of the NO-PATH object body is as follows:




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       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
       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
       |C|        Flags                |          Reserved             |
       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
       |                                                               |
       //                      Optional TLV(s)                        //
       |                                                               |
       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+


                      Figure 4 NO-PATH object format


   Flags (16 bits).  The C flag is defined in [PCEP].

   Two new bit flags are defined in the NO-PATH-VECTOR TLV carried in
   the NO-PATH Object:

   0x08: when set, the PCE indicates that no path was found.

   0x10: when set, the PCE indicates that no wavelength was found
   associated with RWA computation in the PCRep message.



6. Manageability Considerations

   Manageability of WSON Routing and Wavelength Assignment (RWA) with
   PCE must address the following considerations:

    6.1. Control of Function and Policy

   In addition to the parameters already listed in section 8.1 of [PCEP],
   a PCEP implementation SHOULD allow configuring the following PCEP
   session parameters on a PCC:

   o The ability to send a WSON RWA request.

   In addition to the parameters already listed in section 8.1 of [PCEP],
   a PCEP implementation SHOULD allow configuring the following PCEP
   session parameters on a PCE:



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   o The support for WSON RWA.

   o The maximum number of synchronized path requests associated with
      WSON RWA per request message.

   o A set of WSON RWA specific policies (authorized sender, request
      rate limiter, etc).


   These parameters may be configured as default parameters for any PCEP
   session the PCEP speaker participates in, or may apply to a specific
   session with a given PCEP peer or a specific group of sessions with a
   specific group of PCEP peers.


    6.2. Information and Data Models, e.g. MIB module

   Extensions to the PCEP MIB module defined in [PCEP-MIB] should be
   defined, so as to cover the WSON RWA information introduced in this
   document.

    6.3. Liveness Detection and Monitoring

   Mechanisms defined in this draft does not imply any new liveness
   detection and monitoring requirements in addition to those already
   listed in section 8.3 of [PCEP].


    6.4. Verifying Correct Operation

   Mechanisms defined in this draft does not imply any new verification
   requirements in addition to those already listed in section 8.4 of
   [PCEP]


    6.5. Requirements on Other Protocols and Functional Components

   The PCE Discovery mechanisms ([ISIS PCED] and [OSPF PCED]) may be
   used to advertise WSON RWA path computation capabilities to PCCs.


    6.6. Impact on Network Operation

   Mechanisms defined in this draft does not imply any new network
   operation requirements in addition to those already listed in section
   8.6 of [PCEP].



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7. Security Considerations

   This document has no requirement for a change to the security models
   within PCEP [PCEP]. However the additional information distributed in
   order to address the RWA problem represents a disclosure of network
   capabilities that an operator may wish to keep private. Consideration
   should be given to securing this information.



8. IANA Considerations

   A future revision of this document will present requests to IANA for
   codepoint allocation.



9. Acknowledgments



10. References

    10.1. Normative References

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

   [RFC2234] Crocker, D. and Overell, P.(Editors), "Augmented BNF for
             Syntax Specifications: ABNF", RFC 2234, Internet Mail
             Consortium and Demon Internet Ltd., November 1997.

   [RFC4655] Farrel, A., Vasseur, J., and J. Ash, "A Path Computation
             Element (PCE)-Based Architecture", RFC 4655, August 2006.

   [RFC4657] Ash, J. and J. Le Roux, "Path Computation Element (PCE)
             Communication Protocol Generic Requirements", RFC 4657,
             September 2006.

   [PCEP]    Vasseur, JP., Ed. and JL. Le Roux, Ed., "Path Computation
             Element (PCE) communication Protocol (PCEP) - Version 1",
             draft-ietf-pce-pcep, work in progress.





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   [PCE-OF]  Le Roux, JL., Vasseur, JP., and Y. Lee, "Objective Function
             encoding in Path Computation Element communication and
             discovery protocols", draft-ietf-pce-pce-of, work in
             progress.

   [PCE-GCO] Y. Lee, J.L. Le Roux, D. King, and E. Oki, "Path
             Computation Element Communication Protocol (PCECP)
             Requirements and Protocol Extensions In Support of Global
             Concurrent Optimization", draft-ietf-pce-global-concurrent-
             optimization, work in progress.



    10.2. Informative References

   [WSON-FRAME] Bernstein, G. and Lee, Y. (Editors), and W. Imajuku,
             "Framework for GMPLS and PCE Control of Wavelength Switched
             Optical Networks", draft-bernstein-ccamp-wavelength-
             switched, work in progress.

   [ISIS-PCED] Le Roux, J. and JP. Vasseur, "IS-IS protocol extensions
             for Path Computation Element (PCE) Discovery", draft-ietf-
             pce-disco-proto-isis, work in progress.

   [OSPF-PCED] Le Roux, J. and JP. Vasseur, "OSPF protocol extensions
             for Path Computation Element (PCE) Discovery", draft-ietf-
             pce-disco-proto-ospf, work in progress.




Author's Addresses

   Young Lee (ed.)
   Huawei Technologies
   1700 Alma Drive, Suite 100
   Plano, TX 75075, USA

   Phone: (972) 509-5599 (x2240)
   Email: ylee@huawei.com









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   Greg Bernstein (ed.)
   Grotto Networking
   Fremont, CA, USA

   Phone: (510) 573-2237
   Email: gregb@grotto-networking.com


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