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Versions: 00 01 02 03 04 05 draft-ietf-pce-wson-rwa-ext

Network Working Group                                            Y. Lee
Internet Draft                                                   Huawei
Intended status: Standard                                   R. Casellas
Expires: September 2011                                            CTTC
                                                             C. Margaria
                                                                     NSN
                                                           O. G. de Dios
                                                              Telefonica




                                                          March 4, 2011


         PCEP Extension for WSON Routing and Wavelength Assignment


                     draft-lee-pce-wson-rwa-ext-01.txt


Status of this Memo

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Copyright Notice

   Copyright (c) 2011 IETF Trust and the persons identified as the
   document authors. All rights reserved.



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   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.


Abstract

   This draft provides the Path Computation Element communication
   Protocol (PCEP) extensions for the support of Routing and Wavelength
   Assignment (RWA) in Wavelength Switched Optical Networks (WSON).
   Lightpath provisioning in WSONs requires a routing and wavelength
   assignment (RWA) process.  From a path computation perspective,
   wavelength assignment is the process of determining which wavelength
   can be used on each hop of a path and forms an additional routing
   constraint to optical light path computation.

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. Introduction...................................................3
   2. WSON PCE Architectures and Requirements........................6
      2.1. Encoding of a new RWA path request........................7
         2.1.1. Wavelength Range Constraint..........................9
         2.1.2. Signal processing capability restrictions............9
            2.1.2.1. MODULATION-FORMAT TLV..........................11
            2.1.2.2. FEC TLV........................................11
         2.1.3. New XRO sub-object: signal processing exclusion.....12
         2.1.4. IRO sub-object: signal processing inclusion.........13
      2.2. Encoding of a RWA Path Reply.............................13
      2.3. Error Indicator..........................................14
      2.4. NO-PATH Indicator........................................14
   3. Manageability Considerations..................................15
      3.1. Control of Function and Policy...........................15
      3.2. Information and Data Models, e.g. MIB module.............15



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      3.3. Liveness Detection and Monitoring........................16
      3.4. Verifying Correct Operation..............................16
      3.5. Requirements on Other Protocols and Functional Components16
      3.6. Impact on Network Operation..............................16
   4. Security Considerations.......................................16
   5. IANA Considerations...........................................16
   6. Acknowledgments...............................................17
   7. References....................................................17
      7.1. Normative References.....................................17
      7.2. Informative References...................................17
   8. Contributors..................................................19
   Authors' Addresses...............................................19
   Intellectual Property Statement..................................19
   Disclaimer of Validity...........................................20



       1. 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 Path Computation
   Clients (PCCs).  A PCC is shown to be any network component that
   makes such a request and may be for instance an Optical Switching
   Element within a Wavelength Division Multiplexing (WDM) network.
   The PCE, itself, can be located anywhere within the network, and may
   be within an optical switching element, a Network Management System
   (NMS) or Operational Support System (OSS), or may be an independent
   network server.

   The PCE communications Protocol (PCEP) 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 PCEP.
   Additional application-specific requirements for PCEP are deferred
   to separate documents.

   This document provides the PCEP extension for the support of Routing
   and Wavelength Assignment (RWA) in Wavelength Switched Optical
   Networks (WSON) based on the requirements specified in [PCE-RWA].

   WSON refers to WDM based optical networks in which switching is
   performed selectively based on the wavelength of an optical signal.
   In this document, it is assumed that wavelength converters require
   electrical signal regeneration. Consequently, WSONs can be
   transparent (A transparent optical network is made up of optical
   devices that can switch but not convert from one wavelength to


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   another, all within the optical domain) or translucent (3R
   regenerators are sparsely placed in the network).

   A LSC Label Switched Path (LSP) may span one or several transparent
   segments, which are delimited by 3R regenerators (typically with
   electronic regenerator and wavelength conversion). Each transparent
   segment or path in WSON is referred to as an optical path. An
   optical path may span multiple fiber links and the path should be
   assigned the same wavelength for each link. In such case, the
   optical path is said to satisfy the wavelength-continuity
   constraint. Figure 1 illustrates the relationship between a LSC LSP
   and transparent segments (optical paths).

   +---+       +-----+       +-----+      +-----+         +-----+
   |   |I1     |     |       |     |      |     |       I2|     |
   |   |o------|     |-------[(3R) ]------|     |--------o|     |
   |   |       |     |       |     |      |     |         |     |
   +---+       +-----+       +-----+      +-----+         +-----+
       [X  LSC]     [LSC  LSC]    [LSC  LSC]     [LSC  X]       SwCap
       <------->     <------->      <----->      <------->
       <----------------------->  <---------------------->
         Transparent Segment         Transparent Segment
       <------------------------------------------------->
                              LSC LSP


       Figure 1:  Illustration of a LSC LSP and transparent segments



   Note that two optical paths within a WSON LSP need not operate on
   the same wavelength (due to the wavelength conversion capabilities).
   Two optical paths that share a common fiber link cannot be assigned
   the same wavelength.  To do otherwise would result in both signals
   interfering with each other. Note that advanced additional
   multiplexing techniques such as polarization based multiplexing are
   not addressed in this document since the physical layer aspects are
   not currently standardized. Therefore, assigning the proper
   wavelength on a lightpath is an essential requirement in the optical
   path computation process.

   When a switching node has the ability to perform wavelength
   conversion, the wavelength-continuity constraint can be relaxed, and
   a LSC Label Switched Path (LSP) may use different wavelengths on
   different links along its route from origin to destination. It is,
   however, to be noted that wavelength converters may be limited due
   to their relatively high cost, while the number of WDM channels that


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   can be supported in a fiber is also limited. As a WSON can be
   composed of network nodes that cannot perform wavelength conversion,
   nodes with limited wavelength conversion, and nodes with full
   wavelength conversion abilities, wavelength assignment is an
   additional routing constraint to be considered in all lightpath
   computation.

   [Ed note: in general, WSON LSC may not be the only switching layer
   with switching constraints. From a GMPLS/PCEP perspective,
   wavelength assignment corresponds to label allocation. This document
   should align with GMPLS extensions for PCEP. Wavelength restrictions
   and constraints should be formulated in terms of labels (i.e.
   LABEL_SET, SUGGESTED_LABEL, UPSTREAM_LABEL, etc.)

   [Ed Note] For example, within a translucent WSON, a LSC LSP may be
   established between interfaces I1 and I2, spanning 2 transparent
   segments (optical paths) where the wavelength continuity constraint
   applies (i.e. the same unique wavelength MUST be assigned to the LSP
   at each TE link of the segment). If the LSC LSP induced a Forwarding
   Adjacency / TE link, the switching capabilities of the TE link would
   be [X X] where X < LSC (PSC, TDM, ...).

   In addition to those label switching constraints, each optical path
   is constrained by the optical signal quality. The optical signal
   quality depends first on the optical sender and receiver
   capabilities. Second contributors to optical signal constraints are
   the optical elements used on the path (optical fibers, amplifiers,
   boosters, optical components). All those elements have an impact on
   the optical signal quality that limits the ability of the optical
   path to carry traffic. In order to improve the signal quality and
   limit some optical effects several advanced modulation processing
   are used. Those modulation properties contribute not only to optical
   signal quality checks but also constrain the selection of sender and
   receiver, as they should have matching signal processing
   capabilities.

   The optical modulation properties, also referred to as signal
   compatibility, are already considered in signaling in [RWA-Encode]
   and [WSON-OSPF].

   This document includes signal compatibility constraint as part of
   RWA path computation. That is, the signal processing capabilities
   (e.g., modulation and FEC) must be compatible between the sender and
   the receiver of the optical path across all optical elements.





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   This document, however, does not address optical impairments as part
   of RWA path computation. See [WSON-Imp] and [PSVP-Imp] for more
   information on optical impairments and GMPLS.

   .



   Listed below are some relevant drafts addressed in the IETF CCAMP
   WG.

     .  WSON RWA Framework:
          o draft-ietf-ccamp-rwa-wson-framework
     .  Label switching constraints:
          o draft-ietf-ccamp-general-constraint-encode
          o draft-ietf-ccamp-rwa-wson-encode
          o draft-ietf-ccamp-rwa-info
     .  Signal processing capabilities:
          o draft-ietf-ccamp-rwa-wson-encode
          o draft-ietf-ccamp-wson-signal-compatibility-ospf
          o draft-ietf-ccamp-wson-signaling
     .  Optical Impairment:
          o draft-ietf-ccamp-wson-impairments
          o draft-agraz-ccamp-wson-impairment-rsvp
          o draft-eb-ccamp-ospf-wson-impairments

   The remainder of this document uses terminology from [RFC4655].

       2. WSON PCE Architectures and Requirements

   Figure 2 shows one typical PCE based implementation, which is
   referred to as Combined Process (R&WA). With this architecture, the
   two processes of routing and wavelength assignment are accessed via
   a single PCE. This architecture is the base architecture from which
   the requirements have been specified in [PCE-RWA] and the PCEP
   extensions that are going to be specified in this document based on
   this architecture.












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                          +----------------------------+
            +-----+       |     +-------+     +--+     |
            |     |       |     |Routing|     |WA|     |
            | PCC |<----->|     +-------+     +--+     |
            |     |       |                            |
            +-----+       |             PCE            |
                          +----------------------------+


              Figure 2: Combined Process (R&WA) architecture

                         2.1. Encoding of a new RWA path request

   The current RP object is used to indicate routing related
   information in a new path request per [RFC5440]. Since a new RWA
   path request involves both routing and wavelength assignment, the
   wavelength assignment related information in the request SHOULD be
   coupled in the path request.

   [Ed note: align with [GMPLS-PCEP] in the sense that Wavelength
   Assignment is a particular case of Label Allocation]

   Label allocation can be performed by the PCE by different means:

   a) By means of Explicit Label Control, in the sense that one (or
     two) allocated labels MAY appear after an interface route
     subobject.
   b) By means of a Suggested Label (and, for bidirectional LSPs, an
     Upstream Label) provided by the PCE
   c) By means of a Label Set, containing one or more allocated Labels,
     provided by the PCE.

   Note that in the b) and c) cases, except when c) includes only one
   Label, the label allocation can be considered an optimization or
   suggestion, allowing to be completed with distributed label
   allocation (performed during signaling).

   Additionally, given a range of potential labels to allocate, the
   request SHOULD convey the heuristic / mechanism to the allocation,
   including vendor-specific approaches.

   The format of a PCReq message after incorporating the WA object is
   as follows:

      <PCReq Message> ::= <Common Header>

                          [<svec-list>]


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                          <request-list>

      Where:

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

         <request>::= <RP>

                      <ENDPOINTS>

                      <WA>

                      [other optional objects...]

   Note: if WA object is present in the request, the WA object MUST be
   encoded after the ENDPOINTS object.

   The format of the Wavelength Assignment (WA) object body 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
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |                          Flags                              |E|
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |                                                               |
      //                      Optional TLVs                          //
      |                                                               |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

                     Figure 3: WA Object Body Format

      Flags (32 bits)



   The following new flags SHOULD be set

   o  E (Explicit - 1 bit): When E bit is set to 1, this indicates that
      the label assigned by the PCE must be explicit. That is, the
      selected way to convey the allocated wavelength is by means of
      Explicit Label Control (ELC) [RFC4003] for each hop of a computed
      LSP. Otherwise, the label assigned by the PCE needs not be
      explicit (i.e., in the form of label sets). This is to allow the
      distributed WA.


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      2.1.1. Wavelength Range Constraint

   For any request that contains a wavelength assignment, the requester
   (PCC) MUST be able to specify a restriction on the wavelengths to be
   used. This restriction is to be interpreted by the PCE as a
   constraint on the tuning ability of the origination laser
   transmitter or on any other maintenance related constraints. Note
   that if the LSP LSC spans different segments, the PCE MUST have
   mechanisms to know the tunability restrictions of the involved
   wavelength converters / regenerators, e.g. by means of the IGP. Even
   if the PCE knows the tenability of the transmitter, the PCC MUST be
   able to apply additional constraints to the request.

   [Ed Note: to align with [PCEP-GMPLS]

   WA TLVs:

   *) WA_PREFERENCES_TLV (TBD) - Allow FF, LF, Random, vendor-specific

   *) IPv4_ADDRESS_TLV | IPv6_ADDRESS_TLV | UNNUMBERED_IF_ID_TLV

   *) LABEL_SET_TLV


   The Wavelength is defined in [Lambda-Label] 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
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |Grid | C.S   |    Identifier   |              n                |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+


   See [Lambda-Label] for a description of Grid, C.S, Identifier and n.

   Note that each 32 bit Wavelength Field is designated to represent
   one wavelength restriction on the associated link identifier.

      2.1.2. Signal processing capability restrictions

   Path computation for WSON include the check of signal processing
   capabilities, those capability MAY be provided by the IGP, however
   this is not a MUST.  Moreover, a PCC should be able to indicate



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   additional restrictions for those signal compatibility, either on
   the endpoint or any given link.

   The supported signal processing capabilities are the one described
   in [RWA-Info]:

     .  Modulation Type List
     .  FEC Type List
     .  Bit rate
     .  Client signal

   The Bit-rate restriction is already expressed in [PCEP-GMPLS] in the
   GENERALIZED-BANDWIDTH object.

   The client signal information can be expressed in the [PCEP-Layer]
   REQ-ADAP-CAP object.

   In order to support the Modulation and FEC information two new TLV
   are introduced as endpoint-restriction in the END-POINTS type
   Generalized endpoint:

        .  Modulation restriction TLV
        .  FEC restriction TLV.

   The END-POINTS type generalized endpoint is extended as follow:

   <endpoint-restrictions> ::= <VENDOR-ENDPOINT-RESTRICTION>|

                               <signal-compatibility-restriction> |

                                <LABEL-REQUEST><label-restriction>

                                [<endpoint-restrictions>]



   Where

         signal-compatibility-restriction ::=

               <MODULATION-FORMAT>|<FEC>

   The MODULATION-FORMAT and FEC TLV are described in the following
   sections.





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2.1.2.1. MODULATION-FORMAT TLV

   This optional TLV represents a modulation format restriction. This
   TLV MAY appear more than once in the endpoint-restriction.

   The TLV type is TBD, recommended value 17.

   The TLV data is defined as follow:


    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
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |S|I| Modulation ID               |     Reserved              |X|
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   | Modulation ID/S bit dependent body                            |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+


   The format follows the definition from [WSON-Encode] section 4.2.1
   with the exception that the modulation length is already represented
   in the TLV Length field.

   The S and I bit are set as described in [WSON-Encode] section 4.2.1.

   The Modulation ID is as defined in [WSON-Encode] section 4.2.1.

   The X bit is set to 1 to exclude the Modulation format, the X bit is
   set to 0 to include the modulation format.

   The reserved bits MUST be set to 0 on transmit and MUST be ignore on
   receive.

   The rest of the TLV is encoded following [WSON-Encode] section
   4.2.1.



2.1.2.2. FEC TLV

   This optional TLV represents a FEC restriction. This TLV MAY appear
   more than once in the endpoint-restriction.

   The TLV type is TBD, recommended value 18.




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   The TLV data is defined as follow:


    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
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |S|I|          FEC ID             |     Reserved              |X|
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |        FEC ID/S bit dependent body                            |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+


   The format follows the definition from [WSON-Encode] section 4.2.2
   with the exception that the FEC length is already represented in the
   TLV Length field.

   The S and I bit are set as described in [WSON-Encode] section 4.2.2.

   The FEC ID is as defined in [WSON-Encode] section 4.2.2.

   The X bit is set to 1 to exclude the FEC; the X bit is set to 0 to
   include the FEC.

   The reserved bits MUST be set to 0 on transmit and MUST be ignore on
   receive.

   The rest of the TLV is encoded following [WSON-Encode] section
   4.2.2.



      2.1.3. New XRO sub-object: signal processing exclusion

   The endpoint restriction only applies to the END-POINTS object.

   The PCC/PCE should be able to exclude a signal processing along the
   path in order to handle client restriction or multi-domain path
   computation.

   In order to support the exclusion a new XRO sub-object is defined:
   the signal processing exclusion:

       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



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   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |X|  Type = X   |     Length    |   Reserved    | Attribute     |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |                 sub-sub objects                               |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+


   The Attribute field indicates how the exclusion sub-object is to be
   interpreted. The Attribute can only be 0 (Interface) or 1 (Node).

   The sub-sub objects  are encoded as in RSVP signaling definition
   [WSON-Sign].

      2.1.4. IRO sub-object: signal processing inclusion

   Similar to the XRO sub-object the PCC/PCE should be able to include
   a signal processing along the path in order to handle client
   restriction or multi-domain path computation.

   This is supported by adding the sub-object "processing" defined for
   ERO in [WSON-Sign] to the PCEP IRO object.



                         2.2. Encoding of a RWA Path Reply

   The ERO is used to encode the path of a TE LSP through the network.
   The ERO is carried within a given path of a PCEP response, which is
   in turn carried in a PCRep message to provide the computed TE LSP if
   the path computation was successful. The preferred way to convey the
   allocated wavelength is by means of Explicit Label Control (ELC)
   [RFC4003].

   In order to encode wavelength assignment, the Wavelength Assignment
   (WA) Object needs to be employed to be able to specify wavelength
   assignment. Since each segment of the computed optical path is
   associated with wavelength assignment, the WA Object should be
   aligned with the ERO object.

   [Ed note: to align with [PCEP-GMPLS] the response WA MAY also
   include

   * SUGGESTED_LABEL_TLV

   * UPSTREAM_LABEL_TLV



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   * LABEL_SET_TLV

   specifying the allocated labels according to the requested policies]



                         2.3. Error Indicator

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

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

   o  Error-Type=TBD; Error-value=1: if a PCE receives a RWA request
      and the PCE is not capable of processing the request due to
      insufficient memory, the PCE MUST send a PCErr message with a
      PCEP-ERROR Object (Error-Type=TDB) and an Error-value(Error-
      value=1).  The PCE stops processing the request.  The
      corresponding RWA request MUST be cancelled at the PCC.

   o  Error-Type=TBD; Error-value=2: if a PCE receives a RWA request
      and the PCE is not capable of RWA computation, the PCE MUST send
      a PCErr message with a PCEP-ERROR Object (Error-Type=15) and an
      Error-value (Error-value=2). The PCE stops processing the request.
      The corresponding RWA computation MUST be cancelled at the PCC.




                         2.4. NO-PATH Indicator


   To communicate the reason(s) for not being able to find RWA for the
   path request, the NO-PATH object can be used in the PCRep message.
   The format of the NO-PATH object body is defined in [RFC5440].  The
   object may contain a NO-PATH-VECTOR TLV to provide additional
   information about why a path computation has failed.

   Two new bit flags are defined to be carried in the Flags field in
   the NO-PATH-VECTOR TLV carried in the NO-PATH Object.

   o  Bit TDB: When set, the PCE indicates no feasible route was found
      that meets all the constraints associated with RWA.



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   o  Bit TDB: When set, the PCE indicates that no wavelength was
      assigned to at least one hop of the route in the response.

   o  Bit TDB: When set, the PCE indicate that no path was found
      satisfying the signal compatibility constraints.



       3. Manageability Considerations

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

                         3.1. 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:

   o  The support for WSON RWA.

   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.


                         3.2. 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. A future revision of this document will list the
   information that should be added to the MIB module.





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                         3.3. Liveness Detection and Monitoring

   Mechanisms defined in this document do not imply any new liveness
   detection and monitoring requirements in addition to those already
   listed in section 8.3 of [RFC5440].


                         3.4. Verifying Correct Operation

   Mechanisms defined in this document do not imply any new
   verification requirements in addition to those already listed in
   section 8.4 of [RFC5440]


                         3.5. Requirements on Other Protocols and
                            Functional Components

   The PCE Discovery mechanisms ([RFC5089] and [RFC5088]) may be used
   to advertise WSON RWA path computation capabilities to PCCs.


                         3.6. Impact on Network Operation

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



       4. 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.



       5. IANA Considerations

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






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       6. Acknowledgments

   The authors would like to thank Adrian Farrel for many helpful
   comments that greatly improved the contents of this draft.

   This document was prepared using 2-Word-v2.0.template.dot.



       7. References

                         7.1. Normative References

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

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

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

   [RFC3477] Kompella, K. and Y. Rekhter, "Signalling Unnumbered Links
             in Resource ReSerVation Protocol - Traffic Engineering
             (RSVP-TE)", RFC 3477, January 2003.

   [RFC4003] Berger, L., "GMPLS Signaling Procedure for Egress Control",
             RFC 4003, February 2005.

   [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.

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

                         7.2. Informative References

   [PCEP-GMPLS] Margaria, et al., "PCEP extensions for GMPLS", draft-
             ietf-pce-gmpls-pcep-extensions, work in progress.


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   [PCEP-Layer] Oki, Takeda, Le Roux, and Farrel, "Extensions to the
             Path Computation Element communication Protocol (PCEP) for
             Inter-Layer MPLS and GMPLS Traffic Engineering", draft-
             ietf-pce-inter-layer-ext, work in progress.

   [WSON-Frame] Lee, Y. and Bernstein, G. (Editors), and W. Imajuku,
             "Framework for GMPLS and PCE Control of Wavelength
             Switched Optical Networks", draft-ietf-ccamp-rwa-wson-
             framework, work in progress.

   [PCE-RWA] Lee, Y., et. al., "PCEP Requirements for WSON Routing and
             Wavelength Assignment", draft-ietf-pce-wson-routing-
             wavelength, work in progress.

   [Lambda-Label] Tomohiro, O. and D. Li, "Generalized Labels for
             Lambda-Switching Capable Label Switching Routers", draft-
             ietf-ccamp-gmpls-g-694-lambda-labels, work in progress.

   [WSON-Sign] Bernstein et al," Signaling Extensions for Wavelength
             Switched Optical Networks", draft-ietf-ccamp-wson-
             signaling, work in progress.

   [WSON-OSPF] Lee and Bernstein," OSPF Enhancement for Signal and
             Network Element Compatibility for Wavelength Switched
             Optical Networks", draft-ietf-ccamp-wson-signal-
             compatibility-ospf, work in progress.

   [RWA-Info] Bernstein and Lee, "Routing and Wavelength Assignment
             Information Model for Wavelength Switched Optical
             Networks",draft-ietf-ccamp-rwa-info, work in progress.

   [RWA-Encode] Bernstein and Lee, "Routing and Wavelength Assignment
             Information Encoding for Wavelength Switched Optical
             Networks", draft-ietf-ccamp-rwa-wson-encode, work in
             progress.

   [WSON-Imp]  Y. Lee, G. Bernstein, D. Li, G. Martinelli, "A Framework
             for the Control of Wavelength Switched Optical Networks
             (WSON) with Impairments", draft-ietf-ccamp-wson-
             impairments, work in progress.

   [RSVP-Imp] agraz, "RSVP-TE Extensions in Support of Impairment Aware
             Routing and Wavelength Assignment in Wavelength Switched
             Optical Networks WSONs)", draft-agraz-ccamp-wson-
             impairment-rsvp,  work in progress.




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   [OSPF-Imp] Bellagamba, et al., "OSPF Extensions for Wavelength
             Switched Optical Networks (WSON) with Impairments", draft-
             eb-ccamp-ospf-wson-impairments, work in progress.





       8. Contributors


Authors' Addresses

   Young Lee
   Huawei Technologies
   1700 Alma Drive, Suite 100
   Plano, TX 75075, USA
   Phone: (972) 509-5599 (x2240)
   Email: leeyoung@huawei.com

   Ramon Casellas
   CTTC PMT Ed B4 Av.  Carl Friedrich Gauss 7
   08860 Castelldefels (Barcelona)
   Spain
   Phone: (34) 936452916
   Email: ramon.casellas@cttc.es

   Cyril Margaria
   Nokia Siemens Networks
   St Martin Strasse 76
   Munich,   81541
   Germany
   Phone: +49 89 5159 16934
   Email: cyril.margaria@nsn.com

   Oscar Gonzalez de Dios
   Telefonica Investigacion y Desarrollo
   C/ Emilio Vargas 6
   Madrid,   28043
   Spain
   Phone: +34 91 3374013
   Email: ogondio@tid.es

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   any Intellectual Property Rights or other rights that might be


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   claimed to pertain to the implementation or use of the technology
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