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PCEP Requirements for WSON Routing and Wavelength Assignment
draft-ietf-pce-wson-routing-wavelength-12

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This is an older version of an Internet-Draft that was ultimately published as RFC 7449.
Authors Young Lee , Greg M. Bernstein , Jonas Mårtensson , Tomonori Takeda , Takehiro Tsuritani , Oscar Gonzalez de Dios
Last updated 2014-04-28
Replaces draft-lee-pce-wson-routing-wavelength
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draft-ietf-pce-wson-routing-wavelength-12
Network Working Group                                            Y. Lee
Internet Draft                                                   Huawei
Intended status: Informational
Expires: October 2014                                      G. Bernstein
                                                      Grotto Networking

                                                       Jonas Martensson
                                                                  Acreo

                                                              T. Takeda
                                                                    NTT

                                                           T. Tsuritani
                                                                   KDDI

                                                           O. G. de Dios
                                                              Telefonica

                                                         April 28, 2014

       PCEP Requirements for WSON Routing and Wavelength Assignment

               draft-ietf-pce-wson-routing-wavelength-12.txt

Status of this Memo

   This Internet-Draft is submitted to IETF in full conformance with
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   This Internet-Draft will expire on September 28, 2014.

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Copyright Notice

   Copyright (c) 2014 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
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Abstract

   This memo provides application-specific requirements for the Path
   Computation Element communication Protocol (PCEP) for the support of
   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. Requirements for Optical impairments will be
   addressed in a separate document.

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 RWA Processes & Architecture ..............................4
   3. Requirements ...................................................6
      3.1. Path Computation Type Option..............................6
      3.2. RWA Processing............................................6
      3.3. Bulk RWA Path Request/Reply...............................7
      3.4. RWA Path Re-optimization Request/Reply....................7

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      3.5. Wavelength Range Constraint...............................7
      3.6. ability of a laser transmitter, any optical element, or an
      policy based restriction. Wavelength Assignment Preference.....8
      3.7. Signal Processing Capability Restriction..................8
   4. Manageability Considerations ...................................9
      4.1. Control of Function and Policy............................9
      4.2. Information and Data Models, e.g. MIB module..............9
      4.3. Liveness Detection and Monitoring.........................9
      4.4. Verifying Correct Operation...............................9
      4.5. Requirements on Other Protocols and Functional Components10
      4.6. Impact on Network Operation..............................10
   5. Security Considerations .......................................10
   6. IANA Considerations ...........................................10
   7. Acknowledgments ...............................................10
   8. References ....................................................11
      8.1. Normative References.....................................11
      8.2. Informative References...................................11
   Authors' Addresses...............................................12
   Intellectual Property Statement..................................13
   Disclaimer of Validity...........................................13

   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 a set of application-specific PCEP
   requirements for support of path computation in Wavelength Switched
   Optical Networks (WSON).  WSON refers to WDM based optical networks
   in which switching is performed selectively based on the wavelength
   of an optical signal.

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   The path in WSON is referred to as a lightpath.  A lightpath may
   span multiple fiber links and the path should be assigned a
   wavelength for each link.  A transparent optical network is made up
   of optical devices that can switch but not convert from one
   wavelength to another. In a transparent optical network, a lightpath
   operates on the same wavelength across all fiber links that it
   traverses. In such case, the lightpath is said to satisfy the
   wavelength-continuity constraint. Two lightpaths 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 lightpath 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 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.

   In this document we first review the processes for routing and
   wavelength assignment (RWA) used when wavelength continuity
   constraints are present and then specify requirements for PCEP to
   support RWA. Requirements for Optical impairments will be addressed
   in a separate document.

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

   2. WSON RWA Processes & Architecture

   In [RFC6163] three alternative process architectures were given for
   performing routing and wavelength assignment. These are shown
   schematically in 0.

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     +-------------------+
     |  +-------+  +--+  |    +-------+    +--+     +-------+    +---+
     |  |Routing|  |WA|  |    |Routing|--->|WA|     |Routing|--->|DWA|
     |  +-------+  +--+  |    +-------+    +--+     +-------+    +---+
     |   Combined        |     Separate Processes   Separate Processes
     |   Processes       |                          WA performed in a
     +-------------------+                          Distributed manner
           (a)                       (b)                    (c)

                    Figure 1. RWA process alternatives.

   These alternatives have the following properties and impact on PCEP
   requirements in this document.

   1. Combined Processes (R&WA) - Here path selection and wavelength
      assignment are performed as a single process. The requirements
      for PCC-PCE interaction with such a combined RWA process PCE is
      addressed in this document.

   2. Routing separate from Wavelength Assignment (R+WA) - Here the
      routing process furnishes one or more potential paths to the
      wavelength assignment process that then performs final path
      selection and wavelength assignment.  The requirements for PCE-
      PCE interaction with one PCE implementing the routing process and
      another implementing the wavelength assignment process are not
      addressed in this document.

   3. Routing and distributed Wavelength Assignment (R+DWA) - Here a
      standard path computation (unaware of detailed wavelength
      availability) takes place, then wavelength assignment is
      performed along this path in a distributed manner via signaling
      (RSVP-TE). This alternative should be covered by existing or
      emerging GMPLS PCEP extensions and does not present new WSON
      specific requirements.

   In the previous section various process architectures for
   implementing RWA have been reviewed. 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
   are specified in this document.

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

              Figure 2. Combined Process (R&WA) architecture

   3. Requirements

   The requirements for the PCC to PCE interface of Figure 2 are
   specified in this section.

   3.1.  Path Computation Type Option

   1. A PCEP request MUST include the path computation type. This can
      be:

     (i)  Both Routing and Wavelength Assignment (RWA), or

     (ii)    Routing only.

   This requirement is needed to differentiate between the currently
   supported routing with distributed wavelength assignment option and
   combined RWA. In case of distributed wavelength assignment option,
   wavelength assignment will be performed at each node of the route.

   3.2. RWA Processing

   1. When  the request is a RWA path computation type, the request
      MUST further include the wavelength assignment options. At the
      minimum, the following option should be supported:

         (i)   Explicit Label Control (ELC) [RFC4003]

         (ii)   A set of recommended labels. The PCC can select the
                label based on local policy.

     Note that option ii) may also be used in R+WA or DWA.

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   2. In case of a RWA computation type, the response MUST include the
      wavelength(s) assigned to the route and an indication of which
      label assignment option has been applied (ELC or Label Sets).

   3. In the case where a valid path is not found, the response MUST
      include why the path is not found (e.g., no route, wavelength not
      found, optical quality check failed, etc.)

   3.3. Bulk RWA Path Request/Reply

   1. A PCEP request MUST be able to specify an option for bulk RWA
      path request. Bulk path request is an ability to request a number
      of simultaneous RWA path requests.

   2. The PCEP response MUST include the route, wavelength assigned to
      the route for each RWA path request specified in the original
      bulk request.

   3.4. RWA Path Re-optimization Request/Reply

   1. For a re-optimization request, the request MUST provide both the
      route and current wavelength to be re-optimized and MAY include
      the following options:

       a. Re-optimize the path keeping the same wavelength(s)

       b. Re-optimize wavelength(s) keeping the same path

       c. Re-optimize allowing both wavelength and the path to change

   2. The corresponding response to the re-optimized request MUST
      provide the re-optimized path and wavelengths.

   3. In case that the path is not found, the response MUST include why
      the path is not found (e.g., no route, wavelength not found, both
      route and wavelength not found, etc.)

   3.5.  Wavelength Range Constraint

   For any RWA computation type request, the requester (PCC) MAY
   specify a restriction on the wavelengths to be used. The requester

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   MAY use this option to restrict the assigned wavelenght for Explict
   Label or Label Sets.

   Note that the requestor (e.g., PCC) is NOT required to furnish any
   range restrictions. This restriction may for example come from the
   tuning

   3.6. ability of a laser transmitter, any optical element, or an
      policy based restriction.
      Wavelength Assignment Preference

   1. A RWA computation type request MAY include the requestor
     preference for (E.g., random assignment, descending order,
     ascending order, etc.) A response SHOULD follow the requestor
     preference unless it conflicts with operator's policy.

   2. A request for 2 or more paths (e.g., 1+1 link disjoint paths) MUST
     be able to specify an option constraining the path to have the
     same wavelength(s) assigned.

   Note that this is extremely useful in the case of protection with
   single transponder.

     In a network with wavelength conversion capabilities (e.g. sparse
     3R regenerators), a request SHOULD be able to indicate whether a
     single, contiguous wavelength should be allocated or not. In other
     words, the requesting PCC SHOULD be able to constrain the
     wavelength continuity even if wavelength conversion is available.

   3.7. Signal Processing Capability Restriction

   A request MUST be able to specify restrictions for signal
   compatibility either on the endpoints or any given links. The
   following signal processing capabilities should be supported at a
   minimum:

      o  Modulation Type List

      o  FEC Type List

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   4. Manageability Considerations

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

   4.1. Control of Function and Policy

   In addition to the parameters already listed in Section 8.1 of
   [RFC5440], 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
   [RFC5440], a PCEP implementation SHOULD allow configuring the
   following PCEP session parameters on a PCE:

      o  The support for WSON RWA.

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

   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.

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

   As this document only concerns the requirements to support WSON RWA,
   no additional MIB module is defined in this document. However, the
   corresponding solution draft will list the information that should
   be added to the PCE MIB module defined in [PCEP-MIB].

   4.3. 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].

   4.4. 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]

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   4.5. 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.

   4.6. 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 [RFC5440].

   5. Security Considerations

   This document has no requirement for a change to the security models
   within PCEP [RFC5440]. 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.

   6. IANA Considerations

   This informational document does not make any requests for IANA
   action.

   7. 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.

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   8. References

   8.1. Normative References

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

   [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.

   [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.

   [PCEP-MIB] Koushik, K, et al., "PCE communication protocol(PCEP)
             Management Information Base", draft-ietf-pce-pcep-mib,
             work in progress.

   8.2. Informative References

   [RFC6566] Lee, Y. and Bernstein, G. (Editors), D. Li and G.
             Martinelli "A Framework for the Control and Measurement of
             Wavelength Switched Optical Networks (WSON) with
             Impairments", RFC 6566, March 2012.

   [RFC6163]  Y. Lee, G. Bernstein, W. Imajuku, "Framework for GMPLS
             and PCE Control of Wavelength Switched Optical Networks",
             RFC 6163, April 2011.

   [RFC5088] Le Roux, JL., Ed., Vasseur, JP., Ed., Ikejiri, Y., and R.
             Zhang, "OSPF Protocol Extensions for Path Computation
             Element (PCE) Discovery", RFC 5088, January 2008.

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   [RFC5089] Le Roux, JL., Ed., Vasseur, JP., Ed., Ikejiri, Y., and R.
             Zhang, "IS-IS Protocol Extensions for Path Computation
             Element (PCE) Discovery", RFC 5089, January 2008.

Authors' Addresses

   Young Lee (Ed.)
   Huawei Technologies
   5340 Legacy Drive, Building 3
   Plano, TX 75245, USA
   Phone: (469)277-5838
   Email: leeyoung@huawei.com

   Greg Bernstein (Ed.)
   Grotto Networking
   Fremont, CA, USA
   Phone: (510) 573-2237
   Email: gregb@grotto-networking.com

   Jonas Martensson
   Acreo
   Email:Jonas.Martensson@acreo.se

   Tomonori Takeda
   NTT Corporation
   3-9-11, Midori-Cho
   Musashino-Shi, Tokyo 180-8585, Japan
   Email: takeda.tomonori@lab.ntt.co.jp

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   Takehiro Tsuritani
   KDDI R&D Laboratories, Inc.
   2-1-15 Ohara Kamifukuoka Saitama, 356-8502. Japan
   Phone:  +81-49-278-7357
   Email:  tsuri@kddilabs.jp

   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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