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RFC 7689

Proposed STD
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Signaling Extensions for Wavelength Switched Optical Networks

 


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Internet Engineering Task Force (IETF)                 G. Bernstein, Ed.
Request for Comments: 7689                             Grotto Networking
Category: Standards Track                                          S. Xu
ISSN: 2070-1721                                                     NICT
                                                             Y. Lee, Ed.
                                                                  Huawei
                                                           G. Martinelli
                                                                   Cisco
                                                                H. Harai
                                                                    NICT
                                                           November 2015


     Signaling Extensions for Wavelength Switched Optical Networks

Abstract

   This document provides extensions to Generalized Multiprotocol Label
   Switching (GMPLS) signaling for control of Wavelength Switched
   Optical Networks (WSONs).  Such extensions are applicable in WSONs
   under a number of conditions including: (a) when optional processing,
   such as regeneration, must be configured to occur at specific nodes
   along a path, (b) where equipment must be configured to accept an
   optical signal with specific attributes, or (c) where equipment must
   be configured to output an optical signal with specific attributes.
   This document provides mechanisms to support distributed wavelength
   assignment with a choice of distributed wavelength assignment
   algorithms.

Status of This Memo

   This is an Internet Standards Track document.

   This document is a product of the Internet Engineering Task Force
   (IETF).  It represents the consensus of the IETF community.  It has
   received public review and has been approved for publication by the
   Internet Engineering Steering Group (IESG).  Further information on
   Internet Standards is available in Section 2 of RFC 5741.

   Information about the current status of this document, any errata,
   and how to provide feedback on it may be obtained at
   http://www.rfc-editor.org/info/rfc7689.

Page 2 
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 ....................................................3
   2. Terminology .....................................................3
      2.1. Conventions Used in This Document ..........................4
   3. Requirements for WSON Signaling .................................4
      3.1. WSON Signal Characterization ...............................4
      3.2. Per-Node Processing Configuration ..........................5
      3.3. Bidirectional WSON LSPs ....................................5
      3.4. Distributed Wavelength Assignment Selection Method .........6
      3.5. Optical Impairments ........................................6
   4. WSON Signal Traffic Parameters, Attributes, and Processing ......6
      4.1. Traffic Parameters for Optical Tributary Signals ...........7
      4.2. WSON Processing Hop Attribute TLV ..........................7
           4.2.1. ResourceBlockInfo Sub-TLV ...........................8
           4.2.2. WavelengthSelection Sub-TLV .........................9
   5. Security Considerations ........................................11
   6. IANA Considerations ............................................11
   7. References .....................................................13
      7.1. Normative References ......................................13
      7.2. Informative References ....................................14
   Acknowledgments ...................................................15
   Contributors ......................................................15
   Author's Addresses ................................................16

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1.  Introduction

   This document provides extensions to Generalized Multiprotocol Label
   Switching (GMPLS) signaling for control of Wavelength Switched
   Optical Networks (WSONs).  Fundamental extensions are given to permit
   simultaneous bidirectional wavelength assignment, while more advanced
   extensions are given to support the networks described in [RFC6163],
   which feature connections requiring configuration of input, output,
   and general signal processing capabilities at a node along a Label
   Switched Path (LSP).

   These extensions build on previous work for the control of lambda and
   G.709-based networks.

   Related documents are [RFC7446] that provides a high-level
   information model and [RFC7581] that provides common encodings that
   can be applicable to other protocol extensions such as routing.

2.  Terminology

   CWDM: Coarse Wavelength Division Multiplexing.

   DWDM: Dense Wavelength Division Multiplexing.

   ROADM: Reconfigurable Optical Add/Drop Multiplexer.  A reduced port
      count wavelength selective switching element featuring ingress and
      egress line side ports as well as add/drop side ports.

   RWA: Routing and Wavelength Assignment.

   Wavelength Conversion/Converters: The process of converting
      information bearing optical signal centered at a given frequency
      (wavelength) to one with "equivalent" content centered at a
      different wavelength.  Wavelength conversion can be implemented
      via an optical-electronic-optical (OEO) process or via a strictly
      optical process.

   WDM: Wavelength Division Multiplexing.

   Wavelength Switched Optical Networks (WSONs): WDM-based optical
      networks in which switching is performed selectively based on the
      frequency of an optical signal.

   AWG: Arrayed Waveguide Grating.

   OXC: Optical Cross-Connect.

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   Optical Transmitter: A device that has both a laser, tuned on a
      certain wavelength, and electronic components that convert
      electronic signals into optical signals.

   Optical Receiver: A device that has both optical and electronic
      components.  It detects optical signals and converts optical
      signals into electronic signals.

   Optical Transponder: A device that has both an optical transmitter
      and an optical receiver.

   Optical End Node: The end of a wavelength (optical lambdas) lightpath
      in the data plane.  It may be equipped with some
      optical/electronic devices such as wavelength
      multiplexers/demultiplexer (e.g., AWG), optical transponder, etc.,
      which are employed to transmit/terminate the optical signals for
      data transmission.

   FEC: Forward Error Correction.  FEC is a digital signal processing
      technique used to enhance data reliability.  It does this by
      introducing redundant data, called error correcting code, prior to
      data transmission or storage.  FEC provides the receiver with the
      ability to correct errors without a reverse channel to request the
      retransmission of data.

   3R Regeneration: The process of amplifying (correcting loss),
      reshaping (correcting noise and dispersion), retiming
      (synchronizing with the network clock), and retransmitting an
      optical signal.

2.1.  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 [RFC2119].

3.  Requirements for WSON Signaling

   The following requirements for GMPLS-based WSON signaling are in
   addition to the functionality already provided by existing GMPLS
   signaling mechanisms.

3.1.  WSON Signal Characterization

   WSON signaling needs to convey sufficient information characterizing
   the signal to allow systems along the path to determine compatibility
   and perform any required local configuration.  Examples of such
   systems include intermediate nodes (ROADMs, OXCs, wavelength

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   converters, regenerators, OEO switches, etc.), links (WDM systems),
   and end systems (detectors, demodulators, etc.).  The details of any
   local configuration processes are outside the scope of this document.

   From [RFC6163], we have the following list of WSON signal
   characteristics:

   1.  Optical tributary signal class (modulation format).
   2.  FEC: whether forward error correction is used in the digital
      stream and what type of error correcting code is used
   3.  Center frequency (wavelength)
   4.  Bit rate
   5.  G-PID: General Protocol Identifier for the information format

   The first three items on this list can change as a WSON signal
   traverses a network with regenerators, OEO switches, or wavelength
   converters.  These parameters are summarized in the Optical Interface
   Class as defined in [RFC7446], and the assumption is that a class
   always includes signal compatibility information.  An ability to
   control wavelength conversion already exists in GMPLS signaling along
   with the ability to share client signal type information (G-PID).  In
   addition, bit rate is a standard GMPLS signaling traffic parameter.
   It is referred to as bandwidth encoding in [RFC3471].

3.2.  Per-Node Processing Configuration

   In addition to configuring a node along an LSP to input or output a
   signal with specific attributes, we may need to signal the node to
   perform specific processing, such as 3R regeneration, on the signal
   at a particular node.  [RFC6163] discussed three types of processing:

      (A) Regeneration (possibly different types)

      (B) Fault and Performance Monitoring

      (C) Attribute Conversion

   The extensions here provide for the configuration of these types of
   processing at nodes along an LSP.

3.3.  Bidirectional WSON LSPs

   WSON signaling can support LSP setup consistent with the wavelength
   continuity constraint for bidirectional connections.  The following
   cases need to be supported separately:

   (a)  Where the same wavelength is used for both upstream and
        downstream directions

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   (b)  Where different wavelengths are used for both upstream and
        downstream directions.

   This document will review existing GMPLS bidirectional solutions
   according to WSON case.

3.4.  Distributed Wavelength Assignment Selection Method

   WSON signaling can support the selection of a specific distributed
   wavelength assignment method.

   This method is beneficial in cases of equipment failure, etc., where
   fast provisioning used in quick recovery is critical to protect
   carriers/users against system loss.  This requires efficient
   signaling that supports distributed wavelength assignment, in
   particular, when the wavelength assignment capability is not
   available.

   As discussed in [RFC6163], different computational approaches for
   wavelength assignment are available.  One method is the use of
   distributed wavelength assignment.  This feature would allow the
   specification of a particular approach when more than one is
   implemented in the systems along the path.

3.5.  Optical Impairments

   This document does not address signaling information related to
   optical impairments.

4.  WSON Signal Traffic Parameters, Attributes, and Processing

   As discussed in [RFC6163], single-channel optical signals used in
   WSONs are called "optical tributary signals" and come in a number of
   classes characterized by modulation format and bit rate.  Although
   WSONs are fairly transparent to the signals they carry, to ensure
   compatibility amongst various networks devices and end systems, it
   can be important to include key lightpath characteristics as traffic
   parameters in signaling [RFC6163].

   LSPs signaled through extensions provided in this document MUST apply
   the following signaling parameters:

      o  Switching Capability = WSON-LSC [RFC7688]
      o  Encoding Type = Lambda [RFC3471]
      o  Label Format = as defined in [RFC6205]

   [RFC6205] defines the label format as applicable to LSC capable
   devices.

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4.1.  Traffic Parameters for Optical Tributary Signals

   In [RFC3471] we see that the G-PID (client signal type) and bit rate
   (byte rate) of the signals are defined as parameters, and in
   [RFC3473] they are conveyed in the Generalized Label Request object
   and the RSVP SENDER_TSPEC/FLOWSPEC objects, respectively.

4.2.  WSON Processing Hop Attribute TLV

   Section 3.1 provides requirements to signal to a node along an LSP
   what type of processing to perform on an optical signal and how to
   configure itself to accept or transmit an optical signal with
   particular attributes.

   To target a specific node, this section defines a WSON Processing Hop
   Attribute TLV.  This TLV is encoded as an attributes TLV; see
   [RFC5420].  The TLV is carried in the ERO and RRO Hop Attributes
   subobjects and processed according to the procedures defined in
   [RFC7570].  The type value of the WSON Processing Hop Attribute TLV
   is 4 as assigned by IANA.

   The WSON Processing Hop Attribute TLV carries one or more sub-TLVs
   with the following format:

    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      |                               |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+                               |
   //                            Value                            //
   |                               +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |           ...                 |        Padding                |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

   Type

      The identifier of the sub-TLV.

   Length

      Indicates the total length of the sub-TLV in octets.  That is, the
      combined length of the Type, Length, and Value fields, i.e., two
      plus the length of the Value field in octets.

   Value

      Zero or more octets of data carried in the sub-TLV.

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   Padding

      Variable

   The entire sub-TLV MUST be padded with zeros to ensure four-octet
   alignment of the sub-TLV.

   Sub-TLV ordering is significant and MUST be preserved.  Error
   processing follows [RFC7570].

   The following sub-TLV types are defined in this document:

   Sub-TLV Name        Type    Length
   --------------------------------------------------------------
   ResourceBlockInfo    1      variable
   WavelengthSelection  2      8 octets (2-octet padding)

   The TLV can be represented in Reduced Backus-Naur Form (RBNF)
   [RFC5511] syntax as:

   <WSON Processing Hop Attribute> ::= <ResourceBlockInfo>
   [<ResourceBlockInfo>] [<WavelengthSelection>]

4.2.1.  ResourceBlockInfo Sub-TLV

   The format of the ResourceBlockInfo sub-TLV value field is defined in
   Section 4 of [RFC7581].  It is a list of available Optical Interface
   Classes and processing capabilities.

   At least one ResourceBlockInfo sub-TLV MUST be present in the WSON
   Processing Hop Attribute TLV.  No more than two ResourceBlockInfo
   sub-TLVs SHOULD be present.  Any present ResourceBlockInfo sub-TLVs
   MUST be processed in the order received, and extra (unprocessed) sub-
   TLVs SHOULD be ignored.

   The ResourceBlockInfo field contains several information elements as
   defined by [RFC7581].  The following rules apply to the sub-TLV:

   o  RB Set field can carry one or more RB Identifier.  Only the first
      RB Identifier listed in the RB Set field SHALL be processed; any
      others SHOULD be ignored.

   o  In the case of unidirectional LSPs, only one ResourceBlockInfo
      sub-TLV SHALL be processed, and the I and O bits can be safely
      ignored.

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   o  In the case of a bidirectional LSP, there MUST be either:

      (a) only one ResourceBlockInfo sub-TLV present in a WSON
          Processing Hop Attribute TLV, and the bits I and O both set to
          1, or

      (b) two ResourceBlockInfo sub-TLVs present, one with only the I
          bit set and the other with only the O bit set.

   o  The rest of the information carried within the ResourceBlockInfo
      sub-TLV includes the Optical Interface Class List, Input Bit Rate
      List, and Processing Capability List.  These lists MAY contain one
      or more elements.  These elements apply equally to both
      bidirectional and unidirectional LSPs.

   Any violation of these rules detected by a transit or egress node
   SHALL be treated as an error and be processed per [RFC7570].

   A ResourceBlockInfo sub-TLV can be constructed by a node and added to
   an ERO Hop Attributes subobject in order to be processed by
   downstream nodes (transit and egress).  As defined in [RFC7570], the
   R bit reflects the LSP_REQUIRED_ATTRIBUTE and LSP_ATTRIBUTE semantic
   defined in [RFC5420], and it SHOULD be set accordingly.

   Once a node properly parses a ResourceBlockInfo sub-TLV received in
   an ERO Hop Attributes subobject (according to the rules stated above
   and in [RFC7570]), the node allocates the indicated resources, e.g.,
   the selected regeneration pool, for the LSP.  In addition, the node
   SHOULD report compliance by adding an RRO Hop Attributes subobject
   with the WSON Processing Hop Attribute TLV (and its sub-TLVs)
   indicating the utilized resources.  ResourceBlockInfo sub-TLVs
   carried in an RRO Hop Attributes subobject are subject to [RFC7570]
   and standard RRO processing; see [RFC3209].

4.2.2.  WavelengthSelection Sub-TLV

   Routing + Distributed Wavelength Assignment (R+DWA) is one of the
   options defined by [RFC6163].  The output from the routing function
   will be a path, but the wavelength will be selected on a hop-by-hop
   basis.

   As discussed in [RFC6163], the wavelength assignment can be either
   for a unidirectional lightpath or for a bidirectional lightpath
   constrained to use the same lambda in both directions.

   In order to indicate wavelength assignment directionality and
   wavelength assignment method, the WavelengthSelection sub-TLV is
   carried in the WSON Processing Hop Attribute TLV defined above.

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   The WavelengthSelection sub-TLV value field is defined as:

    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
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |W|  WA Method  |                    Reserved                   |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

   Where:

   W (1 bit): 0 denotes requiring the same wavelength in both
      directions; 1 denotes that different wavelengths on both
      directions are allowed.

      Wavelength Assignment (WA) Method (7 bits):

      0: unspecified (any); This does not constrain the WA method used
          by a specific node.  This value is implied when the
          WavelengthSelection sub-TLV is absent.

      1: First-Fit.  All the wavelengths are numbered, and this WA
          method chooses the available wavelength with the lowest index.

      2: Random.  This WA method chooses an available wavelength
          randomly.

      3: Least-Loaded (multi-fiber).  This WA method selects the
          wavelength that has the largest residual capacity on the most
          loaded link along the route.  This method is used in multi-
          fiber networks.  If used in single-fiber networks, it is
          equivalent to the First-Fit WA method.

      4-127: Unassigned.

   The processing rules for this TLV are as follows:

   If a receiving node does not support the attribute(s), its behaviors
   are specified below:

   -  W bit not supported: a PathErr MUST be generated with the Error
      Code "Routing Problem" (24) with error sub-code "Unsupported
      WavelengthSelection Symmetry value" (107).

   -  WA method not supported: a PathErr MUST be generated with the
      Error Code "Routing Problem" (24) with error sub-code "Unsupported
      Wavelength Assignment value" (108).

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   A WavelengthSelection sub-TLV can be constructed by a node and added
   to an ERO Hop Attributes subobject in order to be processed by
   downstream nodes (transit and egress).  As defined in [RFC7570], the
   R bit reflects the LSP_REQUIRED_ATTRIBUTE and LSP_ATTRIBUTE semantic
   defined in [RFC5420], and it SHOULD be set accordingly.

   Once a node properly parses the WavelengthSelection sub-TLV received
   in an ERO Hop Attributes subobject, the node use the indicated
   wavelength assignment method (at that hop) for the LSP.  In addition,
   the node SHOULD report compliance by adding an RRO Hop Attributes
   subobject with the WSON Processing Hop Attribute TLV (and its sub-
   TLVs) that indicate the utilized method.  WavelengthSelection sub-
   TLVs carried in an RRO Hop Attributes subobject are subject to
   [RFC7570] and standard RRO processing; see [RFC3209].

5.  Security Considerations

   This document is built on the mechanisms defined in [RFC3473], and
   only differs in the specific information communicated.  The specific
   additional information (optical resource and wavelength selection
   properties) is not viewed as substantively changing or adding to the
   security considerations of the existing GMPLS signaling protocol
   mechanisms.  See [RFC3473] for details of the supported security
   measures.  Additionally, [RFC5920] provides an overview of security
   vulnerabilities and protection mechanisms for the GMPLS control
   plane.

6.  IANA Considerations

   IANA has assigned a new value in the existing "Attributes TLV Space"
   registry located at
   <http://www.iana.org/assignments/rsvp-te-parameters>, as updated by
   [RFC7570]:

   Type  Name        Allowed on  Allowed on   Allowed on   Reference
                     LSP         LSP REQUIRED RO LSP
                     ATTRIBUTES  ATTRIBUTES   Attribute
                                              Subobject

   4     WSON        No          No           Yes          RFC 7689
         Processing
         Hop
         Attribute
         TLV

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   IANA has created a new registry named "Sub-TLV Types for WSON
   Processing Hop Attribute TLV" located at
   <http://www.iana.org/assignments/rsvp-te-parameters>.

   The following entries have been added:

   Value            Sub-TLV Type            Reference

   0                Reserved                RFC 7689

   1                ResourceBlockInfo       RFC 7689

   2                WavelengthSelection     RFC 7689

   All assignments are to be performed via Standards Action or
   Specification Required policies as defined in [RFC5226].

   IANA has created a new registry named "Values for Wavelength
   Assignment Method field in WavelengthSelection Sub-TLV" located at
   <http://www.iana.org/assignments/rsvp-te-parameters>.

   The following entries have been added:

   Value          Meaning                    Reference


   0             unspecified                RFC 7689

   1             First-Fit                  RFC 7689

   2             Random                     RFC 7689

   3             Least-Loaded (multi-fiber) RFC 7689

   4-127         Unassigned

   All assignments are to be performed via Standards Action or
   Specification Required policies as defined in [RFC5226].  The
   assignment policy chosen for any specific code point must be clearly
   stated in the document that describes the code point so that IANA can
   apply the correct policy.

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   IANA has assigned new values in the existing "Sub-Codes - 24 Routing
   Problem" registry located at
   <http://www.iana.org/assignments/rsvp-parameters>:

   Value              Description                          Reference

   107                Unsupported WavelengthSelection
                      symmetry value                       RFC 7689

   108                Unsupported Wavelength Assignment
                      value                                RFC 7689

7.  References

7.1.  Normative References

   [RFC2119]  Bradner, S., "Key words for use in RFCs to Indicate
              Requirement Levels", BCP 14, RFC 2119,
              DOI 10.17487/RFC2119, March 1997,
              <http://www.rfc-editor.org/info/rfc2119>.

   [RFC3209]  Awduche, D., Berger, L., Gan, D., Li, T., Srinivasan, V.,
              and G. Swallow, "RSVP-TE: Extensions to RSVP for LSP
              Tunnels", RFC 3209, DOI 10.17487/RFC3209, December 2001,
              <http://www.rfc-editor.org/info/rfc3209>.

   [RFC3471]  Berger, L., Ed., "Generalized Multi-Protocol Label
              Switching (GMPLS) Signaling Functional Description", RFC
              3471, DOI 10.17487/RFC3471, January 2003,
              <http://www.rfc-editor.org/info/rfc3471>.

   [RFC3473]  Berger, L., Ed., "Generalized Multi-Protocol Label
              Switching (GMPLS) Signaling Resource ReserVation Protocol-
              Traffic Engineering (RSVP-TE) Extensions", RFC 3473,
              DOI 10.17487/RFC3473, January 2003,
              <http://www.rfc-editor.org/info/rfc3473>.

   [RFC5226]  Narten, T. and H. Alvestrand, "Guidelines for Writing an
              IANA Considerations Section in RFCs", BCP 26, RFC 5226,
              DOI 10.17487/RFC5226, May 2008,
              <http://www.rfc-editor.org/info/rfc5226>.

   [RFC5420]  Farrel, A., Ed., Papadimitriou, D., Vasseur, JP., and A.
              Ayyangarps, "Encoding of Attributes for MPLS LSP
              Establishment Using Resource Reservation Protocol Traffic
              Engineering (RSVP-TE)", RFC 5420, DOI 10.17487/RFC5420,
              February 2009, <http://www.rfc-editor.org/info/rfc5420>.

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   [RFC5511]  Farrel, A., "Routing Backus-Naur Form (RBNF): A Syntax
              Used to Form Encoding Rules in Various Routing Protocol
              Specifications", RFC 5511, DOI 10.17487/RFC5511, April
              2009, <http://www.rfc-editor.org/info/rfc5511>.

   [RFC6205]  Otani, T., Ed., and D. Li, Ed., "Generalized Labels for
              Lambda-Switch-Capable (LSC) Label Switching Routers", RFC
              6205, DOI 10.17487/RFC6205, March 2011,
              <http://www.rfc-editor.org/info/rfc6205>.

   [RFC7570]  Margaria, C., Ed., Martinelli, G., Balls, S., and B.
              Wright, "Label Switched Path (LSP) Attribute in the
              Explicit Route Object (ERO)", RFC 7570,
              DOI 10.17487/RFC7570, July 2015,
              <http://www.rfc-editor.org/info/rfc7570>.

   [RFC7581]  Bernstein, G., Ed., Lee, Y., Ed., Li, D., Imajuku, W., and
              J. Han, "Routing and Wavelength Assignment Information
              Encoding for Wavelength Switched Optical Networks", RFC
              7581, DOI 10.17487/RFC7581, June 2015,
              <http://www.rfc-editor.org/info/rfc7581>.

   [RFC7688]  Lee, Y., Ed., and G. Bernstein, Ed., "GMPLS OSPF
              Enhancement for Signal and Network Element Compatibility
              for Wavelength Switched Optical Networks", RFC 7688,
              DOI 10.17487/RFC7688, November 2015,
              <http://www.rfc-editor.org/info/rfc7688>.

7.2. Informative References

   [RFC5920]  Fang, L., Ed., "Security Framework for MPLS and GMPLS
              Networks", RFC 5920, DOI 10.17487/RFC5920, July 2010,
              <http://www.rfc-editor.org/info/rfc5920>.

   [RFC6163]  Lee, Y., Ed., Bernstein, G., Ed., and W. Imajuku,
              "Framework for GMPLS and Path Computation Element (PCE)
              Control of Wavelength Switched Optical Networks (WSONs)",
              RFC 6163, DOI 10.17487/RFC6163, April 2011,
              <http://www.rfc-editor.org/info/rfc6163>.

   [RFC7446]  Lee, Y., Ed., Bernstein, G., Ed., Li, D., and W. Imajuku,
              "Routing and Wavelength Assignment Information Model for
              Wavelength Switched Optical Networks", RFC 7446,
              DOI 10.17487/RFC7446, February 2015,
              <http://www.rfc-editor.org/info/rfc7446>.

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Acknowledgments

   The authors would like to thanks Lou Berger, Cyril Margaria, and Xian
   Zhang for their comments and suggestions.

Contributors

   Nicola Andriolli
   Scuola Superiore Sant'Anna
   Pisa, Italy
   Email: nick@sssup.it

   Alessio Giorgetti
   Scuola Superiore Sant'Anna
   Pisa, Italy
   Email: a.giorgetti@sssup.it

   Lin Guo
   Key Laboratory of Optical Communication and Lightwave Technologies
   Ministry of Education
   P.O. Box 128, Beijing University of Posts and Telecommunications
   China
   Email: guolintom@gmail.com

   Yuefeng Ji
   Key Laboratory of Optical Communication and Lightwave Technologies
   Ministry of Education
   P.O. Box 128, Beijing University of Posts and Telecommunications
   China
   Email: jyf@bupt.edu.cn

   Daniel King
   Old Dog Consulting
   Email: daniel@olddog.co.uk

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Authors' Addresses

   Greg M. Bernstein (editor)
   Grotto Networking
   Fremont, CA
   United States
   Phone: (510) 573-2237
   Email: gregb@grotto-networking.com


   Sugang Xu
   National Institute of Information and Communications Technology
   4-2-1 Nukui-Kitamachi, Koganei,
   Tokyo, 184-8795
   Japan
   Phone: +81 42-327-6927
   Email: xsg@nict.go.jp


   Young Lee (editor)
   Huawei Technologies
   5340 Legacy Dr. Building 3
   Plano, TX  75024
   United States
   Phone: (469) 277-5838
   Email: leeyoung@huawei.com


   Giovanni Martinelli
   Cisco
   Via Philips 12
   20052 Monza
   Italy
   Phone: +39 039-209-2044
   Email: giomarti@cisco.com


   Hiroaki Harai
   National Institute of Information and Communications Technology
   4-2-1 Nukui-Kitamachi, Koganei,
   Tokyo, 184-8795
   Japan
   Phone: +81 42-327-5418
   Email: harai@nict.go.jp