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Versions: (draft-bernstein-ccamp-wson-signaling) 00 01 02 03 04 05 06 07 08 09 10 11 12 RFC 7689

Network Working Group                                      G. Bernstein
Internet Draft                                        Grotto Networking
Intended status: Standards Track                              Sugang Xu
Expires: April 2013                                               Y.Lee
                                                          G. Martinelli
                                                          Hiroaki Harai

                                                       October 22, 2012

     Signaling Extensions for Wavelength Switched Optical Networks


   This memo provides extensions to Generalized Multi-Protocol Label
   Switching (GMPLS) signaling for control of wavelength switched
   optical networks (WSON).  Such extensions are necessary 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. In addition this memo provides mechanisms to
   support distributed wavelength assignment with bidirectional LSPs,
   and choice in distributed wavelength assignment algorithms. These
   extensions build on previous work for the control of lambda and
   G.709 based networks.

Status of this Memo

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

   Internet-Drafts are working documents of the Internet Engineering
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   reference material or to cite them other than as "work in progress."

   The list of current Internet-Drafts can be accessed at

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   The list of Internet-Draft Shadow Directories can be accessed at

   This Internet-Draft will expire on April 22, 2007.

Copyright Notice

   Copyright (c) 2012 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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   warranty as described in the Simplified BSD License.

Conventions used in this document

   The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
   document are to be interpreted as described in [RFC2119].

Table of Contents

   1. Introduction...................................................3
   2. Terminology....................................................3
   3. Requirements for WSON Signaling................................4
      3.1. WSON Signal Characterization..............................4
      3.2. Per LSP Network Element Processing Configuration..........5
      3.3. Bi-Directional WSON LSPs..................................5
      3.4. Distributed Wavelength Assignment Support.................6
      3.5. Out of Scope..............................................6
   4. WSON Signal Traffic Parameters, Attributes and Processing......6
      4.1. Traffic Parameters for Optical Tributary Signals..........6
      4.2. Signal Attributes and Processing..........................7
         4.2.1. WSON Processing Object Encoding......................8
   5. Bidirectional Lightpath Setup..................................8
   6. RWA Related....................................................9
      6.1. Wavelength Assignment Method Selection....................9
   7. Security Considerations.......................................10

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   8. IANA Considerations...........................................10
   9. Acknowledgments...............................................10
   10. References...................................................11
      10.1. Normative References....................................11
      10.2. Informative References..................................11
   Author's Addresses...............................................14
   Intellectual Property Statement..................................15
   Disclaimer of Validity...........................................16

1. Introduction

   This memo provides extensions to Generalized Multi-Protocol Label
   Switching (GMPLS) signaling for control of wavelength switched
   optical networks (WSON).  Fundamental extensions are given to permit
   simultaneous bi-directional 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 LSP.

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

2. Terminology

   CWDM: Coarse Wavelength Division Multiplexing.

   DWDM: Dense Wavelength Division Multiplexing.

   FOADM: Fixed Optical Add/Drop Multiplexer.

   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 an
   information bearing optical signal centered at a given 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.

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

   AWG: Arrayed Waveguide Grating.

   OXC: Optical Cross Connect.

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

   Optical Responder: 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 responder.

   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.

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 MUST 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
   converters, Regenerators, OEO Switches, etc...), links (WDM systems)
   and end systems (detectors, demodulators, etc...). The details of
   any local configuration processes are out of the scope of this

   From [RFC6163] we have the following list of WSON signal
   characteristic information:

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                    List 1. 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 the [WSON-Info] 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 LSP Network Element Processing Configuration

   In addition to configuring a network element (NE) along an LSP to
   input or output a signal with specific attributes, we may need to
   signal the NE to perform specific processing, such as 3R
   regeneration, on the signal at a particular NE.  In [RFC6163] we
   discussed three types of processing not currently covered by GMPLS:

     (A) Regeneration (possibly different types)

     (B) Fault and Performance Monitoring

     (C) Attribute Conversion

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

3.3. Bi-Directional WSON LSPs

   WSON signaling MAY support LSP setup consistent with the wavelength
   continuity constraint for bi-directional connections. The following
   cases MAY be separately supported:

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

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

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

3.4. Distributed Wavelength Assignment Support

   WSON signaling MAY 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 which supports distributed wavelength assignment, in
   particular when the centralized wavelength assignment capability is
   not available.

   As discussed in the [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. Out of Scope

   This draft does not address signaling information related to optical

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].

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

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   [RFC3473] they are conveyed Generalized Label Request object and the
   RSVP SENDER_TSPEC/FLOWSPEC objects respectively.

4.2. Signal Attributes and Processing

   Section 3.2. gave the requirements for signaling to indicate to a
   particular NE along an LSP what type of processing to perform on an
   optical signal or how to configure that NE to accept or transmit an
   optical signal with particular attributes.

   One way of accomplishing this is via a new EXPLICIT_ROUTE subobject.
   Reference [RFC3209] defines the EXPLICIT_ROUTE object (ERO) and a
   number of subobjects, while reference [RFC5420] defines general
   mechanisms for dealing with additional LSP attributes. Although
   reference [RFC5420] defines a RECORD_ROUTE object (RRO) attributes
   subobject, it does not define an ERO subobject for LSP attributes.

   Regardless of the exact coding for the ERO subobject conveying the
   input, output, or processing instructions. This new "processing"
   subobject would follow a subobject containing the IP address, or the
   interface identifier [RFC3477], associated with the link on which it
   is to be used along with any label subobjects [RFC3473].

   In regards to  specific information required, the [WSON-Encode]
   already provides all necessary definitions and encoding. In
   particular the Resource block information sub-TLV which contains,
   among others, a list of available Optical Interface Classes and
   processing capabilities.

   The WSON Signal Processing object is defined as an LSP_ATTRIBUTES
   and extends the PATH message. It is defined as the following:

   <WSON Processing> ::= <RBInformation>


   <RBInformation> is the object defined in Section 5.1 of [WSON-

   This is the only sub-TLV available within the <WSON Processing>.
   Only one <RBInformation> object MUST be present.

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4.2.1. WSON Processing Object Encoding

    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                              ~
   |                                                               |

   Type: to be defined by IANA

   Value: sub-TLVS according to section 4.1.

5. Bidirectional Lightpath Setup

   With the wavelength continuity constraint in CI-incapable [RFC3471]
   WSONs, where the nodes in the networks cannot support wavelength
   conversion, the same wavelength on each link along a unidirectional
   lightpath should be reserved. In addition to the wavelength
   continuity constraint, requirement 3.3 gives us another constraint
   on wavelength usage in data plane, in particular, it requires the
   same wavelength to be used in both directions. [RFC6163] in section
   6.1 reports on the implication to GMPLS signaling related to both
   bi-directionality and Distributed Wavelengths Assignment.

   Current GMPLS solution defines a bidirectional LSP (as defined by
   [RFC3471]). The label distribution is based on Label_Set and
   Upstream_Label objects. In case of specific constraints such as the
   same wavelengths in both directions, it may require several
   signaling attempts using information from the Acceptable_Label_Set
   received from path error messages. Since this mechanism is currently
   available and proven to work, no additional extensions are needed
   for WSON. Potential optimizations are left for further studies.

   The usage of <WSON Processing> object for the bidirectional case is
   the same as per unidirectional. When an intermediate node uses
   information from this object to instruct a node about wavelength
   regeneration, the same information applies to both downstream and
   upstream directions.

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   Some implementations may prefer using two unidirectional LSPs. This
   solution has been always available as per [RFC3209] however recent
   work introduces the association concept [RFC4872] and [ASSOC-Info].
   Recent transport evolutions [ASSOC-ext] provide a way to associate
   two unidirectional LSPs as a bidirectional LSP. In line with this, a
   small extension can make this approach work for the WSON case.

6. RWA Related

6.1. Wavelength Assignment Method Selection

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

   Under this hypothesis the node initiating the signaling process
   needs to declare its own wavelength availability (through a
   label_set object). Each intermediate node may delete some labels due
   to connectivity constraints or its own assignment policy. At the
   end, the destination node has to make the final decision on the
   wavelength assignment among the ones received through the signaling

   As discussed in [HZang00] a number of different wavelength
   assignment algorithms maybe employed. In addition 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.

   A simple TLV could be used to indication wavelength assignment
   directionality and wavelength assignment method. This would be
   placed in an LSP_REQUIRED_ATTRIBUTES object per [RFC5420]. The use
   of a TLV in the LSP required attributes object was pointed out in

   [TO DO: The directionality stuff needs to be reconciled with the
   earlier material]

   Unique Wavelength: 0 same wavelength in both directions, 1 may use
   different wavelengths [TBD: shall we use only 1 bit]

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   Wavelength Assignment Method: 0 unspecified (any), 1 First-Fit, 2
   Random, 3 Least-Loaded (multi-fiber).  Others TBD.

       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
      |    Unique WL  |    WA Method  |           Reserved            |

7. Security Considerations

   This document has no requirement for a change to the security models
   within GMPLS and associated protocols. That is the OSPF-TE, RSVP-TE,
   and PCEP security models could be operated unchanged.

   However satisfying the requirements for RWA using the existing
   protocols may significantly affect the loading of those protocols.
   This makes the operation of the network more vulnerable to denial of
   service attacks. Therefore additional care maybe required to ensure
   that the protocols are secure in the WSON environment.

   Furthermore 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

   TBD. Once finalized in our approach we will need identifiers for
   such things and modulation types, modulation parameters, wavelength
   assignment methods, etc...

9. Acknowledgments

   Authors would like to thanks Lou Berger and Cyril Margaria for
   comments and suggestions.

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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.

   [RFC2578] McCloghrie, K., Perkins, D., and J. Schoenwaelder,
             "Structure of Management Information Version 2 (SMIv2)",
             STD 58, RFC 2578, April 1999.

   [RFC3209] Awduche, D., Berger, L., Gan, D., Li, T., Srinivasan, V.,
             and G. Swallow, "RSVP-TE: Extensions to RSVP for LSP
             Tunnels", RFC 3209, December 2001.

   [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.

   [RFC5420] Farrel, A., Ed., Papadimitriou, D., Vasseur, J.-P., and A.
             Ayyangar, " Encoding of Attributes for MPLS LSP
             Establishment Using Resource Reservation Protocol Traffic
             Engineering (RSVP-TE)", RFC 5420, February 2006.

   [WSON-Encode]  Bernstein G., Lee Y., Li D., and W. Imajuku, "Routing
             and Wavelength Assignment Information Encoding for
             Wavelength Switched Optical Networks", draft-ietf-ccamp-
             rwa-wson-encode-18 (work in progress), September 2012.

10.2. Informative References

   [WSON-CompOSPF] Y. Lee, G. Bernstein, "OSPF Enhancement for Signal
             and Network Element Compatibility for Wavelength Switched
             Optical Networks", work in progress: draft-lee-ccamp-wson-

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   [RFC6163]  Y. Lee, G. Bernstein, W. Imajuku, "Framework for GMPLS
             and PCE Control of Wavelength Switched Optical Networks",
             work in progress: draft-bernstein-ccamp-wavelength-
             switched-03.txt, February 2008.

   [WSON-Info] G. Bernstein, Y. Lee, D. Li, W. Imajuku, "Routing and
             Wavelength Assignment Information Model for Wavelength
             Switched Optical Networks", work in progress: draft-ietf-
             ccamp-rwa-info-16, September 2012.

   [HZang00] H. Zang, J. Jue and B. Mukherjeee, "A review of routing
             and wavelength assignment approaches for wavelength-routed
             optical WDM networks", Optical Networks Magazine, January

   [Xu]     S. Xu, H. Harai, and D. King, "Extensions to GMPLS RSVP-TE
             for Bidirectional Lightpath the Same Wavelength", work in
             progress: draft-xu-rsvpte-bidir-wave-01, November 2007.

   [Winzer06]    Peter J. Winzer and Rene-Jean Essiambre, "Advanced
             Optical Modulation Formats", Proceedings of the IEEE, vol.
             94, no. 5, pp. 952-985, May 2006.

   [G.959.1] ITU-T Recommendation G.959.1, Optical Transport Network
             Physical Layer Interfaces, March 2006.

   [G.694.1] ITU-T Recommendation G.694.1, Spectral grids for WDM
             applications: DWDM frequency grid, June 2002.

   [G.694.2] ITU-T Recommendation G.694.2, Spectral grids for WDM
             applications: CWDM wavelength grid, December 2003.

   [G.Sup43] ITU-T Series G Supplement 43, Transport of IEEE 10G base-R
             in optical transport networks (OTN), November 2006.

   [RFC4427] Mannie, E., Ed., and D. Papadimitriou, Ed., "Recovery
             (Protection and Restoration) Terminology for Generalized
             Multi-Protocol Label Switching (GMPLS)", RFC 4427, March

   [RFC4872] Lang, J., Rekhter, Y., and Papadimitriou, D., "RSVP-TE
             Extensions in Support of End-to-End Generalized Multi-
             Protocol Label Switching (GMPLS) Recovery", RFC 4872,

   [ASSOC-Info] Berger, L., Faucheur, F., and A. Narayanan, "Usage of
             The RSVP Association Object", draft-ietf-ccamp-assoc-info-
             00 (work in progress), October 2010.

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   [ASSOC-Ext] Zhang, F., Jing, R., "RSVP-TE Extension to Establish
             Associated Bidirectional LSP", draft-zhang-mpls-tp-rsvp-
             te-ext-associated-lsp-03 (work in progress), February

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Author's Addresses

   Greg M. Bernstein (editor)
   Grotto Networking
   Fremont California, USA

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

   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,
   Email: guolintom@gmail.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

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

   Daniel King
   Old Dog Consulting

   Email: daniel@olddog.co.uk

   Young Lee (editor)
   Huawei Technologies

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   1700 Alma Drive, Suite 100
   Plano, TX 75075

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

   Giovanni Martinelli
   Via Philips 12
   20052 Monza, IT

   Phone: +39 039-209-2044
   Email: giomarti@cisco.com

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