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Versions: 00 01                                                         
CCAMP                                                       Grammel, Ed.
Internet-Draft                                            D. Hiremagalur
Intended status: Informational                                   Juniper
Expires: September 10, 2017                            G.Galimberti, Ed.
                                                                   Cisco
                                                                 R.Kunze
                                                        Deutsche Telekom
                                                     O. Gonzalez de Dios
                                                          Telefonica I+D
                                                           March 9, 2017


          Controlling pre-standard coherent Optical Interfaces
                 draft-many-coherent-dwdm-if-control-01

Abstract

   Modulated optical interfaces with coherent detection receivers are in
   widespread use in Internet networking equipment.  Various
   implementations are in deployment since 2012 but there is no standard
   available defining those interfaces, nor their capabilities.  This
   document identifies the need for work on control plane aspects pre-
   standard coherent optical DWDM applications.

Status of This Memo

   This Internet-Draft is submitted 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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   Internet-Drafts are draft documents valid for a maximum of six months
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   This Internet-Draft will expire on September 10, 2017.

Copyright Notice

   Copyright (c) 2017 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



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   (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  . . . . . . . . . . . . . . . . . . . . . . . .   2
   2.  Requirements Language . . . . . . . . . . . . . . . . . . . .   3
   3.  Abbreviations . . . . . . . . . . . . . . . . . . . . . . . .   3
   4.  Motivation  . . . . . . . . . . . . . . . . . . . . . . . . .   3
   5.  Applicability to CCAMP  . . . . . . . . . . . . . . . . . . .   3
   6.  State of Standards  . . . . . . . . . . . . . . . . . . . . .   3
     6.1.  Data Plane  . . . . . . . . . . . . . . . . . . . . . . .   4
     6.2.  Control Plane . . . . . . . . . . . . . . . . . . . . . .   5
   7.  Addressing the gap in controlling PRESCO-DWDM interfaces  . .   5
   8.  Progressing PRESCO related work . . . . . . . . . . . . . . .   5
   9.  Contributors  . . . . . . . . . . . . . . . . . . . . . . . .   6
   10. Acknowledgements  . . . . . . . . . . . . . . . . . . . . . .   6
   11. IANA Considerations . . . . . . . . . . . . . . . . . . . . .   7
   12. Security Considerations . . . . . . . . . . . . . . . . . . .   7
   13. References  . . . . . . . . . . . . . . . . . . . . . . . . .   7
     13.1.  Normative References . . . . . . . . . . . . . . . . . .   7
     13.2.  Informative References . . . . . . . . . . . . . . . . .   8
   Appendix A.  Additional Stuff . . . . . . . . . . . . . . . . . .   9
   Authors' Addresses  . . . . . . . . . . . . . . . . . . . . . . .   9

1.  Introduction

   The dominant interconnection technology in the Internet is based on
   fiber and optical transceiver interfaces.  Multiple SDOs are working
   on control-plane and data-plane standards in this field.  Some are
   covering LAN applications (IEEE), while others work on WAN and in
   particular DWDM based applications (ITU-T SG15).  Those DWDM related
   recommendations are based on non-coherent detection schemes and do
   not cover modulated optical suignals and coherent detection.  DWDM
   wavelengths of 40Gb/s, 100Gb/s and beyond use higher order modulation
   techniques with coherent detection schemes and are used throughout
   the industry.  Current implementations are already heading towards
   capacities of 400Gb/s and 1Tb/s per Interface.  The gap between
   standards availability and practical deployment creates a mounting
   need in the industry for a common data model that can be used to
   control Pre Standard Coherent Optical (PRESCO) DWDM interfaces.  This
   document addresses the issue of progressing control plane work
   related to PRESCO-DWDM technology.



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2.  Requirements Language

   The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
   "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this
   document are to be interpreted as described in RFC 2119 [RFC2119].

3.  Abbreviations

   o  DWDM: Dense Wavelength Division Multiplexing

   o  PRESCO-interface: PRE-Standard-Coherent-Optical DWDM interface

   o  PRESCO-wavelength: pre-standard coherent DWDM signal with phase
      modulated transmitter and coherent detection receiver

   o  PRESCO-Module: Transmitter/receiver Module of pre-standard
      coherent DWDM signals

   o  SDO: Standards Developing Organization

4.  Motivation

   As data plane standards for standard coherent optical interfaces are
   in flux, there is a lack of common ground on modeling and encoding
   interface parameters related to higher order modulation techniques
   with coherent detection schemes.  This unnecessarily burdens control
   systems with complexity in coping with incompatible implementations
   and complex operation.  As data plane standards are insufficient to
   provide guidance on control plane work for PRESCO devices, work on
   data models for PRESCO applications need to proceed independently of
   data plane standards.

5.  Applicability to CCAMP

   "The CCAMP working group is responsible for standardizing a common
   control plane and a separate common measurement plane for non-packet
   technologies found in the Internet and in the networks of telecom
   service providers (ISPs and SPs)."" As such CCAMP is chartered with
   "the definition of management objects (e.g., as part of MIB modules
   or YANG models) and control of OAM techniques relevant to the
   protocols and extensions specified within the WG" [ccamp-charter].
   Hence work to control PRESCO devices is in the scope of ccamp.

6.  State of Standards







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6.1.  Data Plane

   The first version of [superseded-ITU.G698.2] was published July 2007.
   A key role plays the concept of "application codes" to characterize
   transmitters and receivers using an character-string.  When a Tx/Rx
   pair, with the same code, is connected over a link with specific
   optical properties, the DWDM connection is guaranteed to interoperate
   regardless of their origin, i.e. their manufacturer within the
   conditions set out in this recommendation.

   The now in-force [ITU.G698.2] recommendation "includes unidirectional
   DWDM applications at 2.5 and 10 Gbit/s with 100 GHz channel frequency
   spacing as well as applications at 10 Gbit/s with 50 GHz channel
   frequency spacing."  No comparable Recommendation exists for higher
   bitrates and higher modulated signals and the current vesionof
   [RFC7581] is based on those codes as well.  Also related standards
   like [ITU.G697] "Optical monitoring for dense wavelength division
   multiplexing systems" and [ITU.G680] "Physical transfer functions of
   optical network elements" are written based on 2.5G and 10G
   technology using direct detection.

   ITU-T Study Group 15 set out in 2010 to begin work toward "revision
   of [SG15-2012], establishing sets of parameters and associated values
   to enable multi-vendor interoperability for 40 Gbit/s application
   codes with various modulation formats".  At the time this work began,
   there were several candidate modulation formats e.g DQPSK, PM-QPSK,
   OFDM-QPSK.  NRZ modulation used for 2.5G and 10G is simpler than the
   so called advanced phase modulation schemes required for higher
   bitrates.  For DP-QPSK, for example, it is necessary to determine and
   specify suitable parameters for the characterization of the
   polarization and phase components of the signal.  The challenge
   experts had in advancing that work has been brought to the attention
   of ccamp in 2013 when it was reported that progress have been made
   such that "there is only 1 modulation format candidate for 100G
   standardization" and "what we're struggling with is doing fundamental
   work on standardizing phase modulated
   transmission"[IETF-86-ccamp-minutes].

   We recognize the complex nature of the task and acknowledge the
   amount of diligent work that has been put, and is still being put
   into coherent DWDM data-plane standardization.  Still, at the time of
   this writing, the fundamental underlying problem in standardizing
   phase modulated optical signals is not yet solved.  Even when that
   work would be completed, the relevant aspects of the link and
   receiver, together with an appropriate FEC standardization, will need
   to be addressed as well.  By Sept 2016 there is no deadline
   communicated by when this work is expected to be finalized.




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6.2.  Control Plane

   Standardization control aspects in relevant SDOs naturally follows
   the work on data plane which provides the base for monitoring
   capabilities and identification of critical parameters.  Available
   recommendations utilize application codes defined in [ITU.G698.2].
   Such application code can be considered a character based
   abbreviation (such as e.g.  DScW-ytz(v) from [ITU.G698.2]) to
   characterize transceiver characteristics.  Consequently control
   information in WSON (see [RFC3591] and [ITU.G874.1]) is also based on
   the use of such application codes.  [RFC3591] is based on [ITU.G872].
   and provides a starting point for the definition and structuring of
   objects.  However, given that [RFC3591] is also a standards track
   document, it naturally based on standard definitions and can not
   include parameters required to describe PRESCO devices.  In parallel,
   individual contributions in ccamp (e.g. [draft-2012]) were proposing
   to work by introducing extensions for parameters describing PRESCO
   devices.  As data-plane standards did not conclude, such extensions
   were considered pre-mature.  So by Sept. 2016 no common reference
   model exists as a basis that would allow to define a data model for
   modulated optical interfaces with coherent detection receivers.

7.  Addressing the gap in controlling PRESCO-DWDM interfaces

   As the Industry is surpassing standards development in providing
   PRESCO applications, it would benefit from commonality in
   implementing yang data models to control PRESCO-DWDM Modules.
   Existing PRESCO Modules already provide extensive FCAPS capabilities
   and are used to provide commercial services.  Data models for such
   devices are in active development but suffer from commonality.  On
   the positive side this situation allows defining PRESCO related data
   models based on those FCAPS functionalities.

8.  Progressing PRESCO related work

   PRESCO related work should be based on creating a common abstracted
   model based on PRESCO-FCAPS implementations, rough consensus and
   running code.  The aim is provide the basis to enable PRESCO
   applications in a consistent manner by reducing implementation
   differences in the data structure.

   As PRESCO data models would need to evolve in parallel or even
   precede a data-plane standard the following list of considerations
   should be applied going forward:

   1.  Control work for PRESCO SHALL have the status INFORMATIONAL or
       EXPERIMENTAL as it is not standards based




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   2.  A PRESCO model SHOULD be based on control parameters available
       PRESCO DWDM modules

   3.  PRESCO modeling SHOULD aim to fit into existing data models in
       IETF

   4.  the model SHOULD allow augmentation of parameters by vendor
       specific extensions

   5.  the model SHOULD re-using existing standard parameter definitions
       and encoding where possible

   6.  Since the full set of parameters needed to characterize PRESCO
       modules and their encoding are undefined, application codes are
       not available for use in PRESCO.  Therefore controlling PRESCO
       Modules SHALL NOT mandate the use application codes.

   7.  threshold levels derived from measurement values SHOULD be
       adjustable such that a comparable system behaviour can be
       achieved.

   PRESCO related work evidently needs to be separate from standards
   related work and we need to outline what PRESCO work is not about:

   o  PRESCO is NOT suggesting to perform data-plane work in IETF.

   o  PRESCO is NOT providing data models for non-PRESCO interfaces

   o  PRESCO does NOT propose to utilize Data models defined for PRESCO
      modules to be re-used for standard models when those become
      available

   o  PRESCO does NOT require multi-vendor compatibility of PRESCO-
      Modules on data plane.  I.e. a pair of PRESCO-DWDM interfaces
      having identical parameter sets describing the data-plane is not
      guaranteed to be compatible by ITU-T standards.

9.  Contributors



10.  Acknowledgements

   TBD







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11.  IANA Considerations

   This memo includes no request to IANA.

12.  Security Considerations

   This document discusses the need for a non-standard YANG data Model.
   It has no security impact on the Internet.

13.  References

13.1.  Normative References

   [ITU.G680]
              International Telecommunications Union, "Physical transfer
              functions of optical network elements",
              ITU-T Recommendation G.680, July 2007.

   [ITU.G697]
              International Telecommunications Union, "Optical
              monitoring for dense wavelength division multiplexing
              systems", ITU-T Recommendation G.697, February 2012.

   [ITU.G698.2]
              International Telecommunications Union, "Amplified
              multichannel dense wavelength division multiplexing
              applications with single channel optical interfaces",
              ITU-T Recommendation G.698.2, November 2009.

   [ITU.G872]
              International Telecommunications Union, "Architecture of
              optical transport networks", ITU-T Recommendation G.872,
              October 2012.

   [ITU.G874.1]
              International Telecommunications Union, "Optical transport
              network:Protocol-neutral management information model for
              the network element view", ITU-T Recommendation G.874.1,
              October 2012.

   [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>.







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   [RFC3591]  Lam, H-K., Stewart, M., and A. Huynh, "Definitions of
              Managed Objects for the Optical Interface Type", RFC 3591,
              DOI 10.17487/RFC3591, September 2003,
              <http://www.rfc-editor.org/info/rfc3591>.

   [superseded-ITU.G698.2]
              International Telecommunications Union, "Amplified
              multichannel dense wavelength division multiplexing
              applications with single channel optical interfaces",
              ITU-T Recommendation G.698.2, July 2007.

13.2.  Informative References

   [ccamp-charter]
              "Responsible AD: Deborah Brungard; Charter Edit AD: Adrian
              Farrel ", "Charter for Working Group", 2014,
              <https://datatracker.ietf.org/doc/charter-ietf-ccamp/>.

   [draft-2012]
              "D. Hiremagalur, Ed. et. al.", "Extension to the Link
              Management Protocol (LMP/DWDM -rfc4209) for Dense
              Wavelength Division Multiplexing (DWDM) Optical Line
              Systems to manage black-link optical interface parameters
              of DWDM application", 2012, <https://tools.ietf.org/html/
              draft-dharinigert-ccamp-g-698-2-lmp-00>.

   [IETF-86-ccamp-minutes]
              "Chairs: Lou Berger, Deborah Brungard", "CCAMP Minutes of
              IETF-86 Orlando", 2013,
              <https://www.ietf.org/proceedings/86/minutes/minutes-
              86-ccamp>.

   [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>.

   [SG15-2012]
              "SG15 Chairman; Yoichi Maeda", "Overview of the third SG15
              meeting of the 2009-2012 study period", 2010,
              <https://www.itu.int/en/ITU-T/studygroups/com15/Pages/
              summary-201006.aspx>.








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Appendix A.  Additional Stuff

   Parameters that need to be encoded addressing PRESCO applications
   are:

   o  Modulation Format

   o  Spectral efficiency or Bit per symbols

   o  baud rate

   o  bandwidth required by the PRESCO-DWDM carrier

   o  Carrier central frequency (this might not follow the ITU-T grid)

   o  Forward Error Correction code

   o  Tx and Rx power

   o  Frequency/Wavelength

   o  ...

   As for PRESCO applications the completeness of these Parameters to
   fully characterize PRESCO interfaces is not guaranteed, additional
   parameters will be added as needed.

Authors' Addresses

   Gert Grammel (editor)
   Juniper
   Oskar-Schlemmer-Str. 15
   Muenchen  80807
   Germany

   Phone: +1 408 940 1375
   Email: ggrammel@juniper.net


   Dharini Hiremagalur
   Juniper
   1194 N Mathilda Avenue
   Sunnyvale - 94089 California
   USA

   Email: dharinih@juniper.net





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   Gabriele Galimberti (editor)
   Cisco
   Via Santa Maria Molgora, 48 c
   20871 - Vimercate
   Italy

   Phone: +390392091462
   Email: ggalimbe@cisco.com


   Ruediger Kunze
   Deutsche Telekom
   Winterfeldtstrasse, 21
   Berlin
   Germany

   Email: RKunze@telekom.de


   Oscar Gonzalez de Dios
   Telefonica I+D
   TDon Ramon de la Cruz, 82
   Madrid  28006
   Spain

   Phone: +34 913 129 041
   Email: oscar.gonzalezdedios@telefonica.com
























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