Internet DRAFT - draft-many-coherent-dwdm-if-control
draft-many-coherent-dwdm-if-control
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
Task Force (IETF). Note that other groups may also distribute
working documents as Internet-Drafts. The list of current Internet-
Drafts is at http://datatracker.ietf.org/drafts/current/.
Internet-Drafts are draft documents valid for a maximum of six months
and may be updated, replaced, or obsoleted by other documents at any
time. It is inappropriate to use Internet-Drafts as reference
material or to cite them other than as "work in progress."
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
Grammel, et al. Expires September 10, 2017 [Page 1]
Internet-Draft coherent-DWDM-if-control March 2017
(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.
Grammel, et al. Expires September 10, 2017 [Page 2]
Internet-Draft coherent-DWDM-if-control March 2017
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
Grammel, et al. Expires September 10, 2017 [Page 3]
Internet-Draft coherent-DWDM-if-control March 2017
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.
Grammel, et al. Expires September 10, 2017 [Page 4]
Internet-Draft coherent-DWDM-if-control March 2017
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
Grammel, et al. Expires September 10, 2017 [Page 5]
Internet-Draft coherent-DWDM-if-control March 2017
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
Grammel, et al. Expires September 10, 2017 [Page 6]
Internet-Draft coherent-DWDM-if-control March 2017
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>.
Grammel, et al. Expires September 10, 2017 [Page 7]
Internet-Draft coherent-DWDM-if-control March 2017
[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>.
Grammel, et al. Expires September 10, 2017 [Page 8]
Internet-Draft coherent-DWDM-if-control March 2017
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
Grammel, et al. Expires September 10, 2017 [Page 9]
Internet-Draft coherent-DWDM-if-control March 2017
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
Grammel, et al. Expires September 10, 2017 [Page 10]
