1、 I n t e r n a t i o n a l T e l e c o m m u n i c a t i o n U n i o n ITU-T G.697 TELECOMMUNICATION STANDARDIZATION SECTOR OF ITU (11/2016) SERIES G: TRANSMISSION SYSTEMS AND MEDIA, DIGITAL SYSTEMS AND NETWORKS Transmission media and optical systems characteristics Characteristics of optical system
2、s Optical monitoring for dense wavelength division multiplexing systems Recommendation ITU-T G.697 ITU-T G-SERIES RECOMMENDATIONS TRANSMISSION SYSTEMS AND MEDIA, DIGITAL SYSTEMS AND NETWORKS INTERNATIONAL TELEPHONE CONNECTIONS AND CIRCUITS G.100G.199 GENERAL CHARACTERISTICS COMMON TO ALL ANALOGUE CA
3、RRIER-TRANSMISSION SYSTEMS G.200G.299 INDIVIDUAL CHARACTERISTICS OF INTERNATIONAL CARRIER TELEPHONE SYSTEMS ON METALLIC LINES G.300G.399 GENERAL CHARACTERISTICS OF INTERNATIONAL CARRIER TELEPHONE SYSTEMS ON RADIO-RELAY OR SATELLITE LINKS AND INTERCONNECTION WITH METALLIC LINES G.400G.449 COORDINATIO
4、N OF RADIOTELEPHONY AND LINE TELEPHONY G.450G.499 TRANSMISSION MEDIA AND OPTICAL SYSTEMS CHARACTERISTICS G.600G.699 General G.600G.609 Symmetric cable pairs G.610G.619 Land coaxial cable pairs G.620G.629 Submarine cables G.630G.639 Free space optical systems G.640G.649 Optical fibre cables G.650G.65
5、9 Characteristics of optical components and subsystems G.660G.679 Characteristics of optical systems G.680G.699 DIGITAL TERMINAL EQUIPMENTS G.700G.799 DIGITAL NETWORKS G.800G.899 DIGITAL SECTIONS AND DIGITAL LINE SYSTEM G.900G.999 MULTIMEDIA QUALITY OF SERVICE AND PERFORMANCE GENERIC AND USER-RELATE
6、D ASPECTS G.1000G.1999 TRANSMISSION MEDIA CHARACTERISTICS G.6000G.6999 DATA OVER TRANSPORT GENERIC ASPECTS G.7000G.7999 PACKET OVER TRANSPORT ASPECTS G.8000G.8999 ACCESS NETWORKS G.9000G.9999 For further details, please refer to the list of ITU-T Recommendations. Rec. ITU-T G.697 (11/2016) i Recomme
7、ndation ITU-T G.697 Optical monitoring for dense wavelength division multiplexing systems Summary Recommendation ITU-T G.697 defines optical monitoring (OM) that can help in dense wavelength division multiplexing (DWDM) systems to perform the following activities: configuration management for system
8、 and channel activation, addition of new channels, etc.; fault management to detect and to isolate faults; degradation management in order to keep the system running and to detect degradations before a fault occurs. DWDM technology is improving at a rapid pace, continuously stretching the channel co
9、unt, channel speeds and reach limits. Long-haul multi-span DWDM systems are capable of taking optical signals thousands of kilometres without electrical terminations or regeneration. This continuing trend is driving the increasing importance of OM, which is the subject of this Recommendation. This e
10、dition of this Recommendation provides additional information on OM for 40 Gbit/s and 100 Gbit/s signals, adds beat noise method to the clause for optical signal-to-noise ratio (OSNR) measurements, and introduces a new clause on security considerations. History Edition Recommendation Approval Study
11、Group Unique ID* 1.0 ITU-T G.697 2004-06-13 15 11.1002/1000/7322 2.0 ITU-T G.697 2009-11-13 15 11.1002/1000/10394 2.1 ITU-T G.697 (2009) Cor. 1 2011-02-25 15 11.1002/1000/11327 3.0 ITU-T G.697 2012-02-13 15 11.1002/1000/11483 4.0 ITU-T G.697 2016-11-13 15 11.1002/1000/13079 * To access the Recommend
12、ation, type the URL http:/handle.itu.int/ in the address field of your web browser, followed by the Recommendations unique ID. For example, http:/handle.itu.int/11.1002/1000/11830-en. ii Rec. ITU-T G.697 (11/2016) FOREWORD The International Telecommunication Union (ITU) is the United Nations special
13、ized agency in the field of telecommunications, information and communication technologies (ICTs). The ITU Telecommunication Standardization Sector (ITU-T) is a permanent organ of ITU. ITU-T is responsible for studying technical, operating and tariff questions and issuing Recommendations on them wit
14、h a view to standardizing telecommunications on a worldwide basis. The World Telecommunication Standardization Assembly (WTSA), which meets every four years, establishes the topics for study by the ITU-T study groups which, in turn, produce Recommendations on these topics. The approval of ITU-T Reco
15、mmendations is covered by the procedure laid down in WTSA Resolution 1. In some areas of information technology which fall within ITU-Ts purview, the necessary standards are prepared on a collaborative basis with ISO and IEC. NOTE In this Recommendation, the expression “Administration“ is used for c
16、onciseness to indicate both a telecommunication administration and a recognized operating agency. Compliance with this Recommendation is voluntary. However, the Recommendation may contain certain mandatory provisions (to ensure, e.g., interoperability or applicability) and compliance with the Recomm
17、endation is achieved when all of these mandatory provisions are met. The words “shall“ or some other obligatory language such as “must“ and the negative equivalents are used to express requirements. The use of such words does not suggest that compliance with the Recommendation is required of any par
18、ty. INTELLECTUAL PROPERTY RIGHTSITU draws attention to the possibility that the practice or implementation of this Recommendation may involve the use of a claimed Intellectual Property Right. ITU takes no position concerning the evidence, validity or applicability of claimed Intellectual Property Ri
19、ghts, whether asserted by ITU members or others outside of the Recommendation development process. As of the date of approval of this Recommendation, ITU had received notice of intellectual property, protected by patents, which may be required to implement this Recommendation. However, implementers
20、are cautioned that this may not represent the latest information and are therefore strongly urged to consult the TSB patent database at http:/www.itu.int/ITU-T/ipr/. ITU 2017 All rights reserved. No part of this publication may be reproduced, by any means whatsoever, without the prior written permis
21、sion of ITU. Rec. ITU-T G.697 (11/2016) iii Table of Contents Page 1 Scope . 1 2 References . 1 2.1 Normative references 1 3 Terms and definitions . 2 3.1 Terms defined elsewhere 2 3.2 Terms defined in this Recommendation . 2 4 Abbreviations and acronyms 3 5 Optical monitoring overview 4 6 Classific
22、ation of monitoring methods . 5 6.1 Signal monitoring . 5 6.2 Equipment monitoring (indirect methods) . 6 6.3 Fibre link monitoring 6 6.4 Monitoring based on received signals 6 6.5 Embedded monitoring equipment 6 6.6 External monitoring equipment 7 7 Optical impairments 7 8 Optical monitoring parame
23、ters . 9 9 Correlation between impairment effects and optical monitoring parameters degradation . 10 9.1 Variation of attenuation 10 9.2 Frequency (or wavelength) deviation from nominal 10 9.3 Optical channel power changes due to gain variations 10 10 Applications 11 11 Optical safety considerations
24、 11 12 Security considerations . 11 Appendix I Severity of optical impairments . 12 Appendix II Penalty severity value X . 14 Appendix III Optical monitoring performance . 15 III.1 Optical signal-to-noise ratio measurement . 17 III.2 Q-factor measurement (for up to approximately 10 Gbit/s signals) .
25、 21 Appendix IV Possible positions for suitable monitoring equipment and their relative functions in several optical network elements 25 IV.1 Introduction 25 IV.2 Embedded monitoring points . 26 IV.3 External monitoring points . 28 iv Rec. ITU-T G.697 (11/2016) Page Appendix V Parameter encoding 30
26、V.1 Wavelength ID (32 bits) . 30 V.2 Parameter ID source (8 bits) . 31 V.3 Parameter ID (8 bits) 31 V.4 Value of parameters (32 bits) . 31 Bibliography. 32 Rec. ITU-T G.697 (11/2016) 1 Recommendation ITU-T G.697 Optical monitoring for dense wavelength division multiplexing systems 1 Scope The purpos
27、e of this Recommendation is to indicate a minimum, but not exhaustive, set of optical parameters that can be used to perform optical monitoring (OM) functions in dense wavelength division multiplexing (DWDM) systems and optical network elements ONEs, e.g., reconfigurable optical add-drop multiplexer
28、s (ROADMs), particularly relevant to those network elements without optical-electrical-optical conversions. In order to achieve this objective, this Recommendation: 1) indicates methods for measuring the optical signal degradation; 2) classifies those methods by type; 3) defines suitable optical par
29、ameters to detect optical signal degradation; and 4) describes the applications or conditions where these optical parameters can be relevant. This Recommendation refers to DWDM systems and ONEs with optical channels with bit rates up to approximately 10 Gbit/s using non-return to zero (NRZ) or retur
30、n to zero (RZ) line coding and bit rates at approximately 40 Gbit/s and 100 Gbit/s using advanced modulation formats, such as (dual polarization) quadrature phase shift keying. Bit rates above 100 Gbit/s and systems employing other modulation formats are for further study. 2 References 2.1 Normative
31、 references The following ITU-T Recommendations and other references contain provisions which, through reference in this text, constitute provisions of this Recommendation. At the time of publication, the editions indicated were valid. All Recommendations and other references are subject to revision
32、; users of this Recommendation are therefore encouraged to investigate the possibility of applying the most recent edition of the Recommendations and other references listed below. A list of the currently valid ITU-T Recommendations is regularly published. The reference to a document within this Rec
33、ommendation does not give it, as a stand-alone document, the status of a Recommendation. ITU-T G.650.2 Recommendation ITU-T G.650.2 (2015), Definitions and test methods for statistical and non-linear related attributes of single-mode fibre and cable. ITU-T G.652 Recommendation ITU-T G.652 (2016), Ch
34、aracteristics of a single-mode optical fibre and cable. ITU-T G.653 Recommendation ITU-T G.653 (2010), Characteristics of a dispersion-shifted single-mode optical fibre and cable. ITU-T G.655 Recommendation ITU-T G.655 (2009), Characteristics of a non-zero dispersion-shifted single-mode optical fibr
35、e and cable. ITU-T G.663 Recommendation ITU-T G.663 (2011), Application-related aspects of optical amplifier devices and subsystems. ITU-T G.664 Recommendation ITU-T G.664 (2012), Optical safety procedures and requirements for optical transmission systems. ITU-T G.692 Recommendation ITU-T G.692 (200
36、5), Optical interfaces for multichannel systems with optical amplifiers. 2 Rec. ITU-T G.697 (11/2016) ITU-T O.201 Recommendation ITU-T O.201 (2003), Q-factor test equipment to estimate the transmission performance of optical channels. ITU-T X.805 Recommendation ITU-T X.805 (2003), Security architect
37、ure for systems providing end-to-end communications. 3 Terms and definitions 3.1 Terms defined elsewhere This Recommendation uses the following term defined in ITU-T G.650.2: stimulated Brillouin scattering (SBS) This Recommendation uses the following terms defined in ITU-T G.663: polarization mode
38、dispersion (PMD) (1st and higher orders) four-wave mixing (FWM) amplified spontaneous emission (ASE) noise in optical amplification (OA) chromatic dispersion reflections (see reflectance) cross-phase modulation (XPM) self-phase modulation (SPM) stimulated Raman scattering (SRS) This Recommendation u
39、ses the following term defined in ITU-T G.692: Frequency (or wavelength) deviation from nominal (see central frequency deviation) This Recommendation uses the following term defined in ITU-T. O.201: Q-factor This Recommendation uses the following terms defined in b-ITU-T G-Sup.39: optical signal-to-
40、noise ratio (OSNR) inter-channel crosstalk interferometric crosstalk 3.2 Terms defined in this Recommendation This Recommendation defines the following terms: 3.2.1 chromatic dispersion slope: The slope of the curve of chromatic dispersion coefficient versus wavelength. 3.2.2 fully regenerated optic
41、al network: Optical network where optical-electrical-optical conversion is performed in each network element using re-amplification, reshaping and retiming (3R) regeneration. 3.2.3 transparent optical network element: An optical network element where there is no optical-electrical-optical conversion
42、 of the optical signal. Rec. ITU-T G.697 (11/2016) 3 4 Abbreviations and acronyms This Recommendation uses the following abbreviations and acronyms: 3R Re-amplification, Reshaping and Retiming ASE Amplified Spontaneous Emission BER Bit Error Ratio CWDM Coarse Wavelength Division Multiplexing DCM Dis
43、persion Compensation Module Demux Demultiplexer DGD Differential Group Delay DSP Digital Signal Processing DWDM Dense Wavelength Division Multiplexing EME Embedded Monitoring Equipment EMP External Monitoring Point ESR Errored Second Ratio FEC Forward Error Correction FWM Four-Wave Mixing Mux Multip
44、lexer NOC Network Operations Centre NRZ Non-Return to Zero OA Optical Amplification OADM Optical Add-Drop Multiplexer OD Optical Demultiplexing O/E Optical to Electrical OM Optical Monitoring ONE Optical Network Element OSA Optical Spectrum Analyser OSNR Optical Signal-to-Noise Ratio OTDR Optical Ti
45、me Domain Reflectometer OTN Optical Transport Network PDL Polarization-Dependent Loss PMD Polarization Mode Dispersion ROADM Reconfigurable Optical Add-Drop Multiplexer RZ Return to Zero SBS Stimulated Brillouin Scattering SDH Synchronous Digital Hierarchy 4 Rec. ITU-T G.697 (11/2016) SESR Severely
46、Errored Second Ratio SLA Service Level Agreement SPM Self-Phase Modulation SRS Stimulated Raman Scattering XPM cross-Phase Modulation 5 Optical monitoring overview The management of existing synchronous digital hierarchy (SDH) networks relies on monitoring digital parameters such as bit error ratio
47、(BER), errored second ratio (ESR) and severely errored second ratio (SESR), which are measured at the electrical layer (at 3R regenerators), as described in b-ITU-T G.826. A similar approach is used in the optical transport network (OTN), using ITU-T G.709 framing, for monitoring the end-to-end conn
48、ections and the optical connections at the electrical level. While these methods give a reliable measure of the end-to-end performance of an optical channel, they cannot be applied inside a transparent optical domain where no 3R regenerators are available to terminate the frame overhead. Therefore,
49、they may not provide sufficient information to isolate the root cause of problems in complex DWDM networks. Moreover, the rapid progress in optical technology is leading to ever-increasing channel counts and transmission speeds and to longer all-optical connections inside an optical domain. This leads to the increasing influence of linear and non-linear distortions, which makes system commissioning an increasingly complex task. An optimum solution for an OTN combin
