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.695 TELECOMMUNICATION STANDARDIZATION SECTOR OF ITU (01/2015) SERIES G: TRANSMISSION SYSTEMS AND MEDIA, DIGITAL SYSTEMS AND NETWORKS Transmission media and optical systems characteristics Characteristics of optical system
2、s Optical interfaces for coarse wavelength division multiplexing applications Recommendation ITU-T G.695 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 ANALO
3、GUE CARRIER-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 COORD
4、INATION 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.6
5、50G.659 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-
6、RELATED 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.695 (01/2015) i R
7、ecommendation ITU-T G.695 Optical interfaces for coarse wavelength division multiplexing applications Summary Recommendation ITU-T G.695 provides optical parameter values for physical layer interfaces of coarse wavelength division multiplexing (CWDM) applications with up to 16 channels and up to 25
8、Gbit/s. Applications are defined using two different methods, one using multichannel interface parameters and the other using single-channel interface parameters. Both unidirectional and bidirectional applications are specified. In this version of this Recommendation, codes for 4-channel NRZ 10G lon
9、g-haul and NRZ 25G short-haul black-box applications have been added. History Edition Recommendation Approval Study Group Unique ID* 1.0 ITU-T G.695 2004-02-22 15 11.1002/1000/7058 2.0 ITU-T G.695 2005-01-13 15 11.1002/1000/7474 3.0 ITU-T G.695 2006-12-14 15 11.1002/1000/8979 4.0 ITU-T G.695 2009-11
10、-13 15 11.1002/1000/10393 5.0 ITU-T G.695 2010-10-22 15 11.1002/1000/10872 6.0 ITU-T G.695 2015-01-13 15 11.1002/1000/12362 _ * To access the Recommendation, type the URL http:/handle.itu.int/ in the address field of your web browser, followed by the Recommendations unique ID. For example, http:/han
11、dle.itu.int/11.1002/1000/11830-en. ii Rec. ITU-T G.695 (01/2015) FOREWORD The International Telecommunication Union (ITU) is the United Nations specialized agency in the field of telecommunications, information and communication technologies (ICTs). The ITU Telecommunication Standardization Sector (
12、ITU-T) is a permanent organ of ITU. ITU-T is responsible for studying technical, operating and tariff questions and issuing Recommendations on them with a view to standardizing telecommunications on a worldwide basis. The World Telecommunication Standardization Assembly (WTSA), which meets every fou
13、r 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 Recommendations is covered by the procedure laid down in WTSA Resolution 1. In some areas of information technology which fall within ITU-Ts purview, the
14、 necessary standards are prepared on a collaborative basis with ISO and IEC. NOTE In this Recommendation, the expression “Administration“ is used for conciseness to indicate both a telecommunication administration and a recognized operating agency. Compliance with this Recommendation is voluntary. H
15、owever, the Recommendation may contain certain mandatory provisions (to ensure, e.g., interoperability or applicability) and compliance with the Recommendation is achieved when all of these mandatory provisions are met. The words “shall“ or some other obligatory language such as “must“ and the negat
16、ive equivalents are used to express requirements. The use of such words does not suggest that compliance with the Recommendation is required of any party. INTELLECTUAL PROPERTY RIGHTSITU draws attention to the possibility that the practice or implementation of this Recommendation may involve the use
17、 of a claimed Intellectual Property Right. ITU takes no position concerning the evidence, validity or applicability of claimed Intellectual Property Rights, whether asserted by ITU members or others outside of the Recommendation development process. As of the date of approval of this Recommendation,
18、 ITU had not received notice of intellectual property, protected by patents, which may be required to implement this Recommendation. However, implementers are cautioned that this may not represent the latest information and are therefore strongly urged to consult the TSB patent database at http:/www
19、.itu.int/ITU-T/ipr/. ITU 2015 All rights reserved. No part of this publication may be reproduced, by any means whatsoever, without the prior written permission of ITU. Rec. ITU-T G.695 (01/2015) iii Table of Contents Page 1 Scope . 1 2 References . 1 3 Definitions 2 3.1 Terms defined elsewhere 2 4 A
20、bbreviations and acronyms 3 5 Classification of optical interfaces 4 5.1 Applications 4 5.2 Reference points . 4 5.3 Nomenclature . 7 5.4 Multichannel interfaces at the reference points MPI-SM and MPI-RM . 8 5.5 Single-channel interfaces at the reference points SS and RS 10 6 Transverse compatibilit
21、y 11 7 Parameter definitions 11 7.1 General information 13 7.2 Interface at point MPI-SM or SS . 14 7.3 Common optical path parameters (single span) from point MPI-SM to MPI-RM, or from SS to RS 16 7.4 Interface at point MPI-RM or RS 18 7.5 Additional parameters for the optical path from SS to RS 20
22、 8 Parameter values . 20 9 Optical safety considerations 46 Appendix I Wavelength dependence of attenuation and chromatic dispersion 47 I.1 Attenuation . 47 I.2 Chromatic dispersion . 48 Appendix II Optical path from point RPS to RPR 50 Appendix III Black links containing OADMs 52 III.1 Number of OA
23、DMs in a black link 52 III.2 Mixed application codes . 53 III.3 Protection 54 Appendix IV Parameter values for 16-channel NRZ 2.5G applications . 55 Bibliography. 62 Rec. ITU-T G.695 (01/2015) 1 Recommendation ITU-T G.695 Optical interfaces for coarse wavelength division multiplexing applications 1
24、Scope This Recommendation applies to optical interfaces for coarse wavelength division multiplexing (CWDM) optical line systems for network applications using single-mode optical fibres. This Recommendation defines and provides values for optical interface parameters of physical point-to-point and r
25、ing CWDM system applications. Their principal purpose is to enable transversely (multi-vendor) compatible interfaces. Applications are defined using two different methods, one using multichannel interface parameters and the other using single-channel interface parameters. Both unidirectional and bid
26、irectional applications are specified. This Recommendation describes optical line systems that include the following features: Maximum number of channels: Up to 16. Bit-rate of signal channel: Up to NRZ 25G. The CWDM wavelength grid is provided in ITU-T G.694.2. Specifications are organized accordin
27、g to application codes. In the future, applications enabling full transverse compatibility at both the multichannel and single-channel interface points may be included. 2 References The following ITU-T Recommendations and other references contain provisions which, through reference in this text, con
28、stitute provisions of this Recommendation. At the time of publication, the editions indicated were valid. All Recommendations and other references are subject to revision; users of this Recommendation are therefore encouraged to investigate the possibility of applying the most recent edition of the
29、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 Recommendation does not give it, as a stand-alone document, the status of a Recommendation. ITU-T G.652 Recommendation ITU-T G.652 (2
30、009), Characteristics 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 opti
31、cal fibre and cable. ITU-T G.664 Recommendation ITU-T G.664 (2012), Optical safety procedures and requirements for optical transmission systems. ITU-T G.671 Recommendation ITU-T G.671 (2012), Transmission characteristics of optical components and subsystems. ITU-T G.691 Recommendation ITU-T G.691 (2
32、006), Optical interfaces for single channel STM-64 and other SDH systems with optical amplifiers. ITU-T G.692 Recommendation ITU-T G.692 (1998), Optical interfaces for multichannel systems with optical amplifiers. 2 Rec. ITU-T G.695 (01/2015) ITU-T G.694.2 Recommendation ITU-T G.694.2 (2003), Spectr
33、al grids for WDM applications: CWDM wavelength grid. ITU-T G.707 Recommendation ITU-T G.707/Y.1322 (2007), Network node interface for the synchronous digital hierarchy (SDH). ITU-T G.709 Recommendation ITU-T G.709/Y.1331 (2012), Interfaces for the optical transport network. ITU-T G.872 Recommendatio
34、n ITU-T G.872 (2012), Architecture of optical transport networks. ITU-T G.957 Recommendation ITU-T G.957 (2006), Optical interfaces for equipments and systems relating to the synchronous digital hierarchy. ITU-T G.959.1 Recommendation ITU-T G.959.1 (2012), Optical transport network physical layer in
35、terfaces. IEC 60825-1 IEC 60825-1 (2014), Safety of laser products Part 1: Equipment classification and requirements. IEC 60825-2 IEC 60825-2 (2010), Safety of laser products Part 2: Safety of optical fibre communication systems (OFCS). 3 Definitions 3.1 Terms defined elsewhere This Recommendation u
36、ses the following terms defined in ITU-T G.671: coarse wavelength division multiplexing (CWDM); optical wavelength multiplexer/demultiplexer; channel insertion loss; channel spacing; differential group delay; reflectance. This Recommendation uses the following term defined in ITU-T G.694.2: waveleng
37、th grid. This Recommendation uses the following term defined in ITU-T G.709: completely standardized OTUk (OTUk). This Recommendation uses the following terms defined in ITU-T G.872: inter-domain interface (IrDI); 3R regeneration. This Recommendation uses the following terms defined in ITU-T G.957:
38、joint engineering; receiver sensitivity; transverse compatibility. This Recommendation uses the following terms defined in ITU-T G.959.1: minimum equivalent sensitivity; optical tributary signal class NRZ 1.25G; optical tributary signal class NRZ 2.5G; Rec. ITU-T G.695 (01/2015) 3 optical tributary
39、signal class NRZ 10G. optical tributary signal class NRZ 25G. 4 Abbreviations and acronyms This Recommendation uses the following abbreviations and acronyms: 3R Reamplification, reshaping and retiming (regeneration) ALS Automatic Laser Shutdown APR Automatic Power Reduction APSD Automatic Power Shut
40、down ASE Amplified Spontaneous Emission BER Bit Error Ratio DGD Differential Group Delay EX Extinction ratio ffs for further study IrDI Inter-Domain Interface MPI Main Path Interface MPI-RM Multichannel Main Path Interface reference point at the CWDM network element aggregate input MPI-SM Multichann
41、el Main Path Interface reference point at the CWDM network element aggregate output NA Not Applicable NE Network Element NRZ Non-Return to Zero OA Optical Amplifier OADM Optical Add-Drop Multiplexer OD Optical Demultiplexer OTL Optical channel Transport Lane OM Optical Multiplexer ONE Optical Networ
42、k Element OTUk completely standardized Optical channel Transport Unit k PMD Polarization Mode Dispersion RPR Link reference point at the CWDM network element aggregate input RPS Link reference point at the CWDM network element aggregate output RS Single-channel reference point at the CWDM network el
43、ement tributary output SS Single-channel reference point at the CWDM network element tributary input WDM Wavelength Division Multiplexing 4 Rec. ITU-T G.695 (01/2015) 5 Classification of optical interfaces 5.1 Applications This Recommendation provides the physical layer parameters and values for CWD
44、M multichannel and single-channel interfaces in physical point-to-point and ring applications. CWDM systems can realize cost-effective applications through a combination of uncooled single mode lasers, relaxed laser wavelength selection tolerances and wide passband filters. CWDM systems can be used
45、in transport networks for a variety of clients, services and protocols. The specification method used in this Recommendation is categorized into two types. The first one is a “black box“ approach, which means that it is not intended to restrict or specify the internal elements and/or the connections
46、 between the elements within the black box. There are, however, functional requirements for the black box, the most important being the inclusion of 3R regeneration. This approach enables transverse compatibility at the multichannel points. The second type is a “black link“ approach which means that
47、 optical interface parameters for only (single-channel) optical tributary signals are specified. Additional informative descriptions are provided for the fibre link parameters of the multichannel section, such as maximum attenuation, chromatic dispersion and polarization mode dispersion. This approa
48、ch enables transverse compatibility at the single-channel point using a direct wavelength-multiplexing configuration. However, it does not enable transverse compatibility at the multichannel points. In this approach, the optical multiplexer (OM) and optical demultiplexer (OD) are treated as a single
49、 set of optical devices and OADMs can be included. This Recommendation considers non-amplified multichannel interfaces only; however, in the future, amplified interfaces may be considered. 5.2 Reference points 5.2.1 Unidirectional applications Figure 5-1 shows a set of reference points for multichannel connection (MPI-SM and MPI-RM) only, for the use of the “black box“ approach. Here the CWDM network element includes an OM a
