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.872 TELECOMMUNICATION STANDARDIZATION SECTOR OF ITU (01/2017) SERIES G: TRANSMISSION SYSTEMS AND MEDIA, DIGITAL SYSTEMS AND NETWORKS Digital networks Optical transport networks Architecture of optical transport networks R
2、ecommendation ITU-T G.872 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 CARRIER-TRANSMISSION SYSTEMS G.200G.299 INDIVIDUAL CHARACTERISTICS OF INTER
3、NATIONAL 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 COORDINATION OF RADIOTELEPHONY AND LINE TELEPHONY G.450G.499 TRANSMISSION MEDIA AND
4、OPTICAL SYSTEMS CHARACTERISTICS G.600G.699 DIGITAL TERMINAL EQUIPMENTS G.700G.799 DIGITAL NETWORKS G.800G.899 General aspects G.800G.809 Design objectives for digital networks G.810G.819 Synchronization, quality and availability targets G.820G.829 Network capabilities and functions G.830G.839 SDH ne
5、twork characteristics G.840G.849 Management of transport network G.850G.859 SDH radio and satellite systems integration G.860G.869 Optical transport networks G.870G.879 DIGITAL SECTIONS AND DIGITAL LINE SYSTEM G.900G.999 MULTIMEDIA QUALITY OF SERVICE AND PERFORMANCE GENERIC AND USER-RELATED ASPECTS
6、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.872 (01/2017) i Recommendation IT
7、U-T G.872 Architecture of optical transport networks Summary Recommendation ITU-T G.872 describes the functional architecture of optical transport networks (OTNs) using the modelling methodology described in Recommendations ITU-T G.800 and ITU-T G.805. The OTN functionality is described from a netwo
8、rk level viewpoint, taking into account an optical network layered structure, client characteristic information, client/server layer associations, networking topology, and layer network functionality providing optical signal transmission, multiplexing, routing and supervision. The optical portion of
9、 the network is described in terms of media constructs, media elements and optical signal maintenance entities. The use of the black link approach defined in Recommendations ITU-T G.698.1 and ITU-T G.698.2 within the context of an OTN network is also described. History Edition Recommendation Approva
10、l Study Group Unique ID* 1.0 ITU-T G.872 1999-02-26 13 11.1002/1000/4576 2.0 ITU-T G.872 2001-11-29 15 11.1002/1000/5606 2.1 ITU-T G.872 (2001) Amd. 1 2003-12-14 15 11.1002/1000/7064 2.2 ITU-T G.872 (2001) Cor. 1 2005-01-13 15 11.1002/1000/7483 2.3 ITU-T G.872 (2001) Amd. 2 2010-07-29 15 11.1002/100
11、0/10880 3.0 ITU-T G.872 2012-10-29 15 11.1002/1000/11786 3.1 ITU-T G.872 (2012) Amd. 1 2013-11-06 15 11.1002/1000/11986 4.0 ITU-T G.872 2017-01-12 15 11.1002/1000/13086 Keywords Media architecture, network media channel, optical transport networks (OTN), OTN functional architecture. _ * To access th
12、e 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:/handle.itu.int/11.1002/1000/11830-en. ii Rec. ITU-T G.872 (01/2017) FOREWORD The International Telecommunication Union (ITU) is the United Nati
13、ons specialized 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
14、on them with 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
15、 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 necessary standards are prepared on a collaborative basis with ISO and IEC. NOTE In this Recommendation, the expression “Administration“ is
16、 used for conciseness 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
17、 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 negative equivalents are used to express requirements. The use of such words does not suggest that compliance with the Recommendation is required
18、 of any party. 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
19、Property Rights, 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, im
20、plementers 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 wri
21、tten permission of ITU. Rec. ITU-T G.872 (01/2017) iii Table of Contents Page 1 Scope . 1 2 References . 1 3 Definitions 2 3.1 Terms defined elsewhere 2 3.2 Terms defined in this Recommendation . 3 4 Abbreviations and acronyms 3 5 Conventions 4 5.1 Notational . 4 5.2 Diagrammatic . 5 5.3 Terminologi
22、cal . 5 5.4 Representational . 5 6 Functional architecture of OTN 6 7 OTN digital layers 7 7.1 Optical data unit (ODU) layer network 9 7.2 Optical transport unit (OTU) layer network . 14 7.3 Client/server associations . 16 8 Architecture of the media layer 17 8.1 Media constructs . 17 8.2 Media elem
23、ent 21 8.3 Optical tributary signals and interfaces 22 8.4 Management of optical signals . 25 8.5 Management of media and signals . 31 8.6 Modulator and termination functions . 34 8.7 Client/server associations . 36 9 Media topology . 38 9.1 Unidirectional and bidirectional connections . 38 9.2 Poin
24、t-to-multipoint media channels . 38 10 Management . 39 10.1 Requirements 39 10.2 Connection supervision techniques 43 10.3 Connection or media channel supervision applications . 43 11 OTN survivability techniques . 43 12 The black link approach 44 Annex A Media change and physical domain change 46 A
25、ppendix I Relationship between OCh and OTSi terminology . 47 Appendix II Use of the OTN to carry Flex Ethernet . 49 II.1 Overview of Flex Ethernet . 49 iv Rec. ITU-T G.872 (01/2017) Page II.2 FlexE unaware 49 II.3 FlexE aware 49 II.4 FlexE terminating . 50 Appendix III Examples of views of an ODU la
26、yer network . 51 Appendix IV Examples of multi-domain OTN applications 54 Appendix V Examples of the configuration of media channels . 56 V.1 Construction of network media channels . 56 V.2 Use of flexible grid capable filter to route media channels 56 Appendix VI Example of media network using tune
27、able modulator/demodulator for routing . 58 VI.1 Network using couplers 58 VI.2 Network using wide-band filters and couplers . 58 Bibliography. 60 Rec. ITU-T G.872 (01/2017) 1 Recommendation ITU-T G.872 Architecture of optical transport networks 1 Scope This Recommendation describes the functional a
28、rchitecture of optical transport networks (OTNs) using the modelling methodology described in ITU-T G.800 and ITU-T G.805. The OTN functionality is described from a network-level viewpoint. This takes into account an optical network layered structure, client characteristic information (CI), client/s
29、erver layer associations, networking topology, and layer network functionality providing optical signal transmission, multiplexing, routing, supervision, performance assessment and network survivability. The optical portion of the network is described in terms of media constructs, media elements and
30、 optical signal maintenance entities. This Recommendation provides the functional description of OTN that support digital clients. The support of analogue signals as clients is outside the scope of this Recommendation. 2 References The following ITU-T Recommendations and other references contain pro
31、visions 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; users of this Recommendation are therefore encouraged to investigate the possi
32、bility 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 Recommendation does not give it, as a stand-alone document, the status of a Recomme
33、ndation. ITU-T G.663 Recommendation ITU-T G.663 (2011), Application-related aspects of optical amplifier devices and subsystems. ITU-T G.665 Recommendation ITU-T G.665 (2005), Generic characteristics of Raman amplifiers and Raman amplified subsystems. ITU-T G.671 Recommendation ITU-T G.671 (2012), T
34、ransmission characteristics of optical components and subsystems. ITU-T G.680 Recommendation ITU-T G.680 (2007), Physical transfer functions of optical network elements. ITU-T G.694.1 Recommendation ITU-T G694.1 (2012), Spectral grids for WDM applications: DWDM frequency grid. ITU-T G.695 Recommenda
35、tion ITU-T G.695 (2015), Optical interfaces for coarse wavelength division multiplexing applications. ITU-T G.697 Recommendation ITU-T G.697 (2012), Optical monitoring for dense wavelength division multiplexing systems. ITU-T G.698.1 Recommendation ITU-T G.698.1 (2009), Multichannel DWDM application
36、s with single-channel optical interfaces. ITU-T G.698.2 Recommendation ITU-T G.698.2 (2009), Amplified multichannel dense wavelength division multiplexing applications with single channel optical interfaces. ITU-T G.709 Recommendation ITU-T G.709/Y.1331 (2016), Interfaces for the optical transport n
37、etwork (OTN). ITU-T G.709.1 Recommendation ITU-T G.709.1 (2016), Flexible OTN short reach interface. 2 Rec. ITU-T G.872 (01/2017) ITU-T G.798 Recommendation ITU-T G.798 (2016), Characteristics of optical transport network hierarchy equipment functional blocks. ITU-T G.800 Recommendation ITU-T G.800
38、(2016), Unified functional architecture of transport networks. ITU-T G.805 Recommendation ITU-T G.805 (2000), Generic functional architecture of transport networks. ITU-T G.873.1 Recommendation ITU-T G.873.1 (2014), Optical Transport Network (OTN): Linear protection. ITU-T G.873.2 Recommendation ITU
39、-T G.873.2 (2015), ODUk shared ring protection. ITU-T G.874 Recommendation ITU-T G.874 (2013), Management aspects of optical transport network elements. ITU-T G.874.1 Recommendation ITU-T G.874.1 (2012), Optical transport network: Protocol-neutral management information model for the network element
40、 view. ITU-T G.959.1 Recommendation ITU-T G.959.1 (2016), Optical transport network physical layer interfaces. ITU-T G.7712 Recommendation ITU-T G.7712/Y.1703 (2010), Architecture and specification of data communication network. 3 Definitions 3.1 Terms defined elsewhere This Recommendation uses the
41、following terms defined elsewhere: 3.1.1 frequency slot: See ITU-T G.694.1 3.1.2 slot width: See ITU-T G.694.1 3.1.3 optical tributary signal (OTSi): See ITU-T G.959.1 3.1.4 optical data unit (ODU): See ITU-T G.709 3.1.5 optical payload unit (OPU): See ITU-T G.709 3.1.6 optical transport network (OT
42、N): See ITU-T G.709 3.1.7 optical tributary signal assembly (OTSiA): See ITU-T G.709 3.1.8 optical tributary signal group (OTSiG): See ITU-T G.709 3.1.9 optical tributary signal overhead (OTSiG-O): see ITU-T G.709 3.1.10 optical transport unit (OTU): See ITU-T G.709 3.1.11 forwarding point: SeeITU-T
43、 G.800 3.1.12 transitional link: See ITU-T G.800 3.1.13 transport entity: See ITU-T G.800 3.1.14 access point: See ITU-T G.805 3.1.15 adaptation: See ITU-T G.805 3.1.16 adapted information (AI): See ITU-T G.805 3.1.17 administrative domain: See ITU-T G.805 3.1.18 characteristic information (CI): See
44、 ITU-T G.805 Rec. ITU-T G.872 (01/2017) 3 3.1.19 connection: See ITU-T G.805 3.1.20 connection supervision: See ITU-T G.805 3.1.21 layer network: See ITU-T G.805 3.1.22 link: See ITU-T G.805 3.1.23 network connection: See ITU-T G.805 3.1.24 subnetwork: See ITU-T G.805 3.1.25 topological component: S
45、ee ITU-T G.805 3.1.26 trail: See ITU-T G.805 3.1.27 transport processing function: See ITU-T G.805 3.2 Terms defined in this Recommendation This Recommendation defines the following terms: 3.2.1 effective frequency slot: The effective frequency slot of a media channel is that part of the frequency s
46、lots of the filters along the media channel that is common to all of the filters frequency slots. It is described by its nominal central frequency and its slot width. 3.2.2 media channel: A media association that represents both the topology (i.e., the path through the media) and the resource (frequ
47、ency slot) that it occupies. 3.2.3 media subnetwork: A media subnetwork is a topological construct that allows the associations (media channels) between its ports to be created or deleted. 3.2.4 network media channel: A network media channel is the serial concatenation of all media channels between
48、an OTSi modulator and an OTSi demodulator. The network media channel may exist without an active OTSi. NOTE A network media channel supports a single unidirectional OTSi. 3.2.5 optical power monitor (OPM): A function that monitors the optical power in one or more media channels. 3.2.6 OSC: The OSC s
49、upports the transfer of the non-associated overhead information for the OTSiA, OMS OSME and the OTS OSME. 4 Abbreviations and acronyms This Recommendation uses the following abbreviations and acronyms: AI Adapted Information AIS Alarm Indication Signal AP Access Point BDI Backward Defect Indication BEI Backward Error Indication CI Characteristic Information FDI Forward Defect Indication FlexE FlexEthernet;
