1、INTERNATIONAL TELECOMMUNICATION UNION ITU-T TE LEC0 MM UN I CATI0 N STANDARDIZATION SECTOR OF ITU G.871 N.1301 (1 0/2000) SERIES G: TRANSMISSION SYSTEMS AND MEDIA, DIGITAL SYSTEMS AND NETWORKS Digital networks - Optical transport networks SERIES Y: GLOBAL INFORMATION INFRASTRUCTURE AND INTERNET PROT
2、OCOL ASPECTS Internet protocol aspects - Transport Framework for optical transport network Reco m mend at i on s ITU-T Recommendation G.871/Y.1301 (Formerly CCITT Recommendation) ITU-T G-SERIES RECOMMENDATIONS TRANSMISSION SYSTEMS AND MEDIA, DIGITAL SYSTEMS AND NETWORKS INTERNATIONAL TELEPHONE CONNE
3、CTIONS AND CIRCUITS TRANSMISSION SYSTEMS INDIVIDUAL CHARACTERISTICS OF INTERNATIONAL CARRIER TELEPHONE SYSTEMS ON METALLIC LINES GENERAL CHARACTERISTICS OF INTERNATIONAL CARRIER TELEPHONE METALLIC LINES COORDINATION OF RADIOTELEPHONY AND LINE TELEPHONY TESTING EQUIPMENTS TRANSMISSION MEDIA CHARACTER
4、ISTICS DIGITAL TERMINAL EQUIPMENTS DIGITAL NETWORKS GENERAL CHARACTERISTICS COMMON TO ALL ANALOGUE CARRIER- SYSTEMS ON RADIO-RELAY OR SATELLITE LINKS AND INTERCONNECTION WITH General aspects Design objectives for digital networks Quality and availability targets Network capabilities and functions SD
5、H network characteristics Management of transport network SDH radio and satellite systems integration DIGITAL SECTIONS AND DIGITAL LINE SYSTEM G.lOO-G.199 G.200-G.299 G.300-G.399 G.400-G.449 G.450-G.499 G.500-G.599 G.600-G.699 G.700-G.799 G. 800-6.899 G.800-G.809 G.8 10-G.8 19 G.820-G.829 G. 830G.83
6、9 G.840-G.849 G.850-G.859 G.900-G.999 For further details, please refer to the list of ITU-T Recommendations. ITU-T Recommendation G.871N.1301 Framework for optical transport network Recommendations Summary This Recommendation concerns the Optical Transport Network (OTN) and gives an overview of the
7、 ITU-T Recommendations on the different aspects of OTNs. It provides a framework for their development, indicating the rationale followed in their preparation together with the linkages among them. The time-frame for the development of these Recommendations is also provided. Source ITU-T Recommendat
8、ion G.87 1N. 130 1 was prepared by ITU-T Study Group 15 (1 997-2000) and approved by the World Telecommunication Standardization Assembly (Montreal, 27 September - 6 October, 2000). Keywords IP over OTN, IP over WDM, Optical Networking, Optical Transport Network, OTN. ITU-T G.871/Y.l3011O/2OOO i FOR
9、EWORD The International Telecommunication Union (ITU) is the United Nations specialized agency in the field of telecommunications. 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 iss
10、uing Recommendations 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 to
11、pics. 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 necessary standards are prepared on a collaborative basis with IS0 and IEC. NOTE In this Recommendation, the expressio
12、n “Administration“ is used for conciseness to indicate both a telecommunication administration and a recognized operating agency. INTELLECTUAL PROPERTY RIGHTS ITU draws attention to the possibility that the practice or implementation of this Recommendation may involve the use of a claimed Intellectu
13、al 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, ITU had not received no
14、tice of intellectual property, protected by patents, which may be required to implement this Recommendation. However, implementors are cautioned that this may not represent the latest information and are therefore strongly urged to consult the TSB patent database. O ITU 2001 All rights reserved. No
15、part of this publication may be reproduced or utilized in any form or by any means, electronic or mechanical, including photocopying and microfilm, without permission in writing from ITU. ITU-T G.87lN.l301(1O/2OOO 11 CONTENTS 1 2 3 3.1 3.2 4 5 5.1 5.2 5.3 5.4 5.5 5.6 Scope References Terms and defin
16、itions . Optical Transport Network . Optical Network Element . Abbreviations . Work plan for OTN Recommendations . OTN architectural aspects OTN equipment functional characteristics . OTN management aspects Relationship among the OTN Recommendations OTN structures and mapping OTN physical layer aspe
17、cts Annex A . Time-frame for the OTN Recommendations development Annex B . Perspectives on the optical transport of IP ITU-T G.871N.1301(10/200O) 1 1 2 2 2 3 6 7 . 111 ITU-T Recommendation G.871N.1301 Framework for optical transport network Recommendations 1 Scope The purpose of this Recommendation
18、is to provide a framework for coordination among the various activities in ITU-T on Optical Transport Network (OTN), in order to ensure that Recommendations covering the various aspects of OTN be developed in a consistent and exhaustive way. As such, this Recommendation provides references for defin
19、itions of high-level characteristics of OTN, along with a description of the relevant ITU-T Recommendations, together with the time-frame for their development (which are either already prepared, or under development). Note that the development of many of these Recommendations will be phased to addr
20、ess the pace of technology. It is also the purpose of this Recommendation to provide guidance to the reader of OTN Recommendations, indicating the linkages among them and the rationale followed in their preparation. NOTE - Initially, the OTN Recommendations described will consider only digital clien
21、t signals. 2 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 subjec
22、t to revision; 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. ITU-T G.661 (1998), Definition
23、 and test methods for the relevant generic parameters of optical amplifier devices and subsystems. ITU-T G.662 (1 998), Generic characteristics of optical amplifier devices and subsystems. ITU-T G.663 (2000), Application related aspects of optical amplifier devices and subsystems. ITU-T G.664 (1999)
24、, Optical safe procedures and requirements for optical transport systems. ITU-T G.67 1 (200 i), Transmission characteristics of optical components and subsystems. ITU-T G.69 1 (2000), Optical interfaces for single-channel STM-64, STM-256 and other SDH with optical amplifiers. ITU-T G.692 (1 998), Op
25、tical interfaces for multichannel systems with optical amplifiers. ITU-T G.805 (2000), Generic functional architecture of transport networlts. ITU-T G.872 (1999), Architecture of optical transport networlts. 1 ITU-T G.87lN.l301(1O/2OOO 3 Terms and definitions The relevant specific terms used in the
26、OTN Recommendations listed in clause 2 are defined therein. For terms concerning general characteristics of OTN the definitions given below apply. 3.1 Optical Transport Network An Optical Transport Network (OTN) is composed of a set of Optical Network Elements connected by optical fibre links, able
27、to provide functionality of transport, multiplexing, routing, management, supervision and survivability of optical channels carrying client signals, according to the requirements given in ITU-T G.872 9. A distinguishing characteristic of the OTN is its provision of transport for any digital signal i
28、ndependent of client-specific aspects, i.e. client independence. As such, according to the general functional modelling described in ITU-T G.805 SI, the OTN boundary is placed across the Optical ChanneUClient adaptation, in a way to include the server specific processes and leaving out the client sp
29、ecific processes, as shown in Figure 1. NOTE - The client specific processes related to Optical ChannelKlient adaptation are described within ITU-T G.709. . Optical Transport Network 1 T1540470-00 Figure 1/G.871N.1301- Boundary of an optical transport network and client-server relationship 3.2 Optic
30、al Network Element The Optical Network Element (ONE) is that part of a network element that contains transport processing functions from one or more OTN layer networks, as architectural components which process information between its inputs and outputs. An ONE may therefore be a stand-alone physica
31、l entity or a subset of a network element. 2 ITU-T G.87lN.l301(1O/2OOO 4 Abbreviations This Recommendation uses the following abbreviations: ATM IP OAM OCh ONE OTN PDH SDH TDM WDM 5 Asynchronous Transfer Mode Internet Protocol Operation, Administration and Maintenance Optical Channel Optical Network
32、 Element Optical Transport Network Plesiochronous Digital Hierarchy Synchronous Digital Hierarchy Time Division Multiplexing Wavelength Division Multiplexing Work plan for OTN Recommendations The harmonized development of the Optical Transport Network with full optical networking functionality requi
33、re the study of a number of subjects pertaining to the different aspects of OTN. These subjects include: e OTN architectural aspects: - network layering and functionality; - - - switching optical networking architecture; - network capacity, scalability and service transparency; network topologies an
34、d survivability architectures; considerations for optimized IP optical networking. network node interface regarding structure, overhead, and client signal mappings (e.g. IP, SDH, ATM, Ethernet); features to support an automatically switched optical network. e OTN structures and mapping: - - e OTN eq
35、uipment functional characteristics: - optical equipment functions for each layer, including connection, termination, adaptation of various clients (e.g. IP, SDH, ATM, Ethernet); supervision including defects, consequent actions, information flows, generic processes; considerations; - - survivability
36、 functions and characteristics, including multilayer survivability - impact on synchronization functions. - connection, configuration, including wavelength administration, fault performance management; management requirements and information models to support the interworking of OTN equipment and sy
37、stems with those of other technologies (e.g. IP, SDH, ATM, Ethernet). e OTN management aspects: - ITU-T G.871N.1301(10/2000) 3 e OTN physical layer characteristics: - - - - application code structures; - OTNs utilizing soliton-type transmission; - OTN optical components and subsystems. definition of
38、 general terms of OTN; collection of data and definition of objectives for reliability/availability of an OTN. specifications for longitudinally and transversely compatible optical systems; optical frequency plan, including optical supervisory channel and wavelength range; optical aspects, such as p
39、ower level management; e OTN general aspects: - - In order to coordinate the study of these various OTN subjects in ITU-T, such that to ensure that they are developed in a consistent and exhaustive way, a work plan has been agreed. This work plan involves the development of a series of Recommendatio
40、ns covering the various aspects of OTN in a manner analogous to that established for other networks, as summarized in Table 1. Table 1/G.871N.1301- ITU-T Recommendations (existing and proposed) on the various aspects of PDH, SDH, ATM and OTN Topic PDH SDH ATM OTN Architectural aspects G.803, G.805 8
41、 G.805 8, 1.326 G.872 9, G.873. G.ason Structures and mapping G.704, G.73x, G.74x, G.75x, G.804 G.707, G.832 1.361, 1.362,1.363, 1.610 G.709 Equipment functional characteristics G.706, G.73x, G.74x, G.75 G.783, G.784, G.813, G.841, G.842 1.731, 1.732 G.798 Management aspects G.774-, G.784, G.83 1 1.
42、75 1 G.874, G.875 Physical layer characteristics G.703 G.664 4, G.691 6, G.692 7, G.703, G.957 G.703, G.957,1.432 G.664 4, G.959.1, G.dsn Components and subsystems G.661 i, G.66 G.671 5 21, 3.663 31, G.661 i, G.662 2, G.663 3, G.671 51 G.661 i, G.662 2, G.663 3, G.671 51 Error performance G.821, G.8
43、22, G.823, G.824, G.826 G.825, G.826, G.958, G.827, G.828, G.829 1.356, 1.357 G.optperf Bringing-into-service, maintenance, test M.2100, 0.151, 0.171, 0.172 M.2101, M.2102, 0.181,0.172 M.2201, M.2210, M.2220, O. 191 Framework for Recommendations G.871 NOTE - Entries in bold face type indicate the ne
44、w OTN Recommendations. 4 ITU-T G.87lN.l301(1O/2OOO Furthermore, it is expected that existing Recommendations may be augmented, or new Recommendations defined, to address issues associated with the reliability and availability of OTN systems, and possible interface aspects pertinent to the inclusion
45、of access and submarine systems in oms. 5.1 OTN architectural aspects Specification of network architectural aspects are provided by two Recommendations. A Recommendation on OTN architecture, ITU-T G.872 9 describes the optical transport network layered structure, characteristic information, client/
46、server layer associations, networking topology, and layer network functionality, including optical signal transmission, multiplexing, routing, supervision, performance assessment, and network survivability. The other Recommendation, ITU-T G.873, on OTN requirements will address definition of OTN app
47、lications, including interconnection with other networks. In addition, recognizing the need for network requirements for the Automatic Switched Optical Network (fast set-up and automatic switching of OCh connections), work on a new Recommendation, provisionally named G.ason, has been initiated. Rega
48、rding the aspect of OTN error performance, a new Recommendation, provisionally named G.optperf, will be subsequently developed to address error and availability aspects of OTN, defining the proper parameters and objectives. 5.2 OTN structures and mapping Based on the OTN architecture defined in ITU-
49、T G.872 9, a structure and mappings Recommendation, ITU-T G.709 describes the Network Node Interface necessary to enable the interconnection of ONEs for the transport of different types of client signals in the OTN. This Recommendation therefore defiies the optical transport modules, their structures, the functionality of the overheads and the formats for mapping and multiplexing client signals. 5.3 OTN equipment functional characteristics With ITU-T G.872 9 and ITU-T G.709 serving as a foundation, ITU-T G.798 will describe the functional
