1、1 , INTERNATIONAL TELECOMMUNICATION UNION ITU-T TELECOMMUNICATION STANDARDIZATION SECTOR OF ITU G.823 (O 31200 O) SERIES G: TRANSMISSION SYSTEMS AND MEDIA, DIGITAL SYSTEMS AND NETWORKS Digital networks - Quality and availability targets The control of jitter and wander within digital networks which
2、are based on the 2048 kbitls h era rc h y ITU-T Recommendation G.823 (Formerly CCITT Recommendation) ITU-T G-SERIES RECOMMENDATIONS TRANSMISSION SYSTEMS AND MEDIA, DIGITAL SYSTEMS AND NETWORKS INTERNATIONAL TELEPHONE CONNECTIONS AND CIRCUITS TRANSMISSION SYSTEMS INDIVIDUAL CHARACTERISTICS OF INTERNA
3、TIONAL CARRIER TELEPHONE SYSTEMS ON METALLIC LINES GENERAL CHARACTERISTICS OF INTERNATIONAL CARRIER TELEPHONE METALLIC LINES COORDINATION OF RADIOTELEPHONY AND LINE TELEPHONY DIGITAL NETWORKS GENERAL CHARACTERISTICS COMMON TO ALL ANALOGUE CARIUER- SYSTEMS ON RADIO-RELAY OR SATELLITE LINKS AND INTERC
4、ONNECTION WITH General aspects Design objectives for digital networks Quality and availability targets Network capabilities and functions SDH network characteristics Management of transport network SDH radio and satellite systems integration Optical transport networks DIGITAL SECTIONS AND DIGITAL LI
5、NE SYSTEM G. 1 OM. 199 G.200-G.299 G .300-G ,399 G.400-G.449 G.450-G.499 G.800-G.899 G.800-G.809 G.810-G.819 G.820-G.829 G.830-G.839 G.840-G.849 G.8504.859 G.860-G.869 G.870-G.879 G.900-G.999 For further details, please refer to the list of ITU-T Recommendations. ITU-T Recommendation G.823 The contr
6、ol of jitter and wander within digital networks which are based on the 2048 kbit/s hierarchy Summary This ITU-T Recommendation specifies the maximum network limits of jitter and wander that shall not be exceeded and the minimum equipment tolerance to jitter and wander that shall be provided at any r
7、elevant transport or synchronization interfaces which are based on the 2048 kbit/s hierarchy. The requirements for the jitter and wander characteristics that are specified in this ITU-T Recommendation must be adhered to in order to ensure interoperability of equipment produced by different manufactu
8、rers and a satisfactory network performance. Source ITU-T Recommendation G.823 was revised by ITU-T Study Group 13 (1997-2000) and approved under the WTSC Resolution 1 procedure on 10 March 2000. Keywords Clocks, Input Jitter Tolerance, Input Wander Tolerance, Network Limits, Output Jitter, Output W
9、ander, Synchronization, Timing. i ITU-T G.823 (03/2000) FOREWORD 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 fo
10、r 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 Conference (WTSC), which meets every four years, establishes the topics for study by the ITU-T st
11、udy groups which, in turn, produce Recommendations on these topics. The approval of ITU-T Recommendations is covered by the procedure laid down in WTSC Resolution 1. In some areas of information technology which fall within ITU-Ts purview, the necessary standards are prepared on a collaborative basi
12、s with IS0 and IEC. NOTE In this Recommendation, the expression “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 t
13、his 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 Rights, whether asserted by ITU members or others outside of the Recommendation development process. As of the da
14、te of approval of this Recommendation, ITU had not received notice 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 consul
15、t the TSB patent database. O ITU 2001 All rights reserved. No 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 the ITU. ITU-T G.823 (03/2000) 11 CONTENTS 1 2 3 4 5 5.
16、1 5.2 6 6.1 6.2 7 7.1 7.2 Scope . References . Definitions Abbreviations Network limits for traffic interfaces . Network limits for output jitter at traffic interfaces Network limits for output wander at traffic interfaces 5.2.1 2048 kbit/s interface output wander limit 5.2.2 34 368 kbit/s interface
17、 output wander limit . 5.2.3 139 264 kbit/s interface output wander limit . Network limits for synchronization interfaces Network limits for output jitter at synchronization interfaces Network limits for output wander at synchronization interfaces 6.2.1 PRC interface output wander limit 6.2.2 SSU in
18、terface output wander limit 6.2.3 SEC interface output wander limit 6.2.4 PDH synchronization interface output wander limit . Jitter and wander tolerance of network interfaces Jitter and wander tolerance of traffic interfaces 7.1.1 64 kbit/s input jitter and wander tolerance 7.1.2 7.1.3 7.1.4 7.1.5
19、2048 kbits input jitter and wander tolerance 8448 kbit/s input jitter and wander tolerance 34 368 kbit/s input jitter and wander tolerance . 139 264 kbit/s input jitter and wander tolerance . Jitter and wander tolerance of synchronization interfaces Annex A . Network model underlying the synchroniza
20、tion network limit . A . 1 Introduction . A.2 Considerations on the network model A.3 Information regarding the simulations . Annex B - Network wander reference model and parameters Wander reference model for traffic interfaces B . 1.1 Asynchronous PDH connection . B . 1.2 Synchronous PDH connection
21、 . B . 1.3 Specification of wander by MRTE parameter B . 1 ITU-T G.823 (03/2000) Page 1 2 2 3 4 4 5 6 7 8 8 9 9 10 11 13 14 16 16 17 18 19 20 21 22 22 22 22 25 26 26 26 27 27 . 111 B.2 Wander reference model for synchronization interfaces B.2.1 Specification of wander by MTIE and TDEV parameters . A
22、ppendix I . Wander limit considerations for SDH transport networks . I . 1 Introduction . 1.1.1 Wander reference model for SDH . 1.1.2 Sources of wander I . 1.3 Wander accumulation limiting effects . I . 1.4 Network configuration and performance . I . 1.5 Correlation of wander sources . I . 1.6 Netw
23、ork conditions for the output wander limits Derivation of wander specification limits . 1.2.1 Wander specification limits . 1.2 Appendix II . Measurement methodologies for output wander II . 1 Synchronization interfaces II . 1.1 Synchronous signals II.2 Traffic interfaces . Synchronous signals (PDH
24、bit-rates) . Asynchronous signals (PDH bit-rates) 11.2.1 II.2.2 Appendix III . Measurement guidelines for input jitter and wander tolerance of equipment interfaces . Page 28 30 30 30 30 31 32 32 32 32 33 34 34 34 34 35 35 36 iv ITU-T G.823 (03/2000) Introduction and background In a digital network,
25、jitter and wander accumulate on transmission paths according to the jitter and wander generation and transfer characteristics of each equipment interconnected. This equipment may be different types of multiplexers/demultiplexers, cross-connects, clocks and line systems, for example. An excessive amo
26、unt of jitter and wander can adversely affect both digital (e.g. by generation of bit errors, slips and other abnormalities) and analogue signals (e.g. by unwanted phase modulation of the transmitted signal). The consequences of such impairment will, in general, depend on the particular service that
27、 is being carried and the terminating or adaptation equipment involved. It is therefore necessary to set limits on the maximum magnitude of jitter and wander, and the corresponding minimum jitter and wander tolerance at network interfaces, in order to guarantee a proper quality of the transmitted si
28、gnals and a proper design of the equipment. These network limits are independent of the particular service that is being carried. ITU-T G.823 (03/2000) V ITU-T Recommendation G.823 The control of jitter and wander within digital networks which are based on the 2048 kbit/s hierarchy 1 Scope This ITU-
29、T Recommendation specifies the relevant parameters and their limiting values that are able to satisfactorily control the amount of jitter and wander present at Network Node Interfaces (“1) of Plesiochronous Digital Hierarchy (PDH) and synchronization networks which are based on the first- level hier
30、archical bit rate of 2048 kbit/s. This ITU-T Recommendation also specifies the jitter and wander requirements at PDH User-Network Interfaces (UNI). However, particular terminals or services may have additional jitter and wander requirements and in those cases the relevant ITU-T Recommendations shall
31、 apply. Requirements for NNI of PDH and synchronization networks which are based on the first-level hierarchical bit rate of 1544 kbit/s are specified in ITU-T Recommendation G.824 and requirements for Synchronous Digital Hierarchy (SDH) NNI are specified in ITU-T Recommendation G.825. The jitter an
32、d wander requirements specified in this ITU-T Recommendation are applicable to the interfaces irrespective of the underlying transport mechanism (PDH, SDH or ATM networks, for example). The jitter and wander requirements for an interface will be different, depending on whether the signal at the inte
33、rface is used to transport traffic and/or synchronization. The requirements for both traffic and synchronization interfaces are specified in this ITU-T Recommendation in the appropriate clauses. A synchronization network that conforms to the network limits for jitter and wander specified in this ITU
34、-T Recommendation will be suitable for the synchronization of SDH and Public Switched Telephone Network (PSTN) networks. This ITU-T Recommendation also specifies the jitter and wander requirements for interfaces using the generic frame structures at PDH rates as defined in IT-T Recommendation G.832.
35、 The electrical characteristics of the relevant PDH network interfaces are defined in ITU-T Recommendation G.703. The jitter and wander control philosophy of this ITU-T Recommendation is based on the need: a) to specifj a maximum network limit of jitter and wander that shall not be exceeded at any r
36、elevant interface; to specifj a minimum equipment tolerance to jitter and wander that shall be provided at any relevant interface; to establish a consistent framework for the specification of individual digital equipment types; and to provide sufficient information and guidelines for organizations t
37、o measure and study jitter and wander characteristics in any network configuration. b) c) d) 1 ITU-T G.823 (03/2000) 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 ti
38、me of publication, the editions indicated were valid. All Recommendations and other references are subject to revision; all users of this Recommendation are therefore encouraged to investigate the possibility of applying the most recent edition of the Recommendations and other references listed belo
39、w. A list of the currently valid ITU-T Recommendations is regularly published. - ITU-T Recommendation G.703 (1 998), Physical/electrical characteristics of hierarchical digital interfaces. ITU-T Recommendation G.707 (1996), Network node interface for the Synchronous Digital Hierarchy (SDH). ITU-T Re
40、commendation G.783 (1 997), Characteristics of Synchronous Digital Hierarchy (SDH) equipment functional blocks. ITU-T Recommendation G.803 (2000), Architecture of transport networks based on the Synchronous Digital Hierarchy (SDH). ITU-T Recommendation G.8 10 (1 996), Definitions and terminology for
41、 synchronization networks. ITU-T Recommendation G.811 (1 997), Timing characteristics ofprimary reference clocks. ITU-T Recommendation G.812 (1998), Timing requirements of slave clocks suitable for use as node clocks in synchronization networks. ITU-T Recommendation G.8 13 (1 996), Timing characteri
42、stics of SDH equipment slave clocks (SEC). CCITT Recommendation G.822 (1988), Controlled slip rate objectives on un international digital connection. ITU-T Recommendation G.824 (2000), The control of jitter and wander within digital networks which are based on the 1544 kbit/s hierarchy. ITU-T Recomm
43、endation G.825 (2000), The control of jitter and wander within digital networks which are based on the Synchronous Digital Hierarchy (SDH). ITU-T Recommendation G.832 (1998), Transport of SDH elements on PDH networks - Frame and multiplexing structures. ITU-T Recommendation O. 150 (1 996), General r
44、equirements for instrumentation for performance measurements on digital transmission equipment. ITU-T Recommendation O. 17 1 (1 997), Timing jitter and wander measuring equipment for digital systems which are based on the Plesiochronous Digital Hierarchy (PDH). ITU-T Recommendation O. 172 (1999), Ji
45、tter and wander measuring equipment for digital systems which are based on the Synchronous Digital Hierarchy (SDH). - - - - - - - - - - - - - - 3 Definitions This ITU-T Recommendation defines the following terms. Additional definitions relating to synchronization networks are provided in ITU-T Recom
46、mendation G.8 1 O, whilst the architectural principles of synchronization networks are described in ITU-T Recommendation G.803. Information regarding the wander reference models used in this ITU-T Recommendation is provided in Annexes A and B. 2 ITU-T G.823 (03/2000) 3.1 synchronous interface: These
47、 interfaces provide an output signal with frequency that is normally traceable to a PRC. 3.2 asynchronous interface: These interfaces provide an output signal with frequency that is not traceable to a PRC and that meets the frequency offset requirements given in ITU-T Recommendation G.703. 3.3 traff
48、ic interface: These interfaces may be asynchronous or synchronous and network jitter and wander limits are specified using the Maximum Relative Time Interval Error (MRTIE) parameter in this ITU-T Recommendation. Input jitter and wander tolerance is also specified in this ITU-T Recommendation. This i
49、nterface category can be further sub-divided as follows: a) Interface is not able to provide synchronization, and is not required to. An example is an interface supporting only 34 368 or 139 264 kbits PDH signals according to ITU-T Recommendation G.703. Interface is not able to provide synchronization at the defined performance level, but nevertheless is used to provide timing to other network elements such as terminal equipment, remote concentrators, etc. Examples include 2048, 34 368 and 139 264 kbit/s PDH signals transported on SDH, which may be subject to pointer justifications. ITU
