1、GENERAL SECRETARIAT INTERNATIONAL TELECOMMUNICATION UNION Subject: ERRATUM Geneva, 13 August 2001 Recommendation ITU-T G.825 (03/00) TELECOMMUNICATION STANDARDIZATION SECTOR OF ITU ITU-T Recommendation G.825 (03/00) The control of jitter and wander within digital networks which are based on the sync
2、hronous digital hierarchy (SDH) In paragraph 1.2, the following text that appears before formula 1.2-4: “Similarly, the inputphase tolerance corresponding to H2(s) and its amplitude ofA1 = O. UIpp is given by:“ should read: “Similarly, the inputphase tolerance corresponding to H2(s) and its amplitud
3、e ofA1 = O.fi UIpp is given by:“ Union internationale des tlcommunications Place des Nations 121 1 GENEVE 20 Suisse - Switzerland - Suiza STD-ITU-T RECMN G.825-ENGL 2000 9 48b257L Ob8b372 T25 = INTERNATIONAL TELECOMMUNICATION UNION ITU=T TELECOMMUNICATION STANDARDIZATION SECTOR OF TU G.825 (03/2000)
4、 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 are based on the synchronous dig i tal h ierarc hy (SDH) ITU-T Recommendation G.825 (Formerly CCITT Recommendatio
5、n) STD-ITU-T RECMN G.825-ENGL 2000 4b259L ObAb373 9bL m ITU-T G-SERIES RECOMMENDATIONS TRANSMISSION SYSTEMS AND MEDIA, DIGITAL SYSTEMS AND NETWORKS INTERNATIONAL TELEPHONE CONNECTIONS AND CIRCUITS INTERNA TIONAL ANALOGUE CARRIER SYSTEM GENERAL CHARACTERISTICS COMMON TO ALL ANALOGUE CARRIER- TRANSMIS
6、SION 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 TERMINAL EQUIPMENTS DIGITAL NETWORKS SYSTEMS ON RADIO-RELAY OR SATELLITE LI
7、NKS AND INTERCONNECTION 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
8、AND DIGITAL LINE SYSTEM G. 1 00-G. 199 (3.200-G.299 G ,300-G . 399 G.400-G.449 G.450-G.499 (3.700-G.799 G.800-G.899 (3.800-G.809 G. 8 1 O-G .8 1 9 G.820-G.829 G. 83 O-G. 839 G.840-G.849 G. 850-G. 8 59 G.860-G.869 G.870-G.879 G.900-G.999 I l For further details, please refer to the list of ITU-T Reco
9、mmendations. - STD-ITU-T RECMN G.825-ENGL 2000 48b257L Ob8b374 8TB ITU-T Recommendation G.825 The control of jitter and wander within digital networks which are based on the synchronous digital hierarchy (SDH) Summary This ITU-T Recommendation specifies the maximum network limits of jitter and wande
10、r that shall not be exceeded and the minimum equipment tolerance to jitter and wander that shall be provided at any relevant transport or synchronization interfaces which are based on the Synchronous Digital Hierarchy (SDH). The requirements for the jitter and wander characteristics that are specifi
11、ed in this ITU-T Recommendation must be adhered to in order to ensure interoperability of equipment produced by different manufacturers and a satisfactory network performance. Source ITU-T Recommendation G.825 was revised by ITU-T Study Group 13 (1997-2000) and approved under the WTSC Resolution 1 p
12、rocedure on 10 March 2000. Keywords Clocks, Input Jitter Tolerance, Input Wander Tolerance, Network Limits, Output Jitter, Output Wander, Synchronization, Timing. ITU-T G.825 (03/2000) 1 STD-ITU-T RECMN G.825-ENGL 2000 m 48b2591 ObBb375 FOREWORD The International Telecommunication Union (ITU) is the
13、 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 issuing Recommendations on them with a view to standardizing te
14、lecommunications on a worldwide basis. The World Telecommunication Standardization Conference (WTSC), 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 Recommendations is covered by
15、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 basis with IS0 and IEC. NOTE In this Recommendation, the expression “Administration“ is used for conciseness to indicate bot
16、h 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 Intellectual Property Right. ITU takes no position concerning the ev
17、idence, 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 notice of intellectual property, protected by patents, which
18、 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 part of this publication may be reproduced or utilized in
19、any form or by any means, electronic or mechanical, including photocopying and microfilm, without permission in writing from the ITU. 11 ITU-T G.825 (03/2000) CONTENTS 1 Scope . 2 References . 3 Definitions 4 Abbreviations 5 Network limits for the maximum output jitter and wander at any hierarchical
20、 interface Network limits for jitter Network limits for wander 5.1 5.2 6 6.1 The specification of individual digital equipment Jitter and wander tolerance for STM-N input ports 6.1.1 STM-N input wander tolerance . 6.1.2 STM-N input jitter tolerance . Jitter and wander generation . Jitter and wander
21、transfer 6.2 6.3 Appendix I . Relationship between network interface jitter requirements and input jitter I . 1 1.2 tolerance Network interface jitter requirements . Input jitter tolerance of network equipment . Appendix II . Measurement methodology for output wander of synchronous interfaces Append
22、ix III . SDH Line systems and Intenvorking implications . Page 1 1 2 2 4 4 6 6 10 10 11 11 12 14 14 . ITU-T C.825 (03/2000) 111 STDeITU-T RECMN G-825-ENGL 2000 = 48L257L ObAb377 507 D Introduction and background In a digital network, jitter and wander accumulate on transmission paths according to th
23、e 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 amount of jitter and wander can adversely affect both digital (e.g. b
24、y 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 is being carried and the terminating or adaptation equipment invo
25、lved. 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 signals and a proper design of the equipment. These network limits a
26、re independent from the particular service that is being carried. iv ITU-T G.825 (03/2000) STDmITU-T RECMN 6.825-ENGL 2000 = 48b257L Ob8b378 443 W ITU-T Recommendation G.825 The control of jitter and wander within digital networks which are based on the synchronous digital hierarchy (SDH) 1 Scope Th
27、e scope of this ITU-T Recommendation is to define the parameters and the relevant values that are able to control satisfactorily the amount of jitter and wander present at the SDH network-network interfaces (“I). SDH network interfaces, to which this ITU-T Recommendation is applicable, are defined i
28、n terms of bit rates and frame structures in ITU-T Recommendation G.707; their electrical characteristics are described in ITU-T Recommendation G.703 and the optical characteristics in ITU-T Recommendations G.957 and G.691. Additional information regarding the architecture of SDH networks is found i
29、n ITU-T Recommendation G. 803. Jitter and wander requirements for PDH and synchronization networks are specified in ITU-T Recommendation G.823, for networks based on the first level bit rate of 2048 kbit/s, and in ITU-T Recommendation G.824 for networks based on the first-level bit rate of 1544 kbit
30、/s. The jitter and wander control philosophy is based on the need: - to recommend a maximum network limit that should not be exceeded at any relevant interface; to recommend a consistent framework for the specification of individual digital equipment (i.e. jitter and wander transfer, tolerance and g
31、eneration requirements); to provide sufficient information and guidelines for organizations to measure and study jitter and wander accumulation in any network configuration. - - 2 References The following ITU-T Recommendations and other references contain provisions which, through reference in this
32、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; all users of this Recommendation are therefore encouraged to investigate the possibility of applying the most recent ed
33、ition of the Recommendations and other references listed below. A list of the currently valid ITU-T Recommendations is regularly published. - ITU-T Recommendation G.69 1 (draft), Optical interfaces for single-channel STM-64, STM-256 and other SDH systems with optical ampl$ers. ITU-T Recommendation G
34、.703 ( 1998), Physical/electrical characteristics of hierarchical digital interfaces. ITU-T Recommendation G.707 (1 996), Network Node interface for the Synchronous Digital Hierarchy (SOH). ITU-T Recommendation G.783 (1 997), Characteristics of synchronous digital hierarchy (SOH) equipment jiinction
35、al blocks. ITU-T Recommendation G.803 (ZOOO), Architecture of transport networks based on the synchronous digital hierarchy (SDH). - - - - ITU-T G.825 (03/2000) 1 STD-ITU-T RECMN G.825-ENGL 2000 W iBb2591 ObAb379 30T I ITU-T Recommendation G.8 10 (1 996), DeJinitions and terminology Jbr synchronizat
36、ion networks. ITU-T Recommendation G.8 1 1 (1 997), Timing characteristics ofprimary reference clocks. ITU-T Recommendation G.8 12 (1 998), Timing requirements of slave clocks suitable for use as node clocks in synchronization networks. ITU-T Recommendation G.8 13 (1996), Timing characteristics of S
37、DH equipment slave clocks (SEC). ITU-T Recommendation G.823 (2000), The control of jitter and wander within digital networks which are based on the 2048 kbith hierarchy. ITU-T Recommendation G.824 (2000), The control of jitter und wunder within digital networks which are based on the 1544 kbith hier
38、archy. ITU-T Recommendation G.832 (1998), Transport of SDH elements on PDH networks - Frame and multiplexing structures. ITU-T Recommendation G.957 (1999), Optical interfaces for equipments und systems relating to the synchronous digital hierarchy. ITU-T Recommendation O. 17 1 (1 997), Timing jitter
39、 and wander measuring equipment for digital systems which are based on the Plesiochronous Digital Hierarchy (PDH). ITU-T Recommendation O. 172 (1999), Jitter and wander measuring equipment for digital systems which are based on the Synchronous Digital Hierarchy (SDH). 3 Definitions I This ITU-T Reco
40、mmendation defines the following terms. Additional definitions relating to synchronization networks are provided in ITU-T Recommendation G.8 1 O. 3.1 synchronous interface: These interfaces provide an output signal with frequency that is normally traceable to a PRC. 3.2 asynchronous interface: These
41、 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 synchronization interface: These interfaces are synchronous and network wander limits are specified using Maximum Time Interval
42、 Error (MTIE) and Time Deviation (TDEV) parameters with values given in this ITU-T Recommendation. 4 Abbreviations This ITU-T Recommendation uses the following abbreviations. Additional abbreviations will be added. CMI Code Mark Inversion ITU-T MRTIE MS-AIS MTIE Maximum Time Interval Error NE Networ
43、k Element NNI Network Node Interface International Telecommunication Union - Telecommunication Standardization Sector Maximum Relative Time Interval Error Multiplex Section Alarm Indication Signal 2 ITU-T G.825 (03/2000) Pk-Pk Peak-to-Peak RTIE Relative Time Interval Error SDH Synchronous Digital Hi
44、erarchy TDEV Time Deviation TIE Time Interval Error u1 Unit Interval UNI User Network Interface Measurement bandwidth, -3 dB frequencies (Hz) Interface 5 Network limits for the maximum output jitter and wander at any hierarchical interface Peak-to-peak amplitude WPP) 5.1 Network limits for jitter Th
45、e limits given in Table 1 represent the maximum permissible levels of jitter at interfaces within a digital network. Jitter as measured over a 60 second interval shall not exceed the limits given in Table 1, when using the specified measurement filters. The limits shall be met for all operating cond
46、itions and regardless of the amount of equipment preceding the interface. In general, these network limits are compatible with the minimum tolerance to jitter that all equipment input ports are required to provide. Guidelines for the derivation of the parameters values of Table 1 are given in Append
47、ix I. There is a close relationship between network limits and input tolerance such that the jitter measurement filter cut-off frequencies used in Table 1 have the same values as the jitter tolerance mask comer frequencies used in 6.1. Appendix I provides further information about this relationship.
48、 The high-pass measurement filters of Table 1 have a first-order characteristic and a roll-off of 20 dB/decade. The low-pass measurement filters have a maximally-flat, Butterworth characteristic and a roll-off of -60 dB/decade. ITU-T Recommendation O. 172 contains a functional description of equipme
49、nt appropriate for measurement of jitter in SDH systems. Further specifications for the frequency response of the jitter measurement function such as measurement filter accuracy and additional allowed filter poles are also given in ITU-T Recommendation O. 172. I STM- 1 e (Notes 1, 2) Table UG.825 - Maximum permissible jitter at network interfaces 500 to 1.3 M 1.5 65 k to 1.3 M 0.075 STM- 1 (Note 4) STM-4 (Note 4) 500 to 1.3 M 1.5 65 k to 1.3 M 0.15 1kto5M 1.5 0.15 250 k to 5 M STM- 16 (Note 4) 5 kto 20 M 1.5 1 M to 20 M 0.15 ITU-T G.825 (0312000) 3 Ta
