1、 INTERNATIONAL TELECOMMUNICATION UNION ITU-T M.2120TELECOMMUNICATION STANDARDIZATION SECTOR OF ITU (07/2002) SERIES M: TMN AND NETWORK MAINTENANCE: INTERNATIONAL TRANSMISSION SYSTEMS, TELEPHONE CIRCUITS, TELEGRAPHY, FACSIMILE AND LEASED CIRCUITS International transport network International multi-op
2、erator paths, sections and transmission systems fault detection and localization procedures ITU-T Recommendation M.2120 ITU-T M-SERIES RECOMMENDATIONS TMN AND NETWORK MAINTENANCE: INTERNATIONAL TRANSMISSION SYSTEMS, TELEPHONE CIRCUITS, TELEGRAPHY, FACSIMILE AND LEASED CIRCUITS Introduction and gener
3、al principles of maintenance and maintenance organization M.10M.299 International transmission systems M.300M.559 International telephone circuits M.560M.759 Common channel signalling systems M.760M.799 International telegraph systems and phototelegraph transmission M.800M.899 International leased g
4、roup and supergroup links M.900M.999 International leased circuits M.1000M.1099 Mobile telecommunication systems and services M.1100M.1199 International public telephone network M.1200M.1299 International data transmission systems M.1300M.1399 Designations and information exchange M.1400M.1999 Inter
5、national transport network M.2000M.2999 Telecommunications management network M.3000M.3599 Integrated services digital networks M.3600M.3999 Common channel signalling systems M.4000M.4999 For further details, please refer to the list of ITU-T Recommendations. ITU-T Rec. M.2120 (07/2002) i ITU-T Reco
6、mmendation M.2120 International multi-operator paths, sections and transmission systems fault detection and localization procedures Summary This Recommendation provides procedures for fault detection and localization with and without in-service monitoring for international multi-operator paths, sect
7、ions, and transmission systems. Filtering and thresholding of performance information are described for reporting to the TMN. Returning into service and long-term trend analysis are considered. These procedures are applicable whatever the technology used. Source ITU-T Recommendation M.2120 was revis
8、ed by ITU-T Study Group 4 (2001-2004) and approved under the WTSA Resolution 1 procedure on 14 July 2002. Keywords Fault detection, filtering, in-service monitoring, localization, long-term trend analysis, path, returning into service, section, thresholding, TMN, transmission system. ii ITU-T Rec. M
9、.2120 (07/2002) 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 for studying technical, operating and tarif
10、f 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 four years, establishes the topics for study by the ITU-T study groups which, in turn, produce Recommen
11、dations 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 necessary standards are prepared on a collaborative basis with ISO and IEC. NOTE In this Recommenda
12、tion, 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 this Recommendation may involve the use of a
13、 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, ITU
14、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 consult the TSB patent database. ITU 2002 All rig
15、hts reserved. No part of this publication may be reproduced, by any means whatsoever, without the prior written permission of ITU. ITU-T Rec. M.2120 (07/2002) iii CONTENTS Page 1 Scope 1 2 References. 1 3 Terms and definitions . 2 4 Abbreviations 2 5 Maintenance techniques with ISM . 2 5.1 Relations
16、hip with ITU-T Rec. M.20. 2 5.2 Fault localization information 3 5.2.1 Performance information 3 5.2.2 Performance level information. 4 5.2.3 Performance primitives information. 4 5.2.4 Supplementary information 4 5.3 Performance filtering, thresholding, reporting and historical storage 4 5.3.1 Even
17、ts . 4 5.3.2 Transmission states. 4 5.3.3 Threshold reports 4 5.3.4 Filter types used for evaluating transmission states and threshold reports 5 5.3.5 Evaluation of transmission states and threshold reports. 5 5.3.6 Performance history storage in network elements 7 5.3.7 Performance history reportin
18、g from network elements 7 5.3.8 Accuracy and resolution. 8 5.3.9 Single-ended monitoring capability . 8 6 Fault localization procedures on transmission systems and multiplex sections. 8 6.1 Fault localization in a pre-ISM environment 8 6.2 Fault localization in an ISM environment 8 7 Fault localizat
19、ion procedures on paths . 9 7.1 Fault localization in a pre-ISM environment or using OOS means . 9 7.2 Fault localization in an ISM environment 10 8 Returning a maintenance entity into service. 10 9 Trend analysis and signatures. 11 ITU-T Rec. M.2120 (07/2002) 1 ITU-T Recommendation M.2120 Internati
20、onal multi-operator paths, sections and transmission systems fault detection and localization procedures 1 Scope The TMN, as described in ITU-T Rec. M.3010 5, is being progressively implemented by many operators. The maintenance procedures described here cover both the case where full In-Service Mon
21、itoring (ISM) is available (as in the TMN) and the case where no ISM or partial ISM is available. The latter case is referred to as pre-ISM. Information processing will be more integrated or less integrated depending on the TMNs degree of development. ISM should be understood as a situation where a
22、dedicated full-time performance monitor exists for a path and/or transmission system. This facilitates performance data collection and storage, scheduled periodic reporting of current and historic data, exception reporting, and setting of thresholds. A pre-ISM situation exists if any condition does
23、not meet the definition of ISM (e.g. existence of time-shared monitoring, no monitoring at all). 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, t
24、he 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 below. A list of the cur
25、rently valid ITU-T Recommendations is regularly published. 1 ITU-T Recommendation G.784 (1999), Synchronous digital hierarchy (SDH) management. 2 ITU-T Recommendation M.20 (1992), Maintenance philosophy for telecommunication networks. 3 ITU-T Recommendation M.60 (1993), Maintenance terminology and d
26、efinitions. 4 ITU-T Recommendation M.2110 (2002), Bringing into service international multi-operator paths, sections and transmission systems. 5 ITU-T Recommendation M.3010 (2000), Principles for a telecommunications management network. 6 ITU-T Recommendation O.150 (1996), General requirements for i
27、nstrumentation for performance measurements on digital transmission equipment. 7 ITU-T Recommendation O.151 (1992), Error performance measuring equipment operating at the primary rate and above. 8 ITU-T Recommendation O.161 (1984), In-service code violation monitors for digital systems. 9 ITU-T Reco
28、mmendation O.162 (1992), Equipment to perform in-service monitoring on 2048, 8448, 34 368 and 139 264 kbit/s signals. 10 ITU-T Recommendation O.163 (1988), Equipment to perform in-service monitoring on 1544 kbit/s signals. 11 ITU-T Recommendation O.181 (2002), Equipment to assess error performance o
29、n STM-N interfaces. 2 ITU-T Rec. M.2120 (07/2002) 3 Terms and definitions General terms and definitions relating to this Recommendation are provided in ITU-T Rec. M.60 3. 4 Abbreviations This Recommendation uses the following abbreviations: BBE Background Block Error BIS Bringing-Into-Service CRC Cy
30、clic Redundancy Check DPL Degraded Performance Limit ES Errored Second ISM In-Service Monitoring ME Maintenance Entity NE Network Element OOS Out-Of-Service RTR Reset Threshold Report SDH Synchronous Digital Hierarchy SES Severely Errored Second STM Synchronous Transport Module TMN Telecommunication
31、 Management Network TR Threshold Report UPL Unacceptable Performance Limit VC Virtual Channel 5 Maintenance techniques with ISM 5.1 Relationship with ITU-T Rec. M.20 ITU-T Rec. M.20 2, Maintenance philosophy for telecommunications networks, provides guidance for maintenance operations. This clause e
32、xpands on the principles given in ITU-T Rec. M.20 2 with specific application to transmission systems and ISM. Figure 1 includes abridged versions of Figures 7/M.20 2 and 9/M.20 2. ITU-T Rec. M.2120 (07/2002) 3 M.2120_F01PerformanceinformationSEF MEFOthersourcesLevel of performanceAlarminformationpr
33、ocessMaintenance processSupplementaryinformationPerformanceevaluationFigure 9/M.20 2PerformanceprimitivesDefectsupervisionprocessSupervisionprocess foranomaliesFigure 7/M.20 2Figure 1/M.2120 Process of elaboration of information used for maintenance 5.2 Fault localization information Once an alarm i
34、ndication is received, the fault localization process must begin. For this purpose several categories of information are required: performance information; performance level information; performance primitives; supplementary information. 5.2.1 Performance information Performance information is in te
35、rms of error performance events and is used to calculate the performance levels. Normally it will be time-stamped and stored for correlation analysis and for long-term trend analysis (see clause 9). Error performance events, and the set of them that applies to maintenance and their limits, are defin
36、ed in specific technology Recommendations. 4 ITU-T Rec. M.2120 (07/2002) 5.2.2 Performance level information Performance level information (unacceptable performance limit (UPL), degraded performance limit (DPL), normal performance level) is derived from performance information (or the equivalent per
37、formance primitives). It is the information which will start the alarm information process, as shown in Figure 1, when a performance limit is reached. The performance limits are also referred to as alarm thresholds. The alarm generated (i.e. prompt maintenance alarm, deferred maintenance alarm or ma
38、intenance event information) determines the urgency of subsequent actions. 5.2.3 Performance primitives information Performance primitives are the basic information in the form of anomalies and defects used to determine the event counts defined in the specific technology Recommendations. Performance
39、 primitives depend on the type of entity being monitored. 5.2.4 Supplementary information Supplementary information is information other than that obtained from monitoring. It includes derived information such as the identification of a faulty maintenance entity (ME) or subentity, or information fro
40、m other MEs. It also includes administrative information such as the constitution of a path. Supplementary information also includes such information as direct transmission restoration (protection switching) counts. 5.3 Performance filtering, thresholding, reporting and historical storage The functi
41、ons described in this clause can be performed inside or outside the network element (NE). 5.3.1 Events The evaluation of error performance and availability performance is based on the processing of the performance events. The derivation of these events from standardized signal information is given i
42、n specific technology Recommendations. 5.3.2 Transmission states A path can be in one of two transmission states: unavailable state; available state. The transmission state is determined from filtered SES/non-SES data (see 5.3.4 and 5.3.5). 5.3.3 Threshold reports A Threshold Report (TR) is an unsol
43、icited error performance report from a ME with respect to either a 15-minute or 24-hour evaluation period. TRs can only occur when the concerned direction is in the available state. Several TRs are defined based on filtered error performance events. 5.3.3.1 TRs based on a 15-minute evaluation period
44、 There are one TR15 and one Reset TR15 (RTR15) for each performance event. TR15s occur as soon as the 15-minute threshold is reached or exceeded. RTR15s optionally occur at the end of a 15-minute period in which the count is less than or equal to the “reset“ threshold and there has not been any unav
45、ailable time during that period. A RTR15 can only occur subsequent to a 15-minute period containing a TR15. Clause 5.3.5.3 gives precise details. 5.3.3.2 TRs based on a 24-hour evaluation period There is one TR24 for each performance event. TR24s occur as soon as the 24-hour threshold is reached or
46、exceeded. Clause 5.3.5.4 gives precise details. There is no RTR24 for the 24-hour ITU-T Rec. M.2120 (07/2002) 5 evaluation period defined in this Recommendation, but RTR24 may be implemented in some equipment. 5.3.4 Filter types used for evaluating transmission states and threshold reports Care need
47、s to be taken with the error performance event counters and the generation of TRs during changes in transmission states. Guidance on this issue is given in 5.3.5.5. 5.3.4.1 Unavailable state and available state filters The unavailable state filter is a 10-second rectangular sliding window, with 1-se
48、cond granularity of slide. The available state filter is also a 10-second rectangular sliding window, with 1-second granularity of slide. 5.3.4.2 TR15 and RTR15 filters The TR15 and RTR15 filters are 15-minute rectangular fixed windows. The start and end time for the 15-minute rectangular fixed wind
49、ows are the same for all performance events and must occur on the hour and at 15, 30, and 45 minutes after the hour. 5.3.4.3 TR24 filter The TR24 filter is a 24-hour rectangular fixed window. The start and end time for the 24-hour rectangular fixed windows are the same for all performance events and must occur on a 15-minute window boundary. 5.3.5 Evaluation of transmission states and threshold reports 5.3.5.1 Evaluation of the unavailable and available states The unavailable state is detected at the end of 10 consecutive SE
