1、 STD-ITU-T RECMN E.43b-ENGL I1998 4862591 Ob47055 498 INTERNATIONAL TELECOMMUNICATION UN ION ITU=T TELECOMMUNICATION STANDARDIZATION SECTOR OF ITU E.436 (03/98) SERIES E: OVERALL NETWORK OPERATION, TELEPHONE SERVICE, SERVICE OPERATION AND HUMAN FACTORS Quality of service, network management and traf
2、fic engineering - Network management - Checking the quality of the international telephone service Customer Affecting Incidents and blocking Defects Per Million I TU-T Reco m mend at ion E .436 (Previously CCITT Recommendation) ITU-T E-SERIES RECOMMENDATIONS OVERALL NETWORK OPERATION, TELEPHONE SERV
3、ICE, SERVICE OPERATION AND HUMAN FACTORS PERA TION, NUMBERING, ROUTING AND MOBILE SER VICES NTERNATIONAL OPERATION Definitions General provisions concerning Administrations General provisions concerning users Operation of international telephone services Numbering plan of the international telephone
4、 service International routing plan Tones in national signalling systems Maritime mobile service and public land mobile service DPERATIONAL PROVISIONS RELATING TO CHARGING AND ACCOUNTING IN THE INTERNATIONAL TELEPHONE SERVICE Charging in the international telephone service Measuring and recording ca
5、ll durations for accounting purposes UTILIZATION OF THE INTERNATIONAL TELEPHONE NETWORK FOR NON- TELEPHONY APPLICATIONS General Phototelegraphy ISDN PROVISIONS CONCERNING USERS QUALITY OF SERVICE, NETWORK MANAGEMENT AND TRAFFIC ENGINEERING NETWORK MANAGEMENT International service statistics E.100-E.
6、103 E.104-E.119 E. 120-E. 139 E. 140-E. 159 E. 160-E. 169 E. 170-E. 179 E. 180-E. 199 E.200-E.229 E.230-E.249 E .260-E ,269 E.300-E.3 19 E.320-E.329 E .3 30-E.399 E.400-E.409 International network management E.410-E.419 TRAFFIC ENGINEERING Measurement and recording of traffic Forecasting of traffic
7、Determination of the number of circuits in manual operation Determination of the number of circuits in automatic and semi-automatic operation Grade of service Definitions ISDN traffic engineering Mobile network traffic engineering QUALITY OF TELECOMMUNICATION SERVICES : CONCEPTS, MODELS, OBJECTIVES
8、AND DEPENDABILITY PLANNING Terms and definitions related to the quality of telecommunication services Models or telecommunication services Objectives for quality of service and related concepts of telecommunication services E.490-ES05 E.506-ES09 ES 10-e5 19 E.520-ES39 E.540-ES99 E.600-E.699 E.700-E.
9、749 E.750-E.799 E.800-E.809 E.810-E.844 E.845-E.859 Use of quality of service objectives for planning of telecommunication networks Field data collection and evaluation on the performance of equipment, networks and services E.860-E.879 E.880-E.899 Forfirther details, please refer fo ITU-T List of Re
10、commendations. STD-ITU-T RECMN E.43b-ENGL 1998 4862591 Ob47057 260 ITU-T RECOMMENDATION E.436 CUSTOMER AFFECTING INCIDENTS AND BLOCKING DEFECTS PER MILLION Summary This Recommendation addresses outages that result in “Customer Affecting Incidents“ (CAI) and relates them to the call blocking Defects
11、Per Million (DPM) metric for the switched network. It is discussed that these outages affect both the customers and the service provider in a significant manner. Definition of what constitutes a Customer Affecting Incident is presented. A methodology for tracking Defects Per Million metric is develo
12、ped along with a recommended method for Root Cause Analysis. There are various parameters for exchanging network performance results among Administrations. CAI and DPM are additional performance parameters that may be exchanged to take network improvement actions. Source ITU-T Recommendation E.436 w
13、as prepared by ITU-T Study Group 2 (1997-2000) and was approved under the WTSC Resolution No. 1 procedure on the 9th of March 1998. Recommendation E.436 (03/98) i FOREWORD ITU (International Telecommunication Union) is the United Nations Specialized Agency in the field of telecommuni- cations. The I
14、TU Telecommunication Standardization Sector (ITLJ-T) is a permanent organ of the 1TU. The ITU-T is responsible for studying technical, operating and tariff questions and issuing Recommendations on them with a view to standardizing telecommunications on a worldwide basis. The World Telecommunication
15、Standardization Conference (WTSC), which meets every four years, establishes the topics for study by the ITU-T Study Groups which, in their turn, produce Recommendations on these topics. The approval of Recommendations by the Members of the ITU-T is covered by the procedure laid down in WTSC Resolut
16、ion No. 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 both a telecommunication administratio
17、n and a recognized operating agency. INTELLECTUAL PROPERTY RIGHTS The ITU draws attention to the possibility that the practice or implementation of this Recommendation may involve the use of a claimed Intellectual Property Right. The ITU takes no position concerning the evidence, validity or applica
18、bility 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, the ITU had not received notice of intellectual property, protected by patents, which may be required to imp
19、lement 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 1998 All rights reserved. No part of this publication may be reproduced or utilized in any form or by any mean
20、s, electronic or mechanical, including photocopying and microfilm, without permission in writing from the ITU. 11 Recommendation E.436 (03/98) . . . STD-ITU-T RECMN E-43b-ENGL 1998 YB62591 Ob47059 033 CONTENTS i Introduction 2 References 3 Definitions of CAI and Blocking DPM 4 CAI classifications .
21、4.1 Owned . 4.2 Correspondent . 4.3 Global Transport . 5 Root Cause Analysis 6 Tracking CAI and DPM . 6.1 CAI . 6.2 DPM Recommendation E.436 (0398) Page 1 1 1 . 111 STD-ITU-T RECMN E-43b-ENGL 3998 m 4862573 0647060 855 m Recommendation E.436 CUSTOMER AFFECTING INCIDENTS AND BLOCKING DEFECTS PER MILL
22、ION (Geneva, 1998) 1 Introduction In switched networks, significant blocking can occur whenever there is a loss of capacity due to some form of network outage. These outages can be loosely called Customer Affecting incidents or CAIs. CAIs cause focused blocking over and above those that occur due to
23、 engineered blocking. Calls blocked due to CAI can be termed “Defects“. An appropriate network measure is the Defects Per Million (DPM) of call attempts. CAIs are indications of a serious lack of reliability in intemational networks. CAIs directly impact customers in their ability to communicate. CA
24、Is result in loss of revenue, and also affect the efficiency of network operations. Not only is time wasted in clearing troubles that could have been prevented, but also cause morale problems if they are chronic. The root causes of CAIs can be due to many reasons: switching and transmission facility
25、 failures; 0 power outages; 0 process errors such as provisioning and maintenance errors. 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 edit
26、ions 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 currently
27、valid ITU-T Recommendations is regularly published. - - IT-T Recommendation E.801 (1996), Framework for Service Quality Agreement. CCITT Recommendation E.420 (1988), Checking the quality of the international telephone service - General considerations. CCITT Recommendation E.421 (1988), Service quali
28、ty observations on a statistical basis. ITU-T Recommendation E.422 (1996), Observations on international outgoing telephone calls for quality of service. CCITT Recommendation E. 425 (1992), Internal automatic observations. ITU-T Recommendation E. 410 (1996), International trafic management - General
29、 information. ITU-T Recommendation E.411 (1996), International traffic management - Operational guidance. ITU-T Recommendation E.412 (1996), Network management controls. - - - - - - 3 This Recommendation defines the following terms: 3.1 one of the following criteria. These are grouped into various c
30、ategories as listed below: - Transmission facility related: Definitions of CAI and Blocking DPM customer Affecting Incident (CAI): An incident is declared as a Customer Affecting Incident if it satisfies 0 More than A?! of the direct-routed capacity to a country is lost due to some form of transmiss
31、ion capacity failure. Recommendation E.436 (03198) 1 STDmITU-T RECMN E-43b-ENGL 1998 4862571 0647063 791 NOTE 1 - For well-trunked routes (say four uncompressed EI worth of capacity), the value for X could for example be 10%. If the direct routed capacity is less than or equal to 1 T1 ( Le. twenty-f
32、our 64 kbitk circuits) or 1 EI (i.e. thirty 64 kbitk circuits), 50% may be an example threshold. An incident lasts longer than Mminutes and blocks more than Ph of calls. NOTE 2 - For example the value of M could be 30 minutes and the blocked call threshold could be 50%. This case applies to situatio
33、ns where multiple destinations/terminations are affected. - Switching, signalling or other equipment failures and software failures occur affecting call completion. Since these incidents should normally not occur and can have a huge impact, these should be counted in all cases. - There is a provisio
34、ning, maintenance, network management, or new technology introduction process error. Since these incidents should normally not occur and can have a huge impact, these should be counted in all cases. - There is a certain increased level of customer complaints with regard to call completion over and a
35、bove the nominal level of complaints. These triggers may be able to catch chronic problems that may not be acute and may not be detected by network-oriented surveillance tools. The Network Management (NM) Center or some other organization within an Administration may be utilized to keep count of the
36、 blocked call attempts from the beginning of CAI event till that event is cleared. Alternate routing, both automatic and manual, naturally reduce the impact of the CAI to some extent, but, in general, there can be a significant number of blocked call attempts. 3.2 (cumulative) and year-to-date (cumu
37、lative) basis. NOTE 1 - CAIS should also be classified with respect to the levellseverity of blocked calls to set priority for root cause analysis (see Clause 5). number of CAIs: Number of CAIS is counted as the number of occurrences of CAIS on a daily, monthly 3.3 to total attempts in millions on a
38、 daily, monthly (cumulative) and year-to-date (cumulative) basis. defects per millions (DPM): Defects Per Million due to CAIs is counted as the ratio of blocked call attempts 4 CAI classifications CAIS may be classified as Owned, Correspondent or Global Transport. 4.1 Owned These are CAIs caused by
39、the actions of ones own Administration or those whose responsibility lies primarily with ones own Administration. 4.2 Correspondent These are CAIS caused by the actions of the correspondent Administration or those whose responsibility lies primarily with the correspondent Administration. 4.3 Global
40、Transport These are CAIs caused by the actions of a Global Transport Administration or those whose responsibility lies primarily with a Global Transport Administration. Examples of Global Transport Administrations include Consortia that provide Satellite or Cable transport or those that provide rest
41、oration services. Assignment of the responsibility for a CAI should be accomplished through mutual discussions between Administrations. The methods for reaching agreements on CAI assignments and further analysis could be part of Service Quality Agreements. 2 Recommendation E.436 (03198) STDmITU-T RE
42、CMN E.436-ENGL 3998 W 4862573 0647062 628 D 5 Root Cause Analysis Root Cause Analysis (RCAs) help identify the root causes so that repetition of the problems can be prevented. RCAs could identi new technology bugs, gaps in testing, surveillance and monitoring, process errors and training gaps. O O O
43、 0 6 in order to set some level of priority for Root Cause Analysis (RCA), thresholds should be established for the number of blocked calls: Any single event blocking more than N attempts requires a mandatory Root Cause Analysis. Each Administration should set the value of N based on their specific
44、situation depending on the volume of traffic, the number of CAIs that would require an RCA and the amount of analysis resources that can be allocated, etc. NOTE 1 - An example value of N is 2000. Approximately, 2000 blocked call attempts would result from a 3-hour outage of 30 uncompressed circuits,
45、 assuming 10% utilization and a retrial rate of 3 attempts. RCA is encouraged for CAIs caused by provisioning or maintenance process errors even if they block less than N call attempts. Such errors could mask an underlying problem that could potentially have had a much larger impact. A technology (i
46、.e. a piece of network equipment such as a Mux, Modem, Connector, etc.) failure that occurs repeatedly (say, more than 3 times a year) also requires an RCA. RCAs are also encouraged for those CAIs that affect specific customers and are triggered by chronic customer complaints. In this case, the RCA
47、followed by corrective action can result in direct improvement of customer satisfaction. Tracking CAI and DPM 6.1 CAI CAIs could be tracked on monthly and yearly basis to determine if the underlying network reliability is in a steady state, improving or deteriorating. These results could be shared a
48、s appropriate with partner Administrations based on the prevailing Service Quality Agreements. 6.2 DPM Defects Per Million blocked call counts could be tracked by a variety of techniques including Statistical Process Control (SPC) charts. For example, if SPC is used, the basic approach would be to e
49、xamine: a) b) Corrective action should be taken if either the average or the variation exceed acceptable levels. if the DPM average over a period (month, quarter, year) is at an acceptable level; if the DPM variation is within control limits, i.e. the processes contributing to the defects are under control. Recommendation E.436 (03198) 3 STDmITU-T RECMN E.43b-ENGL 1998 9 4862591 0647063 564 9 Series A :cries B Series C Series D Series E Series F Series G Series H Series I Series J Series K Series L Series M Series N Series O Series P Series Q Series R Series S Serie
