1、INTERNATIONAL TELECOMMUNICATION UNION)45G134 - TELECOMMUNICATIONSTANDARDIZATION SECTOROF ITU-!).4%.!.#% ).4%2.!4)/.!,G0G005“,)#G0G04%,%0(/.%.%47/2+G0G0-!).4%.!.#%53%G0G0/&G0G0!54/-!4)#!,9G0G0%.%2!4%$4%34G0G0#!,3G0G0&/2G0G0!33%33-%.4/&G0G0.%47/2+G0G00%2&/2-!.#%)45G134G0G0RecommendationG0G0- (Extract
2、from the “LUEG0“OOK)NOTES1 ITU-T Recommendation M.1235 was published in Fascicle IV.2 of the Blue Book. This file is an extract fromthe Blue Book. While the presentation and layout of the text might be slightly different from the Blue Book version, thecontents of the file are identical to the Blue B
3、ook version and copyright conditions remain unchanged (see below).2 In this Recommendation, the expression “Administration” is used for conciseness to indicate both atelecommunication administration and a recognized operating agency. ITU 1988, 1993All rights reserved. No part of this publication may
4、 be reproduced or utilized in any form or by any means, electronic ormechanical, including photocopying and microfilm, without permission in writing from the ITU.Fascicle IV.2 - Rec. M.1235 1Recommendation M.1235Fascicle IV.2 - Rec. M.1235USE OF AUTOMATICALLY GENERATED TEST CALLS FOR ASSESSMENTOF NE
5、TWORK PERFORMANCE1 General1.1 This Recommendation describes the use of automatic subscriber-to-subscriber test calls as one of the methodsfor assessing overall network performance 1. It is intended as a basis for bilateral or multilateral agreements betweenAdministrations interested in this method o
6、f investigating network performance.1.2 In correspondence with the objectives of efficient maintenance methods as described in Recommenda-tion M.730 2 and, in particular, in line with the application of controlled maintenance methods as explained in 4 ofRecommendation M.730 2, there is a recognized
7、need to continuously assess network performance.1.3 Considering the fact that an international call engages both national and international links, any method forassessing overall network performance should cover the entire chain of national and international links.1.4 Modern switching and transmissi
8、on systems may have built-in facilities for checking the overall networkperformance by means of test calls set up automatically from the exchange of origin to the exchange of destination ofinternational calls. Similar facilities may be provided by independent test call generators having access to th
9、e switchingmultiple at the exchange of origin and making test calls to various test call responders in distant countries. Such test callresponders may be connected to test numbers in various terminal exchanges in the distant country.1.5 Automatic subscriber-to-subscriber test calls performed either
10、by system-independent test call generators andtest call responders, or by built-in facilities performing the same functions, can be applied in bilateral test callprogrammes involving the networks of two Administrations or regional programmes involving more than twoAdministrations. It is important th
11、at such programmes are well planned and not interfered with by the use of the sametest number for other purposes as well.1.6 In order to reflect the real network performance, test call programmes should be carried out both duringnon-busy and busy periods. The number of test calls to be generated on
12、each selected route will depend on the frequencyof difficulties encountered on the route and is independent of the traffic load carried on the route, or the size of the route.In other words, the higher the fault frequency, the fewer test calls will be required to arrive at statistically significantr
13、esults. Considering that most of a test generators occupation time is used for sending address information to its ownnational switching equipment, international links and national links in the distant country are only occupied for a veryshort time by a test call. The additional load created by test
14、call generators on international traffic routes is thereforenormally negligible even on very small routes.1.7 It should be stressed that test call programmes of the type described here always necessitate an agreementbetween Administrations concerned.2 Methods of assessment2.1 Distribution of test ca
15、ll facilitiesFor practical purposes it is quite sufficient to generate, and observe, test calls from a few major traffic points inthe originating country to a few major points in the distant country.2.2 Programming of test call trafficIn order to avoid interference with other test calls, test call p
16、rogrammes should be carefully planned and agreedupon by the parties concerned. It might be advisable to prepare periodical test call programmes for bilateral exchangebetween Administrations. Test calls should, if possible, also be evenly distributed over a period of time including bothnon-busy and b
17、usy periods of traffic.2 Fascicle IV.2 - Rec. M.12352.3 Number of test callsThe number of test calls to be generated to each selected destination is only dependent on the frequency ofdifficulties encountered and is independent of the traffic load carried to that destination. Fewer test calls are nee
18、ded toidentify the network performance level when the rate of difficulty encountered is high.The number of test calls to be generated in a test call programme for a defined period of time can normally bedivided between all destinations to be tested. It is recommended, however, that a certain proport
19、ion of the total test callproduction capacity be utilized for special fault investigations on certain indicated destinations.2.4 Result of test call programmesNetwork performance may be expressed as the ratio of successful to total test call attempts to a certaininternational destination during a pe
20、riod of time. The accuracy of the results of the test calls may be judged by ordinarystatistical methods.The definition of a successful or nonsuccessful call is, to some extent, dependent on the range of tests beinginterchanged between the test call generator and the responder. In general, the follo
21、wing criteria must be met by asuccessful test call:i) the called party answers,ii) acceptable general transmission quality,iii) correct charging,iv) correct disconnection of the call.Furthermore, certain test facilities may be designed to carry out more stringent test programmes under thenetwork per
22、formance concept.The nonsuccessful calls should be specified with regard to the type of fault which occurred.2.5 Reports and exchange of informationAdministrations involved in test call programmes are urged to exchange test results regularly.An unusually high number of network difficulties encounter
23、ed in a test call programme should be treated as afault report and be dealt with according to fault reporting procedures, without interrupting the test call programme.It is recommended that the Administration making test calls should be responsible for the compilation of theresults of those tests.3
24、EquipmentAs tone signals and other local conditions vary from one national network to another, test call generators andresponders must be specifically designed for each international application. Furthermore, test call generators may bedesigned to interwork with responders in the distant country, wh
25、ich regenerate test calls back to the country of origin.Until such time as Recommendations are available giving the specifications for test call generating andresponding equipments, it is recommended that Administrations initiating test call programmes supply the respondersrequired.References1 CCITT Recommendation Test calls, Vol. II, Rec. E.424.2 CCITT Recommendation Maintenance methods, Vol. IV, Rec. M.730.
