1、INTERNATIONAL TELECOMMUNICATION UNION)45G134 - TELECOMMUNICATIONSTANDARDIZATION SECTOROF ITU-!).4%.!.#% G0G0).4%2.!4)/.!,G0G0$!4!42!.3-)33)/.G0G03934%-3-!).4%.!.#%G0G0/&G0G0).4%2.!4)/.!,G0G0$!4!42!.3-)33)/.G0G03934%-3G0G0/0%2!4).).G0G04(%G0G02!.%G0G0 G0G04/G0G0 G0KBIT S)45G134G0G0RecommendationG0G0-
2、 (Extract from the “LUEG0“OOK)NOTES1 ITU-T Recommendation M.1355 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
3、the Blue Book 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 publi
4、cation may 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.1355 1Recommendation M.1355Fascicle IV.2 - Rec. M.1355MAINTENANCE OF INTERNATIONAL DATA TRANSMISSION SYST
5、EMS OPERATINGIN THE RANGE 2.4 TO 14.4 kbit/s1 General1.1 This Recommendation deals with maintenance procedures applicable to international data systems in therange 2.4 to 14.4 kbit/s.1.2 The constituent parts of the data system are shown in Figures 1/M.1300 and 2/M.1300.1.3 In some instances it may
6、be necessary to provide modems at a centre, for testing purposes only, to achieveadequate performance in fault localization.2 Fault reporting procedures2.1 As far as possible, the provisions of Recommendations M.1012, M.1013 and M.1014 apply. Any additionalspecial procedures must be devised by the A
7、dministrations concerned.3 Fault localization3.1 Upon receipt of a complaint about the performance of an international data transmission system the control orsub-control station should obtain specific assurance that all terminal equipment has been tested and is working correctly.3.2 The control stat
8、ion should first ensure that all major systems are performing normally, then efforts should bemade to localize and clear the fault.3.3 It is essential that the control and sub-control stations inform each other of all relevant information andsignificant actions taken which may assist their efforts.3
9、.4 Control and sub-control stations should arrange that a suitable test pattern is transmitted in each direction.Then, if the fault is not cleared, suitable modems and test equipment can be applied at intermediate points as appropriatein order to isolate the fault to a particular section.3.5 To loca
10、lize the fault, the data transmission system should normally be tested in sections so that the need forinternational cooperation is reduced and rapid progress is made. In some instances loops may be utilized in order toisolate the faulty section. Care must be taken to avoid the simultaneous operatio
11、n of loops if the system configuration issuch that erroneous results would occur.3.6 The purpose of the initial fault localization process is to identify as quickly as possible whether the fault lies inone of the national sections or the international section. This allows the Administrations to begi
12、n the detailedinvestigation necessary to clear the fault.3.7 See Figure 1/M.1375 for a guide to fault localization.4 Overall data system check4.1 When the fault has been localized to the international or a national section and cleared, that section should betested to ensure that its bit error ratio
13、meets the requirements of 5 below.4.2 The overall data transmission system should also meet the requirements of 5, and the data transmissionperformance should be tested before the system is offered back to the renter.5 Maintenance parameters5.1 Maintenance measurements should normally be evaluated b
14、y comparison with those made during the line-upof the system and with the specified limits given in Recommendation M.1350.5.2 For data transmission performance, it will normally be sufficient to check the bit error ratio over 15 minutes.Alternatively, error free seconds may be used as a measure of performance, where agreed between Administrationsconcerned. The maintenance standards are given in Table 1/M.1350.
