1、ITU-T RECMN*R-338 93 4862.593 058bLb2 3b5 INTERNATIONAL TELECOMMUNICATION UNION ITU-T TELECOMMUNICATION STANDARDIZATION SECTOR OF ITU TELEGRAPHY TELEGRAPH TRANSMISSION R.118 (03/93) PERFORMANCE AND AVAILABILITY MONITORING IN REGENERATIVE TDM ITU-T Recommendation RI18 (Previously “CCITT Recommendatio
2、n”) ITU-T RECMN*R.118 93 = 48b259l 0586163 2Tl = FOREWORD The ITU Telecommunication Standardization Sector (ITU-T) is a permanent organ of the International Telecom- munication Union. The ITU-T is responsible for studying technical, operating and tariff questions and issuing Recommendations on them
3、with a view to standardizing telecommunications on a worldwide basis. The World Telecommunication Standardization Conference (WTSC), which meets every four years, established the topics for study by the ITU-T Study Groups which, in their turn, produce Recommendations on these topics. ITU-T Recommend
4、ation R.118 was prepared by the ITU-T Study Group IX (1988-1993) and was approved by the WTSC (Helsinki, March 1-12, 1993). NOTES 1 As a consequence of a reform process within the International Telecommunication Union (ITU), the CCITT ceased to exist as of 28 February 1993. In its place, the ITU Tel
5、ecommunication Standardization Sector (ITU-T) was created as of 1 March 1993. Similarly, in this reform process, the CCIR and the IFRE3 have been replaced by the Radiocommunication Sector. In order not to delay publication of this Recommendation, no change has been made in the text to references con
6、taining the acronyms “CCITT, CCIR or IFRB” or their associated entities such as Plenary Assembly, Secretariat, etc. Future editions of this Recommendation will contain the proper terminology related to the new ITU structure. 2 telecommunication administration and a recognized operating agency. In th
7、is Recommendation, the expression “Administration” is used for conciseness to indicate both a O ITU 1994 All rights reserved. No part of this publication may be reproduced or utilized in any form or by any means, electronic or mechanical, including photocopying and microfilm, without permission in w
8、riting from the ITU. ITU-T RECMN*R-LLB 93 4862591 0586364 138 Recommendation R.118 PERFORMANCE AND AVAILABILITY MONITORING IN REGENERATIVE TDM (Helsinki, 1993) The CC, considering (a) that the error rate is the main performance criterion for end-to-end connection with regeneration; (b) that code- an
9、d speed-dependent multiplexers are regenerators; (cl synchronization scheme in a specific channel and the same modulation rate (50 bauds); that multiplexers conforming to Recommendations R. 101(B), R. 102, R. 105 and R. 1 12 use the same (d) that the general performance objectives are defined in Rec
10、ommendation R.117, unanimously recommends that multiplexing systems with regeneration should enable channel performance and availability to be monitored in accordance with the following principles: 1 The error rate of the aggregate will be monitored by checking the synchronization bits. 2 signalled
11、to internal or external equipment. The occurrence of a faulty synchronization bit (or word) when the TDM system is synchronized should be 3 thus improve performance in the long term. If possible, such events and the time of occurrence should be recorded to use the analysis of their cause and 4 Thres
12、holds can be set such that alarm devices will alert operators: - the first threshold set for “errored intervals”; - the second set for “severely errored intervals”. 5 a loss of synchronism to that when it is restored. The monitoring of invalid synchronizm pulses is discontinued from the moment when
13、the TDM system signals 6 intervals, but must be recorded among the errored intervals. A sudden isolated loss of synchronism should not be counted by the device monitoring the severely-errored 7 Operators must be warned whenever the “severely-errored interval” state is reached. This may entail precau
14、tionary measures such as locking channels designated for switched circuits in order to avoid their seizing (since an error during the numbering phase is generally more troublesome and it is not desirable to initiate a call unless a minimum performance level can be assured). 8 availability of the tra
15、nsmission system. Loss of synchronism in a TDM system must be monitored in such a way as to obtain information on the 9 national standards. The interface between the telegraph muldex and the measuring and monitoring equipment must meet the 10 may be between 20 and loo0 ms; the exact figure remains to be decided. The monitoring equipment can be either a simple gauge or a computerized system; the system “dead time” Recommendation R.118 (03/93) 1
