1、ITU-T RECMN*Q.542 93 4862593 0585772 802 INTERNATIONAL TELECOMMUNICATION UNION ITU=T TELECOMMUNICATION STANDARDIZATION SECTOR OF ITU DIGITAL EXCHANGES (2.542 (03/93) DIGITAL EXCHANGE DESIGN OBJECTIVES - OPERATIONS AND MAINTENANCE ITU-T Recommendation Q.542 (Previously CCIlT Recommendation”) ITU-T RE
2、CMNmQ-542 93 4862591 0585773 749 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 with a view to s
3、tandardizing 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 Recommendation 4.542 was
4、revised by the ITU-T Study Group XI (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 CCIJT ceased to exist as of 28 February 1993. In its place, the ITU Telecommunication St
5、andardization Sector (ITU-T) was created as of 1 March 1993. Similarly, in this reform process, the CCIR and the IFRB have been replaced by the Radiocommunication Sector.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 containing the acrony
6、ms “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 this Recommendation,
7、 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 writing from the IT
8、U. ITU-T RECMN*Q.542 93 = 4862593 0585774 b5 = CONTENTS General . Maintenance design objectives . 2.1 2.2 2.3 2.4 2.5 2.6 2.7 2.8 2.9 2.10 2.1 1 2.12 2.13 2.14 2.15 2.16 2.17 Status and other information . Inputs and outputs . Routine testing Trouble localization Fault and alarm detection and action
9、s at interfaces A. B. V2. Vg and V4 . Fault and alarm signal detection and actions at interface V1 Fault and alarm signal detection and actions at interface Z Fault and alarm signal detection and actions for transmission systems Fault and alarm signal detection and actions for channel associated sig
10、nalling (2048 and 8448 kbits) . Fault and alarm signal detection and actions for channel associated channel signalling ( 1544 kbits) Fault and alarm signal detection and actions for common channel signalling . Fault and alarm detection and consequent actions - Other functions of the exchange . Super
11、vision or testing of interface function Supervision or testing of signalling functions Supervision or testing of exchange connections . Supervision or testing of digital link performance . Supervision or testing of analogue link performance . Subscriber line maintenance and testing design objectives
12、 3.1 Analogue subscriber lines . 3.2 Digital subscriber lines . Operations design objectives 4.1 General 4.2 Operations features . Exchange functions related to the TMN . Network management design objectives 5.1 General 5.2 Network management elements 5.3 Information provided by an exchange for netw
13、ork management purposes 5.4 5.5 5.6 4.3 Exchange controls for network management Automatic controls for network management . Order of application of controls Recommendation Q.542 (03/93) Page 1 1 1 1 1 1 2 4 4 5 5 6 6 6 7 7 7 8 8 8 8 9 9 9 9 10 10 10 11 11 13 15 21 i ITU-T RECMN*Q-542 93 W 4862593 0
14、585775 513 W Recommendation Q.542 DIGITAL EXCHANGE DESIGN OBJECTIVES - OPERATIONS AND MAINTENANCE (Melbourne, 1988; modified at Helsinki, 1993) 1 General This Recommendation applies to digital local, combined, transit and international exchanges for telephony in Integrated Digital Networks (IDN) and
15、 mixed (anaiogddigital) networks, and also to local, combined, transit and international exchanges in an Integrated Services Digital Network (ISDN). The field of application of this Recommendation is more fully defined in Recommendation Q.500. Some objectives only apply to a certain type (or types)
16、of exchange. Where this occurs, the application is defined in the text. Where no such qualification is made, the objective applies to all exchange applications. 2 Maintenance design objectives The exchange shall be arranged so that normal maintenance activities can be easily performed by maintenance
17、 personnel. It should be capable of providing all information necessary for the identification of trouble conditions and the direction of repair activities. 2.1 Status and other information The exchange shall provide information to maintenance personnel so that they can quickly ascertain: - equipmen
18、thystem status; - critical load levels; - trouble conditions; - network management controls in effect. 2.2 Inputs and outputs The exchange shall be able to transmit and receive maintenance information and respond to commands from on-site and if appropriate, from remote maintenance centre(s) or syste
19、ms over the recommended interace(s) (see Recommen- dation Q.513). Depending on the degree of processing desired by the Administration, the humadmachine terminal could offer the following features: - - - exchange status observation. operational data processing and analysis; maintenance data processin
20、g and analysis; In performing operations and maintenance functions, the exchange shall use CCITT MML at its inpuVoutput terminals as covered in the 2.300-Series Recommendations. 2.3 Routine testing The exchange shall have facilities for performing or directing routine test activities on its componen
21、t parts and possibly with interfacing equipment or systems. 2.4 Trouble localization The exchange shall have adequate facilities for diagnosing and locating faults within the exchange. Recommendation Q.542 (03/93) 1 ITU-T RECMN*Q-542 93 W 4862591 058-5776 458 2.5 Fault and alarm detection and action
22、s at interfaces A, B, V2, V3 and V4 The exchange shall interact with transmission systems as required to detect fault and alarms and take appropriate actions. 2.5.1 Fault detection The following fault conditions should be detected: - - loss of incoming signal; failure of local power supply (if pract
23、icable); NOTE - The detection of this fault condition is required only when the fault does not result in an indication of loss of frame alignment. loss of frame alignment (see Recommendation G.706; the loss of frame alignment will also be assumed if no CRC multiframe alignment can be achieved or if
24、the proportion of corrupted CRC checks exceeds a certain value); excessive error ratio (without CRC procedure). The criteria for activating and deactivating the indication of the fault condition are given in Recommendation G.707. Consequent actions are given in 2.5.3; CRC error reporting, if applica
25、ble: a) - - - every time a received CRC block is detected errored by the exchange termination: - - a report will be transmitted to the error monitoring function; the information “one multiframe errored” is transmitted in the outgoing signai at the interface using an E bit (see 2.3.3.4/G.704); every
26、time that an E bit in the binary state O is received, a report will be transmitted to the error monitoring functions. (On a provisional basis the considerations related to the E bit may only apply to V interfaces - for further study.) b) 2.5.2 Alarm signal detection The following alarm indications s
27、hould be detected: - - Alarm indication (remote alarm) received from the remote end. AIS (alarm indication signal). The equivalent binary content of the alarm indication signal (AIS) is a continuous stream of “1”s at 2048 or 8448 kbit/s. The strategy for detecting the presence of the AIS should be s
28、uch that the AIS is detectable even in the presence of an error ratio of 1 in lo3. However, a signal with all bits except the frame alignment bit in the 1 state should not be mistaken as an AIS. 2.5.3 Consequent actions 2.5.3.1 Generation of alarm signais for action within the exchange - The service
29、 alarm indication should be generated to signify that the service is no longer available (see Table 1). The prompt maintenance alarm indication should be generated to signify that performance is below acceptable standards and that immediate maintenance attention is required locally (see Table 1). -
30、2.5.3.2 Generation of alarm signals transmitted by the exchange - Alarm signais sent in the outgoing direction at the exchange interface. The relevant alarm bits for the remote alarm indication, as recommended in Recommendation G.704 should be effected as soon as possible (see Table I). Alarm signal
31、s sent towards the switching function. Alarm indication signal applied in ail received time-slots containing speech, data and/or signalling should be applied as soon as possible and not later than 2 ms after the detection of the fault condition (see Table 1). - 2 Recommendation 9.542 (03/93) ITU-T R
32、ECMN*Q.542 93 m 4862593 0585777 394 m Prompt maintenance alarm signals detected Service alarm alarm indication indication generated generated TABLE VQ.542 Fault conditions and alarms detected by exchange termination functions and consequent actions (excluding interface VI) I Consmuent actions I AIS
33、towards the switching stages Alarm indication to remote end generated Failure of power supply Loss of incoming signal Loss of frame alignment Excessive error ratio Yes Yes Yes, Yes, if practicable if practicable Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Alarm indication received from remote en
34、d Yes 2048 + 8448 kbitls: 1544 + 63 12 kbitls: optional AIS received Yes 2.5.3.3 Removal of alarm indications 1544 + 63 12 kbitls: Yes Yes Yes When ail fault conditions have been cleared and alarm indication signal is no longer received, the alarm indication signal and remote alarm indication should
35、 be removed within the same respective time limits as specified in 2.5.3.4 after the conditions have cleared. 2.5.3.4 Alarm procesSing The following items are required to ensure that equipment is not removed from service due to short breaks in transmission (e.g. due to noise or transient fault) and
36、to ensure that maintenance action does not result where no direct maintenance action is required. The persistence of service alarm and of the prompt maintenance alarm indications may be verified for 100 ms before action is taken. When the AIS is detected, the prompt maintenance alarm indication, ass
37、ociated with loss of frame alignment and excessive error rate in the frame alignment pattern, should be inhibited. When the fault conditions cease, the service alarm and prompt maintenance alarm indications, if given, should be removed. Again, the persistence of this change in condition may be verif
38、ied for 100 ms before action is taken. - - - - It is possible that some systems could suffer from frequent transient faults resulting in an unacceptable quality of service. For this reason, if a persistence check is provided, fault rate monitoring should also be provided for each digital transmissio
39、n system. This monitoring will result in permanent removal from service of digital transmission system which are frequently removed from the service or frequently produce transient alarm conditions. The threshold for removal from service needs study. When this action is taken, the service alarm indi
40、cation and the prompt maintenance alarm indication shall be given. Recommendation Q.542 (03/93) 3 ITU-T RECMN*d.542 73 W 4862573 0585778 220 2.5.4 Error performance monitoring using CRC 2.5.4.1 General When the CRC procedure is implemented at the interface, the exchange should monitor the error perf
41、ormance of the interface to report on the performance (see Recommendation G.821). 2.5.4.2 Error performance parameters The exchange should derive the following information from CRC checks in the incoming signal and received E bits: - degraded minutes (DM); - severely errored seconds (SES); - error-f
42、ree seconds (EFS). NOTES 1 2 3 4 These parameters are defined in Recommendation G.821. The definition of a value for the suitable time interval during which the parameters should be assessed needs further The choice has to be made between the association of one type of parameter to each direction of
43、 transmission and the The correlation between the results of CRC checks and the parameters quoted above requires further study. study. integration of the two directions in one type of parameter. This needs further study. 2.5.4.3 Error performance evaluation Each of the performance parameters will be
44、 processed separately in order to evaluate the performance of the interface. The following classification of the interface maintenance conditions has to be made by the exchange (see I.6-Series Recommendations): - correct functioning interface; - degraded transmission interface; - unacceptable transm
45、ission interface. NOTES 1 2 3 This subclause may only apply to V interfaces (for study). The level at which an interface for ISDN access enters the degraded transmission condition may be dependent on the The levels at which an interface enters the degraded or unacceptable transmission conditions are
46、 for further study and quality of service provided to the customer. are outside the scope of this Recommendation. 2.5.4.4 Consequent actions For further study. 2.6 The exchange shall interact with transmission systems as required to detect fault and alarm signals and take appropriate actions. Fault
47、and alarm signal detection and actions at interface Vi To be specified a) Fault detection b) Alarm detection c) Consequent actions 2.7 Fault and alarm signal detection and actions at interface 2 a) Fault detection b) Alarm detection c) Consequent actions To be specified 4 Recommendation Q.542 (03/93
48、) ITU-T RECNN*G-542 93 Y862591 0585779 Lb7 2.8 Fault and alarm signal detection and actions for transmission systems Faults and alarms which cannot be directly detected by the exchange termination function but which are detected by transmission equipment (e.g. group pilot failure) should be accepted
49、 by the exchange as needed to take appropriate action. 2.9 Fault and alarm signal detection and actions for channel associated signalling (2048 and 8448 kbis) 2.9.1 Fault detection The exchange signalling function should detect the following fault conditions for each multiplex carrying a 64 kbit/s signalling channel: - failure of local power supply (if practicable); - loss of 64 kbit/s incoming signal; NOTE - The detection of this fault condition is required only when the fault does not result in an indication of loss of multiframe alignment. - loss of multiframe alignment. Th
