1、CCITT RECM“CM.3604 92 ri 4862591 0579116 259 INTERNATIONAL TELECOMMUNICATION UNION CCITT THE INTERNATIONAL TELEGRAPH AND TELEPHONE CONSULTATIVE COMMITTEE MAINTENANCE: ISDN M.3604 (1 0/92) APPLICATION OF MAINTENANCE PRINCIPLES TO ISDN PRIMARY RATE ACCESS Recommendation M.3604 CCITT RECMN*M-3604 92 48
2、b2.591 0579LL7 17.5 FOREWORD The CCITT (the International Telegraph and Telephone Consultative Committee) is a permanent organ of the International Telecommunication Union (ITU). CCIT is responsible for studying technical, operating and tariff questions and issuing Recommendations on them with a vie
3、w to standardizing telecommunications on a worldwide basis. The Plenary Assembly of CCIT which meets every four years, establishes the topics for study and approves Recommendations revised by its Study Groups. The approval of Recommendations by the members of CCIT between Plenary Assemblies is cover
4、ed by the procedure laid down in CCIT Resolution No. 2 (Melbourne, 1988). Recommendation M.3604 was revised by Study Group IV and was approved under the Resolution No. 2 procedure on the 5th of October 1992. CCIT NOTE In this Recommendation, the expression “Adminisuation” is used for conciseness to
5、indicate both a telecommunication administration and a recognized private operating agency. O ITU 1993 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 wri
6、ting from the ITU. CCITT RECMN*M-3604 92 Lid62591 0579LLB O21 Recommendation M.3604 APPLICATION OF MAINTENANCE PRINCIPLES TO ISDN PRIMARY RATE ACCESS (Melbourne 1988 as Rec. 1.604; revised and renumbered 1992) Abstract This Recommendation defines capabilities and functions used by the network to mai
7、ntain the physical layer of ISDN primary rate access. Keywords - ISDN, - maintenance; - primary rate access. 1 Scope of application This Recommendation covers the maintenance of that part of the ISDN subscriber primary rate access which is controlled by the network. The Recommendation follows the ma
8、intenance principles as defined in Recommen- dation M.20 11 and applies to the primary rate access connected to the local exchange. The scope of this Recommendation is to describe the minimum functions required to maintain the subscriber primary rate access. They are applicable to any primary rate a
9、ccess. The principle of controlled maintenance (as defined in Recommendation M.20 i) is applied for maintaining the subscriber primary rate access. Controlled maintenance is a method of sustaining a desired technical performance by the systematic application of supervision, testing and performance s
10、ampling in order to minimize preventive maintenance and to reduce corrective maintenance. 2 Network configuration for maintenance activities Figure 1M.3604 gives the basis for the general maintenance principles of the subscriber access. 3 Failure detection 3.1 General Unlike the ISDN basic access, t
11、he digitai section of the ISDN subscriber primary rate access is never deactivated (as seen by the exchange); continuous automatic supervision of the correct functioning of layer 1 up to NT2 is always operating. This supervision is called continuous automatic supervision of layer 1. Automatic superv
12、ision of the correct functioning of the D-channel layers 2 and 3 is ais0 operating. This supervision is called automatic supervision of layers 2 and 3 of the D-channel protocol. Recommendation M.3604 (10192) 1 - CCITT RECMN*M*3b04 92 486259L 0579LL9 Tb8 Subscriber access I I installation I Subscribe
13、r i LI; I li u . i, 1-1 I OAMC I Configuration to be maintained L-J ,- I- MSP Management Service Provider OAMC Operation Administration Maintenance Centre SAMF Subscriber Access Management Function SIMF Subscriber Installation Management Function See Recommendation M.3600 2 for detailed discussion o
14、f the terms. Nute 1 - The subscriber access contains a digital link which can use different varieties of transmission techniques and media. Figure uM.3604 shows examples of configurations made by using existing digital line systems and multiplexers complying with G.700 7 - and G.900 SI - Series Reco
15、mmendations. Nute 2 - A local exchange should be able to connect different types of dipital line systems and different spes of subscriber installations at V3 interfaces complying with Recommendation 4.512 9. Nute 3 - The use of different types of digital line systems shall not affect the subscriber
16、installation complying with Recommendation 1.431 IO. Nute 4 -The subscriber access shall comply with the CRC procedure dehed in Recommendations G.704 5 and G.706 6. Nute 5 - In some countries. the subscriber installation is allowed to control maintenance functions in the subscriber access. FIGURE 1/
17、M.3604 Configuration for the maintenance of primary access 3.2 Automatic supervision 3.2.1 Objectives This supervision is realized by continuous automatic mechanisms located in various pieces of equipment of the ISDN primary rate access. These automatic mechanisms are never deactivated and are gener
18、ally based on the operation of CRC information which is given by the CRC procedure associated with the link between the customer and the local exchange. These mechanisms are complemented by the detection of malfunctioning of particular items, e - detection of loss of frame alignment; - detection of
19、AIS and RAI; - generation of frame signal; - CRC code generation; 2 Recommendation M.3604 (10/92) CCITT RECMN*M.3bOY 92 48bZ571 0579120 78T - Wgeneration; - - - CRC monitoring of the incoming signal (network-to-user); detection of CRC error information (user-to-network); CRC error reporting to the n
20、etwork (optional in 1544 kbids systems). Digital section *II T “3 Noie - Digital sections may include zero, one or more regenerators. FIGURE 2m.3604 Examples of equipment configurations in the ISDN subscriber primary rate access 3.2.3 ETfunctions The functions which are allocated to the ET are liste
21、d below: - - - - detection of RAI; - generation of frame signal; - CRC code generation; - RAI generation; - - - The exchange termination may optionally detect the CRC error information reported by the user side. The RAI is generated towards NT2 upon detection by the ET of a fault in the input direct
22、ion (loss of signal, detection of loss of incoming signal; detection of loss of frame alignment; detection of AIS, generation of AIS (optional in 1544 kbids systems); CRC monitoring of the incoming signal (user-to-network); detection of the CRC error information (network-to-user); CRC error reportin
23、g to the user (optional in 1544 kbit/s systems). loss of frame alignment, detection of AIS). Recommendation M.3604 (10D2) 3 CCITT RECMN*M.3604 92 48b2591 0.579121 bLb The ET has the option to evaluate the transmission performance based on the statistical treatment of the local and remote CRC mor rep
24、orts and on the fault indications. The transmission performance evaluation is based on a permanent processing of the elemenary results presented by the continuous error monitoring of the digital transmission link. The result of this processing will give information. on the transmission quality level
25、 (nod quality, degraded quality, unacceptable quality) and on the unavailability of the access (see Q 5.6). 3.3 Automatic supervision of layers 2 and 3 of the D-channel protocol This covers supervision of activities of layers 2 and 3 of the D-channel protocol. Automatic supervision of layers 2 and 3
26、 will be made by self-acting mechanisms implemented in the network (e.g. in the ET). There are three categories of automatic supervision which may be performed by layer 2 and layer 3 of the D-channel protocols: - - protocol misoperation detection; - service provision incapability detection (e.g. inc
27、apability of layer 2 to establish a data link connection); error monitoring (e.g. the layer 2 CRC procedure can detect the occurrence of an errored frame). These events should be recorded as discussed in Recommendation M.3640 4. 3.4 Continuity test For further study. 4 System protection When a confi
28、rmed fault is detected which has an adverse effect on the availability andlor functionality of network equipment, the access is considered “out of service due to failure” and call attempts may be rejected to prevent further damage or to remove the adverse effect. 5 5.1 5.2 5.3 5.4 Failure indication
29、 Default indication signals a) AIS - as defined in Recommendation 1.43 1 103. b) RAI - as defined in Recommendation 1.43 1 101. State tables State tables associated with failures in the primary rate access are given in Recommendation 1.43 1 101. Generation of defect indication signals by the hT2 The
30、 NT2 functions are listed in Q 3.2.2. The generation of RAI toward the ET is used to indicate the loss of incoming layer 1 capability. Generation of defect indication signals by the subscriber access The digital link functions are listed in Annex A for each option within the access. 4 Recommendation
31、 M.3604 (10192) CCITT RECMN*M.3604 92 m 4862593 0579322 552 m 5.5 Generation of defect indication signals by the exchange termination The exchange termination functions are listed in 4 3.2.3. The generation of RAI toward the NT1 is used to indicate the loss of incoming layer 1 capability. 5.6 Transm
32、ission quality monitoring by the exchange 5.6.1 Error performance parameters According to Recommendations M.20 i and M.2100 3, the anomaly and defect indications are treated on a statistical basis. 5.6.2 Error performance evaluations The access is considered by the local exchange to be “unavailable”
33、, “unacceptable” or “degraded” according to Recommendation 21 O0 3. 5.7 Failure information from the exchange A defect confmed by the exchange and related to a subscriber access andor a subscriber installation shall be reported to the OAMC in a message. exchange shall be reported to the OAMC in a me
34、ssage. been made (see 0 6). The detection of a degraded or an unacceptable quality level or of the unavailability of the access by the The message could be presented after an automatic identification of a failed Maintenance Entity (ME) has 5.8 Failure information to the subscriber installation The d
35、etection of a degraded or unacceptable quality level by the exchange may be reported to the user by the transmission of a state indication. 6 Failure localization 6.1 Automatic confirmation of failure within the subscriber primary rate access An automatic test procedure to confm a detected possible
36、failure condition within the subscriber access should be provided. It shall be initiated by an automatic reaction of the exchange, following abnormal conditions which have been detected by the processes presented above, i.e. continuous supervision of layer 1, supervision of layers 2 and 3 of the D-c
37、hannel protocol. within the subscriber installation and within the subscriber access should be possible. If failures are detected in the D-channel layers 2 and 3 communication, clear differentiation between failures 6.2 Failed maintenance entity identification 6.2.1 General Such a function has to be
38、 made on demand or automatically following the indication of failure conditions by the network or following a subscriber complaint. It is necessary, before undertaking the appropriate action, to identify (i.e. to know) the maintenance entity affected by the failure. 6.2.2 Objectives The main objecti
39、ve of this function, which is controlled by the SAMF, is to indicate to the OAMC whether - within the ET; - - within the subscriber installation. the failure is: within the digital transmission link (NT1 to LT); Recommendation M.3604 (10D2) 5 CCITT RECMN*M*3b04 92 II 48b259L 0579123 499 - 4;qFl L II
40、 I LT 6.3 6.3.1 Location of loopbacks Loopbacks for maintenance of the subscriber primary rate access PQssibie loopback locations for failure localization and verification controlled by the SAMF are shown in Figure 3M.3604. Digital section T Reaenerator v 31 2 1A 1 (Note 1) E FIGURE 3FI.3604 Locatio
41、n of the loopbacks for maintenance of the general equipment conflguration of the subscriber primary rate access 6.3.2 6.4 Characteristics of loopbacks The characteristics of the loopbacks are given in Table 1M.3604. Failure localization mechanisms See Figure 4M.3604. If a subscriber access failure i
42、s confirmed by the exchange and if the failure is not located in the exchange, then - either the loopback 2 can be established under control of the exchange, in which case: i) if the loopback 2 is successful, the exchange considers the subscriber access to be functioning correctly; ii) if the loopba
43、ck 2 is unsuccessful, the exchange reports to the OAMC; or, if the loopback 2 cannot be established under control of the exchange, then the exchange informs the OAMC that the digital link is affected by a failure. - in the case of a failed maintenance entity being detected, an automatic localization
44、 process is initiated. This process could localize the failure within the digital link by the use of loopbacks or subscriber access fault information. 6 Recommendation M.3604 (10/92) CCITT RECMN*M.3604 72 E 48b257L 0577L24 325 E 1 TABLE 1M.3604 Channe(s) looped back Characteristics of the loopbacks
45、for subscriber primary rate access Control mechanism Loopback type Control point Loopback Complete loopback (Note 3) Location Non-transparent ET or other NE Local (Note 4) within subscriber maintenance access Complete loopback (Note 3) Complete loopback 1 Non-transparent ET or other NE Layer 1 (Note
46、 4) within subscriber access Non-transparent ET or other NE Layer i (Notes 1 and 4) within subscriber 1A , B,HO,Hl B, HO, H1 In LT, as near as possible to the line, towards the ET In the regenerator Partial, Under control of Layer 3 transparent or local exchange non-transparent Partial, Under contro
47、l of Layer 3 transparent or N or WA non-transparent 2 4 In NT1, as near as possible to T reference point, towards ET (Note 2) In NT2, as near as possible to T reference point, towards T (Note 5) In the TE or TA E In ET, towards the line Layer 3 I Under control of I Partial, B*Ho7H1 I transparent or
48、local exchange Implementation optional optional Optional optional optional Optional Note 1 - When option 2 (see Annex A) is used, only the B- and D-channels are returned through the NT1 unaltered and therefore only those channels can be used by a loopback test. Note 2 - In the case of using existing
49、 digital systems, a manual loopback may replace loopback 2. This loopback is implemented between NT2 and NT1 and is controlled by the user at the request of the network staff. Nofe 3 - These complete primary rate loopbacks operate on the full bit stream including time slot O in 2048 kbitls systems and the F bits of 1544 kbitls systems. Note 4 - These loopbacks are normally non-transparent and send AIS in the forward direction. However, when the network can continue to provide good network clock, these loopbacks may be transparent When transparen
