1、 ITU-T RECMN*M=3b21 95 m 4862593 0603101 936 m INTERNATIONAL TELECOMMUN CATION UN ION ITU-T TELECOMMUNICATION STANDARDIZATION SECTOR OF ITU M.3621 MAINTENANCE INTEGRATED SERVICES DIGITAL NETWORKS (07195) INTEGRATED MANAGEMENT OF THE ISDN CUSTOMER ACCESS ITU-T Recommendation M.3621 (Previously “CCITT
2、 Recommendation”) FOREWORD The ITU-T (Telecommunication Standardization Sector) is a permanent organ of the International Telecommunication Union (ITU). The ITU-T is responsible for studying technical, operating and tariff questions and issuing Recommen- dations on them with a view to standardizing
3、telecommunications on a worldwide basis. The World Telecommunication Standardization Conference (WTSC), which meets every four years, establishes the topics for study by the ITU-T Study Groups which, in their turn, produce Recommendations on these topics. The approval of Recommendations by the Membe
4、rs of the ITU-T is covered by the procedure laid down in WTSC Resolution No. 1 (Helsinki, March 1-12, 1993). ITU-T Recommendation M.3621 was prepared by ITU-T Study Group 4 (1993-1996) and was approved under the WTSC Resolution No. 1 procedure on the 27th of July 1995. NOTE In this Recommendation, t
5、he expression “Administration” is used for conciseness to indicate both a telecommunication administration and a recognized operating agency. I O ITU 1995 All rights reserved. No part of this publication may be reproduced or utilized in any form or by any means, electronic or mechanical, including p
6、hotocopying and microfilm, without permission in writing from the ITU. CONTENTS Page 1 General . 1 1.1 Scope 1 2 References 1 3 Sample relationships between management information from different layers . 1 4 Layer faults and indications . 2 BRI and PRI Layer 1, 2 and 3 events and indications 4.1 2 R
7、ecommendation M.3621 (07/95) 1 ITU-T RECMN*M=362L 95 48b2.593 Ob03104 645 ABSTRACT It has been observed that events occurring at the lower layers of a protocol stack may impact higher layers. This Recommendation provides information which may be used to correlate event indications from each of the f
8、irst three layers of ISDN BRI and PRI to determine if they are related to a single lower layer event. KEYWORDS ISDN customer access; Fault Management; Management of ISDN D-channel. ii Recommendation M.3621 (07/95) Recommendation M.3621 INTEGRATED MANAGEMENT OF THE ISDN CUSTOMER ACCESS (Geneva, 1995)
9、 1 General This Recommendation provides potential relationships between fault indications from management information provided by the three protocol layers. This information could be used by network managers to correlate, where applicable, various indications from the three protocol layers to a sing
10、le fault. TMN developers could utilize these relationships in their software to provide tools to solve customer access problems more rapidly. Future activities in the area of protocol stack design may benefit from this work due to the observation that the current layers notifications are not entirel
11、y independent where faults are concerned. 1.1 Scope For the management of the ISDN customer access, several recommendations are available. In Recommenda- tion M.3640 3, management of the data link and network layers of the D-channel is described. In Recommen- dations M.3603 i and M.3604 2, the appli
12、cation of maintenance principles to the ISDN basic and primary rate accesses is described. The management of the customer access is rather complex. Therefore a subdivision for the management of the three protocol layers was applied. The management of each protocol layer is considered separately. In
13、this way, the management of the ISDN customer access is subdivided into three parts. However, these three parts are strongly related. For example there may be several alarms from different layers, caused by the same error. A problem is the way in which an operator has to deal with all the management
14、 information about the network, data link and physical layers. It is expected that the management information, received from different layers will often be related. It is not described which relations exist and how the relations between the ISDN customer access management Recommendations should be d
15、ealt with. This Recommendation only describes fault relationships between the management information in Recommendations M.3603 i, M.3604 2 and M.3640 3. 2 References The following Recommendations and other references contain provisions which, through reference in this text, constitute provisions of
16、this Recommendation. At the time of publication, the editions indicated were valid. All Recommendations and other references are subject to revision: all users of this Recommendation are therefore encouraged to investigate the possibility of applying the most recent edition of the Recommendations an
17、d other references listed below. A list of the currently valid ITU-T Recommendations is regularly published. i CCITT Recommendation M.3603 (1992), Application of maintenance principks to ISDN basic rate access. 2 CCITT Recommendation M.3604 (1992), Application of maintenance principles ro ISDN prima
18、ry rate acces. 3 CCITT Recommendation M.3640 (1992), Management of D-channel -Data Link and Network Layer. 3 Sample relationships between management information from different layers There is a relationship between management information from layers 1 and 2 as described in the following three exampl
19、es: The reception of Invalid frames or Frames with errors at layer 2 may be a consequence of Loss of frame alignment at layer 1. Recommendation M.3621 (07/95) 1 It is possible that Invalid frames are caused due to Loss of incoming signal or perhaps Loss of power at layer 1. When layer 2 cannot be es
20、tablished after N200 SABME frames are sent without proper response being received, it is possible that at layer 1 loss of frame alignment, loss of power or loss of incoming signal occurred. There is a relationship between management information from layers 2 and 3 as described in the following examp
21、le: As a result of a data link failure, timers may expire at layer 3. For some timers, this results in a notification. When these timers expire, one of the following notifications may be issued at layer 2: - The proper responses not received to establish or restore the link after N200 SABE frames we
22、re sent. - DM frames received in response to a SABME frame. - DM frames sent in response to a SAJ3ME frame. From the examples, it is clear that a manager will receive a large amount of management information, but may have problems investigating the cause of a fault. In Figure 1, an example is given
23、on how errors from different layers may be related in case of a layer 3 timer expiry (cause value 102). 4 Layer faults and indications In general, it is better to first solve lower layer problems and then the higher layer problems. The reason for this is that higher layer problems may be caused by l
24、ower layer problems but not the other way around. In the first case, when a lower layer problem is solved, the higher layer error messages that were received may be neglected, because they were generated due to the same error cause. When related errors from different layers are detected at approxima
25、tely the same time, it is expected that they were caused by the same root cause. Of course, it is necessary to check the complete error message to verify if the error messages were related to a single cause. This Recommendation gives the relationships between the management information of layers 3 a
26、nd 2, between the management information of layers 2 and 1 and between the management information of layers 1, 2 and 3. This means that for each error of layer 3, a list of possible layer 2 errors should be given, that could be the cause of the layer 3 error. This also holds for the relations betwee
27、n layer 2 and layer 1 and layers 3,2 and 1. 4.1 BRI and PRI Layer 1,2 and 3 events and indications Each of the following tables provides examples of events and possible indications for an event occumng at a specific layer. The tables also provide possible indications generated by the layers above th
28、e layer where the event occurred. For example, in Table 1, extreme impulse noise at layer 1 may cause a L1 indication of a loss of frame alignment and may also be responsible for causing an FCS error at layer 2 and might also lead to RESTART messages at layer 3. More detailed information which provi
29、ded the basis of the table entries can be found in the references. (See Tables 1 to 4.) 2 Recommendation M.3621 (07/95) I I Timerexpiry L3 layer3 i2 Layer2 L1 Layer1 FIGURE 1M.3621 Example of layer faults and indications Recommendation M.3621 (07/95) 3 ITU-T RECMN*!.3b23 95 m i.lBb2593 0603308 290 m
30、 TABLE 1M.3621 Layer 1 events L1 event - Impulse noise - Wideband noise - 50/60Hz noise - Excessive insertion loss - Extreme case of above faults - Loss of power at the customer premise - Loss of frame alignment at the customer premise - Short or open circuit - Failure to activate or deactivate . L1
31、 indication - Block error (near or far end error) - Loss of frame alignment at the ET - Loss of power at the customer premise - RAI (Remote Alarm - RFI (Remote Failure Indication) Indication, if supported) - Loss of incoming signal - Failure to activate or deactivate (only applicable to interfaces s
32、upporting deactivation) L2 indication - FCS error - Frames retransmitted Threshold exceeded - Invalid frames (Errors where L2 recovers) - Invalid frames - Frames with errors - Frames retransmitted Threshold exceeded - Proper Responses not rec. after N200 SABME - FCSError - Invalid frames - Proper re
33、sponses not rec. after N200 SABME - Invalid frames - Frames retransmitted Threshold exceeded - Proper responses not rec. after N200 SABME - Invalid Frames - Frames retransmitted Threshold exceeded - Proper responses not rec. after N200 SABME - No indication L3 indication - No indication - Timers exp
34、ire (T303, T308, T309, T310, T316, T317) - RELEASE messages transmitted (cause 102) - DISCONNECT messages transmitted (cause 102) - RESTART messages transmitted - STATUS - Timers expire (T303, T308, T309, T310, T316, T317) - RELEASE messages transmitted (cause 102) - DISCONNECT messages transmitted
35、cause 102) - RESTART messages transmitted - STATUS - Timers expire (T303, T308, T309, T310, T316, T317) - RELEASE messages transmitted (cause 102) - DISCONNECT messages transmitted (cause 102) - RESTART messages transmitted - STATUS - Timers expire (T303, T308, T309, T310, T316, T317) - RELEASE mes
36、sages transmitted (cause 102) - DISCONNECT messages transmitted (cause 102) - RESTART messages transmitted - STATUS - No indication 4 Recommendation M.3621 (07/95) - - ITU-T RECMN*M*362L 95 4862593 Ob03109 127 L2 event I L1 indication - Malfunctioning state machine in CPE or ET - Missing TE1 - Malfu
37、nctioning state machine in CPE or ET - Malfunctioning state machine in ET I - Conformance - Incorrect window TABLE 2M.3621 Layer 2 events - No indication - No indication - No indication - No indication - No indication - No indication L2 indication - DM frames received in response to a SABME - Invali
38、d frames - Unexpected messages - DM frames sent in response to a SABME - Info too long - Sequence error L3 indication - Timers expire (T303, T308, T309, T310, T316, T317) - RELEASE messages transmitted (cause 102) - DISCONNECT message (cause 102) - RESTART messages transmitted - Timers expire (T303,
39、 T308, T309, T310, T316, T317) - RELEASE messages transmitted (cause 102) - DISCONNECT messages transmitted (cause 102) - RESTART messages transmitted - Timers expire (T303, T308, T309, T310, T316, T317) - RELEASE messages transmitted (cause 102) - DISCONNECT messages transmitted (cause 102) - RESTA
40、RT messages transmitted - Timers expire (T303, T308, T309, T310, T316, T317) - RELEASE messages transmitted (cause 102) - DISCONNECT messages transmitted (cause 102) - RESTART messages transmitted - No indication - No indication Recommendation M.3621 (07/95) 5 TABLE 3M.3621 Layer 3 events L3 event -
41、 Malfunctioning state machine in CPE Malfunctioning state machine in ET I - Malfunctioning state machine in ET - Malfunctioning state machine in CPE L1 indication - No indication - No indication - No indication - No indication - No indication L2 indication - No indication - No indication - No indica
42、tion - No indication - No indication L3 indication - Messages with mandatory information element missing - Messages with general information element missing - STATUS messages transmitted (cause 96 or 100) - RELEASE COMPLETE messages transmitted (cause 96 or 100) - RELEASE messages transmitted (cause
43、 96 or 100) - Messages with mandatory information element missing - Messages with general information element missing - STATUS messages received (cause 96 or 100) - RELEASE COMPLETE messages received (cause 96 or 100) - RELEASE messages received (cause 96 or 100) - Message with call reference error
44、 RELEASE COMPLETE messages transmitted (cause 81) - RELEASE messages transmitted (cause 81) - STATUS messages transmitted (cause 81) - Message with call reference error - RELEASE COMPLETE messages received (cause Si) - RELEASE messages received (cause 81) - STATUS messages received (cause Si) - Tim
45、er expires - RELEASE messages transmitted (cause 102) - DISCONNECT messages transmitted (cause 102) - RESTART messages transmitted 6 Recommendation M.3621 (07195) - ITU-T RECMN*M-3621 95 W 4862593 0603113 885 W TABLE 4M.3621 TE1 events TE1 event - Duplicate TE1 Non-automatic assignment Duplicate TE1
46、 Automatic assignment - Unassigned TE1 used - User errors - CPE failure - Number of unused TE1 values gets too high - Too many data links requested by users - TE1 removal fails - TE1 removed by user L1 indication - No indication - No indication - No indication L2 indication - Unexpected frames - TE1 resources exhausted - Proper responses not received to establish or restore the link after N2 SABME frames were sent L3 indication - No indication - No indication - No indication Recommendation M.3621 (07/95) 7
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