1、- CCITT RECMN*E*415 91 4862.591 05b0575 4 INTERNATIONAL TELECOMMU N CATION UN ION CCITT E.415 THE INTERNATIONAL TELEGRAPH AND TELEPHONE CONSULTATIVE COMMITTEE TELEPHONE NETWORK AND ISDN QUALITY OF SERVICE, NETWORK MANAGEMENT AND TRAFFIC ENGINEERING INTERNATIONAL NETWORK MANAGEMENT GUIDANCE FOR COMMO
2、N CHANNEL SIGNALLING SYSTEM No. 7 Recommendation E.415 Geneva, 1991 CCITT RECMN*E.*415 91 48b2591i 0560576 b INTERNATIONAL TELECOMMUNICATION UNION CCITT TH E INTERNATIONAL TELEGRAPH AND TELEPHONE CONSULTATIVE COMMITTEE TELEPHONE NETWORK AND ISDN QUALITY OF SERVICE, NETWORK MANAGEMENT AND TRAFFIC ENG
3、INEERING INTERNATIONAL NETWORK MANAGEMENT GUIDANCE FOR COMMON CHANNEL SIGNALLING SYSTEM No. 7 Recommendation E41 5 I Geneva, 1991 I CCITT RECMN*E*435 93 4862593 0560577 8 FOREWORD The CCIT (the International Telegraph and Telephone Consultative Committee) is a permanent organ of the International Te
4、lecommunication Union 0. CCIIT is responsible for studying technical, operating and tariff questions and issuing Recommendations on them with a view to standardizing telecommunications on a worldwide basis. The Plenary Assembly of CCIT which meets every four years, establishes the topics for study a
5、nd approves Recommendations prepared by its Study Groups. The approval of Recommendations by the members of CCIT between Plenary Assemblies is covered by the procedure laid down in CCIZT Resolution No. 2 (Melbourne, 1988). Recommendation E.415 was prepared by Study Group II and was approved under th
6、e Resolution No. 2 procedure on the 23rd of August 1991. CCITT NOTES 1) telecommunication Administration and a recognized private operating agency. 2) In this Recommendation, the expression “Administration” is used for conciseness to indicate both a A list of abbreviations used in this Recommendatio
7、n can be found in Annex B. o ITU 1991 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 ITU. CCITT RECMN*E.*415 91 4b259L 05b0578 T Recomme
8、ndation E.41 1 Introduction INTERNATIONAL NETWORK MANAGEMENT GUIDANCE FOR COMMON CHANNEL SIGNALLING SYSTEM No.7 1.1 As the use of common channel Signalling System No. 7 increases, its performance becomes increasingly important to the network and the services it supports. Since problems in the signal
9、ling network can affect the switched networks that it supports, and vice versa, network managers must know the current status and performance of - exchanges; - intelligent network nodes. b) signalling links; c) signalling link sets; d) signalling routes. The status and performance of the various use
10、r application parts are also importar - Message Transfer Part (MTP) - Telephone User Part (TUP) - ISDN User Part (ISUP) (see Recommendations Q.700 to Q.704) (see Recommendations Q.721 to Q.725) (see Recommendations Q.761 to Q.764) Signalling Connection Control Part (SCCP) (see Recommendations 4.71 1
11、 to Q.714 and Q.716) Transaction Capabilities Application Part (TCAP) (see Recommendations Q.771 to Q.775) Operations and Maintenance Application Part (OMAP) (see Recommendation Q.795) - - - These include: Recommendation E.415 1 CCITT RECMN*E-*4L5 9L 48b2591 0560579 L 2.2 AU signalling points should
12、 make available signalling status and performance data (counts and occurrences of critical events) to their network management center and/or operations support system. The following categories of data should be provided: - signalling link congestion status indicators; - signalling link load and perf
13、ormance measurements (utilization and congestion); - signalling link status indicators for the availability of links in a linkset; - signalling linksethoute status indicators for the availability of each signalling linksethoute; - user application part status indicators and load and performance meas
14、urements. Each category is explained below. 2.2.1 Signalling link congestion status indicators Signailing link congestion indications are significant in that they can identify the location and severity of the congestion. The onset of the transfer controlled (TFC) procedure is a key indicator of sign
15、alling link congestion. There are two types of impact associated with link congestion; local and remote. Local impact includes those signalling messages that are discarded consistent with the local link congestion control strategy. Remote impact constitutes those signaliing messages that are control
16、led at originating signalling points in response to the transfer controlled (TFC) procedure. 2.2.2 Signalling link load and pe ormance measurements Signalling link load and performance measurements are considered appropriate for the network management function and should be provided to the network m
17、anagement center and/or operations support system (see Recommendations E502 and 4.791). It is recommended that these measurements be provided on a five minute basis. Signalling link measurements can be used to anticipate signalling link load/utilization capacity problems in near real time, particula
18、rly when they are used with thresholds. Load measurement counts may be used to determine the anticipated short-term capacity of an individual link. The same measurements can be used to analyze the load balance among links of a link set. In some cases, a major component of the load might be retransmi
19、tted messages, and consequently the count of retransmitted octets can be used to identify this situation. Also important in this set of measurements are the number of messages removed due to signalling link congestion. 2.2.3 Signalling link availability status indicators Status indications of link a
20、vailability can be used to evaluate the potencial for linkset failure. For any linkset with more than one link, a single remaining available link represents a high potential for linkset failure. Out-of-service status on the links of a linkset can be used to determine the vulnerability of the signall
21、ing network to the potential loss of all links in that set, resulting in route unavailability, and the possibility of destination inaccessibility. 2.2.4 Linksethoute availability status indicators A direct signalling route between any two adjacent signalling points is the linkset connecting them. Th
22、e route is said to be available when at least one link in the linkset is available. The loss of all links in a linkset will cause the direction seignalling route between the adjacent points to be unavailable. 2 Recommendation E.415 CCITT RECMN*E.*435 91 4862593 0560580 8 = In the extreme case, multi
23、ple concurrent unavailable routes wiU create a signalling network isolation, which occurs when there is no available signalling route between two adjacent signalling points (SPs). This results in a destination inaccessible condition. The unavailability, restriction and availability of a signalling r
24、oute is communicated by the transfer prohibited (TF), transfer restricted (TFR) and transfer allowed PA) signals, respectively, Network managers must know when these conditions are present and when they have ended. Note - A complete description of these and other internal signalling network manageme
25、nt functions may be found in Recommendation 4.704. 2.2.5 Annex A to this Recommendation contains a listing of Signalling System No. 7 status indicators and load and performance measurements which are considered useful to the network management function. Additional details may be found in Recommendat
26、ions ES02 and Q.791. The listing in Annex A is considered appropriate for a fuily developed signalling network using a mesh network configuration. A selected sub-set of status indicators and measurements may be sufficient for smaller implementations. 2.2.6 User application part status indicators and
27、 load and performance measurements Status indicators of user application part availability should be provided to the network management center and/or its operation support system. Analysis of user application part load and performance measurements may help to identify the source or nature of a probl
28、em and could give advance warning that difficulties could arise if the load increases. Annex A contains a listing of user application part status indicators and load and performance measurements which may be useful to the network management function. Additional details may be found in Recommendation
29、 E.502 and 4.791. 3 Response to common channel signaiing network failures 3.1 When a problem or failure in the common channel signalling network interrupts the flow of tiaffic in the associated switched network, the affected traffic may be diverted by network management controls to conventional sign
30、alling circuits groups. It is preferable that these actions be planned in advance. These plans should identify the modifications to the automatic common channel signalling (CCS) flow control responses which may be required in the exchanges to permit the planned actions to be implemented for example,
31、 to change the normal programmed response to the receipt of a transfer prohibited signal (TFP). As more of the international networks convert to common channel signalling, the availability of conventional signalling circuit groups may become limited. This further increases the need for careful plann
32、ing. 3.2 In the case of catastrophic failure or overload of the common channel signalling network, where the pent-up demand is of such magnitude that the signalling network cannot recover by itself, it may be necessary to suppress some or ail of the traffic being offered to the affected circuit grou
33、ps until the signalling network can recover and stabilize. This can be done by the use of protective network management controls. Traffic can then be reintroduced by a graduai relaxation of the protective controls consistent with observed signalling network performance. Recommendation E.415 3 CCITT
34、RECMN*E-*435 91 W 4862593 0560581 T ANNEX A (to Recommendation E.415) A.1 Signalling System No. 7 signalling network status indicators A.l.l The following indicators of signalling network status are considered important for the function of monitoring signalling network performance. These indicators
35、should be provided to the network management center and/or operations support system when they occur (see Recommendation Q.704): - local automatic changeover/changeback; - start/stop of remote processor outage; - stadstop of signal link congestion; - start/stop of adjacent signalling point inaccessi
36、ble; - start/stop of link set unavailability; - start/stop of route set unavailability; - receipt of transfer controiled message (TFC); - receipt of transfer prohibited message (TFP); - receipt of transfer restricted message (TFR) (national option); - receipt of transfer allowed message WA). A.1.2 I
37、n addition, the following user application part status indicators should be provided. Note - User Application Part availability indicators may be implementation dependent: - - - - start/stop of local SCCP unavailability; start/stop of local ISDN User Part unavailability; start/stop of local TCAP Una
38、vailability; stadstop of local TUP Unavailability. A.2 Signalling System No. 7 signalling network load and performance measurements A.2.1 the volume of information provided in each measurement period. Measurements indicated with an asterisk (*) could be provided by the use of thresholds, if desired,
39、 to reduce A.2.1.1 MTP load and peormance measurements - Per signal link: a) counts of local automatic changeover/changeback; b) duration of signalling link unavailability; c) duration of signalling link unavailability due to remote processor outage; d) counts of remote processor outage events; e) c
40、ounts of local management inhibit; f) duration of local management inhibit; 4 Recommendation E.415 CCITT RECMN*E.*415 91 4862593 O560582 3 = A.2.1.2 number of octets retransmitted; number of message signal units (MSU) transmitted; number of message signal units received; number of signalling link co
41、ngestion events; cumulative duration of signalling link congestion; number of MSUs discarded due to signalling link congestion; counts of TFCs received; counts of TFps received; counts of TFRs received (national option); counts of TFAs received. Per signalling link set: duration of unavailability of
42、 signalling link set; number of signalling link set unavailability events; number of TFps broadast events caused by failure of signalling link set (at STPs only). Per signalling point: counts of events of adjacent SP inaccessible; duration of adjacent SP inaccessible. Per destinarion: counts of unav
43、ailability of route set to a destination or set of destinations; duration of unavailability of route set to a destination or set destinations. SCCP a)* counts of routing failures - ali reasons; b) counts of start of local SCCP unavailable - failure l); c) counts of start of local SCCP unavailable -m
44、aintenance made busy 11; d) counts of local SCCP Unavailable - congestion 1); e) duration of local SCCP Unavailability; f) counts of total messages handled (from local or remote subsystems); g) counts of total messages intended for local subsystems. A.2.1.3 ISUP a) counts of start of local USP Unava
45、ilability - failure; b) counts of start of local ISUP Unavailability - maintenance made busy; c) counts of start of ISUP unavailibility - congestion; d) duration of ISUP unavailability - all reasons; e)* count of total ISLP messages sent; f)* count of total ISUP messages received; These measurements
46、 are system architecture dependent. Recommendation E.415 5 CCITT RECMN*E.*415 71 Lt862.571 0560583 3 g)* count of total unsuccessful attempts; h)* count of unsuccessful call attempts - switching congestion; i)* count of unsuccessful cd attempts - no circuit available; j)* count of unsuccessful call
47、attempts - no route to destination; k)* count of switching congestion signals received (by Originating point code OPC); 1)“ count of no circuit available signals received (by OPC); m)* count of no route to destination signais received (by OPC). A.2.1.4 TCAP a) counts of start of local TCAP unavailab
48、le - failure; b) counts of start of local TCAP unavailable - maintenance made busy; c) counts of start of local TCAP unavailable - congestion; d) duration of local TCAP unavailable - all reasons; e)* counts of total number of TCAP messages sent by the node (by message type); f)* counts of total numb
49、er of TCAP messages received by the node (by mesage type). A.2.1.5 TUP a) Counts of start of local TUP Unavailability - failure; b) counts of start of local TUP unavailability - maintenance made busy; c) counts of start of local TUP unavailability - congestion; d) duration of TUP unavailability - all reasons; e)* count of total Tup messages sent by type of message; f)* count of total Tup messages received by type of message; g)* count of total unsuccessful call attemps; h)* count of unsuccessful call attempts - switching equipment congestion; i)* count of unsuccessful call
