1、CCITT RECNN*E-Y3L 92 m 486259L 0573574 030 m INTERNATIONAL TELECOMMUN CATION UN ION CCITT E.43 THE INTERNATIONAL TELEGRAPH AND TELEPHONE CONSULTATIVE COMMITTEE TELEPHONE NETWORK AND ISDN QUALITY SERVICE, NETWORK MANAGEMENT AND TRAFFIC ENGINEERING SERVICE QUALITY ASSESSMENT FOR DELAYS CONNECTION SET-
2、UP AND RELEASE Recommendation E.431 Geneva, 1992 CCITT RECMN*E.433 92 m 4862573 0573575 T77 m INTERNATIONAL TELECOMMUN CATION UN ION CCITT E.431 THE INTERNATIONAL TELEGRAPH AND TELEPHONE CONSULTATIVE COMMITTEE TELEPHONE NETWORK AND ISDN QUALITY SERVICE, NETWORK MANAGEMENT AND TRAFFIC ENGINEERING SER
3、VICE QUALITY ASSESSMENT FOR DELAYS CONNECTION SET-UP AND RELEASE Recommendation E.431 I Geneva, 1992 - - CCITT RECMN*E-431 92 W 4862591 057357b 903 W FOmWORD The CCIIT (the International Telegraph and Telephone Consultative Committee) is a permanent organ of the International Telecommunication Union
4、 (ITU). CCIIIT 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 CCIIT which meets every four years, establishes the topics for study and approves Rec
5、ommendations prepared by its Study Groups. The approval of Recommendations by the members of CCIIT between Plenary Assemblies is covered by the procedure laid down in CCIT Resolution No. 2 (Melbourne, 1988). Recommendation E.431 was prepared by Study Group II and was approved under the Resolution No
6、. 2 procedure on the 16th of June 1992. CCI” NOTE In this Recommendation, the expression “Administration” is used for conciseness to indicate both a telecommunication Administration and a recognized private operating agency. O IT 1992 All rights reserved. No part of this publication may be reproduce
7、d or utilized in any form or by any means, electronic or mechanical, including photocopying and microfilm, without permission in writing from the ITU. CCITT RECNN*E-431 72 m 4862571 0573577 84T m Recommendation E.431 SERVICE QUAJJTY ASSESSMENT FOR CONNECTION SET-UP AND RELEASE DELAYS 1 Introduction
8、The communications function of “connection establishment” is influenced by how quickly end-to-end connections are implemented and how quickly the network components are returned to a ready to serve state. It is to be noted that this Recommendation considers a network provider view of service quality
9、 according to the framework given in Recommendation E.430. This Recommendation addresses service quality assessment with respect to connection set up and release delays in the public switched telephone network (PSTN), and the integrated services digital network (ISDN) as it evolves from the PSTN. Ne
10、twork performance design parameters from a grade of service and traffk engineering viewpoint for PSTN are given in the E.500-Series of Recommendations and for circuit switched services in the ISDN are given in Recommendation E.721. 2 Considerata The user (customer) is the primary supervisor of servi
11、ce quality. The users point of view can be properly expressed by general parameters which take into account that this user is mainly interested in the end-to-end aspect of these parameters. From the network providers point of view, the primary function of the network is to carry communications which
12、 produce revenue. To this end, the network should be properly designed and operated. Network providers do not control ali aspects which influence the user perception of the general parameters and are primarily only able to influence the user perception via those network components which influence th
13、e general parameters. It should be noted that factors outside the direct control of network providers affect customer-perceived connection Set-up delays. These factors, which are related to customer equipment and behaviour, may produce significant variations in connection Set-up delays. They include
14、, but are not limited to: - automatic dialling devices; - telephones that use either pulse or tone dialling; - PABXS. From the technical point of view, the three cases below are considered: i) voice service in the PSTN, ii) non-voice services in the PSTN, iU) voice and non-voice services in the ISDN
15、 as it evolves from the PSTN. The concepts forming the basis for the traditional telephone service parameters given in this Recommendation, can be extended to include other network and service combinations. Recommendation E.431 1 3 Definitions1) start dial signal delay (SDSD) Time interval between o
16、ff-hook and reception of start dial signal. post dialling delay (PDD) Time interval between the end of user or terminal equipment dialling and the reception of the appropriate caU clearing delay (CCD) Time interval between the clearance signal from the end users, and the networks return to ready to
17、serve network response. state. 4 Service and networks factors affecting delay measurements It should be noted that customers perception of start dial signal delay, post dialling delay and call clearing delay are affected more by variations rather than by absolute values. These delays will also be in
18、fluenced by the customer and/or customer provided equipment behaviour, or the types of networks that are interconnected, and in some cases by types of service that are being carried by the network. Examples of this, would be facsimile protocols or other voice band data calis using automatic clear do
19、wn methods. When setting objectives for these services, consideration must be given to the types of signalling and/or switching equipment used for processing of the calls. 4.1 Start dial signal delay (SDSD) Start dial signal delay (SDSD) is affected by: i) the switching technology employed at the us
20、ers originating call stage; ii) the traffk level being experienced in the users originating switching equipment, at the time the call attempt commences; iii) the users calling priority level. Customers perception of SDSD is very sensitive to the type of technology and therefore, no definitive quanti
21、ty can be established since the amount of delay acceptable to the users must be in direct relationship to the type of equipment employed and to some extent to the traffic level being experienced on the calling stage at the time of measurement. However, SDSD for new types of exchanges would, normally
22、, be of the order of a few hundred milli-seconds. 4.2 Post dialling delay (PDD) Post dialling delay can be influenced by customer dialling behaviour and/or the types of network, e.g. variable number lengths, that are interconnected, and in some cases, by the type of service that is being carried on
23、the networks. Examples of the last item would be the freephone service and country direct service where a data base access and/or digit manipulation, must be accomplished. When setting objectives for these services, consideration must be given to the extra steps necessary for processing such calls.
24、These definitions are not aligned with the Recommendation E.600 at this time. 2 Recommendation E.431 CCITT RECMN*E-Y3L 92 YBb259L 0573579 bL2 W Post dialling delay will vary according to the transmission media used, switching stages met and signalling system types encountered. The PDD of any end-to-
25、end connection will be governed by the collective delays of the originating, international and terminating networks. To compute the range of total PDD, the following computation should be made: Total PDD = Originating network + International network + Terminating network contribution to PDD contribu
26、tion of PDD contribution to PDD The international contribution may include transit routes with changes in signalling types and switching stage. The average contribution to PDD of signalling types are: - CCITNo. 5: 5seconds - CCITNo.6: 3seconds - - CCIITRS: 5seconds CCIIIT No. 7: less than 3 seconds
27、(for further study) 4.3 Call clearing delay (CCD) CCD is subject to the network technology, equipment configurations and the sequence of cali release. Under normal circumstances it will follow the clear down of ali parties (the end-to-end connection) and is approximately one second. 5 General guide
28、to measurement techniques in general, these parameters (SDSD, PDD, CCD) can be measured using test calls and/or by monitoring live traffic. For additional information on field data collection and evaluation, see Chapter II, Section 3, of CCITI Quaity of Service Handbook (1984), and the 1992 Quality of Service and Network Performance Handbook. Recommendation E.431 3
