CEPT T GSI 03-08 2E-1987 Call Processing Delays in ISDN Circuit- Switched Connections《在ISDN电路交换连接中呼叫处理延迟》.pdf

1、D 232b4L4 0005b04 L D I_* + CEPT T/GSI*03-O/ 2E .I TIOSI 03-0812 E Page 1 Recommendation T/GSI 03-08/2 (Nice 1985, revised by correspondence, June 1987) CONNECTION PROCESSING DELAYS IN ISDN CIRCUITSWITCHED CONNECTIONS Recommendation proposed by the Special Group Integration (GSI) Revised text of the

2、 Recommendation adopted by the “Telecommunications” Commission: “The European Conference of Posts and Telecommunications Administrations, considering - the common CEPT approach to the ISDN and general CEPT assumptions and policies for the evolution towards ISDN, - the I. Series Recommendations of th

3、e CCITT, as well as other CCITT Recommendations on ISDN, to which - the need for CEPT Administrations to have more precise answers to their specific European requirements, i.e. - the need for CEPT Administrations to have as a base a comprehensive set of Recommendations, in order to CEPT Administrati

4、ons have contributed most significantly, to select and further define material from CCITT Recommendations, promote and strengthen European harmonisation, O recommends to the member Administrations of the CEPT that they evolve their telecommunication networks towards ISDN according to the guidelines

5、and specifications given in the attached text.” I Edition of October 31, 1987 1 CEPT T/GSI*03-08/ 2E 232b4L4 0005605 3 TIGSI 03-0812 E Page 2 1. GENERAL 1.1. The values for connection processing delays established in this Recommendation are to be considered as design objectives in network planning a

6、nd system design together with the forecast trafic for the planned period. The actual delay performance that will be obtained will depend on the accuracy of the trafic estimations. Normally the actual delay performance will not coincide with the one used as a basis for planning. Furthermore, if the

7、network is planned for the traffic forecast, the network may be better at the beginning than the design values states, worsening gradually to the end of the planning period as trafic increases. The non-coincide of busy hours in the originating and destination national networks as well as in the inte

8、rnational network will improve the overall delay performance with respect to the sum of the nominal delays of the constituent parts of the connection. The overall delay values of the network have to be divided into subvalues for each network part (switching centers and transmission elements). These

9、subvalues together with the trafic volume and its characteristics are the basis for the designer of switching and transmission systems. 1.2. Delays are specified under normal busy hour load and high load conditions of all switching centers involved in the connection. These delays are expressed where

10、 appropriate in terms of mean and 95% probability values. The term “mean” is taken to be the expected value of delay in the statistical sense. The “95% probability” value is taken as the limit within which 95% of the delays fall. 1.3. Connection processing delays are defined for a basic call which d

11、oes not include any supplementary services. 1.4. Connection processing delays are specified for the - connection Set-up, and - disconnection phase. The parameters characterizing the performance of the connection set-up phase are defined as %onnedon set-up delay” and “calling party alerting delay”. T

12、he parameters characterizing the performance of the disconnect phase are defined as “disconnect delay” and “clearing party release delay”. For circuit-switched connections no processing delays are specified for the information transfer phase. The transmission delay (to be specified in another Recomm

13、endation) will include all propagation delays, transmission element delay and (transmission) delays through the digital circuit switches. Connection processing delays are specified to be observed at the S/T-reference-points of both ends involved in a connection. 1.5. 1.6. An illustration of the conn

14、ection control signals considered is given in Figure 1 (T/GSI 03-08/2). 2. CONNECTION SET-UP PHASE PARAMETERS 2.1. Overall connection connect delay The overall connection Set-up delay is the time interval between the crossing of the set-up message and the crossing of the connect message at the S/T-r

15、eference-point of the calling end. The overall connection set-up delay should not exceed the values given in Table 1 (T/GSI 03-08/2). (Figures for further study.) If on any connection the overall connection set-up delay exceeds X seconds, some user equipment in non-voice communications may consider

16、the connection to have failed. The probability of its occurrence is the subject of another Recommendation on connection failures due to network malfunction. In case of connection failures due to congestion (blocking), the blocking case should be indicated by the receipt of an appropriate message wit

17、hin X seconds. Edition of October 31, 1987 CEPT T/GSI*03-08/ 2E W 232b414 0005bOb 5 Connection Type A 2.2. Access National Intern. National Access (calling) transit transit transit (called) 1212121212 Statistic Mean 95 yo 2.3. 3. 3.1. 3.2. Connection Type I Statistic I Delay values for reference con

18、figuration I I L I 195% I I l B I Mean I I I TIGSI 03-0812 E Page 3 Table 1 (T/GSI 03-08/2). Overall connection set-up delay (milliseconds). Notes to Table I (TIGSI 03-0812) : 1. Delay values will be specified under normal busy hour load and high load conditions. 2. Reference configurations type 1 a

19、nd type 2 may correspond to “moderate length” and “longest length” (see Recommendation T/GSI 03-05 Figures 2 and 3). 3. Under A, B . the relevant connection types as specified in Recommendation T/GSI 03-04 have to be inserted. Network connection Set-up delay per connection element The CONNECTION set

20、-up delay for each connection element is defined in the same way (timewise) as in 2.1. for the overall CONNECTION Set-up delay. Reference points for the boundaries for each connection element are shown in Recommendation T/GSI 03-05. At the boundaries of each connection element the relevant signallin

21、g messages of the signalling system have to be assumed. The contribution from each connection element to the overall connection set-up delay should not exceed the values given in Table 2 (T/GSI 03-08/2). (Figures for further study.) Table 2 (T/GSI 03-08/2). Contributions to overall connection set-up

22、 delay (milliseconds). Calling party ALERTING delay (applicable in case of manually answering terminals) The calling party ALERTING delay is defined as the time interval between the crossing of the set-up message and crossing of the alerting message at the S/T-reference-point of the calling station.

23、 The distinction between “overall alerting delay” and “alerting delay for each connection element” and also the provision of appropriate tables is similar to that described for connection set-up delay in 2.1. and 2.2. above. DISCONNECT PHASE PARAMETERS DISCONNECT delay For the cleared party DISCONNE

24、CT delay may be defined as the time interval between the crossing of the disconnect message at the S/T-reference-point of the clearing end and the crossing of the disconnect message at the S/T-reference-point of the cleared end. Distinction between “overall disconnect delay” and “disconnect delay fo

25、r each connection element” and also the provision of appropriate tables may be developed accordingly as for connection set-up delay. Clearing party RELEASE delay Clearing party RELEASE delay is the time interval between the crossing of the disconnect message and the crossing of the release message a

26、t the S/T-reference-point of the clearing end. Since the release message is sent by the exchange the clearing end is connected to only the access connection element contributing to this delay and the distinction between “overall delay” and “connection element delay” is not relevant. Edition of October 31, 1987 i CEPT T/GSI*03-08/ 2E H 2326434 0005607 7 M TIOSI 03-0812 E Page 4 I l I 1- I I i l a i Edition of October 31, 1987