1、CCITT RECMN*I.352 (REV*3) 93 4862593 0580639 043 INTERNATIONAL TELECOMMUNICATION UNION ITU-T TELECOMMUNICATION STANDARDIZATION SECTOR OF ITU 1.352 (03/93) INTEGRATED SERVICES DIGITAL NETWORK (ISDN) OVERALL NETWORK ASPECTS AND FUNCTIONS NETWORK PERFORMANCE OBJECTIVES FOR CONNECTION PROCESSING DELAYS
2、IN AN ISDN I ITU-T Recommendation 1.352 (Previously “CCITT Recommendation”) COPYRIGHT International Telecommunications Union/ITU TelecommunicationsLicensed by Information Handling ServicesCCITT RECMN*I*352 (REV*L) e13 W 486259L 0580640 Bb5 FOREWORD The IT Telecommunication Standardization Sector (IT
3、-T) is a permanent organ of the International Telecom- munication Union. The ITU-T 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 World Telecommunication Standardizati
4、on Conference (WTSC), which meets every four years, established the topics for study by the ITU-T Study Groups which, in their tum, produce Recommendations on these topics. IT-T Recommendation 1.352 was revised by the IW-T Study Group XVIII (1988-1993) and was approved by the WTSC (Helsinki, March 1
5、-12, 1993). NOTES 1 As a consequence of a reform process within the International Telecommunication Union (IT), the CCITT ceased to exist as of 28 February 1993. In its place, the IT Telecommunication Standardization Sector (ITU-T) was created as of 1 March 1993. Similarly, in this reform process, t
6、he CCIR and the IFRI3 have been replaced by the Radiocommunication Sector. In order not to delay publication of this Recommendation, no change has been made in the text to references containing the acronyms “CCITT, CCIR or IFRB” or their associated entities such as Plenary Assembly, Secretariat, etc
7、. Future editions of this Recommendation will contain the proper terminology related to the new ITU structure. 2 telecommunication administration and a recognized operating agency. In this Recommendation, the expression “Administration” is used for conciseness to indicate both a O ITU 1993 All right
8、s 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. COPYRIGHT International Telecommunications Union/ITU TelecommunicationsLicensed by Informatio
9、n Handling Services1 2 3 CCITT RECMN*I.352 (REV*L) 93 W 4862.573 0580645 7TL CONTENTS General . 1.1 Introduction 1.2 Reference model . 1.3 Measurement 1.4 Network conditions . 1.5 User delay . 1.6 Allocation . 1.7 Basic connection . 1.8 Phases . Purpose Connection processing delays in ISDN circuit-s
10、witched connections 3.1 Connect phase parameters . 3.2 Disconnect phase parameters Annex A -Worst case reference connections for circuit switched connection types . A.l General . A.2 Worst case reference connections Annex B - Calculation of values of connection processing performance parameters B.l
11、Methodology . B.2 Example . Page 1 1 2 2 2 3 3 3 3 3 3 3 9 15 15 15 16 16 17 COPYRIGHT International Telecommunications Union/ITU TelecommunicationsLicensed by Information Handling ServicesCCITT RECRN*I-352 (REVx1) 73 4862571 0580642 638 m Recommendation I352 NETWORK PERFORMANCE OBJECTIVES FOR CONNE
12、CTION PROCESSING DELAYS IN AN ISDN (Melbourne, 1988; revised Helsinki, 1993) 1 General 1.1 Introduction This Recommendation provides network performance objectives for connection processing delays. The parameter values specified include the effects of both congestion and network failures and apply f
13、or an exclusively ISDN connection established by means of CCITT protocols 4.93 1 (DSS i) and Q.764 (ISUP). The network performance objectives provided in this Recommendation are based on the concept of network performance which is defined in Recommendation 1.350 (General aspects of Quality of Servic
14、e and network performance in digital networks, including ISDN). In addition to Recommendation 1.350 the following Recommendations also contain material that either provides background for or are relevant to this Recommendation: 1.324 1.325 Q.41 Q.543 4.706 Q.709 Q.764 4.766 Q.931 G.lO1 E. 172 E.721
15、ISDN Network Architecture Reference configurations for ISDN connection types Mean one-way propagation time Digital exchange performance design objectives Message transfer part signalling performance Hypothetical signalling reference connection Signalling Procedures Performance objectives in the ISDN
16、 applications ISDN user-network interface layer 3 specification for basic call control The transmission plan ISDN routing plan Network grade of service parameters and target values for circuit-switched services in the evolving ISDN The relation with Recommendation E.721 is particularly important. Th
17、e major distinctions between this Recommendation and Recommendation E.721 are: - This Recommendation identifies network performance objectives observable at specified measurement points which are located at specified measurement points and include the effects of both congestion and network failures.
18、 Recommendation E.721 GOS values are intended to be used for network dimensioning and thus consider the network to be in a state where all network components are fully operational. Performance objectives of this Recommendation recommend the performance that worst case reference connections should ac
19、hieve (see NOTE). On the other hand, Recommendation E.721 parameters are used for network dimensioning and therefore traffic weighted averages of the connection type are employed. - NOTE - Connections longer than the worst case reference connection are not covered by this Recommendation. Such very l
20、ong connections may only apply in very unusual cases. Recommendation 1.352 (03/93) 1 COPYRIGHT International Telecommunications Union/ITU TelecommunicationsLicensed by Information Handling Services- The recommended values of this Recommendation apply for an exclusively ISDN connection established by
21、 means of CCITT protocols Q.93 1 (DSS 1) and Q.764 (ISUP). Recommendation E.721 recommended values allow for additional delays from non-ISUP established connections which may be present during the ISDN evolution. 1.2 Reference model The reference model provided in Recommendation 1.325 was used to pr
22、ovide a baseline reference configuration. The network portion boundaries defined in Recommendation 1.325 correspond to the measurement points (MPs) used in this Recommendation as follows: r- 1.325 -r 1.352 -1 For the determination of values a worst case re,rence connection was usei Recommendations G
23、.lO1 am G, 39 were considered for this worst case reference connection. Annex A contains examples of worst case reference connections that can be used to test the objectives specified in this Recommendation. Annex B provides an example for the calculation of the overall connection Set-up delay. NOTE
24、S 1 2 All values specified in this Recommendation were rounded after a calcuiation along that example. This Recommendation does not take into account private networks. In case of private networks connected to the ISDN the recommended values refer to the interface at the T reference point. The interf
25、ace at the S reference point applies when the S and T reference point is coincident. 1.3 Measurement Ail parameter values are specified at measurement points. These values are measured at measurement points (exchange interface Vi or V4 at the S reference point or exchange interface V3 at the T refer
26、ence point and exchange interface A or B located at the national side of an ISC) using call processing performance-significant reference events as defined in this Recommendation for connections established using CCIT protocols Q.931 (DSS 1) and Q.764 (ISUP). 1.4 Network conditions The values for del
27、ay given in this Recommendation include an allowance for the effects on delay that might be introduced by high traffic load during a nominal busy hour (see Note). Consideration was given to the possibility that individual busy hours might not be coincident. The values also include the effects of net
28、work component failures. The specified values do not apply under conditions of network unavailability. These delays are expressed in terms of mean and 95% probability values. NOTE - In cases where the actual traffic load leads to an overload condition in the network, the recommended delay values are
29、 not covered by this Recommendation. 2 Recommendation 1.352 (03193) COPYRIGHT International Telecommunications Union/ITU TelecommunicationsLicensed by Information Handling ServicesCCITT RECMN*I-352 (REV*l) 93 W 4Bb2591 0580644 400 = 1.5 User delay Values are provided for measurements made at a singl
30、e measurement point as well as measurements made between two measurement points. This allows for calculations that would avoid inclusion of any delay that might be introduced by users or user equipment. 1.6 Allocation Overall connection processing delays between interfaces at the S reference point o
31、r the T reference point can be divided into sub-values for national and the international network fabric. The national and the international network fabric is defined in Recommendation 1.325. 1.7 Basic connection Connection processing delays are only defined for a basic connection and therefore do n
32、ot provide for any effects that might be introduced by supplementary services. 1.8 Phases Connection processing delay values are specified for the connection set-up and disconnection phase. 2 Purpose The purpose of this Recommendation is to provide values for connection processing delays that can be
33、 used as a basis for network planning and system design. Quality of Service information should be provided to the user after mapping network performance into user-oriented expressions. 3 Connection processing delays in ISDN circuit-switched connections The values for the connection processing delay
34、parameters bave been determined, taking into account that: - the calling access link; - - - - the internodal links; - - the connected access link the connection processing at the originating local exchange; the connection processing at transit exchanges; the usage of signalling transfer points (STP)
35、; the connection processing at the terminating local exchange; and cause delay. These values are representative for all terrestrial connections and also for connections involving a satellite in an internodal link dowing a smaller number of transit exchanges in that connection. 3.1 Connect phase para
36、meters 3.1.1 Connection Set-up delay Connection Set-up delay is defined first based on observations at a single measurement point, MFi (See Note) as shown in Figure 1, and then between two measurement points (MPj,MPj). In the former case, the connection Set-up delay includes the delay for all connec
37、tion elements on the called user side of h4Pj and the terminal device. In the latter case, the connection Set-up delay includes only the delay between MFi and MPj. Connection Set-up delay is defined using performance-significant reference events. Table i identifies the performance-significant refere
38、nce events and the Recommendation 1,352 (03/93) 3 COPYRIGHT International Telecommunications Union/ITU TelecommunicationsLicensed by Information Handling ServicesCCITT RECMN*I*352 (REV*UL) 93 S 4862593 0580b45 347 - - resulting cai1 states for I.4WQ.931 connection processing messages. Table 2 identi
39、fies the performance-significant reference events and the resulting call states for the relating Signalling System No. 7 user part messages defined in Recommendation Q.764. - - NOTE - MPi is one of the foliowing measurement points: MFT1, MPIi, MPI2, MPT2. User Access CE International transit CE Acce
40、ss CE User TI 81 371 O-91fd01 FIGURE 1A.352 General reference configuration (based on the International ISDN reference configuration in Recommendation 1.325) 3.1.1.1 Definition of connection set-up delay observed at a single measurement point connection Set-up delay at a single measurement point, MP
41、i, is defined using two call processing performance- significant reference events. Table 1 identifies the performance-significant reference events and the resulting call states for 1.45UQ.931 connection processing messages. Table 2 identifies the performance-significant reference events and the resu
42、lting call states for the relating Signalling System No. 7 user part messages defined in Recommendation Q.764. Connection Set-up delay is the length of time that starts when a SETUP or the last address information message creates a performance-significant reference event at mi, and ends when the cor
43、responding CONNECT message returns and creates its performance-significant reference event at MPi. Connection Set-up deiay observed at a single measurement point = (12 - 11) where 11 is the time of occurrence starting performance-significant reference event t2 is the time of occurrence for the endin
44、g performance-significant reference event. The transfer of the I.4511Q.931 messages and their corresponding user-part messages of Signalling System No. 7 is shown in Figure 2 along with measurement points. The specific performance-significant reference events used in measuring connection Set-up dela
45、y are shown in Table 1. NOTE - “Set-up” does not imply a through connection or capability for infomation transfer has been established. 4 Recommendation 1.352 (03D3) COPYRIGHT International Telecommunications Union/ITU TelecommunicationsLicensed by Information Handling ServicesCCITT RECMN*I-352 (REV
46、*l) 93 ssl 48b2591 0580646 283 m1 WTl m2 TABLE 1fi.352 Performance-significant reference events for measuring connection Set-up delay Pla (en bloc) P6b P3 (overlap sending) P6b Plb P6a Measurement point I WIl m2 Performance-significant reference event Starting event code I Ending event code Slb S3b
47、Sla S3a I NOTE - En bloc and overlapiending options at thecalling interface at the S or T reference pz I di International poition National porum IAM ANM D link to signdling MPT, MPI 1 MP12 MPT2 d Q.921, Q.931 Signalling Q.764 Signalling NOTE - Needed if voice call. FIGURE 2n.m Connection set-up dela
48、y 1 71 813720-91/d02 Recommendation 1.352 (03/93) 5 COPYRIGHT International Telecommunications Union/ITU TelecommunicationsLicensed by Information Handling ServicesCCITT RECMN*I.352 (REV*1) 93 4862591 0580b47 LLT W Statistic Mean 3.1.1.2 The connection Set-up the actual target values are for further
49、 study. The set-up delay in the international network fabric should not exceed the values given in Table 3. 6 Recommendation 1.352 (03/93) COPYRIGHT International Telecommunications Union/ITU TelecommunicationsLicensed by Information Handling ServicesCCITT RECMN*I-352 (iiEV*L) 93 4862571 0580b48 05b = Statistic TABLE 3h.352 Connection setup delay Connection Set-up delay for the international network fabric Mean 95% 2900 msa) 3600 msa) I Mean I 1700 msa) 2300 msa) I 95% I a) NOTE - The delays are derived from Table 29/Q.543 and Table 4/Q.709 assuming a processing intensive
