1、INTERNATIONAL TELECOMMUNICATION UNION ITU=T TELECOMMUNICATION STAN DARD IZATION SECTOR OF ITU 1.353 SERIES I: INTEGRATED SERVICES DIGITAL NETWORK Overall network aspects and functions - Performance objectives (08198) Reference events for defining ISDN and B-ISDN performance parameters ITU-T Recommen
2、dation 1.353 (Previously CCIlT Recommendation) COPYRIGHT International Telecommunications Union/ITU TelecommunicationsLicensed by Information Handling ServicesITU-T I-SERIES RECOMMENDATIONS INTEGRATED SERVICES DIGITAL NETWORK GENERAL STRUCTURE Terminology Description of ISDNs General modelling metho
3、ds Telecommunication network and service attributes General description of asynchronous transfer mode Scope General aspects of services in ISDN Common aspects of services in the ISDN Bearer services supported by an ISDN Teleservices supported by an ISDN Supplementary services in ISDN Network functio
4、nal principles Reference models Numbering, addressing and routing Connection types Performance objectives Protocol layer requirements General network requirements and functions Application of I-series Recommendations to ISDN user-network interfaces Layer 1 Recommendations Layer 2 Recommendations Lay
5、er 3 Recommendations Multiplexing, rate adaption and support of existing interfaces Aspects of ISDN affecting terminal requirements SERVICE CAPABILITIES OVERALL NETWORK ASPECTS AND FUNCTIONS ISDN USER-NETWORK INTERFACES INTERNETWORK INTERFACES MAINTENANCE PRINCIPLES B-ISDN EQUIPMENT ASPECTS ATM equi
6、pment Management of ATM equipment I. 100-1.199 I. 1 1 0-1. I 1 9 I. 120-1.129 I. 130-1.1 39 I. 140-1.149 I. 150-1.199 1.200-1.299 I .200-1.209 1.21 0-1.21 9 I .220-1.229 I .230-1.239 I .240-1.249 1.250-1.299 I. 300-1.399 1.31 0-1.31 9 I .320-1.329 1.330-1.339 1.340-1.349 1.350-1.359 1.360-1.369 1.37
7、0-1.399 1.400-1.499 1.420-1.429 1.430-1.439 I .440-1.449 I .450-1.459 I .460-1.469 I .470-1.499 I .500-1.599 1.600-1.699 1.700-1.799 I. 730-1.749 1.750-1.799 For further details, please refer to ITU-T List of Recommendations. COPYRIGHT International Telecommunications Union/ITU TelecommunicationsLic
8、ensed by Information Handling ServicesITU-T RECOMMENDATION 1.353 REFERENCE EVENTS FOR DEFINING ISDN AND B-ISDN PERFORMANCE PARAMETERS Summary This Recommendation is one of the Recommendations (1.350, 1.351 and 1.353) that define general aspects of ISDN performance and provide a basis for the definit
9、ion of specific performance parameters and values in other I-Series and G-Series Recommendations. The ISDN performance parameters are defined in terms of reference events which can be observed at physical measurement points within an ISDN connection. This Recommendation defines the relevant measurem
10、ent points and associated performance-significant ISDN reference events. Source ITU-T Recommendation 1.353 was revised by ITU-T Study Group 13 (1993-1996) and was approved under the WTSC Resolution No. 1 procedure on the 27th of August 1996. Keywords B-ISDN, bit synchronization, entry event, errored
11、 bit, exit event, measurement point, performance, performance-significant reference event, reference event. COPYRIGHT International Telecommunications Union/ITU TelecommunicationsLicensed by Information Handling Services STD-ITU-T RECMN 1-353-ENGL 377b W YBb257L 1623783 252 FOREWORD ITU (Internation
12、al Telecommunication Union) is the United Nations Specialized Agency in the field of telecommunications. The ITU Telecommunication Standardization Sector (ITU-T) is a permanent organ of the ITU. The ITU-T is responsible for studying technical, operating and tariff questions and issuing Recommendatio
13、ns on them with a view to standardizing 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
14、approval of Recommendations by the Members of the ITU-T is covered by the procedure laid down in WTSC Resolution No. 1 (Helsinki, March 1-12, 1993). In some areas of information technology which fall within IT-Ts purview, the necessary standards are prepared on a collaborative basis with IS0 and IEC
15、. NOTE In this Recommendation, the expression “Administration” is used for conciseness to indicate both a telecommunication administration and a recognized operating agency. O IT 1997 All rights reserved. No part of this publication may be reproduced or utilized in any form or by any means, electron
16、ic or mechanical, including photocopying and microfilm, without permission in writing from the ITU. ii Recommendation 1.353 (08/96) COPYRIGHT International Telecommunications Union/ITU TelecommunicationsLicensed by Information Handling Services1 2 3 4 5 5.1 5.2 5.3 5.4 5.5 5.6 5.7 5.8 5.9 5.10 CONTE
17、NTS Page Scope References Terms and definitions . Abbreviations . Performance-significant reference events . Recommendation 4.93 1 (Recommendation 1.45 1) Recommendation 4.92 1 . X.25 layer 2 (LAPB) Recommendation 4.764 . Frame switching . Recommendations 4.293 1 and 4.297 1 Recommendation 4.2762 .
18、Unrestricted digital bearer services 5.10.1 Performance-significant reference events . 5.10.2 The relevant bit of user information Frame relaying B-ISDN ATM layer Recommendation 1.353 (08/96) 1 2 4 5 6 6 8 8 10 10 10 11 11 13 13 13 iii COPYRIGHT International Telecommunications Union/ITU Telecommuni
19、cationsLicensed by Information Handling ServicesRecommendation 1.353 REFERENCE EVENTS FOR DEFINING ISDN AND B-ISDN PERFORMANCE PARAMETERS (revised in 1996) 1 Scope This Recommendation defines the measurement points where the performance of ISDNs and B-ISDNs should be evaluated. It defines the perfor
20、mance-significant reference events that can observed at those measurement points. Specifically, this Recommendation specifies the reference events used in evaluating: - ISDN call processing performance. - B-ISDN X.25 packet performance. - Frame switching performance. - Frame relaying performance. -
21、B-ISDN call processing performance. - - B-ISDN ATM cell transfer performance. Unrestricted digital bearer service performance, 2 References The following Recommendations and other references contain provisions which, through reference in this text, constitute provisions of this Recommendation. At th
22、e time of publication, the editions indicated were valid. All Recommendations 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 listed below. A list of the currently valid ITU-T
23、 Recommendations is regularly published. ITU-T Recommendation 1.350 (1993), General aspects of quality of service and network performance in digital networks, including ISDNs. ITU-T Recommendation 1.35 1 (1 993), Relationships among ISDN performance Recommendations. ITU-T Recommendation 1.356 (1 996
24、), B-ISDN A TM layer cell transfer performance. ITU-T Recommendation 1.361 (1 993, B-ISDN ATM layer speczjkation. ITU-T Recommendation 1.430 (1 995), Basic user-network interface - Layer I specijkation. ITU-T Recommendation 1.45 1 (1 993), ISDN user-network interface layer 3 speccation for basic cal
25、l control. ITU-T Recommendation 1.570 (1 993), Public/private ISDN interworking. ITU-T Recommendation 4.764 (1993), Signalling System No. 7 - ISDN user part signalling procedures. ITU-T Recommendation Q.921 (1 993), ISDN user-network interface - Data link layer specifkation. Recommendation 1.353 (08
26、/96) 1 COPYRIGHT International Telecommunications Union/ITU TelecommunicationsLicensed by Information Handling Services STD-ITU-T RECMN 1.353-ENGL 177b qBb2571 Ob23984 TbL ITU-T Recommendation 4.93 1 (1 993), Digital subscriber Signalling System No. I (DSS I) - ISDN user-network interface layer 3 sp
27、ecjkation for basic call control. ITU-T Recommendation 4.2762 (1 999, General Jirnctions of messages and signals of the B-ISDN user part (B-ISUP) of Signalling System No. 7. ITU-T Recommendation Q.293 1 (1 999, Digital subscriber Signalling System No. 2 (DSS 2). User-network interface (UNI) layer 3
28、specification for basic caWconnection control. ITU-T Recommendation Q.2971 (1999, Digital subscriber Signalling System No. 2 - User-network interface layer 3 specijcation for point-to-multipoint caWconnection control. ITU-T Recommendation X.25 (1 996), Interface between Data Terminal Equipment (DTE)
29、 and Data Circuit-terminating Equipment (DCE) for terminals operating in the packet mode and connected to public data networks by dedicated circuit. ITU-T Recommendation X.75 (1995), Packet-switched signalling system between public networks providing data transmission services. CCITT Recommendation
30、X. 134 (1 992), Portion boundaries and packet layer reference events: basis for dejning packet-switched performance parameters. Terms and definitions For the purposes of ISDN performance Recommendations, the following definitions apply. 3.1 measurement point (MP): A measurement point is located at a
31、n interface that separates either customer equipmentcustomer network (CEQ) or a Switching/Signalling Node (SSN) fkom an attached transmission system at which ITU-recommended protocols can be observed. NOTES 1 The term SSN collectively denotes any equipment that accesses the connection in the transpo
32、rt 2 With regard to the definitions of customer equipment and customer network, see Recommendations 1.430 and 1.570 respectively. 3 As defined, MPs exist at many physical interfaces in a connection. It is not the intention in these Recommendations to speci performance between arbitrary pairs of MPs
33、- particularly pairs within a nation. These Recommendations will only specie the performance of portions delimited by MPTs and MPIs. network under consideration. 4 Recommendation 1.356 locates MPs within the ATM interfaces, see 5.9. 3.2 measurement point T (MPT): A measurement point T is located at
34、an interface associated with a T reference point. This interface separates CEQ from an attached digital section. In order to delimit clearly the national portion and its allocation of performance, the MPT is located at the point that marks the limit of the public network operators responsibility. Th
35、is may be different fkom the ideal location for observing the ITU-recommended protocols. For example, in B-ISDN, the ideal MPs are within the ATM layer. Since a given ATM layer (VP and/or VC) is likely to terminate within CEQ, ATM events will not be directly observable at those termination points. T
36、wo practical methods for measuring at the MPT are: i) locating a physical test set at the MPT and replicating the relevant protocol layers outside of the CEQ; or 2 Recommendation 1.353 (08/96) - COPYRIGHT International Telecommunications Union/ITU TelecommunicationsLicensed by Information Handling S
37、ervicesii) approximating the performance at the MPT by observations made at the nearest convenient point within the network. 3.3 measurement point I (MPI): A measurement point I is located at an interface that terminates a transmission system at an International Switching Centre (ISC). The exact loc
38、ation of the MPI depends on the connection type and is specified, for each connection type, in the associated Network Performance Recommendation (see Note). For each MPT within a nation, the set of associated MPls is the set of MPIs within the same nation. MPTs and individual associated MPIs delimit
39、 portions of an end-to-end ISDN connection for which performance objectives are specified. NOTE - The MPT and MPI for B-ISDN are defined in 5.9. 3.4 ISDN reference event: An ISDN reference event is the transfer of a discrete unit of control or user information encoded in accordance with ITU-recommen
40、ded protocols across an MP. Specified information units and associated resulting protocol states are identified by an event code used for reference in defining performance parameters. The resulting state in turn establishes which reference events can occur subsequently. Two classes of reference even
41、ts are distinguished: exit events and entry events. 3.5 exit event: An exit event occurs when a unit of control or user information crosses the MP exiting the SSN or CEQ into the attached transmission system. 3.6 entry event: An entry event occurs when a unit of control or user information crosses t
42、he MP entering the SSN or CEQ from the attached transmission system. If retransmissions occur, the exit event occurs with the first transmission and the entry event occurs with the last transmission. NOTE - For practical measurement purposes, reference events can be observed at a physical location t
43、hat differs from the actual MP. This physical location should, however, be as near as possible to the MP. In cases where reference events are monitored at a physical interface, the time of occurrence of an actual exit event can best be approximated by the observation of the first bit of the unit of
44、control or user information out of the SSN or CEQ. The time of occurrence of an entry event can best be approximated by the observation of the last bit of the unit of control or user information into the SSN or CEQ. Figures 1 and 2 illustrate these concepts. 1 The differences in MPI location among c
45、onnection types are a result of the need to ensure consistency between the emerging ISDN performance Recommendations and existing Recommendations that speci the performance of service-dedicated networks. As circuit mode, packet mode, and other transfer capabilities are more fully integrated into ISD
46、Ns, it may be possible to identie common measurement points. Recommendation 1.353 (08/96) 3 COPYRIGHT International Telecommunications Union/ITU TelecommunicationsLicensed by Information Handling ServicesNational . * Ti 81 361 0-91 ISDN performance apportionment boundary SSN CEQ or FIGURE 1A.353 Exa
47、mple ISDN connection showing associated performance apportionment boundaries ITU protocols -b SSN f- Transmission System -+ Exit events for A, D Entry events for 6, C f- m nom TI 813600-91 FIGURE 2I.353 Entry and exit events 4 Abbreviations For the purposes of this Recommendation the following abbre
48、viations are used. AAL ATM Adaptation Layer ATM Asynchronous Transfer Mode CEQ Customer equipmenikustomer network HEC Header Error Control ISC International Switching Centre MP Measurement Point 4 Recommendation 1.353 (08/96) COPYRIGHT International Telecommunications Union/ITU TelecommunicationsLic
49、ensed by Information Handling Services MPI MPT SSN vc VCI VP VPI 5 Rec. 4.93 1 (Rec. 1.451) Rec. 4.921 X.25 layer 3 STD-ITU-T RECMN 1-353-ENGL L77b 48b2571 Ob23787 770 5.1 5.2 Rec. X. 134 Measurement Point I Measurement Point T Switching/Signalling Node Virtual Channel Virtual Channel Identifier Virtual Path Virtual Path Identifier X.25 layer 2 (LAPB) Rec. X.75 Rec. 4.764 Performance-significant reference events 5.3 Rec. X. 134 5.4 Performance-significant reference events are those reference events useful in defining performance parameters. Table 1 i
