1、 STD-ITU-T RECMN 1.355-ENGL 2000 D Y8b2592 Ob85702 348 INTERNATIONAL TELECOMMUNICATION UNION ITU-T TELECOMMUNICATION STANDARDIZATION SECTOR OF ITU 1.355 (1 0/2000) SERIES I: INTEGRATED SERVICES DIGITAL NETWORK Overall network aspects and functions - Performance objectives ISDN 64 kbitls connection t
2、ype availability performance ITU-T Recommendation 1.355 (Previously CCITT Recommendation) COPYRIGHT International Telecommunications Union/ITU TelecommunicationsLicensed by Information Handling ServicesSTD-ITU-T RECMN 1.355-ENGL 2000 4862571 Ob85703 284 ITU-T I-SERIES RECOMMENDATIONS INTEGRATED SERV
3、ICES DIGITAL NETWORK 3ENERAL STRUCTURE Terminology Description of ISDNs General modelling methods Telecommunication network and service attributes General description of asynchronous transfer mode SERVICE CAPABILITIES Scope General aspects of services in ISDN Common aspects of services in the ISDN B
4、earer services supported by an ISDN Teleservices supported by an ISDN Supplementary services in ISDN OVERALL NETWORK ASPECTS AND FUNCTIONS Network functional principles Reference models Numbering, addressing and routing Connection types Performance objectives Protocol layer requirements General netw
5、ork requirements and functions Application of I-Lettres Recommendations to ISDN user-network interfaces Layer I Recommendations Layer 2 Recommendations Layer 3 Recommendations Multiplexing, rate adaption and support of existing interfaces Aspects of ISDN affecting terminal requirements INTERNETWORK
6、INTERFACES MAINTENANCE PRINCIPLES ATM equipment Transport functions Management of ATM equipment ISON USER-NETWORK INTERFACES B-ISDN EQUIPMENT ASPECTS 1.110-1.119 I. 120-1.129 I. 130-1.139 I. 140-1.149 I. 150-1.199 I .200-I. 209 1.21 0-1.21 9 I .220-1.229 1.230-1.239 I .240-1.249 I .250-1.299 I .310-
7、I. 3 1 9 I. 320-1.329 I .330-1.339 I. 3404.349 1.350-1.359 I. 3604.369 1.370-1.399 1.420-1.429 I .430-1.439 1.440-1.449 I .450-1.459 I .460-1.469 1.470-1.499 1.500-1.599 1.600-1.699 I. 7304.739 I. 7404.749 I. 750-1.799 For further details, pleuse refer to ITU-T List of Recommendations. COPYRIGHT Int
8、ernational Telecommunications Union/ITU TelecommunicationsLicensed by Information Handling Services - - STD-ITU-T RECMN 1.355-ENGL 2000 4Bb2591 Ob85704 110 m ITU-T RECOMMENDATION 1.355 ISDN 64 kbit/s CONNECTION TYPE AVAILABILITY PERFORMANCE Summary The purpose of this Recommendation is to define par
9、ameters and objectives describing availability performance of the following 64 kbitk ISDN connection types: 0 Packet-Switched Connection Type (PSCT); Circuit-Switched Connection Type (CSCT); Dedicated-Circuit Connection Type (DCCT). Connection types are categorized according to their characteristics
10、 into different portion types, with Measurement Points (MPs) delimiting each portion. Parameters defined are Connection Portion Availability (A) and Mean Time Between Connection Portion Outages (Mo). Availability performance is described by speciing worst-case objectives for these parameters for eac
11、h portion type. These objectives are intended to assist in network design and planning by limiting the aggregate effect of network impairments, including blocking, equipment failures and transmission errors, on ISDN network availability. In order to define the availability function for the different
12、 connection types, the approach taken is to specify a set of performance decision items and associated outage criteria. A two-state availability model is used whereby the availability state of a portion over a specific measurement interval is determined by comparing observed performance with the par
13、ticular outage criteria. Guidance is provided on practical measurement of the parameters, including statistical techniques for sampling. Examples are also included illustrating how representative end-to-end availability performance can be calculated using the observed performance of the individual p
14、ortions. Source ITU-T Recommendation 1.355 was revised by ITU-T Study Group 13 (1997-2000) and was approved by the WTSA (Montreal, September 27-October 6,2000). COPYRIGHT International Telecommunications Union/ITU TelecommunicationsLicensed by Information Handling ServicesSTD-ITU-T RECMN 1.355-ENGL
15、2000 b 48b259L Ob85705 O57 FOREWORD 1TU (International 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, oper
16、ating and tariff questions and issuing Recommendations on them with a view to standardizing telecommunications on a worldwide basis. The World Telecommunication Standardization Assembly (WTSA), which meets every four years, establishes the topics for study by the ITU-T Study Groups which, in their t
17、urn, produce Recommendations on these topics. The approval of Recommendations by the Members of the ITU-T is covered by the procedure laid down in WTSA Resolution 1. In some areas of information technology which fall within ITU-Ts purview, the necessary standards are prepared on a collaborative basi
18、s with IS0 and IEC. NOTE In this Recommendation, the expression “Administration“ is used for conciseness to indicate both a telecommunication administration and a recognized operating agency. INTELLECTUAL PROPERTY RIGHTS The ITU draws attention to the possibility that the practice or implementation
19、of this Recommendation may involve the use of a claimed Intellectual Property Right. The ITU takes no position concerning the evidence, validity or applicability of claimed Intellectual Property Rights, whether asserted by ITU members or others outside of the Recommendation development process. As o
20、f the date of approval of this Recommendation, the ITU had not received notice of intellectual property, protected by patents, which may be required to implement this Recommendation. However, implementors are cautioned that this may not represent the latest information and are therefore strongly urg
21、ed to consult the TSB patent database. O ITU 2001 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. COPYRIGHT International Telecommun
22、ications Union/ITU TelecommunicationsLicensed by Information Handling Services- - STD-ITU-T RECMN 1.355-ENGL 2000 = 4862591 0685706 T93 CONTENTS 1 1.1 1.2 1.3 1.4 1.5 1.6 2 2.1 2.2 2.3 3 3.1 3.2 3.3 4 4.1 4.2 4.3 Introduction Purpose . Scope Abbreviations . Related Recommendations . Methodology of a
23、vailability specification Organization of this Recommendation . ISDN 64 kbits packet-switched connection type (PSCT) availability performance . PSCT availability function . PSCT availability parameters . PSCT availability objectives ISDN 64 kbWs circuit-switched connection type (CSCT) availability p
24、erformance . CSCT availability function . CSCT availability parameters . CSCT availability objectives performance ISDN 64 kbits dedicated-circuit connection type (DCCT) availability DCCT availability function DCCT availability parameters DCCT availability objectives . Annex A . Sampling estimation o
25、f ISDN availability parameters . A . 1 A.2 A.3 A.4 AS Estimation of the availability state of switched ISDN 64 kbit/s connection type A . 1.1 A.1.2 Procedure for estimating availability of switched ISDN 64 kbit/s connection type Procedure for estimating mean time between connection portion outages o
26、f switched ISDN 64 kbits connection types . Statistical basis of Phase I minimal test with N = 4 . Application of the sequential probability ratio test (SPRT) to the Phase I minimal test for availability A.5.1 SPRT test procedure A.5.2 SPRT methodology . portions . Definition of the minimal test for
27、 PSCT availability state determination . Definition of the minimal test for CSCT availability state determination portions . Page 1 1 1 1 2 3 4 4 4 6 6 6 7 8 9 9 9 9 10 11 11 11 12 13 13 15 16 16 16 COPYRIGHT International Telecommunications Union/ITU TelecommunicationsLicensed by Information Handli
28、ng Services- - STD-ITU-T RECMN 1.355-ENGL 2000 48b2571 Ob85707 72T = Page Annex B - Representative end-to-end availability performance of ISDN 64 kbit/s B. 1 connection types . Representative end-to-end design availability performance of ISDN 64 kbits packet-switched connection type (PSCT) B. 1.1 De
29、finition of the example end-to-end PSCT connections . B. 1.2 End-to-end PSCT availability performance for the Case 1 and Case 2 configuration examples . B. 1.3 Representative design availability performance of other ISDN 64 kbits connection types Derivation of the end-to-end “95th percentile“ availa
30、bility from “worst-case“ availabilities of connection portions . B.2 Annex C - Related availability parameters . Annex D - Factors to be specified in reporting ISDN availability performance of 64 kbits connection types . D. 1 Planned hours of connection portion availability . 20 20 20 20 21 22 23 24
31、 24 COPYRIGHT International Telecommunications Union/ITU TelecommunicationsLicensed by Information Handling ServicesRecommendation 1.355 1.355 Connection iype ISDN 64 kbit/s CONNECTION TYPE AVAILABILITY PERFORMANCE I Information Information Establishment transfer mode transfer rate (layer 1) of conn
32、ection 1 Introduction CSCT (Note 2) DCCT (Note 3) 1.1 Purpose The purpose of this Recommendation is to define network performance parameters describing the availability of 64 kbit/s ISDN connection types and to establish values and allocations for these values. This Recommendation also provides guid
33、ance on the measurement of these parameters. The worst-case objectives specified in this Recommendation are intended to assist providers in network design and planning by limiting the aggregate effect of network impairments, including blocking, equipment failures, and transmission errors, on ISDN ne
34、twork availability. The objectives given in this Recommendation for connection type availability do not directly correspond to the level of Quality of Service to be expected by customers. Circuit 64 kbit/s Switched Circuit 64 kbit/s Semi-permanent, permanent 1.2 Scope This Recommendation defines ava
35、ilability parameters and specifies worst-case availability objectives for national and international portions of three 64 kbits ISDN connection types (see Table 1): packet-switched connection type (PSCT), circuit-switched connection type (CSCT), and dedicated-circuit connection type (DCCT). This Rec
36、ommendation also provides methods for estimating the defined availability parameters. Table 1D.355 - 1.355 Connection types I PSCT(Note I) I Packet I 64 kbit/s I Switched I I I I NOTE 1 - Packet-switched connection type (PSCT) includes ISDN connection types B 1 in Table 2A.340 for access via B-chann
37、el (Case B) (Figure 2-2R.3 1). NOTE 2 - Circuit-switched connection type (CSCT) includes ISDN connection type AI in Table 2A.340. NOTE 3 - Dedicated-circuit connection type (DCCT) includes ISDN connection types A2 and A3 in Table 2h.340. 1.3 Abbreviations This Recommendation uses the following abbre
38、viations: A( 1 Connection portion availability CEP Call Set-up Error Probability CFP Call Set-up Failure Probability Availability performance of other ISDN connection types is for further study. COPYRIGHT International Telecommunications Union/ITU TelecommunicationsLicensed by Information Handling S
39、ervicesCSCT DCCT ISC ISDN Mo( ) MP MPI MPT PD PDP PDSP PSCT RE RER RP RSP SES SPRT TC 1.4 STDaITU-T RECMN 1.355-ENGL 2000 9 YBb259L Ob85709 7T2 Circuit-Switched Connection Type Dedicated-Circuit Connection Type International Switching Centre Integrated Services Digital Network Mean time between conn
40、ection portion outages Measurement Point Measurement Point I Measurement Point T Premature Disconnect Premature Disconnect Probability Premature Disconnect Stimulus Probability Packet-Switched Connection Type Reference Event Residual Error Ratio Reset Probability Reset Stimulus Probability Severely
41、Errored Second Sequential Probability Ratio Test Throughput Capacity Related Recommendations In characterizing availability performance, this Recommendation applies concepts and definitions provided in related ISDN performance Recommendations. These include Recommendations 1.3 50 and X. 140 (General
42、 framework), Recommendation 1.353 (Relevant measurement points) and Recommendations 1.354,1.352 and G.821 (Primary performance parameters). ISDN performance is considered in the context of the 3 x 3 matrix defined in Recommendations 1.350 and X. 140. Three protocol-independent communication function
43、s are identified in the matrix: access, user information transfer, and disengagement. These general functions correspond to connection Set-up, data transfer, and clearing of 64 kbis connections conforming to recommended ISDN protocols. Each function is considered with respect to three general perfor
44、mance concerns (or “performance criteria“): speed, accuracy, and dependability. These express, the delay or rate, degree of correctness, and degree of certainty with which the function is performed, respectively. Recommendation 1.353 defines the following: - physical measurement points (MPs) at whic
45、h ITU-T recommended ISDN protocols may be observed; particular MPs (designated MPT and MPI) that delimit portions of an end-to-end ISDN connection for which performance objectives may be specified; a set of performance-significant reference events (RES), each of which corresponds to the transfer of
46、a discrete unit of control or user information across an MP in accordance with an ITU-T recommended protocol; rules for identifying the time of occurrence of any RE at any MP. - - - COPYRIGHT International Telecommunications Union/ITU TelecommunicationsLicensed by Information Handling Services STDeI
47、TU-T RECMN 1.355-ENGL 2000 48b259L Ob85730 414 Recommendation 1.3 54 defines protocol-specific speed, accuracy, and dependability performance parameters for packet-switched ISDN connections. Recommendation 1.352 defines protocol-specific speed, accuracy, and dependability performance parameters for
48、circuit-switched ISDN connection Set-up and clearing. Recommendation G.82 1 defines error (accuracy) performance parameters for user information transfer in circuit-switched and dedicated-circuit ISDN connections. The ISDN performance parameters defined in these three Recommendations are used in dis
49、tinguishing available and unavailable periods. They are called “primary parameters“ to emphasize their direct derivation from ISDN performance-significant reference events. 1.5 Methodology of availability specification A two-state model establishes the basis for describing the overall availability of 64 kbits ISDN connection portions. Specified availability functions compare the values for subsets of the primary parameters with corresponding outage thresholds to classi the connection portion as “available“ (no portion outage) or “unav
