1、 INTERNATIONAL TELECOMMUNICATION UNION ITU-T X.145TELECOMMUNICATION STANDARDIZATION SECTOR OF ITU (10/2003) SERIES X: DATA NETWORKS AND OPEN SYSTEM COMMUNICATIONS Public data networks Network aspects Connection establishment and disengagement performance parameters for public Frame Relay data networ
2、ks providing SVC services ITU-T Recommendation X.145 ITU-T X-SERIES RECOMMENDATIONS DATA NETWORKS AND OPEN SYSTEM COMMUNICATIONS PUBLIC DATA NETWORKS Services and facilities X.1X.19 Interfaces X.20X.49 Transmission, signalling and switching X.50X.89 Network aspects X.90X.149 Maintenance X.150X.179 A
3、dministrative arrangements X.180X.199 OPEN SYSTEMS INTERCONNECTION Model and notation X.200X.209 Service definitions X.210X.219 Connection-mode protocol specifications X.220X.229 Connectionless-mode protocol specifications X.230X.239 PICS proformas X.240X.259 Protocol Identification X.260X.269 Secur
4、ity Protocols X.270X.279 Layer Managed Objects X.280X.289 Conformance testing X.290X.299 INTERWORKING BETWEEN NETWORKS General X.300X.349 Satellite data transmission systems X.350X.369 IP-based networks X.370X.399 MESSAGE HANDLING SYSTEMS X.400X.499 DIRECTORY X.500X.599 OSI NETWORKING AND SYSTEM ASP
5、ECTS Networking X.600X.629 Efficiency X.630X.639 Quality of service X.640X.649 Naming, Addressing and Registration X.650X.679 Abstract Syntax Notation One (ASN.1) X.680X.699 OSI MANAGEMENT Systems Management framework and architecture X.700X.709 Management Communication Service and Protocol X.710X.7
6、19 Structure of Management Information X.720X.729 Management functions and ODMA functions X.730X.799 SECURITY X.800X.849 OSI APPLICATIONS Commitment, Concurrency and Recovery X.850X.859 Transaction processing X.860X.879 Remote operations X.880X.899 OPEN DISTRIBUTED PROCESSING X.900X.999 For further
7、details, please refer to the list of ITU-T Recommendations. ITU-T Rec. X.145 (10/2003) i ITU-T Recommendation X.145 Connection establishment and disengagement performance parameters for public Frame Relay data networks providing SVC services Summary This Recommendation defines performance parameters
8、 for quantifying the connection establishment and disengagement performance of a frame relay Switched Virtual Connection (SVC) service. These include call control delay and accuracy and dependability parameters. The defined parameters are used in combination with the user information transfer perfor
9、mance parameters defined in ITU-T Rec. X.144 to fully quantify SVC service performance. This revision was undertaken to take account of the development of ITU-T Rec. X.147 which specifies network availability objective values together with techniques for assessing frame relay network availability. I
10、nformation previously pertaining to SVC availability has been moved to ITU-T Rec. X.147. Source ITU-T Recommendation X.145 was approved by ITU-T Study Group 17 (2001-2004) under the ITU-T Recommendation A.8 procedure on 29 October 2003. ii ITU-T Rec. X.145 (10/2003) FOREWORD The International Teleco
11、mmunication Union (ITU) is the United Nations specialized agency in the field of telecommunications. The ITU Telecommunication Standardization Sector (ITU-T) is a permanent organ of ITU. ITU-T is responsible for studying technical, operating and tariff questions and issuing Recommendations on them w
12、ith 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 turn, produce Recommendations on these topics. The approval of ITU-T Re
13、commendations 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 basis with ISO and IEC. NOTE In this Recommendation, the expression “Administration“ is used for
14、 conciseness to indicate both a telecommunication administration and a recognized operating agency. Compliance with this Recommendation is voluntary. However, the Recommendation may contain certain mandatory provisions (to ensure e.g. interoperability or applicability) and compliance with the Recomm
15、endation is achieved when all of these mandatory provisions are met. The words “shall“ or some other obligatory language such as “must“ and the negative equivalents are used to express requirements. The use of such words does not suggest that compliance with the Recommendation is required of any par
16、ty. INTELLECTUAL PROPERTY RIGHTS ITU draws attention to the possibility that the practice or implementation of this Recommendation may involve the use of a claimed Intellectual Property Right. ITU takes no position concerning the evidence, validity or applicability of claimed Intellectual Property R
17、ights, whether asserted by ITU members or others outside of the Recommendation development process. As of the date of approval of this Recommendation, ITU had not received notice of intellectual property, protected by patents, which may be required to implement this Recommendation. However, implemen
18、tors are cautioned that this may not represent the latest information and are therefore strongly urged to consult the TSB patent database. ITU 2004 All rights reserved. No part of this publication may be reproduced, by any means whatsoever, without the prior written permission of ITU. ITU-T Rec. X.1
19、45 (10/2003) iii CONTENTS Page 1 Scope 1 2 References. 2 3 Abbreviations 3 4 Performance model and frame relay SVC reference events. 5 4.1 Performance model. 5 4.2 Frame relay SVC reference events. 6 5 Access and disengagement parameters. 6 5.1 Speed of service parameters . 6 5.2 Accuracy and depend
20、ability parameters. 11 ITU-T Rec. X.145 (10/2003) 1 ITU-T Recommendation X.145 Connection establishment and disengagement performance parameters for public Frame Relay data networks providing SVC services 1 Scope The purpose of this Recommendation is to define performance parameters for quantifying
21、the connection establishment and disengagement performance of a frame relay Switched Virtual Connection (SVC) service. These include call control delay and accuracy and dependability parameters. The defined parameters are used in combination with the user information transfer performance parameters
22、defined in ITU-T Rec. X.144 to fully quantify SVC service performance. These parameters may be used to describe the speed, accuracy and dependability of data networks when providing an international frame relay SVC service. The user information transfer performance parameters defined in ITU-T Rec. X
23、.144 are applicable to the information transfer phase of a switched frame relay connection and are included by reference in this Recommendation. Performance is considered in the context of the 3 3 performance matrix defined in ITU-T Rec. X.140 (see Figure 1). Three protocol-independent data communic
24、ation functions are identified in the matrix: access, user information transfer and disengagement. Each function is considered with respect to three general performance concerns (or “performance criteria“): speed, accuracy and dependability. This Recommendation defines a set of primary parameters th
25、at describe the speed, accuracy and dependability performance relative to each function. The parameters defined in this Recommendation may be used to specify or measure the performance of end-to-end frame relay connections or connection portions as specified in ITU-T Rec. X.144. The performance para
26、meters defined in this Recommendation describe the speed, accuracy, dependability and availability of the access and disengagement phases provided by switched frame relay. NOTE 1 The parameters defined in this Recommendation may be augmented or modified based upon further study of the requirements o
27、f frame relay to be supported on networks. NOTE 2 The defined parameters are intended to characterize frame relay connections in the available state. NOTE 3 The parameters of this Recommendation are designed to measure the performance of network elements between pairs of section boundaries. However,
28、 users of this Recommendation should be aware that the behaviour of connection elements outside the pair of boundaries can adversely influence the measured performance of the elements between the boundaries. This Recommendation is organized as follows: clause 2 presents references; clause 3 presents
29、 abbreviations; clause 4 defines a performance model and a set of frame transfer reference events (FEs) that provide a basis for performance parameter definition; clause 5 defines frame-based speed of service, accuracy and dependability parameters using the frame transfer reference events defined in
30、 clause 4. 2 ITU-T Rec. X.145 (10/2003) 2 References The following ITU-T Recommendations and other references contain provisions which, through reference in this text, constitute provisions of this Recommendation. At the time of publication, the editions indicated were valid. All Recommendations and
31、 other references are subject to revision; users of this Recommendation are therefore encouraged to investigate the possibility of applying the most recent edition of the Recommendations and other references listed below. A list of the currently valid ITU-T Recommendations is regularly published. Th
32、e reference to a document within this Recommendation does not give it, as a stand-alone document, the status of a Recommendation. ITU-T Recommendation X.36 (2003), Interface between Data Terminal Equipment (DTE) and Data Circuit-terminating Equipment (DCE) for public data networks providing frame re
33、lay data transmission service by dedicated circuit. ITU-T Recommendation X.76 (2003), Network-to-network interface between public networks providing PVC and/or SVC frame relay data transmission service. ITU-T Recommendation X.140 (1992), General quality of service parameters for communication via pu
34、blic data networks. ITU-T Recommendation X.144 (2003), User information transfer performance parameters for public frame relay data networks. ITU-T Recommendation X.147 (2003), Frame Relay network availability. ITU-T Rec. X.145 (10/2003) 3 X.145_F1Network sectionCircuit sectionDSE DSE(Frame relay ne
35、twork)PhysicalinterfacePhysical interfaceDTE or DSEPhysical interfacePhysicalinterfaceFrame transfer reference eventsClause 4/X.144CriterionFunctionAccess (call set-up)Disengagement (call tear-down)User information transferClause 5/X.145Clause 5/X.144Clause 5/X.145X.147Service available(no outage)Se
36、rvice available(outage)Frame relayavailabilityDTE or DSESpeed Accuracy DependabilityFigure 1/X.145 Scope of ITU-T Rec. X.145 3 Abbreviations This Recommendation uses the following abbreviations: ACS Access Circuit Section ANS Access Network Section Bc Committed burst size 4 ITU-T Rec. X.145 (10/2003
37、) BCTDR Bit-based Conformant Traffic Distortion Ratio Be Excess burst size BECN Backward Explicit Congestion Notification BLR Bit-Loss Ratio CEP Connection set-up Error Probability CFP Connection set-up Failure Probability CIR Committed Information Rate CLLM Consolidated Link Layer Management DE Dis
38、card Eligible DLCI Data link Connection Identifier DSE Data Switching Exchange DTE Data Terminal Equipment EFR Extra Frame Rate EIR Excess Information Rate FCTDR Frame-based Conformant Traffic Distortion Ratio FE Frame Layer Reference Event FECN Forward Explicit Congestion Notification FLR Frame Los
39、s Ratio FRS Frame Relay SVC HDLC High-level Data Link Control I Information frame ICS Internetwork Circuit Section ISDN Integrated Services Digital Network LAPF Link Access Protocol Frame MPI Measurement Point I MPT Measurement Point T MTBSO Mean Time Between Service Outages MTTSR Mean Time To Servi
40、ce Restoral NE Network Element NNI Network-to-Network Interface NT Network Termination PDEP Premature Disconnect Event Probability PDSP Premature Disconnect Stimulus Probability PVC Permanent Virtual Circuit RBER Residual Bit-Error Ratio RE Reference Event RFER Residual Frame-Error Ratio ITU-T Rec.
41、X.145 (10/2003) 5 SA Service Availability SABME Set Asynchronous Balanced Mode Extended SF Switching Function SN Switching Node SVC Switched Virtual Connection TE Terminal Equipment TNS Transit Network Section UA Unnumbered Acknowledgement UI Unnumbered Information UNI User-to-Network Interface 4 Pe
42、rformance model and frame relay SVC reference events The performance model for this Recommendation is identical to that defined in clause 4/X.144. For completeness, this performance model is illustrated in Figures 2 and 3. As there are some differences in the treatment of User-to-Network Interface (
43、UNI) versus network-to-network interface layer 3 control messages in switched frame relay services, this Recommendation utilizes the terms MPT and MPI to distinguish between boundaries at a UNI or NNI, respectively. Performance-significant reference events are reference events useful in defining per
44、formance parameters. Table 1 provides references to information, either in this Recommendation or in other Recommendations, that collectively define a relevant set of frame relay SVC service performance-significant reference events. Table 1/X.145 References to Recommendations specifying frame relay
45、SVC performance-significant reference events Relevant boundary Recommendation/protocol MPT MPI ITU-T Rec. X.76 Not applicable 4.2.1/X.145 ITU-T Rec. X.36 4.2.2/X.145 Not applicable 4.1 Performance model Figures 2 and 3 (corresponding to Figures 2/X.144 and 3/X.144), illustrate the performance model
46、used in this Recommendation. In Figure 2, the boundaries at the DTEs are MPT boundaries and the boundaries delimiting the international portion are MPI boundaries. The terms MPT and MPI represent a T measurement (or monitoring) point and an international measurement (or monitoring) point, respective
47、ly. The concept of a measurement (or monitoring) point is that of a point where standardized protocol reference events may be observed. Figure 3 illustrates this concept. 6 ITU-T Rec. X.145 (10/2003) 4.2 Frame relay SVC reference events 4.2.1 ITU-T Rec. X.76 Table 2a lists performance-significant X.
48、76 message transfer reference events associated with an MPI boundary. For each layer 3 message, codes are given. Each code ends in either an “a“ or “b“. All codes which end in an “a“ represent exit reference events and all codes which end in a “b“ represent entry reference events. The unit of inform
49、ation used in defining the time of occurrence of these reference events is the layer 2 (HDLC) frame that carries the layer 3 message across the relevant boundary. 4.2.2 ITU-T Rec. X.36 Table 2b lists performance-significant X.36 message transfer reference events associated with an MPT boundary. Each layer 3 message code ends in either an “a“ or “b“. Codes ending in an “a“ represent exit reference events; codes ending in a “b“ represent entry reference events. The unit of information used in defining the time of occurrence of
