1、 STD-ITU-T RECMN X-13B-ENGL 1977 D LiBbZ.571 Ub397b4 753 INTERNATIONAL TELECOMMUNICATION UNION ITU-T TELECOMMUNICATION STAN DARD IZATION SECTOR OF ITU X.138 (08197) SERIES X: DATA NETWORKS AND OPEN SYSTEM COMMUNICATION Public data networks - Network aspects Measurement of performance values for publ
2、ic data networks when providing international packet-switched services ITU-T Recommendation X.138 (Previously CCITT Recommendation) ITU-T X-SERIES RECOMMENDATIONS DATA NETWORKS AND OPEN SYSTEM COMMUNICATION UBLIC DATA NETWORKS Services and facilities Interfaces X.1-X.199 X. 1 -X. 19 X.20-X.49 Transm
3、ission. signailing and switching x.50-X.89 Maintenance Administrative arrangements PEN SYSTEM INTERCONNECTION Model and notation Service definitions Connection-mode protocol specifications Connectionless-mode protocol specifications PICS proformas Protocol Identification Security Protocols Layer Man
4、aged Objects Conformance testing General Satellite data transmission systems MESSAGE HANDLING SYSTEMS DIRECTORY OS1 NETWORKING AND SYSTEM ASPECTS INTERWORKING BETWEEN NETWORKS Networking Efficiency Naming, Addressing and Registration Abstract Syntax Notation One (ASN.l) Systems Management framework
5、and architecture Management Communication Service and Protocol Siructure of Management Information Management functions OS1 MANAGEMENT SECURITY OS1 APPLICATIONS Commitment, Concurrency and Recovery Transaction processing Remote operations OPEN DISTRIBUTED PROCESSING X.150-X.179 X.180-X.199 X.200-X.2
6、99 X.200-X.209 X.210-X.219 X.220-X.229 X.230-X.239 X.240-X.259 X.260-X.269 X.270-X.279 X.280-X.289 X.290-X.299 X.300-X.399 X.300-X.349 X.350-X.399 X.400-X.499 X.500-X.599 X.600-X.699 X.600-X.629 X.630-X.649 X.650-X.679 X.680-X.699 X.700-X.799 X.700-X.709 X.7 10-X.719 X.720-X.729 X.730-X.799 X.800-X.
7、849 X.850-X.899 X.850-X.859 X.860-X.879 X.880-X.899 X.900-X.999 For further details, please refer to ITU-T List of Recommendations. STD-ITU-T RECMN X-138-ENGL 1997 = 48b259L Ob377bb 52b W ITU-T RECOMMENDATION X.138 MEASUREMENT OF PERFORMANCE VALUES FOR PUBLIC DATA NETWORKS WHEN PROVIDING INTERNATION
8、AL PACKET-SWITCHED SERVICES Summary This Recommendation provides measurement methods for the performance parameters specified in the X. 1 30-Series Recommendations on PSPDN. Source ITU-T Recommendation X.138 was revised by ITU-T Study Group 7 (1997-2000) and was approved under the WTSC Resolution No
9、. 1 procedure on the 9th of August 1997. Recommendation X.138 (08/97) 1 STD-ITU-T RECMN X.13B-ENGL 1997 D 48b257L Ob397b7 qb2 D FOREWORD ITU (International Telecommunication Union) is the United Nations Specialized Agency in the field of telecommuni- cations. The ITU Telecommunication Standardizatio
10、n Sector (ITU-T) is a permanent organ of the ITU. 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 Standardization Conference (WTSC), w
11、hich 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 approval of Recommendations by the Members of the ITU-T is covered by the procedure laid down in WTSC Resolution No. 1. In some areas of informat
12、ion technology which fall within ITU-Ts purview, the necessary standards are prepared on a collaborative basis 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.
13、 INTELLECTUAL PROPERTY RIGHTS The ITU draws attention to the possibility that the practice or implementation 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 Prope
14、rty Rights, whether asserted by IT members or others outside of the Recommendation development process. As of the date of approval of this Recommendation, the ITU hadhad not received notice of intellectual property, protected by patents, which may be required to implement this Recommendation. Howeve
15、r, implementors are cautioned that this may not represent the latest information and ase therefore strongly urged to consult the TSB patent database. O ITU 1997 All rights reserved. No part of this publication may be reproduced or utilized in any form or by any means, electronic or mechanical, inclu
16、ding photocopying and microfilm, without permission in writing from the ITU. 11 Recommendation X.138 (08/97) 1 2 3 4 5 6 CONTENTS Introduction and scope . 1.1 General 1.2 Parameters to be measured . 1.3 Accuracy requirements of measurements . References Abbreviations . Measurement architectures . 4.
17、1 General considerations and measurement methodologies 4.2 Performance parameters and measurement architectures . 4.3 Loopbacks . 4.4 Summary of measurement architectures . Measurement method using controlled and monitored source and controlled and monitored sink (C,M/C. M) 5.1 General assumptions a
18、nd constraints 5.2 Test devices 5.3 Trial sequences . 5.4 Trial failures and recovery 5.5 Matching packet level reference events 5.6 Testing during service outages . 5.7 Access trial 5.8 Data transfer trial 5.9 Disengagement trial 5.10 Estimating availability parameters Method for synchronizing equi
19、pment 6.1 Equipment synchronization Annex A . Calculation of packet-switched network performance statistics . A.l Statistics A.2 Statistical formulas . A.3 Throughput measurement correction factor Annex B - Factors which may affect measured performance . B . 1 Signalling rates . B.2 Data Link Layer
20、window size . B.3 Packet Layer window size B.4 Packet length . B.5 Other virtual connections B.6 Time of day . B.7 Throughput class . B.9 Inter-packet gaps . Reporting multiple tests made between different locations B.8 D-bit usage B.10 Page 1 1 1 2 2 3 4 4 5 6 7 9 9 9 9 10 10 10 10 12 19 23 28 28 3
21、0 31 34 35 35 35 36 36 36 36 36 36 36 36 36 . . Annex C Examples of measurement uses 37 C.1 Examples 37 C.2 Pairwise and multiple comparisons 37 . Recommendation X.138 (08/97) iii STD-ITU-T RECMN X.138-ENGL 1977 W 48b2.591 Ob377b7 235 D Recommendation X.138 MEASUREMENT OF PERFORMANCE VALUES FOR PUBL
22、IC DATA NETWORKS WHEN PROVIDING INTERNATIONAL PACKET-SWITCHED SERVICES (revised in 1997) 1 Introduction and scope This Recommendation describes architectures for measuring performance values for packet-switched public data networks. Clause 5 defines a measurement method using controlled and monitore
23、d sources and sinks. Clause 6 describes a means of synchronizing measurement equipment. Annex A provides detailed information on the calculation of packet- switched network performance statistics. Annex B provides information on factors which can affect their observation and Annex C provides example
24、s of the use of measurements. Note that other measurement devices and procedures that adhere to the definitions of Recommendations X.134, X. 135, X. 136 and X.137 are also acceptable for estimating the performance of packet-switched public data networks. 1.1 General The network performance may need
25、to be measured for reasons including the following: - to assist network planning; - - - network performance parameters may be included in contractual arrangements; Quality of Service parameters may need to be measured for other Recommendations; network operators may require general service descripti
26、ons. 1.2 Parameters to be measured The speed of service (delay and throughput) performance values for packet-switched public data netporks defined in Recommendation X. 135 are as follows: - Call set-up delay (see clause 4K.135). - Data packet transfer delay (see clause 5K.135). - Throughput (see cla
27、use 6K.135). - Clear indication delay (see clause 7K.135). - Clear confirmation delay (see clause 7B5.135). NOTE - Recommendation X.135 does not specify values for this parameter. The Quality of Service parameters defined in Recommendations X.136 and X.137 are as follows: - Call set-up error probabi
28、lity (see clause 4K.136). - Call set-up failure probability (see clause 4K.136). - Residual error ratio (see clause 5B5.136). - Reset stimulus probability (see clause 5B5.136). - Reset probability (see clause 5K.136). - Premature disconnect (see clause 5K.136). - Premature disconnect probability (se
29、e clause 5E.136). - Cali clear failure probability (see clause 6K. 136). - Availability (see Recommendation X. 137). stimulus probability Recommendation X.138 (08/97) 1 STD-ITU-T RECMN XaL3B-ENGL 1997 m 48b2591 Ob37770 T57 D It should be noted that the expected values for many of the various Quality
30、 of Service parameters defined in Recommendations X.136 make their estimation within reasonable bounds likely to take an excessive number of samples (during which time the structure or performance of the network may have changed). Thus, it may not be practical to estimate these parameters between a
31、single pair of interfaces. However, it may be possible to estimate the values with more certainty averaged over a whole network. 1.3 Accuracy requirements of measurements 1.3.1 Measurement objectives There is always a cost versus sample size trade off which must be resolved when attempting to estima
32、te a given parameter, and as the cost of taking an observation can have a considerable effect on the final estimate achieved, this Recommendation does not recommend a minimum number of observations. Additionally, in certain situations, estimating the parameter with great precision may not be as crit
33、ical as in others. Estimates of means, variances, percentile, modes, maxima and minima are all examples of parameter estimation. In reporting any such estimated parameters, it is always recommended that a measure of the precision of the estimate be included. The variance of the estimate, or a confid
34、ence interval about the estimate, are two common methods of expressing the estimates precision. 1.3.2 Reference events The time of occurrence of various reference events is the basis for the definitions of the speed of service parameters listed above. In this Recommendation and in Recommendation X.1
35、39, times are specified with respect to exit and entry events relative to the test equipment. Thus, the time of occurrence of an entry event into such a DTE is the time at which the last bit of the closing flag of the layer two frame carrying the packet enters the DTE from a circuit section and the
36、time of occurrence of an exit event from such a DTE is the time at which the first bit of the address field of the layer two frame carrying the packet enters the circuit section from the DTE. Comprehensive lists of X.25 and X.75 packet layer reference events are given in Tables 1fi.134 and 2fi.134,
37、and the definition of a packet-layer reference event is given in clause 31x.134. 2 References The following IT-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 indic
38、ated were valid. Ali Recommendations and other references 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 and other references listed below. A list of the currently valid ITU-
39、T Recommendations is regularly published. - ITU-T Recommendation X. 1 (1996), International user classes of service in, and categories of access to, public data networks and Integrated Services Digital Networks (ISDNs) . ITU-T Recommendation X.2 (1996), International data transmission services and o
40、ptional user facilities in public data networks and ISDNs. - - ITU-T Recommendation X.25 (1996), Interface between Data Terminal Equipment (DTE) and Data Circuit- terminating Equipment CE) for terminals operating in the packet mode and connected to public data networks by dedicated circuit. - ITU-T
41、Recommendation X.75 (1996), Packet-switched signalling system between public networks providing data transmission services. - - - ITU-T Recommendation X.96 (1993), Call progress signals in public data networks. ITU-T Recommendation X. 110 (1996), International routingprinciples and routingplan for p
42、ublic data networks. ITU-T Recommendation X.134 (1997), Portion boundaries and packet-layer reference events: Basis for defining packet-switched performance parameters. ITU-T Recommendation X.135 (1997), Speed of service (delay and throughput) performance values forpublic data networks when providin
43、g international packet-switched services. - 2 Recommendation X.138 (08/97) STDSITU-T RECMN XmL3B-ENGL 1777 D iBb2571 Ob39771 973 D IT-T Recommendation X.136 (1997), Accuracy and dependability pet$ormance values for public data networks when providing international packet-switched services. ITU-T Rec
44、ommendation X.137 (1997), Availability performance values for public data networks when providing international packet-switched services. IT-T Recommendation X.139 (1997), Echo, drop, generator and test DTEs for measurement of performance values in public data networks when providing international p
45、acket-switched services. CCITT Recommendation X. 140 (1992), General quality of service parameters for communication via public data networks. ITU-T Recommendation X.213 (1995), Information technology - Open Systems Interconnection - Network service definition. CCIT Recommendation X.323 (1 988), Gen
46、eral arrangements for interworking between Packet-Switched Public Data Networks (PSPDNs) . Abbreviations This Recommendation uses the following abbreviations: ccfp Call Clear Failure Probability cep Call Set-up Error Probability cfp Call Set-up Failure Probability cid Clear Indication Delay csd Call
47、 Set-up Delay DCE Data Circuit-terminating Equipment dlb Data Loopback dpd Data Packet transfer Delay DTE Data Terminal Equipment MTBSO Mean Time between Service Outage OS1 Open Systems Interconnection pdsp Premature Disconnect Stimulus Probability PE Protocol Event PSPDN Packet-Switched Public Data
48、 Network PSTN Public Switched Telephone Network PVC Permanent Virtual Circuit rer Residual Error Ratio rlb Rooting Loopback rp Reset Probability RR Receiver Ready rsP Reset Stimulus Probability sa Service Availability SABM Set Asynchronous Balanced Mode SABME Set Asynchronous Balanced Mode Extended
49、STE Signalling Terminal Equipment SVC Switched Virtual Call tc Throughput Capacity Recommendation X.138 (08197) 3 4 Measurement architectures This clause provides an overview of the various architectures which may be used to measure the Quality of Service parameters for packet-switched public data networks as specified in Recommendations X. 135, X.136 and X.137, together with general considerations for measuring the performance parameters. 4.1 General considerations and measurement methodologies A general measurement methodology involves setting up a call to a data sink and gener
