1、 INTERNATIONAL TELECOMMUNICATION UNION ITU-T Series E.800 TELECOMMUNICATION STANDARDIZATION SECTOR OF ITU Supplement 1 (11/1988) SERIES E: OVERALL NETWORK OPERATION, TELEPHONE SERVICE, SERVICE OPERATION AND HUMAN FACTORS Telephone network management and traffic engineering Table of the Erlang formul
2、a ITU-T E.800-series Recommendations Supplement 1 (Formerly CCITT Recommendations) ITU-T E-SERIES RECOMMENDATIONS OVERALL NETWORK OPERATION, TELEPHONE SERVICE, SERVICE OPERATION AND HUMAN FACTORS INTERNATIONAL OPERATION Definitions E.100E.103 General provisions concerning Administrations E.104E.119
3、General provisions concerning users E.120E.139 Operation of international telephone services E.140E.159 Numbering plan of the international telephone service E.160E.169 International routing plan E.170E.179 Tones in national signalling systems E.180E.189 Numbering plan of the international telephone
4、 service E.190E.199 Maritime mobile service and public land mobile service E.200E.229 OPERATIONAL PROVISIONS RELATING TO CHARGING AND ACCOUNTING IN THE INTERNATIONAL TELEPHONE SERVICE Charging in the international telephone service E.230E.249 Measuring and recording call durations for accounting pur
5、poses E.260E.269 UTILIZATION OF THE INTERNATIONAL TELEPHONE NETWORK FOR NON-TELEPHONY APPLICATIONS General E.300E.319 Phototelegraphy E.320E.329 ISDN PROVISIONS CONCERNING USERS E.330E.349 INTERNATIONAL ROUTING PLAN E.350E.399 NETWORK MANAGEMENT International service statistics E.400E.409 Internatio
6、nal network management E.410E.419 Checking the quality of the international telephone service E.420E.489 TRAFFIC ENGINEERING Measurement and recording of traffic E.490E.505 Forecasting of traffic E.506E.509 Determination of the number of circuits in manual operation E.510E.519 Determination of the n
7、umber of circuits in automatic and semi-automatic operation E.520E.539 Grade of service E.540E.599 Definitions E.600E.649 Traffic engineering for IP-networks E.650E.699 ISDN traffic engineering E.700E.749 Mobile network traffic engineering E.750E.799 QUALITY OF TELECOMMUNICATION SERVICES: CONCEPTS,
8、MODELS, OBJECTIVES AND DEPENDABILITY PLANNING Terms and definitions related to the quality of telecommunication services E.800E.809 Models for telecommunication services E.810E.844 Objectives for quality of service and related concepts of telecommunication services E.845E.859 Use of quality of servi
9、ce objectives for planning of telecommunication networks E.860E.879 Field data collection and evaluation on the performance of equipment, networks and services E.880E.899 For further details, please refer to the list of ITU-T Recommendations. E.800 series Supplement 1 (11/1988) i Supplement 1 to ITU
10、-T E.800-series Recommendations Table of the Erlang formula Source Supplement 1 was approved in Melbourne (1988) and originally published in Blue Book, Fascicle II.3. ii E.800 series Supplement 1 (11/1988) FOREWORD The International Telecommunication Union (ITU) is the United Nations specialized age
11、ncy 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 with a view to standardizing telecommunications on a worldwide
12、 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 turn, produce Recommendations on these topics. The approval of ITU-T Recommendations is covered by the procedure laid down in WTSC
13、 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 publication, the expression “Administration“ is used for conciseness to indicate both a telecommunication administrati
14、on and a recognized operating agency. INTELLECTUAL PROPERTY RIGHTS ITU draws attention to the possibility that the practice or implementation of this publication may involve the use of a claimed Intellectual Property Right. ITU takes no position concerning the evidence, validity or applicability of
15、claimed Intellectual Property Rights, whether asserted by ITU members or others outside of the publication development process. As of the date of approval of this publication, ITU had not received notice of intellectual property, protected by patents, which may be required to implement this publicat
16、ion. However, implementors are cautioned that this may not represent the latest information and are therefore strongly urged to consult the TSB patent database. ITU 2002 All rights reserved. No part of this publication may be reproduced, by any means whatsoever, without the prior written permission
17、of ITU. E.800 series Supplement 1 (11/1988) 1 Supplement 1 to ITU-T E.800-series Recommendations Table of the Erlang formula Table of the Erlang loss formula (Erlang No. 1 formula, also called Erlang B formula) Loss probabilities: 1%, 3%, 5%, 7%. Let p = the loss probability y = the traffic offered
18、(in Erlangs) n = the number of circuits Formula: E1, n(y) = p = !211!2nyyynynn+Ln p = 1 % p = 3 % p = 5 % p = 7 % n p = 1 % p = 3 % p = 5 % p = 7 % 1 0.01 0.03 0.05 0.08 51 38.80 42.89 45.53 47.72 2 0.15 0.28 0.38 0.47 52 39.70 43.85 46.53 48.76 3 0.46 0.72 0.90 1.06 53 40.60 44.81 47.53 49.79 4 0.8
19、7 1.26 1.53 1.75 54 41.50 45.78 48.54 50.83 5 1.36 1.88 2.22 2.50 55 42.41 46.74 49.54 51.86 6 1.91 2.54 2.96 3.30 56 43.31 47.70 50.54 52.90 7 2.50 3.25 3.74 4.14 57 44.22 48.67 51.55 53.94 8 3.13 3.99 4.54 5.00 58 45.13 49.63 52.55 54.98 9 3.78 4.75 5.37 5.88 59 46.04 50.60 53.56 56.02 10 4.46 5.5
20、3 6.22 6.78 60 46.95 51.57 54.57 57.06 11 5.16 6.33 7.08 7.69 61 47.86 52.54 55.57 58.10 12 5.88 7.14 7.95 8.61 62 48.77 53.51 56.58 59.14 13 6.61 7.97 8.84 9.54 63 49.69 54.48 57.59 60.18 14 7.35 8.80 9.73 10.48 64 50.60 55.45 58.60 61.22 15 8.11 9.65 10.63 11.43 65 51.52 56.42 59.61 62.27 16 8.88
21、10.51 11.54 12.39 66 52.44 57.39 60.62 63.31 17 9.65 11.37 12.46 13.35 67 53.35 58.37 61.63 64.35 18 10.44 12.24 13.39 14.32 68 54.27 59.34 62.64 65.40 19 11.23 13.11 14.31 15.29 69 55.19 60.32 63.65 66.44 20 12.03 14.00 15.25 16.27 70 56.11 61.29 64.67 67.49 21 12.84 14.89 16.19 17.25 71 57.03 62.2
22、7 65.68 68.53 22 13.65 15.78 17.13 18.24 72 57.96 63.24 66.69 69.58 23 14.47 16.68 18.08 19.23 73 58.88 64.22 67.71 70.62 24 15.29 17.58 19.03 20.22 74 59.80 65.20 68.72 71.67 25 16.13 18.48 19.99 21.21 75 60.73 66.18 69.74 72.72 26 16.96 19.39 20.94 22.21 76 61.65 67.16 70.75 73.77 27 17.80 20.31 2
23、1.90 23.21 77 62.58 68.14 71.77 74.81 28 18.64 21.22 22.87 24.22 78 63.51 69.12 72.79 75.86 29 19.49 22.14 23.83 25.22 79 64.43 70.10 73.80 76.91 30 20.34 23.06 24.80 26.23 80 65.36 71.08 74.82 77.96 31 21.19 23.99 25.77 27.24 81 66.29 72.06 75.84 79.01 32 22.05 24.91 26.75 28.25 82 67.22 73.04 76.8
24、6 80.06 33 22.91 25.84 27.72 29.26 83 68.15 74.02 77.87 81.11 34 23.77 26.78 28.70 30.28 84 69.08 75.01 78.89 82.16 35 24.64 27.71 29.68 31.29 85 70.02 75.99 79.91 83.21 36 25.51 28.65 30.66 32.31 86 70.95 76.97 80.93 84.26 37 26.38 29.59 31.64 33.33 87 71.88 77.96 81.95 85.31 38 27.25 30.53 32.62 3
25、4.35 88 72.81 78.94 82.97 86.36 39 28.13 31.47 33.61 35.37 89 73.75 79.93 83.99 87.41 40 29.01 32.41 34.60 36.40 90 74.68 80.91 85.01 88.46 41 29.89 33.36 35.58 37.42 91 75.62 81.90 86.04 89.52 42 30.77 34.30 36.57 38.45 92 76.56 82.89 87.06 90.57 43 31.66 35.25 37.57 39.47 93 77.49 83.87 88.08 91.6
26、2 44 32.54 36.20 38.56 40.50 94 78.43 84.86 89.10 92.67 45 33.43 37.16 39.55 41.53 95 79.37 85.85 90.12 93.73 46 34.32 38.11 40.54 42.56 96 80.31 86.84 91.15 94.78 47 35.22 39.06 41.54 43.59 97 81.24 87.83 92.17 95.83 48 36.11 40.02 42.54 44.62 98 82.18 88.82 93.19 96.89 49 37.00 40.98 43.53 45.65 9
27、9 83.12 89.80 94.22 97.94 50 37.90 41.93 44.53 46.69 100 84.06 90.79 95.24 98.99 Printed in Switzerland Geneva, 2002 SERIES OF ITU-T RECOMMENDATIONS Series A Organization of the work of ITU-T Series B Means of expression: definitions, symbols, classification Series C General telecommunication statis
28、tics Series D General tariff principles Series E Overall network operation, telephone service, service operation and human factors Series F Non-telephone telecommunication services Series G Transmission systems and media, digital systems and networks Series H Audiovisual and multimedia systems Serie
29、s I Integrated services digital network Series J Cable networks and transmission of television, sound programme and other multimedia signals Series K Protection against interference Series L Construction, installation and protection of cables and other elements of outside plant Series M TMN and netw
30、ork maintenance: international transmission systems, telephone circuits, telegraphy, facsimile and leased circuits Series N Maintenance: international sound programme and television transmission circuits Series O Specifications of measuring equipment Series P Telephone transmission quality, telephon
31、e installations, local line networks Series Q Switching and signalling Series R Telegraph transmission Series S Telegraph services terminal equipment Series T Terminals for telematic services Series U Telegraph switching Series V Data communication over the telephone network Series X Data networks and open system communications Series Y Global information infrastructure and Internet protocol aspects Series Z Languages and general software aspects for telecommunication systems *21962*
