1、INTERNATIONAL TELECOMMUNICATION UNION ITU=T TELECOMMUNICATION STANDARDIZATION SECTOR OF ITU E.736 (03/2000) SERIES E: OVERALL NETWORK OPERATION, TELEPHONE SERVICE, SERVICE OPERATION AND HUMAN FACTORS Quality of service, network management and traffic engineering - Traffic engineering - ISDN traffic
2、engineering Methods for cell level traffic control in B-ISDN ITU-T Recommendation E.736 (Formerly CCITT Recommendation) ITU-T E-SERIES RECOMMENDATIONS OVERALL NETWORK OPERATION, TELEPHONE SERVICE, SERVICE OPERATION AND HUMAN FACTORS OPERA TION, NUMBERING, ROUTING AND MOBILE SERVICES INTERNATIONAL OP
3、ERATION Definitions General provisions concerning Administrations General provisions concerning users Operation of international telephone services Numbering plan of the international telephone service International routing plan Tones in national signalling systems Maritime mobile service and public
4、 land mobile service OPERATIONAL PROVISIONS RELATING TO CHARGING AND ACCOUNTING IN THE INTERNATIONAL TELEPHONE SERVICE Charging in the international telephone service Measuring and recording call durations for accounting purposes UTILIZATION OF THE INTERNATIONAL TELEPHONE NETWORK FOR NON- TE LEP H O
5、NY AP PLI CATI ONS General Phototelegraphy ISDN PROVISIONS CONCERNING USERS QUALITY OF SERVICE, NETWORK MANAGEMENT AND TRAFFIC ENGINEERING NETWORK MANAGEMENT International service statistics International network management Checking the quality of the international telephone service TRAFFIC ENGINEER
6、ING Measurement and recording of traffic Forecasting of traffic Determination of the number of circuits in manual operation Determination of the num ber of circuits in automatic and semi-automatic operation Grade of service Definitions ISDN traffic engineering Mobile network traffic engineering QUAL
7、ITY OF TELECOMMUNICATION SERVICES: CONCEPTS, MODELS, OBJECTIVES AND DEPENDABILITY PLANNING Terms and definitions related to the quality of telecommunication services Models for telecommunication services Objectives for quality of service and related concepts of telecommunication services Use of qual
8、ity of service objectives for planning of telecommunication networks Field data collection and evaluation on the performance of equipment, networks and services E. 1 00-E. 103 E.104-E.119 E. 120-E. 139 E. 140-E. 159 E. 1 60-E. 1 69 E. 170-E. 179 E. 1 80-E. 1 99 E.200-E.229 E.230-E.249 E.260-E.269 E.
9、300-E.319 E.320-E.329 E. 330-E. 399 E.400-E.409 E.41 0-E.419 E.420-E.489 E.490-E.505 E.506-E509 E.510-E519 E.520-E539 E.540-E599 E.600-E.699 E.750-E.799 E.800-E.809 E.810-E.844 E.845-E.859 E.860-E.879 E.880-E.899 For further details, please rer to ITD-T List of Recommendations. ITU-T RECOMMENDATION
10、E.736 METHODS FOR CELL LEVEL TRAFFIC CONTROL IN B-ISDN Summary This Recommendation is concerned with the definition of control procedures which allow cell level GOS objectives to be fulfilled. The primary objective is to define practical CAC procedures allowing the network operator to decide when a
11、new connection can be accepted on individual ATM links or network VPCs. Theoretical background is included where necessary to clarify assumptions and to situate the context of proposed control options. This Recommendation also addresses adaptive resource management techniques, where these are requir
12、ed by defined ATM transfer capabilities, and it identifies procedures for service integration. Source ITU-T Recommendation E.736 was revised by ITU-T Study Group 2 (1997-2000) and was approved under the WTSC Resolution No. 1 procedure on 13 March 2000. Recommendation E.736 (03/2000) 1 FOREWORD ITU (
13、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, operating and tariff questions and issuing Re
14、commendations 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 t
15、opics. 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 information technology which fall within ITU-Ts purview, the necessary standards are prepared on a collaborative basis with IS0 and IEC. NOTE In this Re
16、commendation, 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 of this Recommendation may involve
17、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 of the date of approval of this Reco
18、mmendation, 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 urged to consult the TSB patent databa
19、se. 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 fi-om the ITU. 11 Recommendation E.736 (03/2000) CONTENTS 1 2 3 4 5 6 6.1 6.2 6.3 6
20、.4 6.5 6.6 7 7.1 7.2 7.3 7.4 8 8.1 Scope . References . Terms and definitions . Abbreviations Introduction . Traffic parameters and parameter control . Source traffic descriptor 6.1.1 Source peak rate and cell delay variation tolerance . 6.1.2 Sustainable cell rate parameter set . Cell traffic varia
21、bles Quality of service requirements Cell loss priority bit Parameter control Traffic shaping Performance of an ATM multiplexer Multiplexing constant bitrate streams . 7.1.1 Buffer overflow probability . Negligible CDV for CBR streams . 7.1.4 Nominal multiplexer rate . 7.1.2 Impact of CDV 7.1.3 Rate
22、 envelope multiplexing 7.2.1 Cell loss ratio . 7.2.2 Multiplexing efficiency . 7.2.3 Cell loss priority 7.2.4 Cell delay priority Rate sharing statistical multiplexing . 7.3.1 Buffer saturation probability 7.3.2 Cell loss priority 7.3.3 Cell delay priority Networks of multiplexer queues . 7.4.2 Rate
23、 envelope multiplexing . 7.4.3 Rate sharing . Connection admission control for DBR and SBR transfer capabilities 7.4.1 Multiplexing constant rate streams CAC for peak rate allocation Recommendation E.736 (03/2000) 1 1 1 2 2 6 7 7 7 9 9 10 10 11 11 12 12 12 13 13 13 13 14 14 14 14 15 . 111 8.2 8.3 9
24、9.1 9.2 9.3 10 10.1 10.2 10.3 10.4 11 12 CAC for rate envelope multiplexing . 8.2.1 Known cell traffic variables . 8.2.2 Worst-case resource allocation 8.2.3 Adaptive CAC . CAC for rate sharing statistical multiplexing . 8.3.1 Known cell traffic variables . 8.3.2 Worst-case resource allocation 8.3.3
25、 Adaptive CAC . Adaptive resource management ABT resource management . 9.1.1 9.1.2 REM and block transfer . Rate sharing and block transfer . ABR resource management Traffic engineering for “elastic traffic“ . 9.3.1 Traffic characteristics 9.3.2 Performance requirements . 9.3.3 Bandwidth sharing alg
26、orithms . 9.3.4 Performance modelling 9.3.5 Connection admission control . Service integration Dedicated resources Loss priorities Delay priorities Scheduling policies . . . 10.3.1 Equivalent cell rate for priority service . Bibliography History . Appendix I . Example methods for calculation of equi
27、valent cell rate for rate envelope I . 1 1.2 1.3 multiplexing Equivalent cell rate method 1 RMV96 . Equivalent cell rate method 2 RMV96 . Equivalent cell rate method 3 Vis 971 iv Recommendation E.736 (03/2000) Page 16 16 18 18 19 20 20 21 21 21 21 21 21 22 22 22 23 23 23 24 24 24 24 25 26 26 26 27 2
28、7 28 28 Recommendation E.736 METHODS FOR CELL LEVEL TRAFFIC CONTROL IN B-ISDN 1 Scope This Recommendation describes performance evaluation methods and traffic control methods enabling a network operator to meet objectives for cell level network performance. This Recommendation clarifies the traffic
29、engineering consequences of traffic control and congestion control mechanisms and procedures defined in Recommendation 1.37 1. Complementary Recommendations are E.735, which outlines the B-ISDN resource allocation fiamework, and E.737 which provides dimensioning guidelines enabling the network opera
30、tor to meet call level performance objectives. 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 Recommendati
31、ons 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-T Recommendations is regularly pu
32、blished. - - - ITU-T Recommendation E. 177 (1 996), B-ISDN routing. ITU-T Recommendation E.7 16 (1 996), User demand modelling in Broadband-ISDN. ITU-T Recommendation E.735 (1997), Framework for trafic control and dimensioning in ITU-T Recommendation E.737 (1 997), Dimensioning methods for B-ISDN. I
33、TU-T Recommendation 1.356 (2000), B-ISDNATM layer cell transfer performance. ITU-T Recommendation 1.37 1 (2000), Trafic control and congestion control in B-ISDN. B-ISDN. - - - 3 Terms and definitions This Recommendation defines the following terms: 3.1 equivalent cell rate: A cell rate attributed to
34、 a connection such that cell level GOS objectives are satisfied on an ATM link or network VPC as long as the sum of equivalent cell rates is not greater than the rate of the ATM link or VPC. 3.2 rate envelope multiplexing: A statistical multiplexing scheme where CAC aims to make negligible the proba
35、bility that the combined arrival rate of multiplexed connections exceeds multiplexer capacity; buffering is employed solely to account for the deviation of the cell arrival process fiom a fluid ideal where no buffer would be required to meet cell level GOS objectives. 3.3 rate sharing: A statistical
36、 multiplexing scheme where a buffer is used to absorb excess cells when the arrival rate is greater than the multiplexer output rate for significant periods of time; a buffer would be necessary to meet cell level GOS objectives even in the fluid ideal. Recommendation E.736 (03/2000) 1 4 Abbreviation
37、s This Recommendation uses the following abbreviations: ABR ABT ATM BECN CAC CDV CLR DBR ECR FECN GCRA GOS IBT IN1 MBS NPC PCR QOS REM RM SBR SCR STD UNI UPC vcc VPC Available Bit Rate ATM Block Transfer Asynchronous Transfer Mode Backward Explicit Congestion Notification Connection Admission Contro
38、l Cell Delay Variation Cell Loss Ratio Deterministic Bit Rate Equivalent Cell Rate Forward Explicit Congestion Notification Generic Cell Rate Algorithm Grade of Service Intrinsic Burst Tolerance Inter-Network Interface Maximum Burst Size Network Parameter Control Peak Cell Rate Quality of Service Ra
39、te Envelope Multiplexing Resource Management Statistical Bit Rate Sustainable Cell Rate Source Traffic Descriptor User-Network Interface Usage Parameter Control Virtual Channel Connection Virtual Path Connection 5 Introduction Recommendation 1.371 defines the scope of ATM layer traffic control and c
40、ongestion control identifymg a variety of functions ranging rom network resource management to priority controls, acting over a wide range of time scales. This Recommendation is concerned with the traffic engineering implications of the different ATM transfer capabilities standardized in Recommendat
41、ion 1.37 1 including the definition of Connection Admission Control (CAC) and resource allocation procedures. Other control actions such as usage parameter control are briefly considered in so far as it is necessary to achieve a high level of consistency between the various control capabilities. 2 R
42、ecommendation E.736 (03/2000) Traffic controls may be distinguished according to whether their function is to enable quality of service guarantees at cell level (e.g. cell loss ratio) or at call level (e.g. call blocking probability). This Recommendation is concerned with cell level controls. Consid
43、eration is restricted to the CAC procedure applied to a single ATM link or network-to-network VPC which determines simply if that ATM link or VPC is capable or not of handling the requested connection. The issue of traffic routing(i.e. determining a network path from among those possible) is dealt w
44、ith in Recommendation E. 177. B-ISDN is a connection-oriented network. Each connection is defined by a set of traffic parameters and QOS requirements. When the establishment of a new connection is requested, the network must decide if it has sufficient resources to accept it without infringing cell
45、level GOS requirements for all established connections as well as the new connection; this is the role of CAC. Given that a connection is accepted, the network must ensure that the user in fact emits traffic in conformity with the declared traffic parameters; this is the role of Usage Parameter Cont
46、rol (UPC). When more than one network is involved in a connection, it is also incumbent on each network to verify that the traffic it receives from the neighbouring network conforms; this is Network Parameter Control (NPC). Standard traffic parameters and the algorithms by which the conformity of co
47、nnections can be checked in UPC/NPC mechanisms are defined in Recommendation 1.37 1. This Recommendation is concerned with the definition of CAC procedures which allow QOS requirements to be fulfilled taking account of the information available about connection traffic and the accuracy with which it
48、 can be controlled. This Recommendation also addresses adaptive resource management techniques, where these are required by defined ATM transfer capabilities, and it identifies procedures for service integration. Depending on network architecture, cell level traffic controls may be applied to differ
49、ent transmission entities. Recommendation E.735 defines the physical and logical network entities which constitute the framework for cell level traffic control. In this Recommendation, it is generally assumed that a connection is offered to an ATM link or anetwork-to-network VPC defined by a DBR traffic descriptor or by traffic variables as considered in Recommendation E.735 (i.e. an uncontrolled constant rate VPC or a variable rate VPC). Effective traffic control of ATM connections, particularly when it is an objective to perform statistical multiplexing of variable bit rate connectio
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