1、INTERNATIONAL TELECOMMUNICATION UNION ITU-T TELECOMMUNICATION STANDARDIZATION SECTOR OF ITU E.716 SERIES E: TELEPHONE NETWORK AND ISDN Quality of service, network management and traffic engineering - Traffic engineering - ISDN traffic engineering (1 0/96) User demand modelling in Broadband-ISDN ITU-
2、T Recommendation E.716 (Previously CCITT Recommendation) STD-ITU-T RECMN E.7Lb-ENGL L99b E iBb2591 ObZbZbZ 7Tb ITU-T E-SERI ES RECOMMENDATIONS TELEPHONE NETWORK AND ISDN OPERATION, NUMBERING, ROUTING AND MOBILE SERVICES INTERNATIONAL OPERATION E. 100-E.229 OPERATIONAL PROVISIONS RELATING TO CHARGING
3、 AND ACCOUNTING IN THE INTERNATIONAL TELEPHONE SERVICE E.230-E.299 UTILIZATION OF THE INTERNATIONAL TELEPHONE NETWORK FOR NON- TEL E P H O N Y APPLICATION S E.300-E.329 QUALIN OF SERVICE, NETWORK MANAGEMENT AND TRAFFIC ENGINEERING NETWORK MANAGEMENT E.400-E.489 International service statistics E.400
4、-E.409 international network management E.410-E.419 Checking the quality of the international telephone service E.420-E.489 TRAFFIC ENGINEERING E.490-E.799 Measurement and recording of traffic E.490-E.505 Forecasting of traffic E.506-E. 509 Determination of the number of circuits in manual operation
5、 ES1 0-ES1 9 Determination of the number of circuits in automatic and semi-automatic operation E.520-ES39 Grade of service E. 540-E. 599 E.600-E.699 Definitions ISDN traffic engineering E.700-E.749 Mobile network traffic engineering E.750-E.799 E.800-E.899 QUALITY OF TELECOMMUNICATION SERVICES: CONC
6、EPTS, MODELS, Terms and definitions related to the quality of telecommunication services Models for telecommunication services OBJECTIVES AND DEPEN DAB1 LITY PLANNING E.800-E.809 E. 81 O-E. 844 Objectives for quality of service and related concepts of telecommunication services Use of quality of ser
7、vice objectives for planning of telecommunication networks Field data collection and evaluation on the performance of equipment, networks and services E. 845-E. 859 E.860-E.879 E.880-E.899 For further details, please refer to ITU-T List of Recommendations. STD-ITU-T RECMN E-7Lb-ENGL L99b YBb257L ObZ
8、b2b3 b32 = ITU-T RECOMMENDATION E.716 USER DEMAND MODELLING IN BROADBAND-ISDN Summary This Recommendation deals with the characterization of user demand as manifested at the User- Network Interface (UNI). This Recommendation focuses on those aspects of user demand modelling that are specific to Broa
9、dband ISDN using Asynchronous Transfer Mode (ATM), and summarizes Recommendation E.711 (which covers user demand modelling in ISDN), in those aspects that are common for narrow-band and Broadband ISDN. Source ITU-T Recommendation E.716 was prepared by ITU-T Study Group 2 (1993-1996) and was approved
10、 under the WTSC Resolution No. 1 procedure on the 8th of October 1996. FOREWORD ITU (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
11、 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), which meets every four years, establishes the topics for stu
12、dy 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 (Helsinki, March 1-12, 1993). In some areas of information technology which fall with
13、in 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. O ITU 1997 All rights reserve
14、d. 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 IT. 11 Recommendation E.716 (10/96) 1 2 3 4 5 6 6.1 6.2 6.3 7 7.1 7.2 7.3 8 STD-ITU-T RECMN E.7Lb-ENGL L97b
15、 = 48b257L ObZb2b5 405 = CONTENTS Scope References Definitions . Abbreviations . Introduction Modelling of a call demand . General . Call attributes . Call pattern and traffic variables 6.3.1 Call traffic variables . 6.3.2 Cell traffic variables . 6.3.3 Relationship between cell traffic variables an
16、d parameters of the source traffic descriptor User characterization . General . Characterization of a CPE user set . Characterization of a population of CPE user sets . History References . Recommendation E.716 (10196) Page 1 1 1 2 2 9 10 10 10 11 Il 11 . 111 STD-ITU-T RECMN E.71b-ENGL 177b 48b257L
17、Ob2bZbb 341 STDmITU-T RECMN E.71b-ENGL 177b 98b2571 Ob2b2b7 288 9 Recommendation E.716 USER DEMAND MODELLING IN BROADBAND-ISDN (Geneva, 1996) 1 Scope This Recommendation deals with the characterization of user demand as manifested at the User- Network Interface (UNI). This Recommendation focuses on
18、those aspects of user demand modelling that are specific to Broadband ISDN using Asynchronous Transfer Mode (ATM), and summarizes Recommendation E.711 (which covers user demand modelling in ISDN), in those aspects that are common for narrow-band and Broadband ISDN. 2 References The following Recomme
19、ndations 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 other references are subject to revision: all users of this Recommendation are
20、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. - - CCITT Recommendation E.7 1 1 (1992), User demand modelling. ITU-T Recommen
21、dation E.735 1, Framework for traffic control and dimensioning in ITU-T Recommendation E.736, Methods for cell level trafic control in B-ISDN. ITU-T Recommendation E.737l, Dimensioning methods for B-ZSDN. ITU-T Recommendation I. 150 ( 1999, B-ISDN asynchronous transfer mode functional characteristic
22、s. ITU-T Recommendation 1.2 1 O ( 1993), Principles of telecommunication services supported by an ISDN and the means to describe them. ITU-T Recommendation 1.3 1 1 (1996), B-ISDN general network aspects. ITU-T Recommendation 1.36 1 (1995), B-ZSDNATM layer specijkation. ITU-T Recommendation 1.37 1 (1
23、 996), Trafic control and congestion control in B-ZSDN. B-ISDN. - - - - - - - 3 Definitions In order to specify key concepts (e.g. call attributes and call pattern) in subsequent clauses of this Recommendation, it is helpful to clarify the use herein of the terms “ATM connection“ and “call“. An “ATM
24、 connection“ refers to either a Virtual Channel Connection (VCC) or a Virtual Path Connection (VPC), see Recommendation 1.150. A VCC or a VPC may be point-to-point or may be Presently at the stage of draft. Recommendation E.716 (10/96) 1 point-to-multipoint. A VCC or a VPC is a connection with unidi
25、rectional communication, i.e. with only one direction of transmission2. A call consists of at least two ATM connections: one VCC in each direction of communication or one VPC in each direction of communication. A call may consist of multiple ATM connections in each direction of a point-to-point Conf
26、iguration or towards each end-point of a multipoint configuration. For example, a multimedia call may use, in each direction, one ATM connection for a video teleconference and another for the transport of data files. 4 Abbreviations For the purposes of this Recommendation, the following abbreviation
27、s are used: ATM B-ISDN B-ISUP CAC CLP CPE NPC QOS STD UNI UPC vc vcc VCI VP VPC VPI Asynchronous Transfer Mode Broadband Integrated Services Digital Network Broadband-ISDN User Part Connection Admission Control Cell Loss Priority Customer Premises Equipment Network Parameter Control Quality of servi
28、ce Source Traffic Descriptor User-Network Interface Usage Parameter Control Virtual Channel Virtual Channel Connection Virtual Channel Identifier Virtual Path Virtual Path Connection Virtual Path Identifier 5 Introduction Recommendation E.711 deals with user demand modelling in ISDN. This Recommenda
29、tion mainly focuses on those aspects of user demand modelling that are specific to Broadband ISDN using Asynchronous Transfer Mode (ATM), and summarizes Recommendation E.7 1 1 in those aspects that are common for narrow-band and Broadband ISDN. Note that, as specified in Recommendation 1.150, at a 3
30、-ISDN interface there are two directions of transmission. When a routing field value a virtual path identifier (VPI) for a VPC or a VPVvirtual channel identifier (VPWCI) for a VCC is assigned to a VP or VC link, the same value is assigned for each direction of transmission. The traffic characteristi
31、cs and the resources allocated for each direction of communication may be the same or may be different. The bandwidth in one of the directions may be equal to zero (unidirectional communication without any reverse information). Also, the bandwidth in one direction may only be large enough to carry A
32、TM layer management information (unidirectional communication with reverse management information). 2 Recommendation E.716 (10/96) The term user demand“ means the demands of the user for telecommunication services through the network to satisfy the users information transfer needs. It includes not o
33、nly the requests made by the user but also the requests received by the user that were made by others attempting to communicate with the said user. Through the mediation of its Customer Premises Equipment (CPE) and of the CPEs of the other user involved in the communication, user demand is manifeste
34、d at its User- Network Interface (UNI), in a way which will also depend on the characteristics of the involved CPEs. This Recommendation deals with the characterization of user demand as manifested at the UNI. For modelling purposes, user demand at the UNI will be seen as an arrival process of “call
35、 demands“ of different types3. Thus the characterization of user demand requires: - characterization of the types of call demands which the user generates or receives, which is covered in clause 6; characterization of the arrival process of call demands of the different types, which is covered in cl
36、ause 7. - This Recommendation identifies parameters to be used for the above characterization. The parameters chosen are those that have a relevant impact on network performance and thus are relevant to modelling the traffic offered by the user to the network, in particular, to the ATM layer in the
37、user plane, and to the signalling layer (layer 3 for Recommendation Q.2931 and layer 4 for B-ISUP) and lower layers in the control plane. The purpose of this Recommendation is to present parameters that are important for the definition of dimensioning methods and traffic control algorithms (includin
38、g connection admission control algorithms). This Recommendation gives guidance to network operators on which parameters of user demand need to be estimated, through measurements or through other means, to be used as input for dimensioning or for traffic controls. How the identified parameters are us
39、ed for these purposes is not covered by this Recommendation but by the Recommendations of the E.730- and E.740-Series. 6 Modelling of a call demand 6.1 General Call demand is the basic manifestation at the UNI of the user demand. A call demand consists of: 1) 2) For traffic engineering purposes, a c
40、all demand is defined by a set of call attributes and by a call pattern? the sequence of call attempts made by the user or by its Customer Premises Equipment (CPE); and the subsequent call, if it is finally established. Note that a call demand, that is, the demand for a call, is considered as the ba
41、sic manifestation of user demand, instead of call or call attempt which has been traditionally used. In contrast to a call, a call demand includes any reattempts needed in the establishment phase of the call. A sequence of reattempts without final success is also considered a call demand. The term “
42、call attributes“ has the same meaning as the term “connection characteristics“ used in Recommendation E.711. The change intends to emphasize that they are characteristics or attributes of the whole call demand, not of one of its connections. “Call attributes“ and “call pattern“ are used instead of “
43、call demand attributes“ and “call demand pattern“ for simplicity. Also for simplicity, if the call has been established, then the term “call“ will frequently be used instead of “call demand“. Recommendation E.716 (10/96) 3 - call attributes are those attributes of the call demand that identify the r
44、esources needed by the call demand in the network, both in the user and control planes; they describe the connections required and how they are established; most of the call attributes match with attributes defined in Recommendation 1.2 10; the call pattern is defined in terms of sequences of events
45、 at the user-network interface and of the times between these events. - The call pattern, together with the call attributes, must be sufficient to define the impact of the call on network performance, and to quantify the resources which have to be allocated to the call and the duration of this alloc
46、ation. 6.2 Call attributes As mentioned in 6.1, call attributes are defined by a set of attribute values that identify the resources needed by the call demand. The call attributes are: - establishment of communication (by control plane functions or by management plane functions; semipermanent, on de
47、mand or on reservation); communication configuration (point-to-point, multipoint, broadcast; number of points and their location); number of ATM connections, in each direction, between each pair of points; use of Virtual Channel Connections (VCCs) or user-to-user Virtual Path Connections - associate
48、d with each ATM connection, the components of the traffic contract (see - - - (VPCS)? Recommendation 1.37 i), which are: 1) the source traffic descriptor; 2) the cell delay variation tolerance; and 3) the quality of service class; signalling access protocol, layers 1/3 (currently, there is just one
49、signalling access protocol, Recommendation Q.293 1); supplementary services; the list of supplementary services which are significant for traffic engineering is for further study. In practice, when call demand modelling is made for a specific traffic engineering task, only some of the above-mentioned attributes are significant. - - 6.3 As mentioned in 6.1, the call pattern of a call demand is defined in terms of sequences of events at the user-network interface and of the times between these events. The call pattern is described by a set of traffic variables.
