1、 STD-ITU-T RECMN E-735-ENGL 1997 4Bb2.591 Ob38843 TL2 9 INTERNATIONAL TELECOMMUNICATION UN ION ITU-T TELECOMMUNICATION STANDARDIZATION SECTOR OF ITU E.735 (05197) SERIES E: OVERALL NETWORK OPERATION, TELEPHONE SERVICE, SERVICE OPERATION AND HUMAN FACTORS Quality of service, network management and tr
2、affic engineering - Traffic engineering - ISDN traffic engineering Framework for traffic control and dimensioning in B-ISDN ITU-T Recommendation E.735 (Previously CCIIT Recommendation) STD-ITU-T RECMN E-735-ENGL 1997 W 48b259L Ob388Liq 959 ITU-T E-SERIES RECOMMENDATIONS OVERALL NETWORK OPERATION, TE
3、LEPHONE SERVICE, SERVICE OPERATION AND HUMAN FACTORS OPERATION, NUMBERING, ROUTING AND MOBILE SER VICES INTERNATIONAL OPERATION OPERATIONAL PROVISIONS RELATING TO CHARGING AND ACCOUNTING IN THE INTERNATIONAL TELEPHONE SERVICE UTILIZATION OF THE INTERNATIONAL TELEPHONE NETWORK FOR NON- TELEPHONY APPL
4、ICATIONS ISDN PROVISIONS CONCERNING USERS QUALITY OF SERVICE, NETWORK MANAGEMENT AND TRAFFIC ENGINEERING NETWORK MANAGEMENT TRAFFIC ENGINEERING Measurement and recording of traffic Forecasting of traffic Determination of the number of circuits in manual operation Determination of the number of circu
5、its in automatic and semi-automatic operation Grade of service E. 100-E.229 E.230-E.299 E.300-E.329 E.330-E.399 E.4WE.489 E.490-E.799 E.490-ES05 E.506-ES09 E.510-ES19 E.520-ES39 E.540-ES99 Definitions E.600-E.699 Mobile network traffic engineering E.750-E.799 E. 800-E. 899 QUALJTY OF TELECOMMUNICATI
6、ON SERVICES: CONCEPTS, MODELS, OBJECTIVES AND DEPENDABILITY PLANNING Terms and definitions related to the quality of telecommunication services E.8WE.809 Models for telecommunication services E.810-E.844 Objectives for quality of service and related concepts of telecommunication services E. 845-E. 8
7、59 Use of quality of service objectives for planning of telecommunication networks Field data collection and evaluation on the performance of equipment, networks and services E. 860-E. 879 E.880-E.899 For firrther details, please refer to ITU-T List of Recommendations. STD-ITU-T RECMN E.73C-ENGL 177
8、7 48b259L 0638845 875 ITU-T RECOMMENDATION E.735 FRAMEWORK FOR TRAFFIC CONTROL AND DIMENSIONING IN B-ISDN Summary This Recommendation provides a framework for traffic control and dimensioning in B-ISDN. This Recommendation gives an overview of the traffic engineering tasks required for configuring t
9、he network; it describes the network aspects that are relevant for traffic engineering; it defines the network resources to be considered and explains the relation between cell-level traffic controls (described in Recommendation E.736) and call-level traffic controls and dimensioning (described in R
10、ecommendation E.737). Finally this Recommendation gives guidelines on strategies for configuration of network VPCs. Source IT-T Recommendation E.735 was prepared by ITU-T Study Group 2 (1997-2000) and was approved under the WTSC Resolution No. 1 procedure on the 26th of May 1997. Recommendation E.73
11、5 (05/97) 1 - - STD-ITU-T RECMN E-735-ENGL 1797 48b2571 0b3884b 721 9 FOREWORD ITU (International Telecommunication Union) is the United Nations Specialized Agency in the field of telecommuni- cations. The Telecommunication Standardization Sector (ITU-T) is a permanent organ of the IT. The ITU-T is
12、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 study b
13、y the IT-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 information technology which fall within ITU-Ts purview, the necessary s
14、tandards 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. INTELLECTUAL PROPERTY RIGHTS The draws attention to the possibi
15、lity 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 Property Rights, whether asserted by IT members or others outside of the
16、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. However, implementors are cautioned that this may not represent the latest
17、 information and are 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, including photocopying and microfilm, without permission in writing from
18、the ITU. 11 Recommendation E.735 (05197) 7 10 STD-ITU-T RECMN E.735-ENGL 1997 = 4862593 0638847 bb8 CONTENTS Scope of this Recommendation References Terms and definitions . Abbreviations . Introduction General considerations on B-ISDN networks 6.1 Layers and levels in the network 6.2 Connection type
19、s 6.3 Nodes 6.4 Types of networks 6.5 ATM transfer capabilities . 6.6 QOS requirements 6.7 GOS objectives . Resources in the ATM layer: definitions and implications 7.1 ATM link 7.2 VPC as a connection and as a resource . 7.3 Characterization of network-to-network VPCs 7.4 ATM link set and WC set 6.
20、8 Traffic controls . Relation between cell-level traffk control and dimensioning 8.1 Iterative approach . 8.2 Equivalent cell rate . Strategies for network configuration 9.1 Applications of VPCs . Drawbacks of the use of VPCs . 9.3 Requirements and guidelines 9.2 History Recommendation E.735 (05197)
21、 Page 1 2 3 3 3 5 6 8 10 10 10 11 12 12 14 15 18 19 19 20 21 21 22 23 25 iii Recommendation E.735 FRAMEWORK FOR TRAFFIC CONTROL AND DIMENSIONING IN B-ISDN (Geneva, 1997) 1 Scope of this Recommendation This Recommendation establishes the framework for traffic control and dimensioning in B-ISDN. These
22、 methods are required to allocate and control resources in the B-ISDN in order to carry the offered traffic (modelled in theE.710Series of Recommendations) while meeting the GOS objectives (to be defined in the E.720-Series of Recommendations). This Recommendation introduces the subject, describes t
23、he network aspects that are relevant for traffic engineering, states the relation between the cell-level traffic controls (described in Recommendation E.736) and call-level traffic controls and dimensioning (described in Recommendation E.737), and gives guidelines on strategies for network configura
24、tions using the VP concept. In this present issue, only the user plane is considered. 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
25、 indicated were valid. All 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 vali
26、d ITU-T Recommendations is regularly published. - IT-T Recommendation E.716 (1996), User demand modelling in Broadband ISDN. - ITU-T Recommendation E.736 (1997), Methods for cell-level trafic control in B-ZSDN. - IT-T Recommendation E.737 (1997), Dimensioning methods for B-ZSDN. - ITU-T Recommendati
27、on 1.3 1 1 (1996). B-ISDN general network aspects. - ITU-T Recommendation 1.356 (1996), B-ISDN ATM layer cell transfer performance. - ITU-T Recommendation 1.37 1 (1996), Trafic control and congestion control in B-ZSDN. 3 Terms and definitions This Recommendation defines the following terms. 3.1 VP-V
28、C) node designates either a VP (or VC or VP-VC) cross-connect or a VP (or VC or VP-VC) switch. ATM node: Generic term used to designate an ATM cross-connect or an ATM switch. The term VP (or VC or 3.2 ATM link Transmission path together with its associated buffer in the upstream node. 3.3 nodes with
29、out any intermediate ATM node. ATM link set: Set of all the ATM links with the same direction of transmission interconnecting two ATM 3.4 any intermediate VC node. VPC set: Set of all the VPCs with the same direction of transmission interconnecting two VC nodes without 3.5 DBR VPC: VPC characterized
30、 by a Peak Cell Rate (PCR) and a Cell Delay Variation Tolerance (CDVT). Recommendation E.735 (0997) 1 3.6 negligible CDV with respect to a reference arrival process. 3.7 variable rate VPC: Network-to-network or network-to-user VPC characterized by cell traffic variables chosen to allow statistical m
31、ultiplexing of the VCCs in the VPC with other connections on the ATM links traversed by the VPC. This Recommendation defines only one type of variable rate VPC, and it is characterized by its ECR in each of the ATM links. uncontrolled constant rate VPC: Network-to-network or network-to-user VPC char
32、acterized by a rate and a 3.8 equivalent cell rate: A cell rate atuibuted to 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. 4 Abbreviations This Recommendati
33、on uses the following abbreviations. ABR ABT ATM B-ISDN CAC CDV CDVT CLP CLR CPE CTD DBR DCC ECBP ECR GCRA GOS IBT NPC OAM PCR PDH QOS SBR SCR SDH STD TP 2 Available Bit Rate ATM Block Transfer Asynchronous Transfer Mode Broadband Integrated Services Digital Network Connection Admission Control Cell
34、 Delay Variation CDV Tolerance Cell Loss Priority Cell Loss Ratio Customer Premises Equipment Cell Transfer Delay Deterministic Bit Rate Digital Cross-Connect . End-to-end Connection Blocking Probability Equivalent Cell Rate Generic Cell Rate Algorithm Grade of Service Intrinsic Burst Tolerance Netw
35、ork Parameter Control Operation and Maintenance Peak Cell Rate Plesiochronous Digital Hierarchy Quality of Service Statistical Bit Rate Sustainable Cell Rate Synchronous Digital Hierarchy Source Traffic Descriptor Transmission Path Recommendation E.735 (05197) STD-ITU-T RECMN E-735-ENGL 1997 48b257L
36、 b38850 152 m UNI UPC vc vcc VCI VP VPC VPI User-Network Interface Usage Parameter Control Virtual Channel VC Connection VC Identifier Virtual Path VP Connection VP Identifier 5 Introduction To solve the problem of resource allocation and control implies providing answers to several questions relate
37、d with the implementation of the network. These questions affect decisions to be taken at different time scales and will be treated in different B-ISDN Recommendations of the E.730- and E.740-Series. They may be enumerated as follows: e e e e e e 6 First, a network topology must be defined. This lar
38、gely depends on the operators policy and is out of the scope of the E.730- and E.740-Series of Recommendations. For a given traffic and a given network topology, the operator may want to define network-to-network virtual paths in order to carry user-to-user VC connections with appreciable gains in t
39、erms of control costs, easier network reconfigurations and possible subnetwork segregation. Guidelines for this VP configuration are given in this Recommendation. This question provides input for VP dimensioning. Network dimensioning involves the dimensioning of the physical network elements, partic
40、ularly ATM link sets (including bandwidth and buffer dimensioning), and will be considered in Recommendation E.737. VP dimensioning relates to the dimensioning of the network-to-network virtual paths defined by the operator, and is considered in Recommendation E.737. The objective is to determine th
41、e number of network-to-network virtual paths in the VP configuration and to assign capacity parameters to them. Caii-level traffic controls must be specified in order to guarantee the required call-level GOS objectives. This involves defining the routing, service protection mechanisms and network ma
42、nagement. Recommendation E.737 deds with the aspects of these controls more related with dimensioning, namely service protection mechanisms and some aspects of routing. Network management controls are out of scope of the E.730- and E.740-Series of Recommendations. Ceii-level traffic controls must be
43、 specified in order for the network to provide the required cell-level GOS objectives and minimize the resources needed for that target. The definition of these traffic controls provides input for VP dimensioning and network dimensioning, because it gives information on the amount of resources neede
44、d by a connection to satisfy the cell-level GOS objectives. This problem is treated in Recommendation E.736. General considerations on B-ISDN networks In B-ISDNs some functionalities, entities and architecturai principles are distinctive of these networks and must be taken into account in engineerin
45、g. These topics are examined in this clause from the viewpoint of their relations with traffic engineering. 6.1 Layers and levels in the network As stated in Recommendation 1.31 1, the ATM transport network is structured in two layers, namely the physical layer and the ATM layer. For traffic enginee
46、ring, the upper level of the physical layer, the Transmission Path (TP) level, and the two levels of the ATM layer, the Virtual Path (VP) level and the Virtual Channel (VC) level, are significant (see Figure 6-1). Recommendation E.735 (05197) 3 STD-ITU-T RECMN E-735-ENGL 1777 48b2.571 Ob38851 079 VC
47、S Tranmiission Path TO206450-97/dOl Figure 6-1E.735 - VP and VC levels in the ATM layer A Virtual Channel Connection (VCC) is formed as a concatenation of VC links, each VC link being established on a Virtual Path Connection (VPC). Thus a VCC is established on a concatenation of VPCs. In its turn, a
48、 VPC is formed as a concatenation of VP links, each VP link being established on a TP. Thus a VPC is established on a concatenation of TPs (see Figure 6-2). Virtual Channel Connection Virtual channel Virtual Channel link level Virtual Path level / / / / / / / / / Virtual Path Connection / . 4 / / /
49、/ / / / / I Vfiiai Path link I . I / / / I4 / Transmission Path I , 4 /- Transmission Path I level / 0 Connection endpoints of the corresponding levels Connection points of the corresponding levels Figure 6-2E.735 - Hierarchical level to level relationship Two important particular cases should be considered: - A VPC established between two users: The VCCs established on these WCs (which are VCCs with only one VC link) are not viewed by the network but only by the users. Thus, from a network point of view,
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