1、INTERNATIONAL TELECOMMUNICATION UNION ITU-T TELECOMMUNICATION STANDARDIZATION SECTOR OF ITU E.352 (03/2000) SERIES E: OVERALL NETWORK OPERATION, TELEPHONE SERVICE, SERVICE OPERATION AND HUMAN FACTORS Operation, numbering, routing and mobile services - ISDN provisions concerning users - International
2、 routing plan Routing guidelines for efficient routing methods ITU-T Recommendation E.352 (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
3、OPERATION 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 Numbering plan of the internatio
4、nal telephone service Maritime mobile service and public 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
5、 THE INTERNATIONAL TELEPHONE NETWORK FOR NON- TE LEP H ONY AP PLI CATI ONS General Phototelegraphy ISDN PROVISIONS CONCERNING USERS E. 1 00-E. 103 E.104-E.119 E. 120-E. 139 E. 140-E. 159 E. 160-E. 169 E. 170-E. 179 E. 180-E. 189 E. 190-E. 199 E.200-E.229 E.230-E.249 E.260-E.269 E.300-E.319 E.320-E.3
6、29 International routing plan E.35-E.399 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 ENGINEERING Measurement and recording of tr
7、affic Forecasting of traffic Determination of the number of circuits in manual operation Determination of the number of circuits in automatic and semi-automatic operation Grade of service Definitions ISDN traffic engineering Mobile network traffic engineering QUALITY OF TELECOMMUNICATION SERVICES: C
8、ONCEPTS, 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 quality of service objectives for planni
9、ng of telecommunication networks Field data collection and evaluation on the performance of equipment, networks and services 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.700-E.749 E.750-E.799 E.800-E.809 E.810-E.844 E.845-E.859 E.860-E.87
10、9 E.880-E.899 For further details, please rer to ITD-T List of Recommendations. ITU-T RECOMMENDATION E.352 ROUTING GUIDELINES FOR EFFICIENT ROUTING METHODS Summary Routing policies typically used in ATM- and IP-based networks do not fully consider the possible instabilities and drastic loss of throu
11、ghput that can occur under congestion. Use of bandwidth reservation and avoidance of long paths are recommended under such congestion, which can lead to more efficient use of network resources. Also, there is an emphasis in ATM- and IP-based networks on the use of state-dependent-routing (SDR) metho
12、ds. However, the flooding methods typically used by these SDR methods to disseminate network status information can lead to inefficient use of network resources. Use of event-dependent-routing (EDR) methods and/or more efficient dissemination of network status information are recommended as other po
13、ssible approaches to consider. Finally, QoS routing rules are recommended to ensure service performance quality, such as avoidance of excessive transfer delay by limiting the number of satellite hops in an end-to-end connection. Source ITU-T Recommendation E.352 was prepared by ITU-T Study Group 2 (
14、1997-2000) and was approved under the WTSC Resolution No. 1 procedure on 13 March 2000. Recommendation E.352 (03/2000) i FOREWORD ITU (International Telecommunication Union) is the United Nations Specialized Agency in the field of telecommunications. The ITU Telecommunication Standardization Sector
15、(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), which meet
16、s 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 information techn
17、ology 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. INTELLEC
18、TUAL 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 Property Right
19、s, whether asserted by ITU members or others outside of the Recommendation development process. As of the date of approval of this Recommendation, the ITU had not received notice of intellectual property, protected by patents, which may be required to implement this Recommendation. However, implemen
20、tors are cautioned that this may not represent the latest information and are therefore strongly urged to consult the TSB patent database. o ITU 2000 All rights reserved. No part of this publication may be reproduced or utilized in any form or by any means, electronic or mechanical, including photoc
21、opying and microfilm, without permission in writing fi-om the ITU. 11 Recommendation E.352 (03/2000) CONTENTS 1 2 3 4 5 5.1 5.2 5.3 6 6.1 6.2 Scope . References . Definitions Abbreviations Recommended routing methods . Bandwidth reservation methods Route selection QoS routing . Examples of recommend
22、ed routing methods Example of bandwidth reservation methods . Example of route selection methods . Annex A . TDM-based intranetwork routing methods . A . 1 Fixed routing (FR) A.2 Time-dependent routing (TDR) A.3 State-dependent routing (SDR) . A.4 Event-dependent routing (EDR) . Appendix I - Bibliog
23、raphy . Recommendation E.352 (03/2000) Page 1 1 2 2 4 4 6 7 8 8 8 10 10 10 11 12 12 . 111 Introduction There are many network operators who have implemented multiple networks using different protocols, which include Public Switched Telephone Networks (PSTNs) which use Time Division Multiplexing (TDM
24、) technology, Asynchronous Transfer Mode (ATM) technology, and/or Internet Protocol (IP) technology. Various routing protocols are used in TDM-, ATM-, and IP-based networks. In TDM-based networks, for example, Recommendation E.350 describes fixed and dynamic routing methods for use in TDM-based netw
25、orks. In ATM-based networks, for example, the Private Network-Network Interface (PNNI) standard adopted by the ATM Forum ATM9600551 provides for exchange of node and link status information, automatic update and synchronization of topology databases, and dynamic route selection based on topology and
26、 status information. In IP- based networks, for example, the open shortest path first (OSPF) and other standards adopted by the Internet Engineering Task Force M98 and S95 provide for many of the same featwes as PNNI, but in a connectionless IP-based packet network. OSPF also provides for exchange o
27、f node and link status information, automatic update and synchronization of topology databases, and dynamic route selection based on topology and status information. This Recommendation addresses guidelines for efficient routing methods that have been studied, learned, and implemented over many year
28、s of experience in TDM-based networks. These routing guidelines and methods are applicable as well to ATM- and IP-based networks, and are recommended for these networks. It is noted in the Recommendation that routing policies typically used in ATM- and IP-based networks do not fully consider the pos
29、sible instabilities and drastic loss of throughput that can occur under congestion. Use of bandwidth reservation and avoidance of long paths are recommended under such congestion, which can lead to more efficient use of network resources. Also, there is an emphasis in ATM- and IP-based networks on t
30、he use of state-dependent- routing (SDR) methods. However, the flooding methods typically used by these SDR methods to disseminate network status information can lead to inefficient use of network resources. Use of event-dependent-routing (EDR) methods and/or more efficient dissemination of network
31、status information are recommended as other possible approaches to consider. Finally, QoS routing rules are recommended to ensure service performance quality, such as avoidance of excessive transfer delay by limiting the number of satellite hops in an end-to-end connection. iv Recommendation E.352 (
32、03/2000) Recommendation E.352 ROUTING GUIDELINES FOR EFFICIENT ROUTING METHODS (Geneva, 2000) Introduction There are many network operators who have implemented multiple networks using different protocols, which include Public Switched Telephone Networks (PSTNs) which use Time Division Multiplexing
33、(TDM) technology, Asynchronous Transfer Mode (ATM) technology, and/or Internet Protocol (IP) technology. Various routing protocols are used in TDM-, ATM-, and IP-based networks. In TDM-based networks, for example, Recommendation E.350 describes fixed and dynamic routing methods for use in TDM-based
34、networks. In ATM-based networks, for example, the Private Network-Network Interface (PNNI) standard adopted by the ATM Forum ATM9600551 provides for exchange of node and link status information, automatic update and synchronization of topology databases, and dynamic route selection based on topology
35、 and status information. In IP- based networks, for example, the open shortest path first (OSPF) and other standards adopted by the Internet Engineering Task Force M98 and S95 provide for many of the same featwes as PNNI, but in a connectionless IP-based packet network. OSPF also provides for exchan
36、ge of node and link status information, automatic update and synchronization of topology databases, and dynamic route selection based on topology and status information. This Recommendation addresses guidelines for efficient routing methods that have been studied, learned, and implemented over many
37、years of experience in TDM-based networks. These routing guidelines and methods are applicable as well to ATM- and IP-based networks, and are recommended for these networks. It is noted in the Recommendation that routing policies typically used in ATM- and IP-based networks do not fully consider the
38、 possible instabilities and drastic loss of throughput that can occur under congestion. Use of bandwidth reservation and avoidance of long paths are recommended under such congestion, which can lead to more efficient use of network resources. Also, there is an emphasis in ATM- and IP-based networks
39、on the use of state-dependent- routing (SDR) methods. However, the flooding methods typically used by these SDR methods to disseminate network status information can lead to inefficient use of network resources. Use of event-dependent-routing (EDR) methods and/or more efficient dissemination of netw
40、ork status information are recommended as other possible approaches to consider. Finally, QoS routing rules are recommended to ensure service performance quality, such as avoidance of excessive transfer delay by limiting the number of satellite hops in an end-to-end connection. 1 Scope This Recommen
41、dation provides guidelines for the design of routing methods within TDM-, ATM-, and IP-based networks, and makes particular recommendations on bandwidth reservation, route selection, and QoS routing. It recommends these guidelines based on established practice, particularly as applied within TDM-bas
42、ed PSTN networks, and addresses the cases when PSTNs evolve to incorporate IP- or ATM-based technology. Guidelines on routing methods are covered in clause 5, and examples are given in clause 6 for the use of the routing methods. 2 References The following ITU-T Recommendations and other references
43、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 therefore encouraged to invest
44、igate the possibility of applying the Recommendation E.352 (03/2000) 1 most recent edition of the Recommendations and other references listed below. A list of the currently valid ITU-T Recommendations is regularly published. E. 1641 E.170 E. 1771 E. 3 501 E.35 11 E .4 1 21 E. 5251 ES291 ITU-T E. 164
45、 (1997), The International Telecommunications Numbering Plan. ITU-T E. 170 (1992), Trafic routing. ITU-T E. 177 (1 996), B-ISDN routing. ITU-T E.350 (2000), Dynamic Routing Interworking. ITU-T E.351 (2000), Routing of multimedia connections across TDM-, ATM-, and IP-based networks. ITU-T E.412 (1998
46、), Network management controls. ITU-T ES25 (1992), Designing networks to control grade of service. ITU-T ES29 (1997), Network dimensioning using end-to-end GOS objectives. 3 Definitions This Recommendation defines the following terms: 3.1 3.2 3.3 capabilities, or an aggregation of such network eleme
47、nts representing a network. 3.4 allocation request. 3.5 3.6 O-D pair. 3.7 3.8 route set for a connectionhandwidth-allocation request. 3.9 3.10 link: A bandwidth transmission medium between nodes that is engineered as a unit. destination node: Terminating node within a given network. node: A network
48、element (switch, routerhwitch, exchange) providing switching and routing O-D pair: An originating node to destination node pair for a given connectionhandwidth- originating node: Originating node within a given network. route: A concatenation of links providing a connectionhandwidth-allocation betwe
49、en an route set: A set of routes connecting the same O-D pair. routing table: Describes the route choices and selection rules to select one route out of the traffic stream: A class of connection requests with the same traffic characteristics. via node: An intermediate node in a route within a given network. 4 Abbreviations This Recommendation uses the following abbreviations: AAR Automatic Alternate Routing ABR Available Bit Rate AESA ATM End System Address ARR Automatic Rerouting AS Autonomous System ATM Asynchronous Transfer Mode BGP Border Gateway Protocol B-ISDN Broa
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