1、INTERNATIONAL TELECOMMUNICATION UNION ITU=T TELECOMMUNICATION STANDARDIZATION SECTOR OF ITU E.177 SERIES E: TELEPHONE NETWORK AND ISDN Operation, numbering, routing and mobile services - International operation - International routing plan (1 0/96) B-ISDN routing ITU-T Recommendation E.177 (Previous
2、ly CClTT Recommendation) COPYRIGHT International Telecommunications Union/ITU TelecommunicationsLicensed by Information Handling ServicesITU-T E-SERIES RECOMMENDATIONS TELEPHONE NETWORK AND SDN OPERATION, NUMBERING, ROUTING AND MOBILE SERVICES INTERNATIONAL OPERATION Definitions E.100-E.229 E. 1 OO-
3、E. 103 General provisions concerning Administrations E. 104-E. 1 19 General provisions concerning users E. 120-E. 139 Operation of international telephone services E. 140-E. 159 Tones in national signalling systems Maritime mobile service and public land mobile service E. 180-E. 199 E.200-E.229 OPER
4、ATIONAL PROVISIONS RELATING TO CHARGING AND ACCOUNTING IN E.230-E.299 THE INTERNATlONAL TELEPHONE SERVICE Charging in the international telephone service E.230-E.249 Procedures for remuneration of Administrations for facilities made available E.250-E.259 Measuring and recording call durations for ac
5、counting purposes Establishment and exchange of international accounts E.260-E.269 E.270-E.299 UTILIZATION OF THE INTERNATIONAL TELEPHONE NETWORK FOR NON- E.300-E.329 TELEPHONY APPLICATIONS General E.300-E.319 Phototelegraphy E.320-E.329 ISDN PROVISIONS CONCERNING USERS E.330-E.399 QUALINOF SERVICE,
6、 NETWORK MANAGEMENT AND TRAFFIC ENGINEERING NETWORK MANAGEMENT E.400-E.489 TRAFFIC ENGINEERING E.490-E.799 QUALITY OF TELECOMMUNICATION SERVICES: CONCEPTS, MODELS, E.800-E.899 OBJECTIVES AND DEPENDABILITY PLANNING For further details, please refer to ITU-T List of Recommendations. COPYRIGHT Internat
7、ional Telecommunications Union/ITU TelecommunicationsLicensed by Information Handling ServicesITU-T RECOMMENDATION E.177 B-ISDN ROUTING Summary This Recommendation provides routing principles in B-ISDN, in particular, guidance on the incorporation of service requirements into the network routing pro
8、cess. Source ITU-T Recommendation E. 177 was prepared by ITU-T Study Group 2 (1993-1996) and was approved under the WTSC Resolution No. 1 procedure on the 8th of October 1996. COPYRIGHT International Telecommunications Union/ITU TelecommunicationsLicensed by Information Handling Services STD.ITU-T R
9、ECMN EmL77-ENGL 1996 m 48b2593 Ob2bL20 3bb B 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 is responsible for studyi
10、ng 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 by the ITU-T Study Grou
11、ps 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 within ITU-Ts purview, the nec
12、essary 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 reserved. No part of this publica
13、tion 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 ITU. 11 Recommendation E.177 (10/96) COPYRIGHT International Telecommunications Union/ITU TelecommunicationsLicensed by Information H
14、andling ServicesCONTENTS Page 1 Introduction 2 3 Scope References and related Recommendations . 4 Definitions Abbreviations . B-ISDN routing principles . Network structure . 8 Routing process 8.1 General 8.2 User-network interface . 8.3 Originating local VC switch . 8.4 Transit VC switches (national
15、 and international) . 8.5 OAM nodes 9 9.1 9.2 9.3 9.4 9.5 9.6 9.7 9.8 9.9 9.10 9.1 1 9.12 10 Information analysis . Calling party . Incoming route Called number Broadband bearer capability . ATM traffic descriptor ATM cell rate (encoded as ATM cell rate as SS No . 7 B-ISUP) . End-to-end transit dela
16、y Maximum end-to-end transit delay . Propagation delay counter Transit network selection Network management conditions . Time, event and state conditions Network capability . 11 Signalling capability . 12 History Recommendation E.177 (10196) 1 1 2 2 2 3 9 9 9 9 10 11 11 11 11 11 11 11 11 11 12 12 .
17、111 COPYRIGHT International Telecommunications Union/ITU TelecommunicationsLicensed by Information Handling ServicesCOPYRIGHT International Telecommunications Union/ITU TelecommunicationsLicensed by Information Handling ServicesRecommendation E.177 B-ISDN ROUTING (Geneva, 1996) 1 Introduction This R
18、ecommendation provides routing principles in B-ISDN, in particular, guidance on the incorporation of service requirements into the network routing process. Contents of this Recommendation will be extended in order to satisfy operational needs which will arise according to the evolution of networkhig
19、nalling capabilities. 2 Scope The scope of this Recommendation is the routing of B-ISDN user information transport network supported by Signalling Capability Set 1 (SCS-1). Service capabilities supported in this Recommendation are as follows: - routing principles for on-demand Virtual Channel Connec
20、tion directed by signalling procedures to provide Broadband Connection Oriented Bearer service are specified. Routing principles for Broadband Connectionless Bearer Service are out of scope of this Recommendation; - Virtual Path Connections to accommodate the Virtual Channel Connection are predefine
21、d, - one and only one connection is established per call in a point-to-point configuration; - intenvorking with N-ISDN circuit mode service is considered; and - no QOS indicationhegotiation is performed between user and network. i.e. semi-permanent connection; Check marks on Table 1 show the service
22、 capabilities supported in this Recommendation. TABLE 1E. 177 Service capabilities supported in this Recommendation Configuration Broadcast Point-to-multipoint JPoint-to-point Number of connections Asymmetric JSymmetric Bandwidth c all connection per call per call Multiple connections per JOne and o
23、nly one Bearer service Indication of QOS JNo indication QOS class ISDN Frame mode Packet mode /Circuit mode Interworking with N- BCLB-D BCOB-B, C JBCOB-A BCOB Broadband Connection Oriented Bearer service BCLB Broadband Connectionless Bearer service I Routing principles for Virtual Path Connection is
24、 out of the scope of this Recommendation. The following separation of concerns between transport function and OAM function should be taken into consideration: Recommendation E.177 (10/96) 1 COPYRIGHT International Telecommunications Union/ITU TelecommunicationsLicensed by Information Handling Servic
25、es- transport network control directed by service request from the user; - policy making for efficient B-ISDN networking in OAM function. Network topology and traffic routing methods are specified in Recommendation E. 170. 3 References and related Recommendations B-ISDN basic description B-ISDN inte
26、rworking B-ISDN network capabilities B-ISDN signalling - User-network interface - Network-node interface B-ISDN switching capabilities and interfaces B-ISDN telecommunication services Network management controls Numbering plans Routing plans I. 100-Series 1.500-Series 1.300-Series 4.293 1 Q.276X-Ser
27、ies Q.2500-Series F.811 E.4 12 E.191 E.170, E.171, E.172 4 Definitions 4.1 virtual path connection group: A group of Virtual Path Connections which have the same permanent characteristics between Virtual Channel switches, e.g. propagation delay. The following points should be taken into consideratio
28、n on grouping VPCs and may consequently impact route selection: - number of VP cross -connects on a connection; - number of VP links on a connection; - propagation delay of each VPC. This current definition may evolve in the future taking account of future capability, e.g. traffic type, 5 Abbreviati
29、ons For the purposes of this Recommendation, the following abbreviations are used. AAL ATM Adaptation Layer ATM Asynchronous Transfer Mode B-BC Broadband Bearer Capability BCOB Broadband Connection Oriented Bearer service B-ISDN Broadband Integrated Services Digital Network B-ISUP Broadband ISDN Use
30、r Part IAM Initial Address Message IN Intelligent Network 2 Recommendation E.177 (10/96) COPYRIGHT International Telecommunications Union/ITU TelecommunicationsLicensed by Information Handling ServicesN-ISDN NP1 OAM OLVS QOS ROA TLVS TON TVS UNI vc vcc VP VPC - - STD-ITU-T RECMN E-177-ENGL L77b qbbZ
31、57L Ob2bL25 7Y8 m Narrow-band Integrated Services Digital Network Numbering Plan Identifier Operation Administration and Maintenance Originating Local Virtual channel Switch Quality of Service Recognized Operating Agency Terminating Local Virtual channel Switch Type of Number Transit Virtual channel
32、 Switch User Network Interface Virtual Channel Virtual Channel Connection Virtual Path Virtual Path Connection 6 B-ISDN routing principles 6.1 Figure 1 shows representation of VPC and VCC between calling and called customer equipment. I vcc I Customer vc Equipment Switch I t L VP Cross-Connect vc Vi
33、rtual Channel VCC Virtual Channel Connection VP Virtual Path VPC Virtual Path Connection FIGURE 1 /E. 177 Representation of VPC and VCC VC Customer Switch Equipment 6.2 The concept of service defined network connections - the matching between the telecommunication service request and network compone
34、nt capability - would be applied to B-ISDN Recommendation E.177 (10/96) 3 COPYRIGHT International Telecommunications Union/ITU TelecommunicationsLicensed by Information Handling ServicesSTI).ITU-T RECNN E.177-ENGL L77b m 48b25711 Ob2b12b 884 m in order to ensure that B-ISDN services can be routed ef
35、fectively and efficiently by various networks which support them. 6.3 Routing of Virtual Channel Connection (VCC) is considered to be a function to select a Virtual Path Connection (VPC) Group from predefined VPC Groups between VC switches at the connection set-up phase. Figure 2 shows the concept o
36、f VCC route selection. Translation of digits may be performed at the transit VC switch. Routing of VCC based on predefined VPC Group is similar to the routing of PSTN and circuit switched services of N-ISDN, i.e. selection of a circuit group between switches at the call Set-up. Appropriate VPC will
37、then be selected from the route (VPC Group) based on the load and the requested traffic rate. According to Recommendation Q.2764, for every VPC it is defined which VC switch controls the assignment of bandwidth and identification of VC. A VC switch should first select the VPC which the switch is con
38、trolling. Figure 3 shows the concept of VPC selection between VC switches. No translation of digits will be performed at the VP cross-connect. Route selection and VPC selection may be performed simultaneously. It is necessary that predefined VPC can be identified unambiguously at both VC switches. 4
39、 vc Switch r- Switch VPC Group 3 x A 1 I VPC Virtual Path Connection FIGURE 2E. 177 Concept of route selection Recommendation E.177 (10/96) vc Switch T0205790-96 COPYRIGHT International Telecommunications Union/ITU TelecommunicationsLicensed by Information Handling ServicesD Switch VPC Group -1 Swit
40、ch T020580096 FIGURE 3E. 177 Concept of Virtual Path Connection (VPC) selection 6.4 Both directions of VCC are routed on the same route. Bandwidth of each direction may be different based on service request. 6.5 B-ISDN routing must be viewed from two perspectives: - feature capabilities as seen by t
41、he customer; - network, operational and commercial attributes as seen by the network operators. 6.6 From a network routing perspective, the physical requirements of a network connection may be determined through analysis of parameters (assessed in detail in clause 8). Bearer service definitions dict
42、ate the minimum capability for information transfer between ISDN access points. The service aspect of B-ISDN routing is based primarily on the bearer service requested by the customer. B-ISDN bearer services are defined in Recommendation F.811. 6.7 In order to support dynamic capabilities in new ser
43、vices, the following separation of concerns between transport function and OAM function should be taken into account: - transport network control directed by service request from the user; - policy making for efficient B-ISDN networking in OAM function. 7 Network structure 7.1 In the B-ISDN era it i
44、s suggested that: a) the network structure should be non-hierarchical; b) for connection routing purpose the network can be subdivided into national and international connection elements; the national element being subdivided into local and trunk if appropriate; c) ROAS should be free to change thei
45、r own connection routing arrangements providing they are still within the guidelines outlined in this plan. 7.2 International outgoing and incoming gateways should be VC switch to provide necessary interworking of routing methods and information analysis for routing purpose, e.g. digit analysis. 7.3
46、 The routing concepts outlined in Recommendation E. 170 can apply in any network elements (e.g. local, national or international) but only by agreements should they be used across a connection elements boundary (see Note). The following points should be taken into consideration and may impact route
47、selection: Recommendation E.177 (10/96) 5 COPYRIGHT International Telecommunications Union/ITU TelecommunicationsLicensed by Information Handling ServicesSTD-ITU-T RECMN E.177-ENGL L77b W 48b259L Ob2bL28 h57 U - number of VC switches and VP cross-connectson an end-to-end VCC; - number of VP links on
48、 an end-to-end VCC; - propagation delay of an end-to-end VCC. Maximum allocations of nodes and links allowed for each connection element are for further study. NOTE - Dynamic routing as defined in Recommendation E. 170 is for further study. 7.4 Figure 4 shows a generic B-ISDN network structure. Sepa
49、ration of transport function and OAM function will be realized either by the separation of physical nodes or integrated function in VC switches. Some of IN-supported services may require that service control node process impact routing on transport layer. Called User Transport Layer (see Rec. Intelligent Layer (see Rec. 1.31 1) 1.31 1) OLVS Originating Local Virtual Channel Switch WS Transit Virtual Channel Switch TLVS Terminating Local Virtual Channel Switch UNI User Network Interface FIGURE 4E. 177 Generic B-ISDN network structure T020644087 6 Recommendation E.177 (10/
