1、INTERNATIONAL TELECOMMUNICATION UNION ITU-T TELECOMMUNICATION STANDARDIZATION SECTOR OF ITU x. I (03/00) SERIES X: DATA NETWORKS AND OPEN SYSTEM COM M U N I CAT I ON S Public data networks - Services and facilities International user classes of service in, and categories of access to, public data ne
2、tworks and integrated services digital networks (ISDNs) ITU-T Recommendation X. 1 (Previously CCITT Recommendation) COPYRIGHT International Telecommunications Union/ITU TelecommunicationsLicensed by Information Handling ServicesITU-T X-SERIES RECOMMENDATIONS DATA NETWORKS AND OPEN SYSTEM COMMUNICATI
3、ONS PUBLIC DATA NETWORKS Services and facilities X.1-X.19 Interfaces Transmission, signalling and switching Network aspects Maintenance Administrative arrangements Model and notation Service definitions Connection-mode protocol specifications Connectionless-mode protocol specifications PICS proforma
4、s Protocol Identification Security Protocols Layer Managed Objects Conformance testing General Satellite data transmission systems MESSAGE HANDLING SYSTEMS DIRECTORY OS1 NETWORKING AND SYSTEM ASPECTS OPEN SYSTEMS INTERCONNECTION INTERWORKING BETWEEN NETWORKS Networking Efficiency Quality of service
5、Naming, Addressing and Registration Abstract Syntax Notation One (ASN. 1) Systems Management framework and architecture Management Communication Service and Protocol Structure of Management Information Management functions and ODMA functions OS1 MANAGEMENT SECURITY OS1 APPLICATIONS Cornmitment, Conc
6、urrency and Recovery Transaction processing Remote operations OPEN DISTRIBUTED PROCESSING X.20-X.49 X.50-X.89 X.90-X. 149 X.150-X. 179 X. 180-X. 199 X.200-X.209 X.2 1 0-X.2 19 X.220-X.229 X.230-X.239 X.240-X.259 X.260-X.269 X.270-X.279 X.280-X.289 X.290-X.299 X.300-X.349 x.350-x.399 X.400-X.499 X.50
7、0-X.599 X.600-X.629 X.630-X.639 X.640-X.649 X.650-X.679 X.680-X.699 X.700-X.709 X.71 0-X.7 19 X.720-X.729 x.730-x.799 X.800-X.849 X.850-X.859 X.860-X.879 X.880-X.899 X.900-X.999 For further details, please rer to ITD-T List of Recommendations. COPYRIGHT International Telecommunications Union/ITU Tel
8、ecommunicationsLicensed by Information Handling ServicesITU-T RECOMMENDATION X.l INTERNATIONAL USER CLASSES OF SERVICE IN, AND CATEGORIES OF ACCESS TO, PUBLIC DATA NETWORKS AND INTEGRATED SERVICES DIGITAL NETWORKS (ISDNs) Summary This Recommendation describes international user classes of service in
9、, categories of access to, public data networks and Integrated Services Digital Networks (ISDN). Details for leased circuit, circuit-switched, packet-switched, and frame relay data transmission services are provided. This revision includes the access to FRDTS via B-ISDN. Source ITU-T Recommendation
10、X.l was revised by ITU-T Study Group 7 (1997-2000) and was approved under the WTSC Resolution No. 1 procedure on 3 1 March 2000. Recommendation X.l (03/00) 1 COPYRIGHT International Telecommunications Union/ITU TelecommunicationsLicensed by Information Handling ServicesFOREWORD ITU (International Te
11、lecommunication Union) is the United Nations Specialized Agency in the field of telecommuni- cations. 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 Recommendations
12、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 topics. The app
13、roval 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 Recommendation,
14、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 the use of a c
15、laimed 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 Recommendation, th
16、e 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 database. O ITU 2000
17、 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 fiom the ITU. Recommendation X.l (03/00) 11 COPYRIGHT International Telecommunications Union/ITU
18、TelecommunicationsLicensed by Information Handling ServicesCONTENTS Page 1 Introduction 1 Access to a leased circuit data transmission service . 3 Access to a circuit-switched data transmission service . 4 2 3 4 Access to a packet-switched data transmission service 6 5 Access to a frame relay data t
19、ransmission service 10 1 Recommendation X.1 (03OO) 111 COPYRIGHT International Telecommunications Union/ITU TelecommunicationsLicensed by Information Handling ServicesCOPYRIGHT International Telecommunications Union/ITU TelecommunicationsLicensed by Information Handling ServicesRecommendation X.l IN
20、TERNATIONAL USER CLASSES OF SERVICE IN, AND CATEGORIES OF ACCESS TO, PUBLIC DATA NETWORKS AND INTEGRATED SERVICES DIGITAL NETWORKS (ISDNs) (Geneva, 1972; amended at Geneva, 1976 and 1980; Malaga-Torremolinos, 1984; Melbourne, 1988; Helsinki, 1993; revised in Geneva, 1996 and 2000) 1 Introduction The
21、 establishment in various countries of public networks for data transmission and ISDNs for integrated services creates a need to standardize user classes of service and categories of access. This Recommendation is required to meet the following goals: a) b) c) d) e) providing sufficient data signall
22、ing rates to meet users needs; allowing optimization of Data Terminal Equipment (DTE) and transmission and switching costs to provide an overall economic service to the user; recognizing particular operating modes of users DTE; allowing users to transfer information consisting of any bit sequence an
23、d of any number of bits up to a certain amount; recognizing the interaction between users requirements, technical limitations and tariff structure that may influence how DTE gains access to public data transmission services. User class of service is a category of data transmission service in which t
24、he DTE operation mode, data signalling rate, call control signalling rates and code structure (in start-stop mode) are standardized. Category of access identifies the method by which DTE gains access to a specific data transmission service. There are four public data transmission services, namely: 1
25、) 2) 3) 4) This Recommendation defiies only the basic user facility(ies) of these data transmission services. Optional user facilities of these data transmission services are defined in Recommendation X.2. leased circuit data transmission service; circuit-switched data transmission service (CSDTS);
26、packet-switched data transmission service (PSDTS); frame relay data transmission service (FRDTS). Access for Data Terminal Equipment (DTE) to data transmission services may be any of the following: a) direct access when DTE is connected to the network providing the service without intermediate switc
27、hed network; or b) port access when DTE is connected to the network providing the service via intermediate switched network (see Figure 1). Port access may be achieved by any of the following: 1) 2) by switched connection when signallingkontrol procedures are required to establishrelease connection
28、of the DTE to the network providing the service; or by permanent connection when no signallingkontrol procedures are required to establishrelease the connection of the DTE to the network providing the service (see Figure 2). The categories of access described in this Recommendation take into account
29、 direct access (see Note) to public data networks and ISDNs and the port access cases where interworking with other public networks is involved. Access to the packet-switched data transmission service via the Packet AssemblyDisassembly (PAD), Facsimile Packet AssemblyDisassembly (FPAD) or Multi-Aspe
30、ct Packet AssemblyDisassembly (MAP) function, as defined in Recommendations X.3, X.5 or X.8, respectively, is also covered in this Recommendation. NOTE - Direct access may be provided by means of leased circuits or by dedicated access circuits. Recommendation X.l (03/00) 1 COPYRIGHT International Te
31、lecommunications Union/ITU TelecommunicationsLicensed by Information Handling Services/ I Leased circuit or dedicated circuit Network providing / from a transmission network J the service a) Direct access Intermediate switched network Network providing the service / b) Pori access Figure lB1.l- Exam
32、ples of direct access and port access . - Switched connection - - - J Network providing - / / Intermediate switched - / DTE network . 0 a) Access with switched connection . - - Permanent connection Network providing 1 / Intermediate switched network 1 “ 0 .- -#HO DTE TO7261 50-96/602 b) Access with
33、permanent connection Figure 2B1.1- Two types of port access For example, packet mode terminals may have access to the public packet-switched data transmission service, in user classes of service 8 to 11 , either via a direct access (see above Note) or via a port access. The port access can be establ
34、ished using a Circuit-Switched Public Data Network (CSPDN), a Public Switched Telephone Network (PSTN), an ISDN or a PDN providing fiame relay data transmission service. In all of these cases, an interworking function will be required to access the packet-switched data transmission service and both
35、permanent and switched connections may be used for the access. 2 Recommendation X.l (03/00) COPYRIGHT International Telecommunications Union/ITU TelecommunicationsLicensed by Information Handling ServicesIt is not mandatory for Administrations to provide all of the data transmission services, user c
36、lasses of service, or categories of access contained in this Recommendation. In addition, categories of access have not been recognized for every user class of service; absence is indicated by an I - I in the tables below. 2 See Tables 2-1 and 2-2. Access to a leased circuit data transmission servic
37、e Table 2-1IX.1- Access by data terminal equipment operating in synchronous mode using X.21 or X.21 bis interfaces User class of service 3 4 5 6 7 19 31 32 33 35 37 45 53 59 Data signalling rate in the data transfer phase (Note) Categories of access Direct access 600 bis 2400 bis 4800 bis 9600 bis 4
38、8 kbis 64 kbis 128 kbis 192 kbis 256 kbis 384 kbis 5 12 kbis 1024 kbis 1536 kbis 1920 kbis F1 F2 F3 F4 F5 F6 F7 F8 F9 F10 F11 F12 F13 F14 NOTE - The support of these user classes of service in the ISDN may be provided by means of a terminal adaptor (in accordance with Recommendation X.30). The conce
39、pt of terminal adaptor functional grouping is defined in Recommendation 1.41 1. Table 2-2IX.1- Access by data terminal equipment operating in start-stop mode User class of service 1 2 14 15 16 17 18 using X.20 or X.20 bis interfaces Data signalling rate and code structure in the data transfer phase
40、(Note) 300 bis, 1 la) unitskharacter start-stop 50 to 200 bis, 7.5 to 1 la) units/character start-stop 600 bis, 10 unitskharacter start-stop 1200 bis, 10 units/character start-stop 2400 bis, 10 units/character start-stop 4800 bis, 10 units/character start-stop 9600 bis, 10 units/character start-stop
41、 Categories of access Direct access E2 El E3 E4 E5 E6 E7 a) NOTE - Some Administrations are offering leased circuits asynchronous services for terminals operating at the data signalling rate of 600 bis, 1200 bis, 2400 bis, 4800 bis and 9600 bis supporting them by the synchronous network bearer chann
42、els with asynchronous to synchronous coding. The asynchronous to synchronous coding is described in Recommendation V.14 for the data signalling rates of 600 bis, 4800 bis, 9600 bis and Recommendation X.52 for 1200 bis. Usage in accordance with Recommendation X.4. Recommendation X.l (03/00) 3 COPYRIG
43、HT International Telecommunications Union/ITU TelecommunicationsLicensed by Information Handling Services3 Access to a circuit-switched data transmission service See Tables 3-1 and 3-2. Table 3-1IX.1- Access by data terminal equipment operating in start-stop mode using X.20 or X.20 bis interfaces (N
44、ote 1) User class of service Data signalling rate and code structure in data transfer phase (Note 2) 1 2 14 15 16 17 18 a) Usagein 300 bit/s, 1 la) unitskharacter start-stop 50 to 200 bit/s, 7.5 to 1 la) unitdcharacter start-stop (Notes 3 and 4) 600 bit/s, 10 unitdcharacter start-stop 1200 bit/s, 10
45、 unitdcharacter start-stop 2400 bit/s, 10 unitdcharacter start-stop 4800 bit/s, 10 unitdcharacter start-stop 9600 bit/s, 10 unitdcharacter start-stop dance with Recommendation X.4. CaU control signals in the call control phase 300 bit/s, International Alphabet No. 5 (1 1 unitskharacter) start-stop 2
46、00 bit/s, International Alphabet No. 5 (1 1 unitdcharacter) start-stop (Note 5) 600 bit/s, International Alphabet No. 5 (10 unitskharacter) start-stop 1200 bit/s, International Alphabet No. 5 (10 unitskharacter) start-stop 2400 bit/s, International Alphabet No. 5 (10 unitdcharacter) start-stop 4800
47、bit/s, International Alphabet No. 5 (10 unitskharacter) start-stop 9600 bit/s, International Alphabet No. 5 (10 unitskharacter) start-stop Categories of access Direct access A2 Al A3 A4 A5 A6 A7 NOTE 1 - There is no user class of service for data signalling rate of 50 bit/s, the transmission mode of
48、 7.5 unitskharacter start- stop and address selection and call progress signals at 50 bit/s, International Telegraph Alphabet No. 2. However, several Administrations have indicated that their telex service (50-baud, International Telegraph Alphabet No. 2) will be provided as one of the many services
49、 carried by their public data network. NOTE 2 -User classes of service 1, 2 and 15 are supported by the synchronous network bearer channels with asynchronous to synchronous coding according to Recommendation X.52. For user classes of service 14, 16, 17 and 18, the asynchronous to synchronous coding of Recommendation V. 14 is used. NOTE 3 -User class of service 2 will provide, in the data transfer phase, for operation at the following data signalling rates and code structures: 5
