1、CEPT T/CD*O-Ob*E 87 m 232b414 0004347 2 MI TCD08-06 Page E 1 Recommendation T/CD 08-06 (Copenhagen 1987) HARMONIZATION OF SWITCHED ACCESS TO A PACKET SWITCHED PUBLIC DATA NETWORK (PSPDN) FOR OS1 END SYSTEMS Recommendation proposed by Working Group TWG 10 “Terminal equipment” (TE) Text of the Recomme
2、ndation adopted by the “Telecommunications” Commission: “The Conference of European Post and Telecommunications Administrations, considering - that European Packet Switched Data Networks are in service and their interconnection has been carried out, - that CCITT Recommendations X.2 and X.25 as well
3、as IS0 Standards IS0 7776 and IS0 8208 provide a large - that CCITT Recommendation X.32 provides a number of options, - that a harmonization of DTEs and networks is needed in order to provide the OS1 Connection-mode Network - that networks may provide additional options for other applications (see R
4、ecommendation T/CD 08-02), number of options, 6 Service in an efficient way, recommends to the members of CEPT that this Functional Standard should be applied for OS1 End System implementation as a minimum subset of options to be provided, and that networks should implement the functions necessary t
5、o support these OS1 End Systems in line with Recommendation T/CD 08-02.” Edition of February 10, 1988 7 d CEPT T/CD*OB-Ob*E 87 I 2326434 0004348 4 W T/CD 08-06 E Page 2 FUNCTIONAL STANDARD T/32 PACKET SWITCHED DATA NETWORK SWITCHED ACCESS - Part 1 OS1 Connection-mode Transport Service over a Connect
6、ion-mode Network Service that satisfies CCITT Recom- mendation T.70. - Part 2 OS1 Connection-mode Transport Service over the OS1 Connection-mode Network Service. Note. Other parts may be added to define other protocol combinations or options that are included in future revisions of M-IT-02. An examp
7、le would be the addition of a part that defines End Systems that operate Class 2 of the Transport protocol and do not operate any non-multiplexing Class of the Transport protocol. FOREWORD The concept and structure of Functional Standards for information systems interconnection are laid down in the
8、CEN/CENELEC/CEPT Memorandum M-IT-01. The purpose of a Functional Standard is to recommend when and how certain information technology standards should be used. This Functional Standard specifies telecommunication function T/32 as defined in the CEN/CENELEC/CEPT Memorandum M-IT-02. This Functional St
9、andard is in two parts. Part 1 dejines: - The provision of the network independent basic Transport Service, as specified in CCITT Recommendation T.70 (1984), between an End System (“The Reference End System”) which uses a Switched Telephone or Data Circuit to access a Packet Switched Data Network (P
10、SDN) and another End System (“The Compatible End System”) which is accessible, by permanent or switched methods, either directly from the same PSDN, or indirectly through the provided Network Service. - The provision of a Connection-mode Network Service provided by the X.25 Network Layer, Link Layer
11、, and Physical Layer Procedures in T.70 (1984). Port 2 dejines: - The provision of the OS1 Connection-mode Transport Service between an End System (“The Reference End System”) which uses a Switched Telephone or Data Circuit to access a Packet Switched Data Network (PSDN) and another End System (“The
12、 Compatible End System”) which is accessible, by permanent or switched methods, either directly from the same PSDN, or indirectly through the provided OS1 Connection-mode Network Service. -The provision of the OS1 Connection-mode Network Service between the Reference End System and the Compatible En
13、d System, using the X.25 subnetwork access procedures to a PSDN. Part 1 is applicable to environments which support the CCITT defined Telematic Services. Part 2 is applicable to environments which support the OS1 Network Service. Two options are defined. Implementa- tion of the first option (Class O
14、 only) requires that the End System does not operate any of the multiplexing Classes (Classes 2, 3 or 4) of the Transport Protocol procedures. Such End Systems will only interwork with End Systems that also implement Class O Transport Protocol procedures. Implementation of the second option (Classes
15、 O and 2) in an End System enables that End System to interwork with any End System conforming to either X.224 or IS0 8073. Parts 1 and 2 of this Functional Standard each specify a set of protocols to provide the function defined above. Part 1 and/or Part 2 do not specify total End System capability
16、. The requirements placed on an End System in Parts 1 and 2 of this Functional Standard are solely those necessary for operation of the protocol sets specified in Parts 1 and 2. Edition of February 10, 1988 CEPT T/CD*OB-Ob*E 87 m 2326414 O004349 b i: 1 . 1 .o. 1.1. 1.2. 1.2.1. 1.2.2. 1.3. 1.3.1. 1.3
17、.2. 1.3.3. 1.3.4. 1.3.5. 1.3.6. 1.4. 1.5. 1.5.1. 1.5.2. 1.6. 1.6.1. 1.6.2. 1.6.3. 1.6.4. 1.6.5. 1.6.6. 1.7. 1.7.1. 1.7.2. 1.7.3. 1.7.4. 1.7.5. 1.7.6. 1.7.7. 1.7.8. 1.7.9. 1.7.10. 1.8. 1.8.1. 1.8.2. 1.8.3. 1.8.4. 1.8.5. 1.8.6. 1.8.7. 1.9. 1.9.1. 1.9.2. 1.9.3. 1.9.4. 1.9.5. 1.10. 1.10.1. 1.10.2. 1.10.
18、3. 1.10.4. 1.11. 1.11.1. 1.1 1.2. 1.11.3. 1.1 1.4. 1.11.5. 1.11.6. 1.11.7. T/CD 08-06 E Page 3 Table of Contents PART1 6 Introduction -6 Scope and field of application . 6 References 6 General reference docirments 6 National network attachment specijications . 6 Definitions . 7 EndSystem 7 Fiinction
19、alStandardOption . 7 Connection-mode network service . 7 Data Circuit . 7 AccessNetwork 7 AccessedNetwork . 7 Abbreviations . 7 Scenario description and Model description . 8 Scenario description . 8 Modeldescription 8 Conformity 8 Conformity principles . 8 Conformity at Layer 4 . : 8 Conformityat L
20、ayer3 . 9 Conformity at Layer 2 9 Coiformityat Layer 1 . 10 Conformity for X.32 defined feattires . 10 Layer 4 10 Strategy for implementation . 10 Optionstobeused . 10 Recommendedparameter valties 10 Addressing . 10 Classnegotiation 10 Quality of Service (QOS) 11 Management of network connections 11
21、 Transport protocol identiJication . 11 Use of the network service II Protocol errors II Layer 3 II Strategy for implementation . Il Establishment of the Circuit . Il Relationships between Circuit and Packet Level . 11 Packet Switched Optional User facilities 11 Addressing . 14 Quality of Service (Q
22、OS) . 14 Details on the protocol 14 Layer2 14 Strategy for implementation . 14 Underlying transmission facility 14 Link level address assignment . 14 Defaiilt parameter values . 14 UseofXIDfiame . 14 Layer1 . 15 Strategy for implementation . 15 Physical interfnce 15 Data Signalling Rates 15 Connecto
23、rs 15 X.32 defined features 15 End System identijication method . 15 Accessed Network identijication method 15 Services 16 X.32 optional user facilifies . 16 Security grade 2 method . 16 X.32 parameters 16 Dialrnode . 16 Edition of February IO. 1988 /- ? i i L CEPT T/CD*JB-Ob*E 7 = 232bYL4 OOOY350 2
24、 W T/CD 08-06 E Page 4 2 . 2.0. 2.1. 2.2. 2.2.1 * 2.2.2. 2.3. 2.3.1. 2.3.2. 2.3.3. 2.3.4. 2.3.5. 2.4. 2.5. 2.5.1. 2.5.2. 2.6. 2.6.1. 2.6.2. 2.6,3. 2.6,4, 2.6.6. 2.6,5. . 2.7. 2.7.1. 2.7.2. 2.7.3. 2.7.4. 2.7.5. 2.7.6. 2.7.7. 2.7.8. 2.7.9. 2.7.10. 2.8. 2.8.1. 2.8.2. 2.8.3. 2.8.4. 2.8.5. 2.8.6. 2.8.7,
25、2.9. 2.9.1, 2.9,2. 2.9.3. 2.9.4. 2.9.5. 2.10. 2.10.1 * 2.10.2. 2.10.3. 2.10.4. 2.11. 2.1 1.1. 2.11.2. 2.1 1.3. 2.11.4. 2.1 1.5. 2.11.6. 2.11.7. PART2 17 Introduction 17 Scope and field of application . 17 References . 17 General reference documents . 17 National network attachment specijcations . 18
26、 Definitions . 18 Etid System 18 Functional Standard Option . 18 Data Circuit 18 Access Network 18 Accessed Network . 18 Abbreviations . 19 Scenario description and Model description . Scenario description . 19 Model description 19 Conformity 20 Conformity principles 20 Conformity at Layes 4 . 20 Co
27、nformity at Layer 3 . 20 Conformity at Layer 2 . 21 Conformity at Layer 1 . 21 Conformity for X.32 dejned features . 21 Layer4 22 Strategy for implementation . 22 Options to be used . 22 Recotnmended parameter values 22 Addressing . 22 Class negotiation 23 Quality of Service (QOS) 23 Management of n
28、etwork connections Transport protocol identijcation . 23 Use of the network service Protocol errors . 23 Layer3 23 Strategy for implementation . 23 Establishment of the Circuit . 23 Relationships between Circuit and Packet Level . Packet Switched Optional User facilities Addressing . 24 Quality of S
29、ervice (QOS) 24 Details on the protocol . 24 Strategy for implementation . 27 Underlying transmission facility 27 Link level address assignment . Default parameter values . 27 Use of XIDfiame . 27 Layer 1 27 Strategy for implementation . 27 Physical interface 27 Data Signalling Rates 27 Connectors .
30、 28 X.32 defined features 28 End System identijcation method . Accessed Network identijcation method 28 Sesvices 28 X.32 optional user facilities . 28 Security grade 2 method . X.32 parameters Dialmode . 28 19 23 23 24 24 Layer2 27 27 28 28 28 Edition of February 10. 1988 CEPT T/CD*O-Ob*E 87 232b434
31、 0004353 4 = T/CD 08-06 E Page 5 ANNEXES Annex A. Additional requirements.for End Systems defined in Part 2 for interworking with End Systems defined inPart 1 . . . . . . , . . . . . . . . . , . . , . . . . . . . . . . . . . . 29 Annex B. Contact points for additional information about X.25 implemen
32、tations in European networks 30 Annex C. Guidelines for the implementation of Transport Classes 1, 3 and 4 . . . . , . . . . . . . 32 Annex D. Restrictions when an X.25 (1980 version) network is involved in the communication . . . . . 33 Annex E. Examples of scenarios . . . . . . . . . . . . . . , .
33、 . . . . . . . . . . . . . . . . 34 Edition of February 10, 1988 CEPT T/CD*OB-Ob*E 7 2326434 0004352 6 I T/CD 08-06 E Page 6 PART 1 OS1 CONNECTION-MODE TRANSPORT SERVICE OVER A CONNECTION-MODE NETWORK SERVICE THAT SATISFIES CCITT RECOMMENDATION T.70 1.0, Introduction The concept and structure of Fun
34、ctional Standards for information systems interconnection are laid down in the CEN/CENELEC/CEPT Memorandum M-IT-01. The purpose of a Functional Standard is to recommend when and how certain information technology standards should be used. This part of the Functional Standard specifies telecommunicat
35、ion function T/321 (Class O, T.70 case) as defined in the CEN/CENELEC/CEPT Memorandum M-IT-02. Scope and field of application This part of the Functional Standard defines: - The provision of the network independent basic Transport Service, as specified in CCITT Recommenda- tion T.70 (1984), between
36、an End System (?The Reference End System?) which uses a Switched Telephone or Data Circuit to access a Packet Switched Data Network (PSDN) and another End System (?The Compatible End System?) which is accessible, by permanent or switched methods, either directly from the same PSDN, or indirectly thr
37、ough the provided Network Service. - The provision of a connection-mode network service provided by the X.25 Network Layer, Link Layer, and Physical Layer Procedures in T.70 (1984). This part of the Functional Standard is applicable to environments which support the CCITT defined Teleinatic Services
38、. This part of the Functional Standard specifies a set of protocols, to provide the function defined above. It does not specify total End System capability. The requirements placed on an End System in this part of the Functional Standard are solely those necessary for operation of the protocol set s
39、pecified. 1.1, ? 1,2, References 1.2.1. General reference documents IS0 77761 IS0 80721 IS0 80731 IS0 82081 w.21 X.21 X. 2 1 bis 13.251 13.321 pc.1211 X, 2 1 41 X,224 T.70 W.1351 V-series Information Processing Systems, Data Communications - HDLC Description of the X.25 LAPB compatible DTE single li
40、nk procedure, Version October 1986. Information Processing Systems, Open Systems Interconnection Transport Service Defini- tion, Version 1986. Information Processing Systems, Open Systems Interconnection Transport Protocol Speci- fication, Version 1986. Infoimation Processing Systems, Data Communica
41、tions - X.25 packet level protocol for DTE, Version 1985-03-27. International data transinission services and optional user facilities in Public Data Networks (PDNs), Version 1984. Interface between DTE and DCE for synchronous operation on PDNs, Version 1984. Use on PDNs of DTE which is designed for
42、 interfacing to synchronous V-series modems, Version 1984. Interface between DTE and DCE for terminals operating in the packet mode and connected to PDNs by dedicated circuit, Version 1984. Interface between DTE and DCE for terminals operating in the packet mode and accessing a PSPDN through a PSTN
43、or a CSPDN, Version 1986. International numbering plan for Public Data Networks, Version 1984. Transport Service Definition for Open Systems Interconnection for CCITT Applications, Version 1984. Transport Protocol Specification for Open Systems Interconnection for CCITT Applica- tions, Version 1984.
44、 Network-independent basic transport service for the Telematic services, Version 1984. Delay aspects of grade of service for public data network when providing international packet switched data services, Version 1984. Recommendations of the V-series, Version 1984. 1.2,2, National network attachment
45、 specjcations Additional information regarding specific national PDNs may be required to find out which facilities and procedures can be used on a specific network. A list of contact points from which such information can be obtained is given in Annex B to this document. Edition of February 10, 1988
46、 CEPT T/CD*OB-Ob*E 7 I 2326414 0004353 B W 1.3. 1.3.1. 1.3.2. 1.3.3. 1.3.4. 1.3.5. 1.3.6. 1.4. T/CD 08-06 E Page 7 Definitions End System The term End System is taken from the OS1 model terminology and is used to refer to the functionality of the communicating system in an abstract form, independent
47、 of the physical realization. An End System in real world terminology may, therefore, as an example, be either a simple self-containedsystem or a group of interconnected main frame computers acting as a whole. All End Systems contain a Transport Layer Entity function. The term Data Terminal Equipmen
48、t (DTE) is used by CCITT to define the users equipment that is connected to a public data network, or a modem in the PSTN case. Note. In the general case a DTE does not necessarily contain a Transport Layer Entity function. Since this Functional Standard is only concerned with equipment that does co
49、ntain Transport Layer Entities, both terms will be used synonymously. Functional Standard Option Standards and Recommendations support many options. In a Functional Standard based on these Stan- dards and Recommendations such an option may be: - precluded, because it may limit the interworking capabilities; - outside the scope, but it does not limit the interworking capabilities; - kept as an option, in this case it is called a Functional Standard Option and it is clearly referenced; or - supported, which means that its implementation is required. A Functional
