1、3 CEPT T/CD*OB-OL*E 8b I 232b4L4 0004272 8 = 08-01 Page E 1 Recommendation T/CD 08-01 (Odense 1986, revised in Copenhagen 1987) HARMONIZATION OF THE DEDICATED PACKET-MODE ACCESS TO A PACKET SWITCHED PUBLIC DATA NETWORK (PSPDN) FOR OS1 EM) SYSTEMS Recommendation proposed by Working Group T/WG 10 “Ter
2、minal equipment” (TE) Text of the Recommendation adopted by the “Telecommunications” Commission: “The Conference of European Post and Telecommunications Administrations, considering - that European public packet switched data networks are inservice and that their interconnection has been carried - t
3、hat CCITT Recommendations X.2 and X.25 as well as IS0 Standards 7776 and 8208 provide a large number - that a harmonization of DTEs and networks is needed in order to provide the IS0 Connection-mode network - that networks may provide additional options for other applications (see Recommendation T/C
4、D 08-02), recommends to the Administrations member of the CEPT that this functional standard should be applied for OS1 End System implementation as a minimum subset of options provided and that networks should implement the functions necessary to support these OS1 End Systems in line with Recommenda
5、tion T/CD 08-02.” out, of options, service in an efficient way, O Edition of February 10, 1988 CEPT T/CD*OB-OL*E b 2326434 0004273 T T/CD 08-01 E Page 2 . FUNCTIONAL STANDARD T/31 ENV 41 104 PACKET SWITCHED DATA NETWORK PERMANENT ACCESS - Part 1 OS1 Connection-mode Transport Service over a Connectio
6、n-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 example
7、 would be the addition of a part that defines End Systems that do 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-O 1. The purpose of a Functional Standard is to recommend when and how certain information technology standards should be used. This Functional Standard specifies telecommunication fiinction T/3 1 as defined in the CEN/CENELEC/CEPT Memorandum M-IT-02. This Functiona
9、l Standard is in two parts. Part 1 dejnes: - 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 Permanent Telephonic or Data Circuit to access a Packet Switched Data Netwo
10、rk (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 through the provided Network Service. - The provision of a Connection-mode Network Service provided by the X.25 Network Layer, Link
11、Layer, and Physical Layer Procedures in T.70 (1984). Past 2 dejnes: - The provision of the OS1 Connection-mode Transport Service between an End System (“The Reference End System”) which uses a Permanent Telephonic or Data Circuit to access a Packet Switched Data Network (PSDN) and another End System
12、 (“The 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 Compat
13、ible End 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 (
14、Class O 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 (
15、Classes O and 2) in an End System enables that End System to interwork with any End Systems 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 ca
16、pability. 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-OL*E 6 2326434 0004274 L m. 1 . 1.0. 1.1. 1.2. 1.2.1. 1.2.2. 1.3. 1.3.1.
17、 1.3.2. 1.3.3. 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. 1.7. 1.7.1. 1.7.2. 1.7.3. 1.7.4. 1.7.5. I .7. 6. I .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. 1.9. 1.9.1. 1.9.2. 1.10. 1.10.1. 1.10.2. 1.10.3. 2 . 2.0. 2.1. 2.2. 2.2.1. 2.2.2. 2.3. 2.3.1.
18、2.3.2. 2.4. 2.5. 2.5.1. 2.5.2. T/CD 08-01 E Page 3 Table of Contents PART1 5 Introduction 5 Scope and field of application . 5 References . 5 General reference documents 5 National network attachment specifications . 5 Definitions . 6 EndSystem 6 Functional Standard option 6 Connection-mode network
19、service . 6 Abbreviations . 6 Scenario description and Model description . 6 Scenario description . 6 Modeldescription 7 Conformity 7 Conformityprinciples . 7 Conformity at Layer 4 . 7 Conformityat Layer3 . 8 Conformityat Layer2 . 8 Conformityat Layerl . 8 Layer4 8 Strategy for implementation . 8 Op
20、tionstobeused . 8 . Recommended parameter values 8 Addressing . 8 Class negotiation 9 Quality of Service (QOS) 9 Management of network connections 9 Transport protocol identification . 9 Use of the network service 9 Protocolerrors . 9 Layer3 9 Strategy for implementation . 9 Optional user facilities
21、 9 Addressing . 11 Quality of Service (QOS) . 11 Details on the protocol 11 Tests . 11 Layer2 11 Strategy for implementation . 11 Default parameter values . 11 Layerl 11 Physical Interface 11 Data Signalling Rates 11 Connectors . 12 PART2 13 Introduction 13 Scope and field of application . 13 Refere
22、nces . 13 General reference documents . 13 National network attachment specifications 14 Definitions . 14 EndSystem . 14 Ftinctional Standardoption 14 Abbreviations . 14 Scenario description and Model description 15 Scenario description . 15 Model description 15 Edition of February 10. 1988 CEPT T/C
23、D*O-OL*E b E 2326414 0004275 3 E T/CD 08-01 E Page 4 2.6. Conformity 15 2.6. I. Conformity principles 15 2.6.2. Conformity at Layer 4 . 15 2.6.3. Conformity at Layer 3 . 16 2.6.4. Conformity at Layer 2 . 16 2.6.5. Conformity at Layer 1 . 16 2.7. Layer4 16 2.7.1. Strategy for implementation . 16 2.1.
24、2. Options to be used . 17 2.1.3. Recommended parameter values 17 2.7.4. Addressing . 17 2.7.5. Class negotiation 17 2.1.6. Quality of Service (QOS) 17 2.1.7. Management of network connections 18 2.1.8. Transport protocol identijcation . 18 2.7.9. Use of the network service 18 2.1.10. Protocol error
25、s . 18 2.8. Layer3 18 2.8.1. Strategy for implementation . 18 2.8.2. Optional user facilities 19 2.8.3. Addressing . 20 2.8.4. Quality of Service (QOS) 20 2.8.5. Details on the protocol . 20 2.8.6. Tests . 20 2.8.7. Number of virtual circuits 20 2.9. Layer2. . 21 2.9.1, Strategy for implementation .
26、 21 2.9,2. Default parameter values . 21 2.10. Layer1 21 2.10.1. Physical Interface 21 2.10.2. Data Signalling Rates 21 2.10.3. Connectors . 21 ANNEXES Annex A . Annex B . Annex C . Annex D . Additional requirements for End Systems defined in Part 2 for interworking with End Systems defined in Part
27、1 22 Contact points for additional information about X.25 implementations in European networks 23 Guidelines for the implementation of Transport Classes 1. 3 and 4 25 Restrictions when an X.25 (1980 version) network is involved in the communication . 26 Edition of February IO. 1988 CEPT T/CD*OB-OL*E
28、 b 232b4L4 0004276 5 m i T/CD 08-01 E Page 5 1. PART 1 1 .O. Introduction The concept and structure of Functional 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 info
29、rmation technology standards should be used. This part of the Functional Standard specifies telecommunication function T/31 (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 defnes: - The provision of the n
30、etwork independent basic Transport Service, as specified in CCITT Recommenda- tion T.70 (1984), between an End System (“The Reference End System”) which uses a Permanent Telephonic OS Data Circuit to access a Packet Switched Data Network (FSDN) and another End System (“The Compatible End System”) wh
31、ich 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, and Physical Layer Procedures in T.70 (1984). This part of
32、the Functional Standard is applicable to environments which support the CCITT defined Telematic Services. 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 Syste
33、m in this part of the Functional Standard are solely those necessary for operation ot the protocol set specified. 1.1. 1.2. References 1.2.1. General reference documents (IS0 7776) (IS0 8072) (IS0 8073) (IS0 8208) (X.2) (X.21) (X.2 1 bis) (X.25) (x.121) (X.214) (X.224) (T.70) (X.135) Information Pro
34、cessing Systems, Data Communications -HDLC-Description of the X.25 LAPB compatible DTE single link procedure, Version October 1986. Information Processing Systems, Open Systems Interconnection Transport Service Defini- tion, Versbn,1986. Information Qrocessing Systems, Open Systems Interconnection T
35、ransport Protocol Speci- fication, Versjon 1986. Information Processing Systems, Data Communications-X.25 packet level protocol for DTE, Version 1985-03-27. International data transmission services and optional user facilities in Public Data Network (PDNs), Version 1984. Interface between DTE and DC
36、E for synchronous operation on PDNs, Version 1984. Use on PDNs of DTE which is designed for 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 circuits; Version 1984. International numb
37、ering 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. Network-independent basic transport service
38、 for the Telematic services, Version 1984. Delay aspects of grade of service for public data networks when providing international packet switched data services, Version 1984. 1.2.2. National network attnchment specijications If additional information regarding specific national PDNs is required to
39、fnd 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 CEPT T/CD*O-OL*E 6 II 2326434 0004277 7 T/CD 08-01 E Page 6 1.3. Definitions 1.3.1. End S
40、ystem 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 of the physical realization. An End System in real world terminology may, therefore, as an example be either a simple self-containe
41、d system 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 Equipment TE) 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.
42、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 contain Transport Layer entities, both terms will be used synonymously. 1.3.2. Functional Standard Option Standards and Recommendations
43、support a lot of options. In a Functional Standard based on these Standards and Recommendations such an option may be: - precluded, because it may limit the interworking capabilities; - out of the scope, but it does not limit the interworking capabilities; - kept as an option, in this case it is cal
44、led a Functional Standard Option and it is clearly referenced; or - supported, which means that its implementation is required. A Functional Standard Option which cannot operate with a mandatory mechanism of the Functional Standard, or two or more Functional Standard Options which cannot operate sim
45、ultaneously with each other, may be implemented in an End System, but in such cases, a system parameter shall be used to select and indicate the mechanism in use. The Connection-mode network service in this part of the Functional Standard is the network service that satisfies CCITT Recommendations T
46、.70. 1.3.3. Connection-mode network sesvice 1.4. Abbreviations CC TPDU CR TPDU D DCE DTE DT TPDU ER TPDU FSO os1 PSDN QOS RPOA TPDU TS 1 TS 2 TSAP-ID vc Connect Confirm TPDU Connect Request TPDU Delivery Confirmation Data Circuit-Terminating Equipment Data Terminal Equipment Data TPDU Error TPDU Fun
47、ctional Standard Option Open System Interconnection Packet Switched Data Network Quality of Service Recognized Private Operating Agency Transport Protocol Data Unit Supervisory timer 1 Supervisory timer 2 Transport Service Access Point identifier Virtual Circuit 1.5, 1.5.1. Scenario description Scen
48、ario description and Model description The Reference End System communicates with the Compatible End System through a Packet Switched Data Network (PSDN). The Reference End System is connected to the PSDN via a permanent telephone or a permanent data circuit. The compatible End System may use the sa
49、me access method or may conform to another Functional Standard. Edition of February IO, 1988 CEPT T/CD*OB-OL*E 86 E 2326414 0004278 9 E - I I Reference End System 1.5.2. End System Intermediate System) PSDN 1.6. 1.6.1. 1.6.2. 1.6.2.1. 1.6.2.2. T/CD 08-01 E Page 7 Figure 1.1 (T/CD 08-01). Communication between an End System 1 (Reference End System) and an End System 2 (Compatible End System). Note 1. Communication between the Reference End System and the Compatible End System is via a single PSDN or via a combination of a PSDN and single or multiple intermediate
