1、CEPT T/TE*08=05*E 89 2326434 0033775 121 TTE08-05 Page E 1 Recommendation T/TE 08-05 (Copenhagen 1987, revised in Edinburgh 1988) HARMONIZATION OF THE DEDICATED USE OF A CIRCUIT SWITCHED PCBLIC DATA NETWORK FOR OS1 END SYSTEMS SLTPORTING THE OS1 COXVTCTION-MODE NETWORK SERVICE Recommendation propose
2、d by Working Group T WG 10 “Terminal equipment” (TE) Text of the Recommendation adopted by the “Telerommunirntions” Commission : “The European Conference of Posts and Telecommunication Administrations. considering - that European Circuit Switched Data Networks are in service. - that CCITT Recommenda
3、tions X.2, X.21, X.25 and X.224 as well as IS0 Standards 7776.8208 and 8073 provide - that a harmonization of OS1 End Systems is needed in order to provide in an efficient way the IS0 Connection- - that networks may provide additional options for other applications. recommends to the members of the
4、CEPT that this Functional Standard should be applied for OS1 End Systems implementation as a minimum subset of options provided.” a large number of options, mode Network Service, Edition of February 28. 1989 CEPT T/TE*OB-OS*E 89 U 232b434 001i377b Ob4 U TITE 08-05 E Page 2 Table of Contents FUNCTION
5、AL STANDARD T/42X: DIGITAL DATA CIRCUIT (CSDN): PROVISION OF THE OS1 CONNECTION-MODE TRANSPORT AND THE OS1 CONNECTION-MODE NETWORK SERVICE O . 1 . 2 . 2.1. 2.2. 2.3. 3 . 3.1. 3.2. 3.3. 3.4. 4 . 5 . 5.1. 5.2. 6 . 6.1. 6.2. 6.3. 6.4. 6.5. 7 . 7.1. 7.2. 7.3. 7.4. 7.5. 7.6. 7.7. 7.8. 7.9. INTRODUCTION .
6、 3 SCOPE AND FIELD OF APPLICATION 3 REFERENCES 3 General reference documents . 3 Nationalnetwork attachmentspccifications . 4 Additional references 4 DEFINITIONS 4 Digital Data Circuit . 4 EndSystem 4 Functional Standard Option . 5 ABBREVIATIONS . 5 SCENARIO DESCRIPTION AND MODEL DESCRIPTION . 5 Sce
7、nario description . 5 Model description 6 CONFORMITY 6 General 6 Conformity at layer 4 6 Conformity at layer 3 7 Conformity at layer 2 7 Conformity at layer 1 7 LAYER4 . 8 Strategy for implementation . 8 Options to be used . 8 Recommended parameter values 8 Addressing . 8 Class negotiation 9 Quality
8、 of service 9 Management of network connections 9 Transport protocol identification . 9 Use of the Network Service . 9 DTE . 4 7.10. Protocol errors . 9 8.1. Strategy for implementation . 9 8.2. Connection establishment phase 10 8.3. Data transfer phase . 11 8.4. Connection release phase . 11 9.1. S
9、trategy for implementation . 13 9.2. Operationmode 13 9.3. Default parameter values . 14 9.4 Address assignment . 14 9.5 Detail on the protocol 14 10.1. Strategy for implementation . 14 10.2. Physical interface 14 10.3. Data signalling rates 14 10.4. Connectors . 15 8 . LAYER3 . 9 9 . LAYER2 . 13 1
10、o . LAYER1 . 14 ANNEXES Annex A . Contact points for additional information on circuit switched data networks 16 Annex B . 18 Guidelines for the implementation of Transport Classes 1 . 3 and 4 Annex C . Examples of scenarios 19 Annex D . TI422 versus TI322 . 20 I Edirion of February 28 . 19x9 CEPT T
11、/TE*OB-OS*E 89 = 2326414 0011777 TT4 T/TE 08-05 E Page 3 O. INTRODLCTION The concept and structure of Functional Standard for information systems interconnection are laid down in the CENjCENELEC CEPT Memorandum M-IT-O 1. The purpose of a Functional Standard is to recommend when and how certain infor
12、mation technology standards should be used. This Functional Standard specifies telecommunication function T 42X as defined in the CEN CESELEC CEPT Memorandum M-IT-02. 1. SCOPE AND FIELD OF APPLICATION This Functional Standard defines: - the provision of the OS1 Connection-mode Transport Service betw
13、een an End System (“The Reference End System”) which uses a Digital Data Circuit and another End System (“The Compatible End System”) which is accessible, by permanent or switched methods, either directly from the same Digital Data Circuit, or indirectly through the provided OS1 Connection-mode Netw
14、ork Service: - the provision of the OS1 Connection-mode Network Service between the Reference End System and the Compatible End System, using the X.25 procedures above the Digital Data Circuit. This Functional Standard is applicable to environments which support the OS1 Network Service. Two options
15、are defined. Implementation of the first optim (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 p
16、rocedures. Implementation of the second option (Classes 0 and 2) in an End System enables that End System to interwork with any End System conforming to either X.724 or IS0 8073. 2. REFERENCES 2.1. General reference documents IS0 77761 IS0 80721 IS0 80731 IS0 8073-DAD i IS0 82081 IS0 83481 IS0 8348-
17、AD21 DIS 88781 DIS 88811 T.70 l3.21 F.211 F.2 1 bis Edition of February 28. 1989 Information Processing Systems, Data Communications - HDLC - Description of the X.25 LAPB compatible DTE single procedure, Version 1985-04-19. Information Processing Systems, Open Systems Interconnection Transport Servi
18、ce Definition, Version 1986. Information Processing Systems. Open Systems Interconnection Transport Protocol Specification, Version 1986. Information Processing Systems. Open Systems Interconnection. Connection-mode Transport Protocol Specification. Addendum covering the Network Connection Managemen
19、t Subprotocol: Version 1986-02-22. Information Processing Systems. Data Communications-X.25 packet level proto- col for DTE, Version 1987. Information Processing Systems, Data Communications-h-etwork Service defini- tion, Version 1987. Information Processing Systems. Data Communication- Addendum to
20、the Net- work Service Definition covering Yetwork Layer Addressing. Version 1986. Use of X.25 to Provide the OS1 Connection-mode Network Service. Main body (Annexes A and B are not considered), Version 1986-05-22. Information Processing Systems, Data Communication- Use of the X.25 packet level proto
21、col in local area networks. Version 1986-02-20. Network independent basic Transport Service for the Telematic Semices. Version 1984. International data transmission services and optional user facilities in Public data networks (PDNsj. Version 1984. Interface between DTE and DCE for synchronous opera
22、tion on PDNs. Version 1984. Use on PDXs 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. Interface between DTE and DCE for termina
23、ls operating in the packet mode and accessing a PDN through a PSTK or a CSPDN, Version 1986. CEPT T/TE*O-5*E 89 M 232b4L4 OOLL? 930 M TITE 08-05 E Page 4 2.2. 2.3. 3. 3.1. 3.2. 3.3. X.75 X.121 X.213 X.214 X. 2241 Terniinal and transit call control procedures and data transfer system on international
24、 circuits between packet switched data network, Version 1984. International numbering pian for Public Data Networks, Version 1984. Network Service Definition for Open Systems Interconnection for CCITT Applica- tions. Version 1986. Transport Service Definition for Open Systems Interconnection for CCI
25、TT Applica- tions, Version 1984. Transport Protocol Specification for Open Systems Interconnection for CCITT Applications. Version 1984. National network attachment specifications If additional information regarding specific national PDNs is required to find out which facilities and procedures can b
26、e used on a specific network, a non-exhaustive list of contact points from which such information can be obtained is given in Annex A to this document. Additional References ENV 41 104 Recommendation ENV 41 105 Recommendation ENV 41 106 Recommendation M-IT-O 1 M-IT-02 Packet Switched Data Network Pe
27、rmanent Access OS1 Connection-mode Trans- port Service over either the OS1 Connection-mode Network Service or the T.70 case (1987) Packet Switched Data Network- Permanent Access OS1 Connection-mode Trans- port Service over either the OS1 Connection-mode Network Service or the T.70 case (1987) Packet
28、 Switched Data Network Switched Access OS1 Connection-mode Transport Service over either the OS1 Connection-mode Network Service or the T.70 case (1988) Packet Switched Data Network Switched Access OS1 Connection-mode Transport Service over either the OS1 Connection-mode Network Service or the T.70
29、case (1988) Digital Data Circuit (Circuit Switched Data Network)-Provision of the OS1 Con- nection-mode Transport Service in the T.70 case for Telematic End Systems (1988) Digital Data Circuit Circuit Switched Data Network) Provision of the OS1 Con- nection-mode Transport Service in the T.70 case fo
30、r Telematic End Systems (1988) CEN/CENELEC/CEPT Memorandum on the Concepts and Structure of Functional Standards for Information Technology (March 1956) CEN/CENELEC/CEPT Memorandum on the Directory of Functional Standards (March 1987) CEPT T/CD 08-01 CEPT TITE 08-06 CEPT TITE 08-04 DEFINIONS Digital
31、 Data Circuit In this Functional Standard, a Digital Data Circuit is provided through a CSDN or through a concatenation of CSDNs, and may be switched or permanent. Note. Some ISDNa or pre-ISDNs provide circuit switched services through an X.71 interface. Those services are equivalent to those provid
32、ed by a CSDN and this Functional Standard is CenFequcnily applicable in this case. End System The terni End System is taken from the OS1 Reference Model terminology and is used to refer to the functionality of the communicating system in an abstract form, independent of the physical realisation. An
33、End System in real world terminology may. therefore. as an example, be either a simple self-contained system or a group of interconnected main frame computers acting as a whole. All End Systems contain a Transport Layer entity function. DTE The term Data Terminal Equipment (DTE) is used by CCITT to
34、define the users equipment that is con- nected to a Publie Data Network (PDN), or a modem in the Public Switched Telephone Network (PSTN) case. Nore. In the general cm u BTE does not necessarily contain a Transport Layer entity function. Edition of February 18. 1989 CEPT T/TE*U-OS*E 89 = 2326434 001
35、1i777 877 TITE 08-05 E Page 5 Since this Functional Standard is only concerned with equipment that does contain Transport Layer entities, both terms will be used synonymously. Note. This is not intended to imply any restriction on the use of NSAP addresses and their relationship to the subnetwork ad
36、dresses. 3.4. Functional Standard Option Standards and Recommendations 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
37、 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 Standard Option which cannot operate with a mandatory mechanism of the Functional Standa
38、rd, or two or more Functional Standard Options which cannot operate simultaneously 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. 4. ABBREVIATIONS AFI CC TPDU CR TPDU CSDN DCE DSP DTE DT TPDU ER T
39、PDU FSO HIC HOC HTC ID1 ISDN LIC LOC LTC NC NCMS NL NS NSAP os1 PSDN QOS TPDU TSAP RPOA SNPA vc TSAP-ID AUTHORITY AND FORMAT IDENTIFIER CONNECT CONFIRAM TPDU CONNECT REQUEST TPDU CIRCUIT SWITCHED DATA NETWORK DOMAIN SPECIFIC PART DATA TERMINAL EQUIPMENT DATA TPDU ERROR TPDU Functional Standard OPTIO
40、N HIGHEST INCOMING CHANNEL HIGHEST OUTGOING CHANNEL INITIAL DOMAIN IDENTIFIER INTEGRATED SERVICE DIGITAL NETWORK LOWEST IWCOMIWG CHANNEL LOWEST OUTGOING CHANWEL NETWORK CONNECTION Network Connection Management Subprotocol NETWORK LAYER NETWORK SERVICE NETWORK SERVICE ACCESS POIKT PACKET SWITCHED DAT
41、A NETWORK QUALITY OF SERVICE TRANSPORT PROTOCOL DATA UNIT TRANSPORT SERVICE ACCESS POINT TRANSPORT SERVICE ACCESS POINT IDENTIFIER RECOGNIZED PRIVATE OPERATING AGENCY SUBNETWORK POINT OF ATTACHMENT VIRTUAL CALL DATA CIRCUIT-TERMINATING EQUIPLMENT HIGHEST TWO-WAY CHANNEL LOWEST TWO-WAY CHANNEL OPEN S
42、YSTEIMS INTERCONNECTION 5. SCENARIO DESCRIPTIOK AND .MODEL DESCRIPTION 5.1. Scenario description The Reference End System communicates lvith the Compatible End System through a Digital Data Circuit and eventually intermediate system(s) (e.g. Relay Function. LAN .). This Digital Data Circuit is provi
43、ded through a CSDN or through a concatenation of CSDXs. The Digital Data Circuit is permanent if a leased circuit of a CSDX is used. In this case. Functional Standard T!421 applies. Edition of February 28, 1989 CEPT T/TE*Od-OS*E 119 23Zb414 0011780 599 TITE 08-05 E X.21 Page 6 5.2. 6. 6.1. 6.2. 6.2.
44、1. 6.2.2. IS0 82081 IS0 77761 - The Digital Data Circuit is switched if a switched circuit of a CSDN is used. In this case, Functional Standard T423 applies. - End System Ir - Reference Intermediate Circuit System I (CSDN) ?L I I - - - - - End System I I (X: 1 =Permanent Digital Daia Circuit; 2=Swit
45、ched Digital Daia Circuit.) Figure 1 (T/TE 08-05). Scenario description. Note 1. Concrete examples of this general scenario are given in Annex C. Noie 2. An End System is only compatible if the sub-option c.g. the transport classes) are compatible. Model description IS0 80731 CONFORMITY General This
46、 Functional Standard states requirements placed upon systems for the purpose of achieving interwork- ing. In addition the Functional Standard contains a number of Recommendations and options that are not required for intenvorking but may affect performance. A claim of conformity to the Functional St
47、andard is a claim that all requirements in the body of the Standard are satisfied. For each layer, the claim of conformity shall indicate: - the supported FSO defined in the Functional Standard; - the general conformity requirements related to the base standards. Conformity at layer 4 Options relute
48、d to the Fimtional Standard An End System claiming conformity to this Functional Standard shrill state which classes are implemented: FSO CLASS O ONLY or FSO CLASSES O AND 2. General conforniity rcquircnients An End System claiming conformity to this Functional Standard shall state: - which compleme
49、ntary optional cla-ss(es) is (are) implemented; - whether it is capable of initiating or responding to CR TPDUs or both; - the maximum TPDU size implemented. Edition of February 28. 1989 CEPT T/TE*08-05*E 89 W 2326414 OOLL7BZ 425 W 6.3. 6.3.1. 6.3.2. 6.4. 6.4.1. 6.4.2. 6.5. 6.5.1. T/TE 08-05 E Page 7 Conformity at layer 3 Options related to this Fiinctional Standard The claim of conformity shall indicate: - the list of circuit switched optional user facilities implemented among those qualified as local choice in - the list of packet level
