1、CEPT T/CD*O-O5*E 7 23261114 0004326 5 T?CD08-05 Page E 1 Recommendation T/CD 08-05 (Copenhagen 1987) HARMONIZATION OF THE DEDICATED USE OF A CIRCUIT SWITCHED PUBLIC DATA NETWORK FOR OS1 END SYSTEMS SUPPORTING THE OS1 CONNECTION-MODE NETWORK SERVICE Recommendation proposed by Working Group T/WG 10 ?T
2、erminal equipment? (TE) Text of the Recommendation adopted by the ?Telecommiinicntions? Commission: ?The European Conference of Posts and Telecommunication Administrations, considering - that European Circuit Switched Data Networks are in service, - that CCITT Recommendations X.2, X.21, X.25 and X.2
3、24 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, a large number of options, mode Network Service, O recommends
4、to the members of the CEPT that this Functional Standard should be applied for OS1 End Systems implementation as a minimum subset of options provided.? Iz - - - Edition of February 10, 1988 i CEPT T/CD*OB-OS*E 87 = 2326414 0004327 7 T/CD 08-05 E Page 2 Table of Contents FUNCTIONAL STANDARD T/42X: DI
5、GITAL DATA CIRCUIT (CSDN): PROVISION OF THE OS1 CONNECTION-MODE TRANSPORT AND THE OS1 CONNECTION-MODE NETWORK SERVICE O . 1 . 2. 2.1. 2.2. 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. 7.10. 8 . 8.1. 8.2. 8.3. 8.4 . 9 . 9.1.
6、9.2 . 9.3. 9.4 9.5 INTRODUCTION . SCOPE AND FIELD OF APPLICATION REFERENCES General reference documents . National network attachment specifications . DEFINITIONS Digital Data Circuit . End System Functional Standard Option . DTE . ABBREVIATIONS . 3 3 3 3 4 4 4 4 4 4 5 SCENARIO DESCRIPTION AND MODEL
7、 DESCRIPTION . 5 Scenario description . 5 Model description 6 Conformity at layer 4 6 Conformity at layer 3 6 Conformity at layer 2 7 Conformity at layer 1 7 Strategy for implementation 8 Options to be used . 8 Recommended parameter values 8 Addressing . 8 Class negotiation 8 Quality of service 8 Ma
8、nagementofnetworkconnections 9 Transport protocol identification . 9 Use of the Network Service . 9 Protocol errors . 9 LAYER3 . 9 Strategy for implementation . 9 Connection establishment phase 9 Data transfer phase . 11 Connection release phase . 11 Strategy for implementation . 13 Operation mode 1
9、3 Default parameter values . 14 Address assignment . 14 Detail on the protocol CONFORMITY 6 General 6 LAYER4 . 8 LAYER2 . 13 14 10 . LAYER1 . 14 10.1, Strategy for implementation . 14 10.2. Physical interface 14 10.3. Data signalling rates 14 10.4. Connectors . 15 ANNEXES Annex 1 . Contact points fo
10、r additional information on circuit switched data networks 16 Annex 2 . 18 Guidelines for the implementation of Transport Classes 1. 3 and 4 Annex 3 . Examples of scenarios 19 Annex 4 . TI422 versus TI322 . 20 ., - Edition of February 10. 1988 CEPT T/CD*O-O5*E 7 W 2326434 0004328 9 TfCD 08-05 E Page
11、 3 O. INTRODUCTION The concept and structure of Functional Standard for information systems interconnection are laid down in the 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 Funct
12、ional Standard specifies telecommunication function T/42X as dened in the CEN/CENELEC/CEPT Memorandum M-IT-02. SCOPE AND FIELD OF APPLICATION This Functional Standard defines: - the provision of the OS1 Connection-mode Transport Service between an End System (“The Reference End System”) attached to
13、a Permanent or Switched Data Circuit, and another End System (“The Compatible End System”) which is attached to the same Data Circuit, or indirectly accessible through the provided Network Service; - the provision of the OS1 Connection-mode Network Service between the Reference End System and the Co
14、mpatible End System, and of a Connection-oriented subnetwork access service over the Data Circuit. This 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 Functional
15、 Standard are solely those necessary for operation of the protocol set specified. Note 1. CSDN may also be used to access a Packet Switched Data Network (PSDN) in which case the Functional Standards T/31 (permanent case) and T/32X will apply. Note 2. CSDN may be used for communication between telema
16、tic terminals as defined in Recommendation T.70, in this case Functional Standard T/41 will apply. 1. 2. REFERENCES 2.1, General reference documents IS0 77761 DSO 80721 IS0 80731 IS0 8073-DAD1 IS0 82081 IS0 83481 IS0 8348-AD21 DIS 88781 DIS 88811 T.70 B.21 B.211 P.21 bis 13.251 13.321 Information Pr
17、ocessing 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 Service Definition, Version 1986. Information Processing Systems, Open Systems Interconnection Transpo
18、rt Protocol Specification, Version 1986. Information Processing Systems, Open Systems Interconnection, Connection-mode Transport Protocol Specification. Addendum covering the Network Connection Management Subprotocol, Version 1986-02-22. Information Processing Systems, Data Communications-X.25 packe
19、t level proto- col for DTE, Version 1985-03-27. Information Processing Systems, Data Communications- Network Service defini- tion, Version 1985-03-27. Information Processing Systems, Data Communication- Addendum to the Net- work Service Definition covering Network Layer Addressing, Version 1986. Use
20、 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 protocol in local area networks, Version 1986-02-20. Networkindependent basicTransport Serv
21、ice for theTelematic Services, Version 1984. International data transmission services and optional user facilities in Public data networks (PDNs), Version 1984. Interface between DTE and DCEfor synchronous operation on PDNs, Version 1984. Use on PDNs of DTE which is designed for interfacing to synch
22、ronous 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 terminals operating in the packet mode and accessing a PDN through a PSTN or a CSPDN, Version 19
23、86. Edition of February 10, 1988 CEPT T/CD*08-U5*E 87 I 2326414 U004329 O I T/CD 08-05 E Page 4 P.751 p.1211 p.2131 p.2141 p.2241 V-series Terminal and transit call control procedures and data transfer system on international circuits between packet switched data network, Version 1984. International
24、 numbering plan for Public Data Networks, Version 1984. Network Service Definition Sor Open Systems Interconnection for CCITT Applica- tions, Version 1986. Transport Service Definition for Open Systems Interconnection for CCITT Applica- tions, Version 1984. Transport Protocol Specification for Open
25、Systems Interconnection Sor CCITT Applications, Version 1984. . Recommendations of the V-series, Version 1984. 2.2. 3. 3.1. 3.2. 3.3. 3.4. National network attachment specifications If additional information regarding specific national PDNs is required to find out which facilities and procedures can
26、 be used on a specific network, a non-exhaustive list of contact points from which such information can be obtained is given in Annex 1 to this document. DEFINITIONS Digital Data Circuit In this Functional Standard, a Digital Data Circuit is provided through a CSDN or through a concatenation of CSDN
27、s, and may be switched or permanent. Note. Some ISDNs or pre-ISDNs provide circuit switched services through an X.21 interface. Those services are equivalent to those provided by a CSDN and this Functional Standard is consequently applicable in this case. End System The term End System is taken from
28、 the OS 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 End System in real world terminology may, therefore, as an example, be either a simple self-contained system or a group of interc
29、onnected main frame computers acting as a whole. All End Systems contain a Transport Layer entity function. DTE The terin Data Terminal Equipment (DTE) is used by CCITT to define the users equipment that is con- nected to a Public Data Network (PDN), or a modem in the Public Switched Telephone Netwo
30、rk (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 contain Transport Layer entities, both terms will be used synonymously. Note. This is not intended to imply any re
31、striction on the use of NSAP addresses and their relationship to the subnetwork addresses. 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
32、 the interworking capabilities; - out of 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 Standard Op
33、tion which cannot operate with a mandatory mechanism OS the Functional Standard, 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 mechani
34、sm in use. Edition of February 10, 1988 CEPT T/CD*08-05*E 7 = 2326434 0004330 7 Reference End System T/CD 08-05 E Page 5 I End System Intermediate System Circuit (CSDN) -L- _ 4. ABBREVIATIONS AFI CC TPDU CR TPDU CSDN DCE DSP DTE DT TPDU ER TPDU FSO HIC HOC HTC ID1 ISDN LIC LOC LTC NC NL NS NSAP os1
35、PSDN TPDU TSAP RPOA SNPA vc NCMS QOS TSAP-ID AUTHORITY AND FORMAT IDENTIFIER CONNECT CONFIRM TPDU CONNECT REQUEST TPDU CIRCUIT SWITCHED DATA NETWORK DOMAIN SPECIFIC PART DATA TERMINAL EQUIPMENT DATA TPDU ERROR TPDU Functional Standard OPTION HIGHEST INCOMING CHANNEL HIGHEST OUTGOING CHANNEL INITIAL
36、DOMAIN IDENTIFIER INTEGRATED SERVICE DIGITAL NETWORK LOWEST INCOMING CHANNEL LOWEST OUTGOING CHANNEL NETWORK CONNECTION NETWORK LAYER NETWORK SERVICE NETWORK SERVICE ACCESS POINT OPEN SYSTEMS INTERCONNECTION PACKET SWITCHED DATA NETWORK QUALITY OF SERVICE TRANSPORT PROTOCOL DATA UNIT TRANSPORT SERVI
37、CE ACCESS POINT TRANSPORT SERVICE ACCESS POINT IDENTIFIER RECOGNIZED PRIVATE OPERATING AGENCY SUBNETWORK POINT OF ATTACHMENT VIRTUAL CALL Network Connection Management Subprotocol DATA CIRCUIT-TERMINATING EQUIPMENT HIGHEST TWO-WAY CHANNEL LOWEST TWO-WAY CHANNEL 5. SCENARIO DESCRIPTION AM MODEL DESCR
38、IPTION 5.1. Scenario description The Reference End System communicates with the Compatible End System through a Digital Data Circuit and eventually intermediate system(s) (e.g. Relay Function, LAN .). This Digital Data Circuit is provided through a CSDN or through a concatenation of CSDNs. The Digit
39、al Data Circuit is permanent if a leased circuit of a CSDN is used. In this case, Functional Standard T/421 applies. The Digital Data Circuit is switched if a switched circuit of a CSDN is used. In this case, Functional Standard T/422 applies. TI42X Tlnnn (X: 1 =Permanent Digital Data Circuit; 2=Swi
40、tched Digital Data Circuit.) Figure I. Scenario description. Note. Concrete examples of this general scenario are given in Annex 3. Edition of February IO, 1988 - I. i CEPT T/CD*08-05*E 87 I 2326434 0004333 9 I 4 TICD 08-05 E X.21 IS0 77761 X.211 or p.2lbisI Page 6 5.2. 6. 6.1. 6.2. 6.2.1. 6.2.2. 6.
41、3. 6.3.1. Model description IS0 80731 CONFORMITY General This 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 interworking but may a
42、ffect performance. A claim of conformity to the Functional Standard 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 relate
43、d to the base standards. Conformity at layer 4 Options related to the Functional Standard An End System claiming conformity to this Functional Standard shall state which classes are implemented : FSO CLASS O ONLY or FSO CLASSES O AND 2. General conformity requirements An End System claiming conformi
44、ty to this Functional Standard shall state: - which complementary optional class(es) is (are) implemented ; - whether it is capable of initiating or responding to CR TPDUs or both; - the maximum TPDU size implemented. Conformity at layer 3 Options related to this Functional Standard The claim of con
45、formity shall indicate: - the list of circuit switched optional user facilities implemented among those qualified as local choice in Table 4 of section 8 (see Table 1); - the list of packet level optional user facilities implemented among those qualified as local choice in Table 5 of section 8 (see
46、Table 2); - which procedure(s) is (are) implemented to determine the DTE or DCE role; - if FSO LOGICAL CHANNEL ASSIGNMENT NEGOTIATION or ALTERNATIVE LOGICAL CHANNEL ASSIGNMENT is implemented. Edition of February IO, 1988 CEPT T/CD*OB-OS*E 87 I 2326434 0004332 O I 6.3.2. 6.4. 6.4.1. 6.4.2. 6.5. 6.5.1
47、. T/CD 08-05 E Page 7 General conformity requirements An End System claiming conformity to this Functional Standard shall state: - the packet size(s) implemented; - the window size(s) implemented; - the throughput class(es) implemented; - the number of two-way channel(s); - whether it is capable of
48、initiating or accepting network connections or both. Conformity at layer 2 Options related to this Functional Standard An End System conforming to this Functional Standard shall indicate if the FSO MODULO 128 FRAME is implemented. General conformity requirements An End System claiming conformity to
49、this Functional Standard shall state: - the supported value of parameter NI (maximum frame length). Conformity at layer 1 Options related to this Functional Standard The claim of conformity shall indicate: - which physical interface(s) is (are) supported; - which connector(s) is (are) supported; - which data signalling rate(s) is (are) supported, Table 1. Notes. Code Note Implemented C.1.18 2 yes/no c.1.1 2 yeslno c.2.1 2 Y4no c.2.2 2 YNno C.2.6 2 ymlno C.2.7 1 yalno C.3.1 2 YdnO c.3.3 1 Ydno c.3.4 1 y=lno List of Circuit Switched Optional User Facilitie
