ITU-T X 445-1995 Asynchronous Protocol Specification - Provision of OSI Connection Mode Network Service Over the Telephone Network - Data Networks and Open System Communications - p《异.pdf

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1、 - ITU-T RECMN*X.445 95 = 4862593 Ob09533 952 INTERNATIONAL TELECOMMUNICATION UNION ITU-T TELECOMMUNICATION STANDARDIZATION SECTOR OF ITU DATA NETWORKS AND OPEN SYSTEM COMMUNICATIONS MESSAGE HANDLING SYSTEMS x.445 (04195) ASYNCHRONOUS PROTOCOL CONNECTION MODE NETWORK SERVICE OVER THE TELEPHONE NETWO

2、RK SPECIFICATION - PROVISION OF OS1 ITU=T Recommendation X.445 (Previously “CCIlT Recommendation”) ITU-T RECMN*X-445 95 4862593 0609532 899 FOREWORD The ITU-T (Telecommunication Standardization Sector) is a permanent organ of the International Telecommunication Union (ITU). The ITU-T is responsible

3、for studying technical, operating and tariff questions and issuing Recommen- dations 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-

4、T Study Groups which, in their turn, produce Recommendations on these topics. The approval of Recommendations by the Members of the ITU-T is covered by the procedure laid down in WTSC Resolution No. 1 (Helsinki, March 1-12, 1993). ITU-T Recommendation X.445 was prepared by ITU-T Study Group 7 (1993-

5、1996) and was approved under the WTSC Resolution No. 1 procedure on the 10th of April 1995. NOTE In this Recommendation, the expression “Administration” is used for conciseness to indicate both a telecommunication administration and a recognized operating agency. O ITU 1996 All rights reserved. No p

6、art 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 from the ITU. ITU-T RECflN*X-445 95 4862593 Ob09533 725 = Services and Facilities In terfaces ITU-T X-SERIES RECOMMENDATION

7、S DATA NETWORKS AND OPEN SYSTEM COMMUNICATIONS (February 1994) ORGANIZATION OF X-SERIES RECOMMENDATIONS X. l-X. 19 X.20-X.49 r Subiect area I Recommendation Series I Transmission, Signalling and Switching Network AsDects I PUBLIC DATA NETWORKS I I X.50-X.89 X.90-X. 149 Administrative Arrangements OP

8、EN SYSTEMS INTERCONNECTION X.180-X. 199 I Maintenance I X.150-X. 179 I Model and Notation Service Definitions x.200-x.209 X.210-X.219 Connectionless-mode Protocol Specifications PICS Proforma 1 Connection-mode Protocol Specifications I X.220-X.229 I X.230-X.239 X.240-X.259 Security Protocols Layer M

9、anaged Objects I Protocol Identification I X.260-X.269 I X.270-X.279 X.280-X.289 Conformance Testing INTERWORKING BETWEEN NETWORKS X.290-X.299 I General I x.300-x.349 I Mobile Data Transmission Systems Management - X.350-X.369 X.370-X.399 MESSAGE HANDLING SYSTEMS DIRECTORY I OS1 NETWORKING AND SYSTE

10、M ASPECTS I I X.400-X.499 X.500-X.599 Networking Naming, Addressing and Registration X.600-X.649 X.650-X.679 Abstract Syntax Notation One (ASN.l) OS1 MANAGEMENT SECURITY OS1 APPLICATIONS Commitment, Concurrency and Recovery X.680-X.699 X.700-X.799 X. 800-X.849 X.850-X.859 Transaction Processing Remo

11、te Operations OPEN DISTRIBUTED PROCESSING X.860-X.879 X.880-X. 899 x.900-x.999 ITU-T RECMN*X.445 95 4862593 0609514 bbl = 4 7.5.1 7.5.2 7.5.3 CONTENTS Scope References Definitions 3.1 Reference model definitions . 3.2 Service conventions definitions 3.3 Network service definitions 3.4 X.25 definitio

12、ns 3.5 APS definitions . Abbreviations . 4.1 Reference model abbreviations . 4.2 Network layer abbreviations . 4.3 X.25 abbreviations 4.4 Data link layer abbreviations 4.5 Other abbreviations . Overview 5.1 Configurations 5.2 5.2.1 V.42-dependent mode . 5.2.2 LAPB mode 5.2.3 X.25 mode . 5.2.4 Mode n

13、egotiations . 5.2.5 Mode support Provision of the OS1 CONS . 6.1 Control of underlying connections . 6.2 Mapping OS1 CONS to/from X.25 PLP . 6.3 Mapping OS1 CONS to/from the APS network protocol . AFS layer 2 protocols . 7.1 Introduction 7.2 Stdstop LAPB 7.3 APS data link protocol 7.3.1 Reception of

14、 incorrect frames . 7.4 Transparency 7.5 APS layer 2 operation and establishment of the underlying connection Point-to-Point configuration . Modes of operation and their APS layers representation . 7.5.1.1 Establishment of the underlying connection . 7.5.1.2 Data link set-up . 7.5.1.3 LAPB addressin

15、g 7.5.1.4 Time fill PAD configuration 7.5.2.1 Establishment of the underlying connection . 7.5.2.2 Data link set-up . 7.5.2.3 LAPB addressing 7.5.2.4 Time fill 7.5.2.5 Mapping of APS layer 2 frames to packets . 7.5.2.6 Exception conditions . Direct network configuration 7.5.3.1 Establishment of the

16、underlying connection . 7.5.3.2 LAPB data link set-up . 7.5.3.3 LAPB addressing 7.5.3.4 Time fill Recommendation X.445 (04195) Page 1 1 2 2 3 3 3 3 3 3 3 4 4 4 5 5 6 6 6 6 6 7 7 7 9 10 10 10 10 10 11 11 11 11 11 12 13 13 14 14 14 15 15 15 15 15 15 15 15 15 1 - . ITU-T RECMN*X.445 95 4Ab2591 Ob09515

17、5T8 M 8 APS layer 3 protocols . 8.1 The APS network protocol . 8.1.1 APS network protocol elements of procedure 8.1.1.1 Connection establishment procedure 8.1.1.2 Data transfer procedure . 8.1.1.3 Disconnect procedure APS network protocol stnicture 8.1.2.1 The connect request PDU . 8.1.2.2 The conne

18、ct confirm PDU 8.1.2.3 The data transfer PDU 8.1.2.4 The disconnect request PDU . 8.1.2.5 The disconnect confirm PDU 8.1.2.6 Maximum user data in APS NPDUs . 8.2 X.25 PLP operation Optional and negotiable parameters 8.1.2 8.2.1 8.2.1.1 Parameter usage in the Direct Network configuration Annex A - Tr

19、ansparency . A.0 Transparency A.l Introduction A.2 APS PAD transparency . APS protocols selection string Annex B - APS protocols selection string B.O B.l Introduction B.2 APS protocols selection string format B.3 Annex C - Use of the APS network protocol to provide the OS1 Connection-mode network se

20、rvice . C.0 Use of the APS network protocol to provide the OS1 connection-mode network service C.l Introduction C.2 Network connection establishment phase . C.3 Data transfer phase . C.3.1 Handling of NS-user-data . Network connection release phase Use of the call user data in X.25 call requests C.3

21、.2 The reset service . C.4.1 Mapping of N-DISCONNECT Parameters . Annex D - Recommended practices for use in MHS environment . C.4 D.0 D . 1 D.2 D.3 D.4 D.5 D.6 Recommended practices . Use of the APS network protocol for simultaneous communications Handling of future versions APS layer 3 protocols .

22、 D.1.1 D . 1.2 APS layer 2 protocols . D.2.1 LAPB retransmission timer . Startistop framing . D.3.1 Modems D.4.1 V.42 modems D.4.2 Modems with automatic data rate switching . D.4.3 Modem flow control . D.5.1 Recommended PAD parameters . D.5.2 Remote PAD parameters . Timers and counters D.6.1 APS lay

23、er 2 . Fast Frame Control Check (FCS) implementation PAD operation D.6.2 APS layer 3 . Page 15 15 16 16 17 17 18 19 19 19 19 19 19 20 21 23 23 23 23 23 24 24 24 24 24 25 25 25 25 25 25 26 26 26 28 28 28 28 28 28 28 29 29 30 30 31 31 31 31 32 32 32 32 11 Recommendation X.445 (04195) SUMMARY This Reco

24、mmendation specifies the protocols to be used to provide OS1 connection mode network service to applications entities such as MHS entities (e.g. UA, MTA, MS) when communicating in an asynchronous environment (i.e. start/stop transmissions) over a telephone network. The communication can be directly

25、over a telephone network connection, or over a telephone network connection to a PSDN through a PAD, or over a telephone network connection to a PSDN using the packet mode. . 111 Recommendation X.445 (04/95) ITU-T RECMN*X.445 95 = 4862571 Ob09517 370 = INTRODUCTION This Recommendation establishes th

26、e rules for asynchronous OS1 communications over the telephone network. This Recommendation is applicable in MHS (and other) environments requiring optimization of data link and network layer protocols for reliable asynchronous communication over the telephone network. These environments include: -

27、- - communications over direct telephone network connection; communications over a telephone network connection to a PSDN through a PAD; communications over a telephone network connection to a PSDN using the packet mode. iv Recommendation X.445 (04195) ITU-T RECMN+X.445 95 4862593 Ob09538 207 Recomm

28、endation X.445 ASYNCHRONOUS PROTOCOL SPECIFICATION - PROVISION OF OS1 CONNECTION MODE NETWORK SERVICE OVER THE TELEPHONE NETWORK (Geneva, 1995) 1 Scope This Recommendation is applicable in MHS (and other) environments requiring optimization of data link and network layer protocols for reliable async

29、hronous communication over the telephone network. These environments include: - - - NOTE - For simplicity, the term MHS is used throughout this Recommendation to represent any application environment. communications over direct telephone network connection; communications over a telephone network co

30、nnection to a PSDN through a PAD; communications over a telephone network connection to a PSDN using the packet mode. For example, other applications environments may include the OS1 Directory, etc. 2 References The following Recommendations and other references contain provisions which, through ref

31、erence in this text, constitute provisions of this Recommendation. At the time of publication, the editions indicated were valid. All Recommendations and other references are subject to revision: ail users of this Recommendation are therefore encouraged to investigate the possibility of applying the

32、 most recent edition of the Recommendations and other references listed below. A list of currently valid ITU-T Recommendations is regularly published. - CCITT Recommendation V.42 (1988), Error-correcting procedures for DCEs using asynchronous-to- synchronous conversion. ITU-T Recommendation X.3 (199

33、3), Packet Assembly/Disassembly facility (PAD) in a public data network. - - ITU-T Recommendation X.25 (1993), Interface between Data Terminai Equipment (DTE) and Data Circuit-terminating Equipment (DCE) for terminals operating in the packet mode and connected to public data networks by dedicated ci

34、rcuit. IT-T Recommendation X.28 (1993), DTUDCE interface for a start-stop mode data terminal equipment accessing the Packet Assembly/Disassembly facility (PAD) in a public data network situated in the same country. ITU-T Recommendation X.29 (1993), Procedures for the exchange of control information

35、and user data between a Packet Assembly/Disassembly (PAD) facility and a packet mode DTE or another PAD. ITU-T Recommendation X.32 (1993), Interface between Data Terminal Equipment (DTE) and Data Circuit-terminating Equipment (DCE) for terminals operating in the packet mode and accessing a packet sw

36、itched public data network through a public switched telephone network or an integrated services digital network or a circuit switched public data network. ITU-T Recommendation X.200 (1994) I ISOAEC 7498-1:1994, Information technology - Open Systems Interconnection - Basic Reference Model: The Basic

37、 Model. ITU-T Recommendation X.210 (1993) I ISOAEC 10731: 1994, Information technology - Open Systems Interconnection - Conventions for the definition of OS1 services. CCITT Recommendation X.213 (1992) I ISOiEC 8348:1993, Informution technology - Open Systems Interconnection - Network service defini

38、tion. - - - - - - 1 Recommendation X.445 (04/95) - ITU-T Recommendation X.223 (1993), Use of X.25 to provide the OS1 connection-mode network service for ITU-T applications. ISOiEC 8878: 1992, Information technology - Telecommunications and information exchange between systems - Use of X.25 to provid

39、e the OSI connection-mode network service. CCITT Recommendation F.400/X.400 (19921, Message handling services: Message handling system and service overview. - ISO/IEC 10021-1 : 1990, Information technology - Text Communication - Message-Oriented Text Interchange Systems (MOTIS) - Part 1: System and

40、Service Overview plus Technical Corrigendum I (1991), Technical Corrigendum 2 (1991), Technical Corrigendum 3 (19921, and Technical Corrigen- dum 4 (1992). CCIT Recommendation X.419 (1992), Message handling systems - Protocol speczjkations. - ISO/IEC 10021-6: 1990, Information technology - Text Comm

41、unication - Message-Oriented Text Interchange Systems (MOTIS - Part 6: Protocol specifications plus Technical Corrigendum 1 (19911, Technical Corrigendum 2 (1991), Technical Corrigendum 3 (1 992), and Technical Corrigen- dum 4 (1992). - ITU-T Recommendation X.500 (1993) I ISOLEC 9594-1:1994, Informa

42、tion technology - Open Systems Interconnection - The Directory: Overview of concepts, models and services. - CCIT Recommendation X.614 (1992) I ISO/IEC 10732:1993, Information technology - Use of the X.25 packet layer protocol to provide the OSI connection-mode network service over the telephone net

43、work. - ISOAEC 3309: 1993, Informution technology - Telecommunications and information exchange between systems - High-level data link control (HDLC) procedures - Frame structure. - IS0 7776: 1986, Information processing systems - Datacommunications - High-level data link control procedures - Descri

44、ption of the X.25 UPB-compatible DTE data link procedures. - ISO/IEC 7809: 1993, Information technology - Telecommunications and information exchange between systems - High-level Data Link Control (HDLC) procedures - Classes of procedures. - ISOAEC 8208: 1990, Information technology - Data communica

45、tions - X.25 Packet Layer Protocol for Data Terminal Equipment. ISO/IEC ISP 10609-9: 1992, Information technology - International Standardized Profiles TB, TC, TD and TE - Connection-mode Transport Service over connection-mode Network Service - Part 9: Subnetwork-type dependent requirements for Netw

46、ork Layer, Data Link Layer, and Physical Layer concerning permanent access to a packet switched data network using virtual calls. ISO/IEC 646: 1991, Information technology - IS0 7-bit coded character set for information interchange. - - - ISOLEC 4335: 1993, Information technology - Telecommunication

47、s and information exchange between systems - High-level Data Link Control (HDLC) procedures - Elements of procedures. 3 Definitions For the purposes of this Recommendation, the following definitions apply. 3.1 Reference model definitions This Recommendation makes use of the following terms defined i

48、n ITU-T Rec. X.200 I ISO/lEC 7498-1: a) Network connection; b) Network layer; c) Network service. 2 Recommendation X.445 (04/95) ITU-T RECMN*X.445 95 = 4862593 Ob09520 965 3.2 Service conventions definitions This Recommendation makes use of the following terms defined in IT-T Rec. X.210 I ISOTEC 107

49、31: a) Network service provider; b) Network service user. 3.3 Network service definitions This Recommendation makes use of the following terms defined in CC Rec. X.213 I ISO/IEC 8348: a) N-CONNECT request; b) N-CONNECT indication; c) N-CONNECT response; d) N-CONNECT confirm; e) N-DISCONNECT indication; f) N-DISCONNECT request; g) N-DATA request; h) N-DATA inditAtion. 3.4 X.25 definitions This Recommendation makes use of the following concepts as developed in Recommendation X.25: a) Virtual circuit; b) Virtual call; c) Data ci