1、INTERNATIONAL TELECOMMUNICATION UNION ITU-T TELECOMMUNICATION STANDARDIZATION SECTOR OF ITU DATA NETWORKS AND OPEN SYSTEM COMM UN ICATIONS PUBLIC DATA NETWORKS - INTERFACES X.31 (1 1 /95) SUPPORT OF PACKET MODE TERMINAL EQUIPMENT BY AN ISDN ITU-T Recommendation X.31 (Previously “CCITT Recommendation
2、”) FOREWORD The ITU-T (Telecommunication Standardization Sector) is a permanent organ of the International Telecommunication Union (ITU). The ITU-T is responsible for studying technical, operating and tariff questions and issuing Recommen- dations on them with a view to standardizing telecommunicati
3、ons on a worldwide basis. The World Telecommunication Standardization Conference (WTSC), which meets every four years, establishes the topics for study by the ITU-T Study Groups which, in their turn, produce Recommendations on these topics. The approval of Recommendations by the Members of the ITU-T
4、 is covered by the procedure laid down in WTSC Resolution No. 1 (Helsinki, March 1-12, 1993). ITU-T Recommendation X.31 was revised by ITU-T Study Group 7 (1993-1996) and was approved under the WTSC Resolution No. 1 procedure on the 21st of November 1995. NOTE In this Recommendation, the expression
5、“Administration” is used for conciseness to indicate both a telecommunication administration and a recognized operating agency. O ITU 1996 AI1 rights reserved. No part of this publication may be reproduced or utilized in any form or by any means, electronic or mechanical, including photocopying and
6、microfilm, without permission in writing from the ITU. ITU-T X-SERIES RECOMMENDATIONS DATA NETWORKS AND OPEN SYSTEM COMMUNICATIONS (February 1994) Subject area Recommendation Series - PUBLIC DATA NETWORKS Services and Facilities X. l-X. 19 ORGANIZATION OF X-SERIES RECOMMENDATIONS Interfaces Transmis
7、sion, Signalling and Switching X.20-X.49 X.50-X.89 Maintenance Administrative Arrangements I Network Aspects I X.90-X. 149 I X.150-X.179 X.180-X.199 OPEN SYSTEMS INTERCONNECTION Model and Notation Service Definitions X.200-X.209 X.210-X.219 Connection-mode Protocol Specifications Connectionless-mode
8、 Protocol Specifications 1 PICS Proformas I X.240-X.259 I X.220-X.229 X.230-X.239 Protocol Identification Security Protocols X.260-X.269 X.270-X.279 Layer Managed Objects Conformance Testing INTERWORKING BETWEEN NETWORKS X.280-X.289 X.290-X.299 I DIRECTORY I X.500-X.599 General Mobile Data Transmiss
9、ion Systems X.300-X.349 X.350-X.369 I Naming, Addressing and Registration I X.650-X.679 I Management MESSAGE HANDLING SYSTEMS X.370-X.399 X.400-X.499 OS1 NETWORKING AND SYSTEM ASPECTS Networking X.600-X.649 I OPEN DISTRIBUTED PROCESSING I X.900-X.999 I Abstract Syntax Notation One (ASN.1) OS1 MANAGE
10、MENT X.680-X.699 X.700-X.799 SECURITY OS1 APPLICATIONS Commitment, Concurrency and Recovery X.800-X.849 X. 850-X. 859 Transaction Processing Remote Ouerations X. 860-X. 879 X.880-X.899 ITU-T RECMN*X*3L 95 m 48b259L Ob08943 LT9 m 1 2 3 4 5 6 7 8 9 10 11 CONTENTS Page Scope 1 References 1 Term and def
11、initions 3 Abbreviations . 3 Conventions 3 General service aspects 3 Reference configurations 4 7.1 Configuration when accessing PSPDN services (Case A) . 4 7.2 Configuration for the ISDN virtual circuit service (Case B) 6 Service aspects . 8.1 Access to PSPDN services (Case A) 8.1.1 Service charact
12、eristics . 8.1.2 User access capabilities . 8.1.3 Basic rules . 8.1.4 Notification classes . Access to the ISDN virtual circuit service (Case B) . 8.2.1 Service characteristics . 8.2.2 User access capabilities . 8.2.3 Notification classes for X.25 incoming calls 8.3 Compatibility checking . Addressi
13、ng and routing aspects 9.1 Terminal interface selection 9.1.1 Terminal interface selection by means of MSNDDI 9.1.2 Terminal interface selection by means of ISDN subaddressing . Access to PSPDN services (Case A) 9.2.1 Channel type selection 9.2.2 Addressing scheme for outgoing calls Access to the IS
14、DN virtual circuit service (Case B) . 9.3.1 Channel type selection 9.3.2 Addressing scheme for outgoing calls 8.2 9.2 9.3 6 6 6 8 9 9 9 9 9 10 12 12 12 12 12 13 13 13 13 13 13 Interworking with dedicated networks . 13 10.1 Circuit-mode access to PSPDN services (Case A) . 13 10.2 Access to PSPDNs via
15、 virtual circuit service (Case B) 13 Packet communications at the S/T-reference point 11.1 Outgoing access 1 1.1.1 Circuit-switched access to PSPDN services (Case A) 1 i . i . 2 Access to the ISDN virtual circuit service (Case B) . i 1.2 Incoming access 11.2.1 Access from PSPDN services (Case A) 11.
16、2.2 Access from the ISDN virtual circuit service (Case B) X.25 Virtual call establishment and release 11.3.1 Link layer establishment and release i 1.3.2 Packet layer virtual call Set-up and release . 11.3 13 14 14 15 16 16 17 20 20 22 Recommendation X.31 (11/95) 1 ITU-T RECMNxX-31 95 m 48b259L Ob08
17、944 035 m 11.4 Call clearing 11.4.1 B-Channel . 11.4.2 D-Channel . 1 1.4.3 Additional error handling information 11.4.4 Cause mappings 11.5 Access collision 12 Terminal adaptor functionalities 12.1 12.2 12.3 12.4 12.5 12.6 12.7 General Physical interfaces 12.3.1 General 12.3.2 Rate adaption 12.3.3 S
18、ignalling 12.3.4 Synchronization Access through the D-channel 12.4.1 General 12.4.2 LAPB-LAPD mapping 12.4.3 Signalling 12.5.1 General 12.5.2 X.25 outgoing call . 12.5.3 X.25 Incoming call Access through the semi-permanent H-channel . 12.6.1 General 12.6.2 Rate adaption 12.6.3 Signalling Test loops
19、12.7.1 12.7.2 Test loops for TA with access through the D-channel Access through the B-channel Access through the B- and D-channels . Test loops for TA with access through the B-channel Appendix I . B-channel TA acting on layers 2 and 3 of X.25 . 1.1 Introduction 1.2 Call control . 1.2.1 Idle phase
20、1.2.2 Establishment phase 1.2.3 Data transfer phase 1.2.4 Clearing phase . Appendix II - Interconnection of packet mode TE2s which use the circuit-mode bearer service of the ISDN . Appendix III - Example message flow diagrams and example conditions for cause mapping . Example message flow diagrams E
21、xample conditions for cause mapping III . 1 Example message flow diagrams 111.1.1 Key to the figures 111.1.2 111.2 Appendix IV - D-channel TAS requiring full protocol termination in the TA . IV . 1 Introduction IV.2 Call control . IV.2.1 Idle phase IV.2.2 Establishment phase IV.2.3 Data transfer pha
22、se IV.2.4 Clearing phase . Page 22 22 23 23 23 27 27 27 27 28 28 28 28 33 33 33 33 35 37 37 37 37 37 37 37 37 37 38 39 39 39 39 40 41 42 43 44 45 45 45 46 51 55 55 55 56 57 58 58 II Recommendation X.31 (11/95) - ITU-T RECNN*X.31 95 4862593 Ob08945 T31 M SUMMARY This Recommendation defines services a
23、vailable and signalling procedures operated at the SIT-reference point of an ISDN for subscribing packet mode terminal equipment, and terminal adaptor functionalities to support existing X.25 terminals at the R-reference point of the ISDN. . Recommendation X.31 (11/95) 111 ITU-T RECMN*X-31 95 486259
24、1 060894b 908 ITU-T RECMNUX.31 95 486257% Ob06947 844 Recommendation X.31) SUPPORT OF PACKET MODE TERMINAL EQUIPMENT BY AN ISDN (Malaga Torremolinos, 1984; amended at Melbourne, 1988; Helsinki, 1993, and Geneva 1995) 1 Scope This Recommendation addresses the following aspects: a) b) c) definition of
25、 the aspects of the packet-mode services provided to the ISDN users in accordance with the bearer services defined in I-Series Recommendations; definition of the procedures at the ISDN user-network interface for accessing packet-mode services in alignment with Recommendations 1.430,1.43 1, 4.921 and
26、 Q.93 1; definition of the TAS functions for adapting existing X.25 terminals. PADS may be supported within the network in which cases existing Recommendations shall apply for asynchronous access (e.g. Recommendations X.3, X.28, X.29, X.52). The support of asynchronous access by an ISDN or through a
27、n ISDN is not within the scope of this Recommendation. 2 References The following Recommendations and other references contain provisions which, through reference in this text, constitute provisions of this Recommendation. At the time of publication, the editions indicated were valid. All Recommenda
28、tions and other references are subject to revision; all users of this Recommendation are therefore encouraged to investigate the possibility of applying the most recent edition of the Recommendations and other references listed below. A list of the currently valid ITU-T Recommendation is regularly p
29、ublished. ITU-T Recommendation X.l (1993), International user classes of service in and categories of access to, public data networks and Integrated Services Digital Networks (ISDNs). ITU-T Recommendation X.2 ( 1993), International data transmission services and optional user facilities in public da
30、ta networks and ISDNs. ITU-T Recommendation X.3 (1993), Packet assembly/disassembly facility (PAD) in a public data network. - CCITT Recommendation X.2 1 (1 992), Interface between data terminal equipment and data circuit-terminating equipment for synchronous operation on public data networks. - CCI
31、TT Recommendation X.21 bis (1988), Use on public data networks of Data Terminal Equipment (DTE) which is designed for interfacing to synchronous V-Series modems. ITU-T Recommendation X.25 (1993), Interface between Data Terminal Equipment (DTE and Data Circuit-terminating Equipment (DCE) for terminal
32、s operating in the packet mode and connected to public data networks by dedicated circuit. ITU-T Recommendation X.28 (1993), DTE/DCE 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.
33、 ITU-T Recommendation X.29 (1993). Procedures for the exchange of control information and user data between a packet assembly/disassembly (PAD) facility and a packet mode DTE or another PAD. - - - - - - This Recommendation js also included in the I-Series Recommendations under number 1.462. Recommen
34、dation X.31 (11/95) 1 ITU-T RECMN*X.33 95 m 4862593 Ob08948 780 m - ITU-T Recommendation X.30fi.461 (1993), Support of X.21, X.21 bis and X.20 bis based Data Terminal Equipments (DTEs) by an Integrated Services Digital Network (ISDN). ITU-T Recommendation X.32 (1993), Interface between DTE and DCE f
35、or terminals operating in the packet mode and accessing a packet switched public data network through a public switched telephone network or an integrated services digital network or a circuit switched public data network. - - CCITT Recommendation X.52 (1988), Method of encoding anisochronous signal
36、s into a synchronous user bearer. - ITU-T Recommendation X.75 (1 993), Packet-switched signalling system between public networks providing data transmission services. - ITU-T Recommendation X.96 (1993), Call progress signals in public data networks. - CCITT Recommendation X. 121 (1992), Internationa
37、l numbering plan for public data networks. - CCITT Recommendation X.2 13 (1 992), Information technology - Network service definition for Open Systems Interconnection. - CCITT Recommendation X.300 (1988), General principles for interworking between public networks and between public networks and oth
38、er networks for the provision of data transmission services. - CCITT Recommendation X.320 (1988), General arrangements for intenuorking between Integrated Services Digital Networks (ISDNs) for the provision of data transmission services. - CCITT Recommendation X.325A.550 (1988). General arrangements
39、 for interworking between Packer Switched Public Data Networks (PSPDNs) and Integrated Services Digital Networks (ISDNs) for the provision of data transmission services. - CCITT Recommendation 1.230 (1988), Definition of bearer service categories. - CCITT Recommendation 1.23 1 (1988), Circuit-mode b
40、earer service categories. - CCITT Recommendation 1.232 (19SS), Packet-mode bearer service categories. - CCITT Recommendation E.164A.331 (1988), Numbering plan for the ISDN era. - ITU-T Recommendation 1.41 1 (1993), ISDN user-network interface - Reference configurations. - ITU-T Recommendation 1.430
41、(1993), Basic user-network interface - Layer I specification. - ITU-T Recommendation 1.43 1 (1993), Primary rate user-network interface - Layer I specifcation. - ITU-T Recommendation Q.921A.441 (1993), ISDN user-network interface - Data link layer specification. - ITU-T Recommendation 4.931 (1993),
42、Digital Subscriber Signalling System No. 1 (DSS 1) - ISDN user-network interface - Data link layer specifcation. - CCITT Recommendation 1.451 (1988), ISDN user-network interface layer 3 specifcation for basic call control. - ITU-T Recommendation Q.920 (1993), Digital Subscriber Signalling System No,
43、 I (DSS 1) - ISDN user-network interface data link layer - General aspects. - CCITT Recommendation V.25 bis (1988), Automatic calling andor answering equipment on the General Switched Telephone Network (GSTN) using the 100-series interchange circuits. - CCITT Recommendation V.110 (1992), Support of
44、data terminal equipments with V-Series type interfaces by an integrated Services Digital Network (ISDN). - CCITT Recommendation E.166K.122 (1992), Numbering plan interworking for the E.164 and X.121 numbering plans. 2 Recommendation X.31 (11/95) 3 Term and definitions For the purposes of this Recomm
45、endation, the following definitions apply: 3.1 semi-permanent connection as defined in Recommendation I. 140. 3.2 and 1.23 1.8, respectively. H-channel: To collectively mean HO, HI1 or H12 channel as defined in Recommendations 1.231.6, 1.231.7 4 Abbreviations For the purposes of this Recommendation,
46、 the following abbreviations are used: AU Access Unit DCE Data Circuit-terminating Equipment DDI Direct-Dialling-In DTE Data Terminal Equipment ET Exchange Termination ISDN Integrated Services Digital Network IWF Interworking Function MSN Multiple Subscriber Number NT Network Termination PH Packet H
47、andler PSDTS Packet Switched Data Transmission Service PSPDN Packet Switched Public Data Network SAP1 Service Access Point Identifier TA Terminal Adaptor TE Terminal Equipment TE1 Terminal Equipment Identifier 5 Conventions No particular conventions are used. 6 General service aspects Two main servi
48、ces for packet switched data transmission are defined for packet-mode terminals connected to the ISDN, namely: - Case A access to a PSPDN (PSPDN services); - Case B use of an ISDN virtual circuit service. The provision of these services is defined in the 1.230-Series Recommendations. In Case A an IS
49、DN transparent circuit connection, either permanent (Le. non-switched) or demand (Le. switched), is used. The corresponding ISDN bearer services are a 64 kbitis service, and optionally, a 384 kbitis service or a 1536 kbitis service or a 1920 kbitis service or combination of these as described in Recommendation 1.231. The service available to the user is that of the PSPDN described in Recommendations X.25 (permanent access) and X.32 (demand access), as well as in other X-Series Recommendations (e.g. Recommendation X.2, Recommendation X. 121). In Case B an ISDN virtual
