1、 - STD-ITU-T RECMN X.32-ENGL L99b 48b259L Ob22393 b91 INTERNATIONAL TELECOMMUNICATION UNION ITU-T TELECOMMUNICATION STANDARDIZATION SECTOR OF ITU X.32 (1 0196) SERIES X: DATA NETWORKS AND OPEN SYSTEM COMMUNICATION Public data networks - Interfaces Interface between Data Terminal Equipment (DTE) and
2、Data Circuit-terminating Equipment (DCE) for 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 ITU-T Recommendation X.32 (Previousl
3、y 4XIlT recommendation) ITU-T X-SERIES RECOMMENDATIONS DATA NETWORKS AND OPEN SYSTEM COMMUNICATION X.90-X. 149 X. 150-X. 179 Administrative arrangements OPEN SYSTEM INTERCONNECTION I Model and notation X. 180-X. 199 X .200-X .299 X.200-X.209 Service definitions X.210-X.219 Connection-mode protocol s
4、pecifications X.220-X.229 Connectionless-mode protocol specification PICS proformas Protocol Identification Security Protocols X.230-X.239 X.240-X.259 X .260-X . 269 X.270-X.279 II Layer Managed Objects X.280-X.289 Conformance testing General INTERWORKING BETWEEN NETWORKS X.290-X.299 X .3 00-X .399
5、X.300-X.349 11 Satellite data transmission networks X .3 50-X . 399 MESSAGE HANDLING SYSTEMS DIRECTORY OS1 NETWORKING AND SYSTEM ASPECTS Networking x.400-x.499 x.500-x.599 X.600-X.699 X .600-X. 629 Efficiency X .63 O-X .649 Naming, Addressing and Registration X.650-X.679 X.680-X.699 I Abstract Synta
6、x Notation One (ASN. 1) OS1 MANAGEMENT Systems Management framework and architecture I/ x.700-x.799 X .700-X. 709 Management Communication Service and Protocol X.7 1 O-X.7 19 Structure of Management Information X.720-X.729 Management functions X.730-X.799 SECURITY OS1 APPLICATIONS Commitment, Concur
7、rency and Recovery X.800-X.849 X.850-X.899 X.850-X.859 X.860-X. 879 I Transaction processing Remote operations OPEN DISTRIBUTED PROCESSING I X.880-X.899 X.900-X.999 For further details, please refer to ITU-T List of Recommendations. FOREWORD The ITU-T (Telecommunication Standardization Sector) is a
8、permanent organ of the International Telecommunication Union (ITU). The IIZT-T is responsible 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
9、 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 is covered by the procedure laid down in WTSC Resolution No. 1 (Hels
10、inki, March 1-12, 1993). ITU-T Recommendation X.32 was revised by IT-T Study Group 7 (1993-1996) and was approved under the WTSC Resolution No. 1 procedure on the 5th of October 1996. NOTE In this Recommendation, the expression “Administration” is used for conciseness to indicate both a telecommunic
11、ation administration and a recognized operating agency. All 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 microfilm, without permission in writing from the ITU. Recommendation X.32 (10/96)
12、1 CONTENTS Preface . Scope 2.1 Functional aspects Dial-in and dial-out considerations . 2.2 Identification . 2.3 Service aspects 2.5 DCE identification methods 2.7 DTE service requirement Duplex and half-duplex operation 2.10 Negotiation of values 3.1 DE service attributes Summary of DTE services 3.
13、3 Non-identified DTE service 3.4 Identified DTE service 3.5 Customized DTE service 4.1 X.21 interface . 4.2 X.21 bis interface 4.3 V-Series interface . Link access procedure across the DTEDCE interface . 5.1 Introduction Data link layer address assignment . Use of exchange identification (XID) frame
14、s . 5.5 Multilink . 5.6 Half-duplex operation . Packet layer Scope and field of application 2.4 DTE identification methods 2.6 Dial-in-by-the-DTE and dial-out-by-the-PSPDN operation . 2.8 2.9 Identification protocol DTE service descriptions . 3.2 Interface characteristics (physical layer) 5.2 5.3 5.
15、4 Link set-up disconnection . 6.1 6.2 Identification and authentication of the DTE using the NUI selection facility in call set-up packets X.32 procedures. formats and facilities 7.1 Identification protocol 7.2 Procedures for X.32 optional user facilities 7.3 7.4 Security grade 2 method . 7.5 DCE ti
16、mers T14 and T14 bis Coding of the identification protocol elements . 7.6 DCE timer TI5 . Annex A . Actions taken by the DCE in the roles of questioning and challenged parties for security grade 1 and security grade 2 identifications A.2 A.3 A.l Introduction Security grade 1 identification Security
17、grade 2 identification 11 Recommendation X.32 (10/96) Page 1 2 3 3 3 4 7 9 9 9 10 10 10 10 10 14 14 16 18 19 20 21 22 23 23 23 24 27 28 28 33 33 33 34 34 36 37 38 39 39 39 39 40 44 . STD-ITU-T RECMN X.32-ENGL 19b = qBh2591 b22397 237 m Annex B . Abbreviations Appendix I . Implementation of LAPX 1.1
18、Introduction 1.2 Control and status functions . 1.3 Table of transitions between states . 1.4 HDWphysical layer control and status functions expressed in terms applicable to a modem interface . Appendix II - RSA public key algorithm Appendix III - Relationship of timers TI4 and TI4 bis to the differ
19、ent methods of DTE identification . Recommendation X.32 (10/96) Page 48 50 50 50 51 52 53 54 . 111 - STD-ITU-T RECMN X-32-ENGL 177b = LiBb2571 Ob22378 173 Recommendation X.32 INTERFACE BETWEEN DATA TERMINAL EQUIPMENT (DTE) AND OPERATING IN THE PACKET MODE AND ACCESSING A PACKET SWITCHED PUBLIC DATA
20、NETWORK THROUGH A PUBLIC SWITCHED TELEPHONE NETWORK OR AN INTEGRATED SERVICES DIGITAL NETWORK OR A CIRCUIT SWITCHED PUBLIC DATA NETWORK DATA CIRCUIT-TERMINATING EQUIPMENT CE) FOR TERMINALS (Malaga-Torremolinos, 1984; amended at Melbourne, 1988 and Helsinki, 1993; revised in 1996) Preface The establi
21、shment in various countries of Packet Switched Public Data Networks (PSPDNs) providing data services creates the need to produce Recommendations to facilitate access to the PSPDN through a Public Switched Telephone Network (PSTN) or an Integrated Services Digital Network (ISDN) or a Circuit Switched
22、 Public Data Network (CSPDN). The iT-T, comidering (a) that Recommendation X.l specifies the user classes of service for DTEs operating in the packet mode, that Recommendation X.2 defines user facilities provided by public data networks, that Recommendation X. 10 defines categories of access, that R
23、ecommendations X.21 and X.21 bis define DTEDCE physical level interface characteristics, that Recommendation X.25 defines the interface between the DTE and the DCE for terminais operating in the packet mode and connected to public data networks by dedicated lines, that Recommendation X.31 defines th
24、e support of packet mode terminai equipment by an ISDN, that Recommendation X.121 defines the international numbering plan for Public Data Networks (PDNs), that Recommendation X.300 defines the principles and arrangements for interworking between PDNs and other public networks; (b) the PSTN; that th
25、e V-Series Recommendations define modem and interface characteristics for use of data services on (c) that Recommendation T.70 defines the procedures and interfaces to be used by telematic terminals, that Recommendation T.71 defines the extension of Link Access Procedure Balanced (LAPB) procedure to
26、 be used in half-duplex transmission facilities (LAPX); (d) that a need has been identified to access a PSPDN through a PSTN, or an ISDN, or CSPDN, because a dedicated circuit to the PSPDN is not justified, or because global service availability is required with back-up network access via public swi
27、tched networks; however permanent virtual circuits are not available in the types of access covered in this Recommendation; (e) that some Administrations have considered the provision of Telematic services in different types of networks, e.g. PSPDN, PSTN, ISDN and CSPDN; (f) that, when this Recommen
28、dation is used to provide the Network Service defined in Recommendation X.213, the physical, link and packet layers correspond to the Physical, Data link and Network layers respectively, as defined in Recommendation X.200, (unanimously) recommends that the functional and procedural aspects of packet
29、 mode DTEs accessing a PSPDN through a PSTN or an ISDN circuit switched bearer service, or CSPDN, are as specified in this Recommendation. NOTE - Packet mode terminai (TE1 or TEZ) conforming to the I-Series Recommendations may access a PSPDN through an ISDN circuit switched bearer service. In this c
30、ase the functional and procedural aspects related to layer 2 and layer 3 in the B-channel are as specified in this Recommendation. Recommendation X.32 (10/96) 1 STD-ITU-T RECMN X.32-ENGL 177b 48b2571 Ob22377 OUT DTE 1 Scope I TA 1 - This Recommendation defines the functional and procedural aspects o
31、f the DTE/DCE interface for packet mode user classes of service DTEs as defined in Recommendations X.l; for DTEs that access a PSPDN via public switched networks. In this Recommendation, a Public Switched Network (PSN) is either a Public Switched Telephone Network (PSTN) or an Integrated Services Di
32、gitai Network (ISDN) providing circuit switched bearer service or a Circuit Switched Public Data Network (CSPDN). NOTE - The ISDN interface specification for transparent circuit connection is described in Recommendation X.31. In this Recommendation only the DTE functionalities for the access to a PS
33、PDN service through an ISDN are considered, In the PSTN case, the X.32 DTE/DCE interface coincides with the interface between the DTE and the modem. In the ISDN case, the X.32 interface coincides with the R reference point (see Figure 1). In the CSPDN case, theX.32 DTE/DCE interface coincides with t
34、he X.21 or X.21 bis interface. This definition applies whether or not the Administration provides the DCE and regardless of how the interface is physically realized (e.g. whether or not the DTE and DCE are contained within the same enclosure). In either case the PSN is involved only: a) in the estab
35、lishment of the switched access path; b) to provide a transmission medium; and c) optionally, to provide a PSN number for purposes of identification and addressing. Administrations may offer one or more of the following physical layer interfaces: 1) for access by way of a CSPDN, either Recommendatio
36、n X.21 or X.21 bis will be used, as described in 4.1 or 4.2, respectively; 2) 3) for access by way of a PSTN, appropriate V-Series Recommendations will be used as described in 4.3; for access by way of an ISDN, refer to Recommendation X.3 1. The exact use of the relevant points in these Recommendati
37、ons is given in clause 4. The transmission facility is duplex or, optionally, half-duplex. Specific procedures are defined in 5.6 for operation over a halfduplex transmission facility. At the link layer, the LAPB link access procedure of Recommendation X.25 is used over a single switched physical ci
38、rcuit. The LAPB formats and procedures shall be in accordance with 2.2Bc.25, 2.3IX.25 and 2.4Bc.25, with additions as noted in clause 5. The formats and the procedures at the packet layer shall be in accordance with 3IX.25, 4iX.25, 5Bc.25, 6Bc.25 and 7Bc.25 with the additions noted in clause 6. NOTE
39、 - The DTE and TA functionalities may be implemented in the same piece of equipment in the case of a TE1 terminal. In this case, this Recommendation covers layers 2 and 3 operation in the B-channel while the S reference point procedures are described in Recommendation X.3 1. FIGURE 1K.32 ISDN refere
40、nce point 2 Recommendation X.32 (10/96) 2 Functional aspects 2.1 Dial-in and dial-out considerations Dial-in operation allows a packet-mode DTE to access a PSPDN by means of selection procedures on a PSTN or CSPDN or ISDN (see Figure 2). This operation is termed “dial-in-by-the-DT within this Recomm
41、endation. TO71 733 or through pre-arrangement between the PSPDN and a PSN or another authority, and direct arrangement between the DTE and that authority (i.e. not explicitly); b) A DTE may incur charges even if not identified because some Administrations collect charges via the PSTN, ISDN or CSPDN.
42、 In any case, DTE identification is used for billing and accounting purposes. In addition to this basic function, DTE identification may optionally be used for one or both of the following purposes: a) b) enabling the PSPDN to provide a calling DTE address to a called DTE; or enabling the DTE to obt
43、ain a different service than that offered to DTEs which do not establish an identity (see 2.3). 2.2.2 DCE identity When a network supports dial-out-by-the-PSPDN access to DTEs, there may be a requirement for identification of the network (i.e. DCE) to the DTE. In the case of dial-in-by-the-DTE acces
44、s, although the identity of the DCE may already be known by the DTE (as the DTE originated the switched access connection), there may also be a DTE requirement for identification of the network. The identification of the DCE to the DTE may be used for different purposes, such as: to enable the DTE t
45、o select the specific security related information (e.g. encrypted key, password, etc.) appropriate to that network for use in exchanges with the DCE; to enable the DTE to select different parameters, procedures or profiles appropriate to that network; to enable a DTE to ascertain by which PSPDN the
46、 switched access has been established, thus enabling proper operation of the optional closed user group facility and of the conveyance of the appropriate calling DTE address provided by the PSPDN, if applicable. a) b) c) For each dial-in-by-the-DTE or dial-out-by-the-PSPDN access, the DCE may establ
47、ish its identity by successfully completing one of the methods for DCE identification described in 2.5. The DCE identity is composed of the networks Data Network Identification Code (DNIC), and optionally, a DTE profile designator (see 3.1.11), except when the identity is provided by the PSN (see 2.
48、5.1.1); in the latter case the identity is a number of the PSN numbering plan. 2.3 Service aspects The switched access service given to a particular DTE is dependent upon: a) thePSPDN; b) c) the usehon-use of DTE identification; and the DTE service available to and chosen by the DTE. Three DTE servi
49、ce types are defined in this Recommendation (see 2.3.2). One of the DTE service types (non-identijied) is independent of the specific DTE identity. One service type (identijed) may or may not be independent of the specific DTE identity. The third type (customized) is related to the specific DTE identity in order to provide customization of some service aspects. 4 Recommendation X.32 (10/96) STD.ITU-T RECMN X.32-ENGL L99b 48b259L b22402 424 m The types of DTE service are further distinguished by whether there is a number assigned by the network to be used to represent the
