1、INTERNATIONAL TELECOMMUNICATION UNION ITU=T TELECOMMUNICATION STANDARDIZATION SECTOR OF ITU X.28 (1 2/97) SERIES X: DATA NETWORKS AND OPEN SYSTEM CO M M U N I CATI O N S Public data networks - Interfaces DTEIDCE interface for a start-stop mode data terminal equipment accessing the Packet Assembly/Di
2、sassembly facility (PAD) in a public data network situated in the same country ITU-T Recommendation X.28 (Previously CCITT Recommendation) ITU-T X-SERIES RECOMMENDATIONS DATA NETWORKS AND OPEN SYSTEM COMMUNICATIONS ir Services and facilities X.l-X.19 interfaces X.20-X.49 Transmission, signalling and
3、 switching Network aspects Maintenance Administrative arrangements OPEN SYSTEM INTERCONNECTION Model and notation Service definitions Connection-mode protocol specifications Connectionless-mode protocol specifications PICS proformas Protocol Identification Security Protocols Layer Managed Objects X.
4、50-X.89 X.90-X.149 X. 150-X. 179 X.180-X. 199 X.200-X.209 X.210-X.219 X.220-X.229 X.230-X.239 X.240-X.259 X.260-X.269 X.270-X.279 X.280-X.289 Conformance testing X.290-X.299 INTERWORKTNG BETWEEN NETWORKS General X.300-X. 349 Satellite data transmission systems X.350-X.399 MESSAGE HANDLING SYSTEMS X.
5、400-X.499 DIRECTORY X.500-X.599 OS1 NETWORKING AND SYSTEM ASPECTS Networking X.600-X.629 Efficiency X.630-X.639 Quality of service X .640-X.649 Naming, Addressing and Registration X.650-X.679 Abstract Syntax Notation One (ASN.l) X.680-X.699 OS1 MANAGEMENT Systems Management framework and architectur
6、e X.700-X.709 Management Communication Service and Protocol X.710-X.719 Structure of Management Information X.720-X.729 Management functions and ODMA functions X.730-X.799 SECURITY X.800-X. 849 OS1 APPLICATIONS Commitment, Concurrency and Recovery X.850-X.859 Transaction processing X.860-X.879 Remot
7、e operations X.880-X.899 OPEN DISTRIBUTED PROCESSING X.900-X.999 For further details, please refer to TU-T List of Recommendations. ITU-T RECOMMENDATION X.28 DTE/DCE INTERFACE FOR A START-STOP MODE DATA TERMINAL EQUIPMENT ACCESSING THE PACKET ASSEMBLYDISASSEMBLY FACILITY (PAD) IN A PUBLIC DATA NETWO
8、RK SITUATED IN THE SAME COUNTRY Summary This Recommendation provides the DTEDCE interface to facilitate access to the public data network from the public telephone network, circuit-switched public data networks and leased circuits. Source ITU-T Recommendation X.28 was revised by ITU-T Study Group 7
9、(1997-2000) and was approved under the WTSC Resolution No. 1 procedure on the 12th of December 1997. Recommendation X.28 (12197) i STD-ITU-T RECMN X-28-ENGL 1777 E LIBb2571 Ohlib2711 LIb7 E FOREWORD ITU (International Telecommunication Union) is the United Nations Specialized Agency in the field of
10、telecommuni- cations. The ITU Telecommunication Standardization Sector (ITU-T) is a permanent organ of the ITU. The ITU-T is responsible for studying technical, operating and tariff questions and issuing Recommendations on them with a view to standardizing telecommunications on a worldwide basis. Th
11、e 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 is covered by the procedure
12、 laid down in WTSC Resolution No. 1. In some areas of information technology which fall within ITU-Ts purview, the necessary standards are prepared on a collaborative basis with IS0 and IEC. NOTE In this Recommendation, the expression “Administration“ is used for conciseness to indicate both a telec
13、ommunication administration and a recognized operating agency. INTELLECTUAL PROPERTY RIGHTS The ITU draws attention to the possibility that the practice or implementation of this Recommendation may involve the use of a claimed Intellectual Property Right. The ITU takes no position concerning the evi
14、dence, validity or applicability of claimed Intellectual Property Rights, whether asserted by ITU members or others outside of the Recommendation development process. As of the date of approval of this Recommendation, the ITU had not received notice of intellectual property, protected by patents, wh
15、ich may be required to implement this Recommendation. However, implementors are cautioned that this may not represent the latest information and are therefore strongly urged to consult the TSB patent database. O ITU 1998 All rights reserved. No part of this publication may be reproduced or utilized
16、in any form or by any means, electronic or mechanical, including photocopying and microfilm, withaut permission in writing from the ITU. 11 Recommendation X.28 (12/97) CONTENTS 1 Procedures for the establishment of a national access information path between a start-stop mode DTE and a PAD 1.1 Access
17、 via a public switched telephone network or leased lines with V-Series jnterfaces 1.2 Access via a public switched data network or via leased lines with X-Senes interfaces . Procedures for character interchange and service initialization between a start-stop mode DTE and a PAD 2.1 Format of characte
18、rs used in the exchange of control information between start-stop mode DTE and a PAD . 2.2 Procedures for initialization Procedures for the exchange of control information between a start-stop mode DTE and a PAD 3.1 General 3.2 Procedures for virtual call control 3.3 Procedures for setting or changi
19、ng the values of PAD parameters 3.4 Procedures for reading the values of one or several parameters by the start-stop mode DTE 3.5 Formats of PAD command signals and PAD service signals . 3.6 3.7 Procedure for request of status of the virtual call . Procedures for the exchange of user data between a
20、start-stop mode DTE and a PAD . 2 3 Editing functions in the PAD 4 4.1 4.2 4.3 4.4 4.5 4.6 4.7 4.8 4.9 4.10 4.11 4.12 4.13 4.14 4.15 4.16 4.17 4.18 4.19 4.20 Data transfer state . Data from the start-stop mode DTE received by the PAD . Delivery of user data to the start-stop mode DTE Data forwarding
21、 conditions Procedure for the PAD to indicate to the start-stop mode DTE, by means of a PAD service signal, a temporary inability to accept additional information . Procedures for transmission of X-ON and X-OFF by the PAD . Procedures for reset Procedure for indication of break . Escape from the dat
22、a transfer state . Echo Selection of the procedure on receipt of the break signal from the start-stop mode DTE Selection of padding characters to be inserted after the character 0/13 (CR) . Selection of line folding Procedure for the start-stop mode DTE to indicate to the PAD a temporary inability t
23、o accept additional information Selection of linefeed insertion after carriage return Selection of padding characters to be inserted after the character 0/10 (LF) . Editing of user data . Page wait . Interleaving of echo and output Display intemipt . 5 Formats of additional PAD command signals and P
24、AD service signals available in the extended dialogue mode . 5.1 5.2 5.3 5.4 5.5 Format of the break PAD command signal . Format of the NUI ON and NUI OFF PAD command signals . Format of the language PAD command signal . Format of the help PAD command signal . Standard format of the help PAD service
25、 signal . Recommendation X.28 (12/97) Page 2 2 3 4 4 5 11 11 12 16 18 18 31 33 33 33 34 34 34 34 35 35 35 36 37 37 38 38 38 39 39 39 39 40 41 41 42 42 43 43 43 iii 6 Multi-Aspect PAD (MAP) operation in accordance with Recommendation X.8 6.1 Procedures required to support MAP . 6.2 Formats of MAP com
26、mand signals . 6.3 Format of MAP service signals . 6.4 Error conditions 6.5 Format of additional MAP command signals and MAP service signals available in the extended dialogue mode . Annex A -PAD command signals and PAD service signals : . Annex B - PAD Time-outs . Annex C - PAD service signals for
27、extended dialogue mode . Possible PAD service signals text in Spanish for extended dialogue mode Possible PAD service signals text in French for extended dialogue mode . C.l C.2 Page 44 44 45 46 47 47 48 50 52 52 54 iv Recommendation X.28 (12/97) STD-ITU-T RECMN X-ZA-ENGL 1777 9 48b2591 Ob4b273 17b
28、Recommendation X.28 DTE/DCE INTERFACE FOR A START-STOP MODE DATA TERMINAL EQUIPMENT ACCESSING THE PACKET ASSEMBLYLlISASSEMBLY FACILITY (PAD) IN A PUBLIC DATA NETWORK SITUATED IN THE SAME COUNTRY (Provisional, Geneva, 1977; amended, Geneva, 1980, Mlaga-Torremolinos, 1984, Melbourne, 1988, Helsinki, 1
29、993; revised in 1997) Preface The establishment in various countries of public data networks providing packet-switched data transmission services creates a need to produce standards to facilitate access from the public telephone network, circuit-switched public data networks and leased circuits. The
30、 ITU-T, considering a) network, and Recommendation X.96 defines call progress signals; b) interworking between PADS; that Recommendations X.l and X.2 define user classes of service and user facilities provided by a public data that Recommendation X.29 defines procedures for a packet mode DTE to cont
31、rol the PAD and for c) that Recommendation X.3 defines the Packet Assembly/Disassembly (PAD) facility in a public data network; d) dation X.92; that the logical control links for packet-switched data transmission services are defined in Recommen- e start-stop mode DE and a PAD; the need for defining
32、 an international Recommendation for the exchange of control information between a f) information in the form of characters according to Recommendation T.50 or the break signal; g) that DTEs operating in the start-stop mode will send and receive network call control information and user that the nec
33、essary elements for an interface Recommendation should be defined independently as: 1) procedures for the establishment of a national access information path between a start-stop mode DE and a PAD, procedures for character interchange and service initialization between a start-stop mode DTE and a PA
34、D, procedures for the exchange of control information between a start-stop mode DTE and a PAD, procedures for the exchange of user data between a start-stop mode DTE and a PAD; 2) 3) 4) h) that the Recommendation X.8 defines the Multi-Aspect PAD (MAP) framework and service definition, unanimously de
35、clares that start-stop mode DTE accessing the PAD should operate in accordance with this Recommendation. Recommendation X.28 (12/97) 1 1 Procedures for the establishment of a national access information path between a start- stop mode DTE and a PAD 1.1 Access via a public switched telephone network
36、or leased lines with V-Series interfaces 1.1.1 DTE/DCE interface The access information path will be provided by the use of modems standardized for use in the public switched telephone network or leased line operating: a) b) at rates up to 300 bit/s in accordance with Recommendation V.21; or at the
37、rate of 1200 bids in accordance with Recommendation V.22 alternative B, mode b) or V.22 bis mode 4, and at the rates of 2400 bit/s in accordance with Recommendation V.22 bis mode 2, on the public switched telephone network or 2-wire leased circuit, or at the rates up to 1200 bit/s in accordance with
38、 Recommendation V.23 without backward channel on 4-wire leased circuits; or at the rate of 75/1200 bit/s (for the signal received by the DTE and 75 bids for the signal sent by the DTE on the backward channel) in accordance with Recommendation V.23. c) The particular interchange circuits provided, an
39、d their operation, shall be in accordance with the relevant modem Recommendations, and clamping of circuit 104 shall be implemented in accordance with 4.3N.24. At rates of up to 300 bivs or at 1200 bids or 2400 bids: d) on the telephone network, the modem shall be set up for channel operation in acc
40、ordance with Recommen- dation V.21, or with Recommendation V.22, or with Recommendation V.22 bis; or on leased lines (2-wire), the channel operation will be determined by the same rule, the modem at the DTE side being considered as the one making the telephone call. e) At the rate of 75/1200 bit/s:
41、the modem shall be set up for channel operation in accordance with Recommendation V.23. NOTE 1 -The interface requirements for other data signalling rates are for further study. NOTE 2 - In some networks, references to modem characteristics do not apply (e.g. for leased lines). 1.1.2 Electrical char
42、acteristics The electrical characteristics of the DTEDCE interface shall be in accordance with this Recommendation. 1.1.3 Procedure for setting up and disconnecting the access information path 1.1.3.1 Setting up the access information path by the DTE The access information path shall be established
43、in accordance with Recommendation V.25 for a manual data station calling an automatic answering station. The mechanism for echo suppressor disablement may not be implemented in some national networks where the access information path does not include echo suppressors. Subsequent to the completion of
44、 the above, both the DTE and DCE shall transmit binary 1 on circuits 103 and 104. 1.1.3.2 Disconnecting the access information path by the DTE The access information path shall be disconnected by: a) reversion of the data circuit to the voice mode, or b) the DTE turning circuit 108/1 or 108/2 OFF fo
45、r a period greater than Z. The value of Z is for further study. 1.1.3.3 Setting up the access information path by the PAD The procedure for the PAD to establish an access information path shall be in accordance with Recommendation V.25 as far as it is perceived by the DTE. 2 Recommendation X.28 (12/
46、97) STD-ITU-T RECMN X-28-ENGL 1997 = 48b257L Ub4b275 T47 = 1.1.3.4 Disconnecting the access information path by the PAD Disconnection by the PAD will be indicated by the DCE turning circuits 106 and 109 OFF, while circuit 108 is ON. NOTE - Access information path clear indication to the DTE is not s
47、ignalled by circuit 107 OFF. Not all DTEs allow circuit 107 to be turned OFF if circuit 108 has not been turned OFF previously. 1.2 Access via a public switched data network or via leased lines with X-Series interfaces 1.2.1 DTE/DCE interface designed for start-stop transmission services on public d
48、ata networks (Recommendation X.20) 1.2.1.1 Physical characteristics The physical characteristics of the DTE/DCE interface are defined in uX.20. 1.2.1.2 Procedures for setting up and disconnecting the access information path (call control) The procedures and formats for call control of the public cir
49、cuit-switched data network are described in 3Bc.20 and 4Bc.20. The procedures for setting up a virtual call in a packet-switched network are those given in clauses 2, 3 and 4. The use of Recommendation X.20 procedures to establish a virtual call via a PAD is for further study. 1.2.2 DTE/DCE interface designed for operation on telephone type networks (Recommendation X.20 bis) In the case of DTEs with interfaces designed for operation on telephone type networks (V-Series interfaces), the access information path will be established by the use of DCEs standardized for start-stop transmission
