1、 INTERNATIONAL TELECOMMUNICATION UNION ITU-T V.42TELECOMMUNICATION STANDARDIZATION SECTOR OF ITU Corrigendum 1(07/2003) SERIES V: DATA COMMUNICATION OVER THE TELEPHONE NETWORK Error control Error-correcting procedures for DCEs using asynchronous-to-synchronous conversion Corrigendum 1 ITU-T Recommen
2、dation V.42 (2002) Corrigendum 1 ITU-T V-SERIES RECOMMENDATIONS DATA COMMUNICATION OVER THE TELEPHONE NETWORK General V.1V.9 Interfaces and voiceband modems V.10V.34 Wideband modems V.35V.39 Error control V.40V.49 Transmission quality and maintenance V.50V.59 Simultaneous transmission of data and ot
3、her signals V.60V.99 Interworking with other networks V.100V.199 Interface layer specifications for data communication V.200V.249 Control procedures V.250V.299 Modems on digital circuits V.300V.399 For further details, please refer to the list of ITU-T Recommendations. ITU-T Rec. V.42 (2002)/Cor.1 (
4、07/2003) i ITU-T Recommendation V.42 Error-correcting procedures for DCEs using asynchronous-to-synchronous conversion Corrigendum 1 Summary Some errors have been found in ITU-T Rec. V.42. They are mainly of an editorial nature, although an extra note clarifies the information in Table 11a/V.42 whic
5、h could have led to confusion. Source Corrigendum 1 to ITU-T Recommendation V.42 was approved by ITU-T Study Group 16 (2001-2004) under the ITU-T Recommendation A.8 procedure on 14 July 2003. ii ITU-T Rec. V.42 (2002)/Cor.1 (07/2003) FOREWORD The International Telecommunication Union (ITU) is the Un
6、ited Nations specialized agency in the field of telecommunications. The ITU Telecommunication Standardization Sector (ITU-T) is a permanent organ of ITU. ITU-T is responsible for studying technical, operating and tariff questions and issuing Recommendations on them with a view to standardizing telec
7、ommunications on a worldwide basis. The World Telecommunication Standardization Assembly (WTSA), which meets every four years, establishes the topics for study by the ITU-T study groups which, in turn, produce Recommendations on these topics. The approval of ITU-T Recommendations is covered by the p
8、rocedure laid down in WTSA Resolution 1. In some areas of information technology which fall within ITU-Ts purview, the necessary standards are prepared on a collaborative basis with ISO and IEC. NOTE In this Recommendation, the expression “Administration“ is used for conciseness to indicate both a t
9、elecommunication administration and a recognized operating agency. Compliance with this Recommendation is voluntary. However, the Recommendation may contain certain mandatory provisions (to ensure e.g. interoperability or applicability) and compliance with the Recommendation is achieved when all of
10、these mandatory provisions are met. The words “shall“ or some other obligatory language such as “must“ and the negative equivalents are used to express requirements. The use of such words does not suggest that compliance with the Recommendation is required of any party. INTELLECTUAL PROPERTY RIGHTS
11、ITU draws attention to the possibility that the practice or implementation of this Recommendation may involve the use of a claimed Intellectual Property Right. ITU takes no position concerning the evidence, validity or applicability of claimed Intellectual Property Rights, whether asserted by ITU me
12、mbers or others outside of the Recommendation development process. As of the date of approval of this Recommendation, ITU had not received notice of intellectual property, protected by patents, which may be required to implement this Recommendation. However, implementors are cautioned that this may
13、not represent the latest information and are therefore strongly urged to consult the TSB patent database. ITU 2004 All rights reserved. No part of this publication may be reproduced, by any means whatsoever, without the prior written permission of ITU. ITU-T Rec. V.42 (2002)/Cor.1 (07/2003) iii CONT
14、ENTS Page 1) Clause 7.2.1.1 Determination of role 1 2) Table 5/V.42 Receiving DCE actions on receipt of break from the remote DCE. 1 3) Figure 4/V.42 Frame structure. 2 4) Table 7/V.42 Control field formats . 2 5) Table 11a/V.42 Parameter/procedures associated with the “parameter negotiation“ subfie
15、ld. 3 6) Clause VI.2 Skipping of originator/answerer detection patterns 3 ITU-T Rec. V.42 (2002)/Cor.1 (07/2003) 1 ITU-T Recommendation V.42 Error-correcting procedures for DCEs using asynchronous-to-synchronous conversion Corrigendum 1 1) Clause 7.2.1.1 Determination of role Modify the last sentenc
16、e as follows: “. determined by parameterization (strapping options or other user indication of desired role to the control function). “ 2) Table 5/V.42 Receiving DCE actions on receipt of break from the remote DCE Modify Table 5 as follows: Table 5/V.42 Receiving DCE actions on receipt of break from
17、 the remote DCE With respect to data Break handling option Going to remote DCE Going to local DTE Destructive/Expedited (Notes 1 and 2) Discard data not yet transmitted Discard data not yet delivered Deliver break signal Non-Ddestructive/Expedited No effect Deliver break signal immediately Resume no
18、rmal data delivery Non-destructive/Non-expedited No effect Deliver break signal in sequence with respect to data NOTE 1 All state variables pertaining to control function and error control function operation, except those pertaining to break transfer, are reset to their initial values. NOTE 2 For al
19、l break options, acknowledgement should be returned as soon as possible. 2 ITU-T Rec. V.42 (2002)/Cor.1 (07/2003) 3) Figure 4/V.42 Frame structure Modify Figure 4 as follows: 8 7 6 5 4 3 2 1 Octet 8 7 6 5 4 3 2 1 Octet Opening flag 1 Opening flag 1 0 1 1 1 1 1 1 0 0 1 1 1 1 1 1 0 Address (Note 1) 2
20、Address (Note 1) 2 Control (Note 2) 3 Control (Note 2) 3 Information (Note 3) Information (Note 3) FCS N-2 N-1 FCS N-4 N-3 N-2 N-1 Closing flag N Closing flag N 0 1 1 1 1 1 1 0 0 1 1 1 1 1 1 0 a) 16-bit FCS b) 32-bit FCS NOTE 1 The maximum size of this field is limited to two octets. NOTE 2 The cont
21、rol field is two octets for frame types with sequence numbers and one octet for frame types without sequence numbers, see 8.2.2. NOTE 3 Not all frame types have an information field. Figure 4/V.42 Frame structure 4) Table 7/V.42 Control field formats Modify Table 7 as follows: Table 7/V.42 Control f
22、ield formats Control field bits (modulo 128) Format 8 7 6 5 4 3 2 1 Octet N(S) 0 3 I format N(R) P 4 X X X X S S 0 1 3 S format N(R) P/F 4 U format M M M P/F M M 1 1 3 N(S) Transmitter send sequence number N(R) Transmitter receive sequence number S Supervisory function bits M Modifier function bits
23、P/F Poll bit when issued as a command Final bit when issued as a response X Reserved and set to 0 ITU-T Rec. V.42 (2002)/Cor.1 (07/2003) 3 5) Table 11a/V.42 Parameter/procedures associated with the “parameter negotiation“ subfield Replace Note 1 in Table 11a as follows: NOTE 1 The length of this ite
24、m is 4 octets (i.e. PL = 4). The bits in these octets constitute a 32-bit mask, each for a particular HDLC optional function. Bit 1 of this mask is the low-order bit of octet 1 and is transmitted first; bit 9 is the low-order bit of octet 2, etc. The bits corresponding to the optional procedures use
25、d within this Recommendation are as follows (in decimal): 3A Selective retransmission procedure (SREJ frame) single I frame request; 14 Loop-back test procedure (TEST frame); 17 Extended FCS procedure (32-bit FCS); 24 Selective retransmission procedure (SREJ frame) multiple I frame request with span
26、 list capability. A bit position set to 1 indicates request/agreement to use the procedure. A bit position set to 0 indicates no request/no agreement to use the procedure. For conformance with the encoding rules in ISO/IEC 8885, the transmitter of an XID command frame shall set bit positions 2, 4, 8
27、, 9, 12 and 16 to 1. The transmitter of an XID response frame shall also set these bit positions to 1, except bit position 16 shall be set to 0 if bit position 17 is set to 1. A receiver of these frames should ignore these bit positions. ISO/IEC 8885:1993 is a normative reference for V.42 and uses a
28、 PL value of three; implementors should note that V.42 devices may use either PL = 3 or PL = 4 and still be compliant with this Recommendation. 6) Clause VI.2 Skipping of originator/answerer detection patterns Correct the Recommendation reference in the note as follows: NOTE Clause 9.3.1/V.9.2V.92 r
29、equires that both the originating and answering modems skip the V.42 detection phase if they both indicate that V.42 is supported in the V.8 protocol octet or in the V.92 short phase 1 signals. Printed in Switzerland Geneva, 2004 SERIES OF ITU-T RECOMMENDATIONS Series A Organization of the work of I
30、TU-T Series B Means of expression: definitions, symbols, classification Series C General telecommunication statistics Series D General tariff principles Series E Overall network operation, telephone service, service operation and human factors Series F Non-telephone telecommunication services Series
31、 G Transmission systems and media, digital systems and networks Series H Audiovisual and multimedia systems Series I Integrated services digital network Series J Cable networks and transmission of television, sound programme and other multimedia signals Series K Protection against interference Serie
32、s L Construction, installation and protection of cables and other elements of outside plant Series M TMN and network maintenance: international transmission systems, telephone circuits, telegraphy, facsimile and leased circuits Series N Maintenance: international sound programme and television trans
33、mission circuits Series O Specifications of measuring equipment Series P Telephone transmission quality, telephone installations, local line networks Series Q Switching and signalling Series R Telegraph transmission Series S Telegraph services terminal equipment Series T Terminals for telematic services Series U Telegraph switching Series V Data communication over the telephone network Series X Data networks and open system communications Series Y Global information infrastructure and Internet protocol aspects Series Z Languages and general software aspects for telecommunication systems
