1、GENERAL SECRETARIAT INTERNATIONAL TELECOMMUNICATION UNION Subject: Erratum Geneva, 1 O May 2002 Recommendation ITU-T V.44 (2000) / Cor.l(03/2002) TELECOMMUNICATION STANDARDIZATION SECTOR OF ITU ITU-T Recommendation V.44 (2000) / Cor. 1 (03/2002) Data compression procedures - Corrigendum 1 Replace La
2、st paragraph: I- Layout: Finally, . . . arrangement?“ by: I- Appendix II, Sections II. 1 and 11.2: For improved readability, the different “Stages“ (O through 11 in 11.1 and O through 5 in 11.2) should be aligned to the top of a page. This layout arrangement will make it easier to see how the differ
3、ent parameters change as the stages progress.“ INTERNATIONAL TELECOMMUNICATION UNION TU-T TELECOMMUNICATION STANDARDIZATION SECTOR OF ITU v.44 Corrigendum I (032002) SERIES V: DATA COMMUNICATION OVER THE TELEPHONE NETWORK Error control Data compression procedures Corrigendum 1 ITU-T Recommendation V
4、.44 (2000) - Corrigendum 1 ITLT-T V-SERIES RECOMMENDATIONS DATA COMMUNICATION OVER TEE TELEPHONE NETWORK General Interfaces and voiceband modems v.l-v.9 V. 10-V.34 Wideband modems v.35-v.39 Transmission quality and maintenance v.50-v.59 - Simultaneous transmission of data and other signals Interwork
5、ing with other networks Interface layer specifications for data communication Control procedures Modems on digital circuits V.60-V.99 V.100-V.199 V.200-V.249 V.250-V.299 V.300-V.399 Il For further details, please refer to the list of ITU-T Recommendations. ITU-T Recommendation V.44 Data compression
6、procedures Corrigendum 1 Source Corrigendum 1 to ITU-T Recommendation V.44 was prepared by ITU-T Study Group 16 (2001-2004) and approved under the WTSA Resolution 1 procedure on 29 March 2002. ITU-T Rec. V.44 (2000)/Cor.l (03/2002) i FOREWORD The International Telecommunication Union TU) is the Unit
7、ed Nations specialized agency in the field of telecommunications. The ITU Telecommunication Standardization Sector TU-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 telecommu
8、nications 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 tuni, produce Recommendations on these topics. The approval of ITU-T Recommendations is covered by the proce
9、dure laid down in WTSA Resolution 1. In some areas of information technology which fall within IT-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 teleco
10、mmunication administration and a recognized operating agency. INTELLECTUAL PROPERTY RIGHTS 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, va
11、lidity 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, ITU had received notice of intellectual property, protected by patents, which may be requir
12、ed 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 2002 All rights reserved. No part of this publication may be reproduced, by any means whatsoever, wit
13、hout the prior written permission of ITU. ITU-T Rec. V.44 (2000)/Cor.l (03/2002) 11 CONTENTS Page 1) Clauses 7.4, 7.4.1, and 7.4.2: Revision . 2) Clause 8 3) Annex A 4) Appendix II . ITU-T Rec . V.44 (2000)/Cor.l(03/2002) 1 2 2 3 iii ITU-T Recommendation V.44 Data Compression Procedures Corrigendum
14、1 1) Replace the following text: Clauses 7.4,7.4.1, and 7.4.2: Revision ORIGINAL TEXT The negotiation of these values may proceed in one of two ways, as indicated in the V.44 capability parameter value: either through the XID capability determination itself, or through negotiation after link establi
15、shment. XID negotiation is the default. A modem receiving an XID requesting XID parameter negotiation must respond with an XID with V.44 parameters; therefore a modem which has requested Parameter Mode negotiation in the XID sequence, but which has received an XID negotiation request, must further r
16、espond with an XID with V.44 parameters. 7.4.1 Negotiation through XID In the User Data Subfield of the XID, the V.44 capability parameter indicates how the data compression parameters are to be negotiated; if it indicates that XID procedures are to be used, the values proposed by the sending entity
17、 are included later in the same subfield. 7.4.2 Negotiation after link establishment If the V.44 capability parameter indicates that parameter negotiation is to take place after the error- corrected link is established, the control function performs this after link establishment and anytime thereaft
18、er, as it deems necessary. The control function shall insure that data transfer between the data compression peers is not in-progress, and that flow control is in-effect, prior to initiating parameter negotiation. END ORIGmAL with the following: The negotiation of these parameter values may be done
19、either through XID negotiation, or through Parameter Mode negotiation after link establishment. XID negotiation is the default. Support of Parameter Mode negotiation is indicated in the V.44 capability parameter as shown in Table A. 1. A modem supporting Parameter Mode negotiation after link establi
20、shment shall also include V.44 compression parameters in its XID command Fame (unless it intends to use default parameter values), since the responding modem may not support Parameter Mode negotiation. 7.4.1 Negotiation through XID V.44 compression parameters are included in the User Data Subfield o
21、f the XID along with the V.44 capability parameter as shown in Table A. 1. If the responding modem does not support Parameter Mode negotiation, it shall indicate this in the XID frame and shall also include V.44 compression parameters, unless it intends to use default parameter values. The initiatin
22、g modem shall then either use these parameter values and proceed with SABME, or disconnect. If V.44 compression parameters are not included in an XID command or response Fame, V.44 default parameter values shall be assumed. ITU-T Rec. V.44 (2000)/Cor.l(03/2002) 1 7.4.2 Negotiation after link establi
23、shment If both modems indicate in their XIDs that Parameter Mode negotiation after link establishment is supported, the control function may perform Parameter Mode negotiation at any time after link establishment, as it deems necessary. The parameter values from the XID negotiation, or default value
24、s (if compression parameters were not included in the XID), shall be used until the first Parameter Mode negotiation. The control function shall ensure that data transfer between the data compression peers is not in-progress, and that flow control is in-effect, prior to initiating parameter negotiat
25、ion. END REPLACEMENT 2) Clause 8 a) Table I O/l? 44, row 3, column 5: Revision Replace: “O 1 parameter negotiation via protocol (i.e. XID) parameter negotiation after link establishment“ with: “O 1 b) Replace: “25 12“ Parameter Mode negotiation after link establishment not supported Parameter Mode n
26、egotiation after link establishment supported“ Table 1 Om44 (concluded), column 6, in rows 2 and 3: Editorial correction with: “2 5 12“ 3) Annex A Table A.I/V.44, row 8, column 3: Revision Replace: “O 1 with: “O 1 Parameter negotiation using XID exchange and parameters below. Parameter negotiation a
27、fter link establishment.“ Parameter Mode negotiation after link establishment not supported. Parameter Mode negotiation after link establishment supported.“ 2 ITU-T Rec. V.44 (20OO)/Cor.l (03/2002) 4) Appendix II a) Replace: Clause II. 1, Stage 1 O, Encoder History, entry under 17 “FF$ with: “FFH“ b
28、) Replace: Clause II. 1, Stage 1 O, Decoder History, entry under 1 7 “FFH“ with: Clauses II. 1 and II. 2 For improved readability, the different “Stages“ (O through 11 in 11.1 and O through 5 in 11.2) should be aligned to the top of a page. This layout arrangement will make it easier to see how the
29、different parameters change as the stages progress. ITU-T Rec. V.44 (2000)/Cor.l(03/2002) 3 SERIES OF ITU-T RECOMMENDATIONS Series A Series B Series C Series D Series E Series F Series G Series H Series I Series J Series K Series L Series M Series N Series O Series P Series Q Series R Series S Serie
30、s T Series U Series V Series X Series Y Series Z Organization of the work of ITU-T Means of expression: definitions, symbols, classification General telecommunication statistics General tariff principles Overall network operation, telephone service, service operation and human factors Non-telephone
31、telecommunication services Transmission systems and media, digital systems and networks Audiovisual and multimedia systems Integrated services digital network Cable networks and transmission of television, sound programme and other multimedia signals Protection against interference Construction, ins
32、tallation and protection of cables and other elements of outside plant TMN and network maintenance: international transmission systems, telephone circuits, telegraphy, facsimile and leased circuits Maintenance: international sound programme and television transmission circuits Specifications of meas
33、uring equipment Telephone transmission quality, telephone installations, local line networks Switching and signalling Telegraph transmission Telegraph services terminal equipment Terminals for telematic services Telegraph switching Data communication over the telephone network Data networks and open system communications Global information infrastructure and Internet protocol aspects Languages and general software aspects for telecommunication systems Printed in Switzerland Geneva, 2002
