1、 I n t e r n a t i o n a l T e l e c o m m u n i c a t i o n U n i o n ITU-T G.994.1 TELECOMMUNICATION STANDARDIZATION SECTOR OF ITU (04/2017) SERIES G: TRANSMISSION SYSTEMS AND MEDIA, DIGITAL SYSTEMS AND NETWORKS Digital sections and digital line system Metallic access networks Handshake procedures
2、 for digital subscriber line transceivers Recommendation ITU-T G.994.1 ITU-T G-SERIES RECOMMENDATIONS TRANSMISSION SYSTEMS AND MEDIA, DIGITAL SYSTEMS AND NETWORKS INTERNATIONAL TELEPHONE CONNECTIONS AND CIRCUITS G.100G.199 GENERAL CHARACTERISTICS COMMON TO ALL ANALOGUE CARRIER-TRANSMISSION SYSTEMS G
3、.200G.299 INDIVIDUAL CHARACTERISTICS OF INTERNATIONAL CARRIER TELEPHONE SYSTEMS ON METALLIC LINES G.300G.399 GENERAL CHARACTERISTICS OF INTERNATIONAL CARRIER TELEPHONE SYSTEMS ON RADIO-RELAY OR SATELLITE LINKS AND INTERCONNECTION WITH METALLIC LINES G.400G.449 COORDINATION OF RADIOTELEPHONY AND LINE
4、 TELEPHONY G.450G.499 TRANSMISSION MEDIA AND OPTICAL SYSTEMS CHARACTERISTICS G.600G.699 DIGITAL TERMINAL EQUIPMENTS G.700G.799 DIGITAL NETWORKS G.800G.899 DIGITAL SECTIONS AND DIGITAL LINE SYSTEM G.900G.999 General G.900G.909 Parameters for optical fibre cable systems G.910G.919 Digital sections at
5、hierarchical bit rates based on a bit rate of 2048 kbit/s G.920G.929 Digital line transmission systems on cable at non-hierarchical bit rates G.930G.939 Digital line systems provided by FDM transmission bearers G.940G.949 Digital line systems G.950G.959 Digital section and digital transmission syste
6、ms for customer access to ISDN G.960G.969 Optical fibre submarine cable systems G.970G.979 Optical line systems for local and access networks G.980G.989 Metallic access networks G.990G.999 MULTIMEDIA QUALITY OF SERVICE AND PERFORMANCE GENERIC AND USER-RELATED ASPECTS G.1000G.1999 TRANSMISSION MEDIA
7、CHARACTERISTICS G.6000G.6999 DATA OVER TRANSPORT GENERIC ASPECTS G.7000G.7999 PACKET OVER TRANSPORT ASPECTS G.8000G.8999 ACCESS NETWORKS G.9000G.9999 For further details, please refer to the list of ITU-T Recommendations. Rec. ITU-T G.994.1 (04/2017) i Recommendation ITU-T G.994.1 Handshake procedur
8、es for digital subscriber line transceivers Summary Recommendation ITU-T G.994.1 provides a flexible mechanism for digital subscriber line (DSL) transceivers to exchange capabilities and to select a common mode of operation. It includes parameters relating to service and application requirements as
9、well as parameters pertinent to various DSL transceivers. This Recommendation is currently an integral part of the start-up procedure for Recommendations ITU-T G.991.2, ITU-T G.992.1, ITU-T G.992.2, ITU-T G.992.3, ITU-T G.992.4, ITU-T G.992.5, ITU-T G.993.1 and ITU-T G.993.2. It is anticipated that
10、future DSL Recommendations will also be able to make use of this Recommendation. Provisions are also included for exchanging non-standard information. This revision integrates all approved amendments and corrigendum into the latest revision of Recommendation ITU-T G.994.1 (version 3). It also: fixes
11、 the allocation of the codepoint “Support of downstream virtual noise in diagnostic mode“ fixes the allocation of the codepoint “Full ITU-T G.993.5-friendly ITU-T G.993.2 operation“ removes the codepoints for O-P-VECTOR-1-1 duration. The 2017 edition of this Recommendation integrates ITU-T G.994.1 (
12、2012) and all its amendments and corrigendum. This edition does not add any new technical material. History Edition Recommendation Approval Study Group Unique ID* 1.0 ITU-T G.994.1 1999-07-02 15 11.1002/1000/4720 1.1 ITU-T G.994.1 (1999) Cor. 1 2000-04-04 15 11.1002/1000/5139 2.0 ITU-T G.994.1 2001-
13、02-09 15 11.1002/1000/5364 3.0 ITU-T G.994.1 2002-07-29 15 11.1002/1000/6119 4.0 ITU-T G.994.1 2003-05-22 15 11.1002/1000/6281 4.1 ITU-T G.994.1 (2003) Amd. 1 2004-02-22 15 11.1002/1000/7080 4.2 ITU-T G.994.1 (2003) Amd. 2 2004-06-13 15 11.1002/1000/7351 4.3 ITU-T G.994.1 (2003) Amd. 3 2005-01-13 15
14、 11.1002/1000/7495 4.4 ITU-T G.994.1 (2003) Amd. 4 2006-01-13 15 11.1002/1000/8549 5.0 ITU-T G.994.1 2007-02-13 15 11.1002/1000/8993 5.1 ITU-T G.994.1 (2007) Amd. 1 2007-11-22 15 11.1002/1000/9167 5.2 ITU-T G.994.1 (2007) Amd. 2 2008-04-13 15 11.1002/1000/9388 5.3 ITU-T G.994.1 (2007) Amd. 3 2009-03
15、-22 15 11.1002/1000/9675 5.4 ITU-T G.994.1 (2007) Amd. 4 2009-06-29 15 11.1002/1000/9891 _ * To access the Recommendation, type the URL http:/handle.itu.int/ in the address field of your web browser, followed by the Recommendations unique ID. For example, http:/handle.itu.int/11.1002/1000/11830-en.
16、ii Rec. ITU-T G.994.1 (04/2017) 5.5 ITU-T G.994.1 (2007) Amd. 5 2010-04-22 15 11.1002/1000/10415 5.6 ITU-T G.994.1 (2007) Amd. 6 2010-11-29 15 11.1002/1000/11018 5.7 ITU-T G.994.1 (2007) Amd. 7 2011-04-13 15 11.1002/1000/11129 5.8 ITU-T G.994.1 (2007) Cor. 1 2011-10-29 15 11.1002/1000/11417 5.9 ITU-
17、T G.994.1 (2007) Amd. 8 2011-12-16 15 11.1002/1000/11416 6.0 ITU-T G.994.1 2012-06-13 15 11.1002/1000/11644 6.1 ITU-T G.994.1 (2012) Amd. 1 2012-10-29 15 11.1002/1000/11797 6.2 ITU-T G.994.1 (2012) Amd. 2 2013-08-29 15 11.1002/1000/11994 6.3 ITU-T G.994.1 (2012) Amd. 3 2014-01-13 15 11.1002/1000/120
18、93 6.4 ITU-T G.994.1 (2012) Amd. 4 2014-12-05 15 11.1002/1000/12094 6.5 ITU-T G.994.1 (2012) Amd. 5 2015-02-13 15 11.1002/1000/12373 6.6 ITU-T G.994.1 (2012) Amd. 6 2015-08-29 15 11.1002/1000/12564 6.7 ITU-T G.994.1 (2012) Amd. 7 2016-06-13 15 11.1002/1000/12797 6.8 ITU-T G.994.1 (2012) Cor. 1 2016-
19、10-29 15 11.1002/1000/13063 6.9 ITU-T G.994.1 (2012) Amd. 8 2017-04-06 15 11.1002/1000/13062 7.0 ITU-T G.994.1 2017-04-06 15 11.1002/1000/13347 Rec. ITU-T G.994.1 (04/2017) iii FOREWORD The International Telecommunication Union (ITU) is the United Nations specialized agency in the field of telecommu
20、nications, information and communication technologies (ICTs). 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 telecommuni
21、cations 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 procedu
22、re 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 telecom
23、munication 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 thes
24、e 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 RIGHTSITU d
25、raws 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 members
26、 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 required to implement this Recommendation. However, implementers are cautioned that this may not repre
27、sent the latest information and are therefore strongly urged to consult the TSB patent database at http:/www.itu.int/ITU-T/ipr/. ITU 2017 All rights reserved. No part of this publication may be reproduced, by any means whatsoever, without the prior written permission of ITU. iv Rec. ITU-T G.994.1 (0
28、4/2017) Table of Contents Page 1 Scope . 1 2 References . 1 3 Definitions 2 4 Abbreviations and acronyms 3 5 System reference diagram . 3 6 Signals and modulation . 4 6.1 Description of signals . 4 6.2 Modulation . 8 6.3 Transmit filter characteristics . 9 7 Description of messages . 9 7.1 CL Capabi
29、lities list 9 7.2 CLR Capabilities list + request 10 7.3 MR Mode request 10 7.4 MS Mode select . 10 7.5 MP Mode proposal 10 7.6 ACK(1) Acknowledgement, type 1 . 10 7.7 ACK(2) Acknowledgement, type 2 . 10 7.8 NAK-EF Negative Acknowledgement, errored frame 10 7.9 NAK-NR Negative Acknowledgement, not r
30、eady 10 7.10 NAK-NS Negative Acknowledgement, not supported 10 7.11 NAK-CD Negative Acknowledgement, cleardown 11 7.12 REQ-MS Request MS message . 11 7.13 REQ-MR Request MR message 11 7.14 REQ-CLR Request CLR message . 11 7.15 REQ-RTX Retransmission message 11 8 Structure of messages . 11 8.1 Format
31、 convention 11 8.2 Frame structure . 12 8.3 Frame check sequence field 12 8.4 Octet transparency 13 8.5 Inter-frame time fill 13 9 Message coding format . 13 9.1 General . 13 9.2 Coding format for parameters in the I and S fields 14 9.3 Identification field (I) . 16 9.4 Standard information field (S
32、) 47 9.5 Non-standard information field (NS) . 866 Rec. ITU-T G.994.1 (04/2017) v Page 9.6 Overall message composition . 867 10 ITU-T G.994.1 transactions 867 10.1 Basic transactions . 867 10.2 Extended transactions . 869 10.3 Message segmentation 870 10.4 State transition diagrams 870 10.5 Retransm
33、ission transactions . 877 11 Start-up/cleardown procedures . 878 11.1 Duplex start-up procedures . 878 11.2 Half-duplex start-up procedures . 879 11.3 Cleardown procedure 880 12 Error recovery procedures 882 13 Management information base (MIB) elements . 883 13.1 Configuration parameters . 883 Anne
34、x A Support for legacy non-ITU-T G.994.1 devices 886 Annex B Operation over multiple wire pairs 887 Annex C An operating mode for use in the same cable as TCM-ISDN . 888 C.1 Scope (supplements clause 1) . 888 C.2 Signals and modulation (pertains to clause 6) 888 C.3 Start-up/cleardown procedures (pe
35、rtains to clause 11) 891 Appendix I ITU-T G.994.1 sample sessions . 894 Appendix II Provider code contact information . 895 Appendix III Support for legacy DMT-based devices 896 Appendix IV Procedure for the assignment of additional ITU-T G.994.1 parameters . 897 IV.1 Introduction 897 IV.2 Procedure
36、 897 Appendix V Rules for code point table numbering 898 Bibliography. 899 Rec. ITU-T G.994.1 (04/2017) 1 Recommendation ITU-T G.994.1 Handshake procedures for digital subscriber line transceivers 1 Scope This Recommendation defines signals, messages and procedures for exchanging these between digit
37、al subscriber line (DSL) equipment, when the modes of operation of the equipment need to be automatically established and selected, but before signals are exchanged which are specific to a particular DSL Recommendation. For interrelationships of this Recommendation with other ITU-T G.99x-series Reco
38、mmendations, see Recommendation ITU-T G.995.1 (informative). The principal characteristics of this Recommendation are as follows: a) use over metallic local loops; b) provisions to exchange capabilities information between DSL equipment to identify common modes of operation; c) provisions for DSL eq
39、uipment at either end of the loop to select a common mode of operation or to request the other end to select the mode; d) provisions for exchanging non-standard information between DSL equipment; e) provisions to exchange and request service and application-related information; f) support for both d
40、uplex and half-duplex transmission modes; g) support for multi-pair operation; h) provisions for DSL equipment at the remote end of the loop (xTU-R) to propose a common mode of operation (new in version 2 of the Recommendation through the use of new message type MP and its associated transactions);
41、i) support for a re-transmission mechanism (new in version 3 of the Recommendation through the use of new message type REQ-RTX). j) support for exchanging the relative transmit and receive level of individual carriers in order to estimate loop characteristics. 2 References The following ITU-T Recomm
42、endations 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 Recommendations and other references are subject to revision; users of this Recommendation are the
43、refore 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 Recommendations is regularly published. The reference to a document within this Recommendation does not give it, as a sta
44、nd-alone document, the status of a Recommendation. ITU-T G.991.2 Recommendation ITU-T G.991.2 (2003), Single-pair high-speed digital subscriber line (SHDSL) transceivers. ITU-T G.992.1 Recommendation ITU-T G.992.1 (1999), Asymmetric digital subscriber line (ADSL) transceivers. ITU-T G.992.2 Recommen
45、dation ITU-T G.992.2 (1999) (except Amd.2), Splitterless asymmetric digital subscriber line (ADSL) transceivers. ITU-T G.992.3 Recommendation ITU-T G.992.3 (2005) (except Amd.2), Asymmetric digital subscriber line transceivers 2 (ADSL2). 2 Rec. ITU-T G.994.1 (04/2017) ITU-T G.992.4 Recommendation IT
46、U-T G.992.4 (2002), Splitterless asymmetric digital subscriber line transceivers 2 (splitterless ADSL2). ITU-T G.992.5 Recommendation ITU-T G.992.5 (2005), Asymmetric digital subscriber line (ADSL) transceivers Extended bandwidth ADSL2 (ADSL2plus). ITU-T G.993.1 Recommendation ITU-T G.993.1 (2004),
47、Very high speed digital subscriber line transceivers (VDSL). ITU-T G.993.2 Recommendation ITU-T G.993.2 (2015), Very high speed digital subscriber line transceivers 2 (VDSL2). ITU-T G.997.1 Recommendation ITU-T G.997.1 (2006) (except Amd.2), Physical layer management for digital subscriber line (DSL
48、) transceivers. ITU-T T.35 Recommendation ITU-T T.35 (1991), Procedure for the allocation of ITU-T defined codes for non-standard facilities. ISO/IEC 3309 ISO/IEC 3309:1993, Information Technology Telecommunications and information exchange between systems High-level data link control (HDLC) procedu
49、res Frame structure. 3 Definitions This Recommendation defines the following terms: 3.1 capabilities: The “enabled“ (= supported) set of functions, not necessarily the complete set of functions implemented in the unit. 3.2 carrier set: A set of one or more frequencies associated with the PSD mask of a particular xDSL Recommendation. 3.3 downstream: The direction of transmission from the xTU-C to the xTU-R. 3.4 errored frame: A fra
