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 Amendment 1 (12/2017) SERIES G: TRANSMISSION SYSTEMS AND MEDIA, DIGITAL SYSTEMS AND NETWORKS Digital sections and digital line system Metallic access networks Handshak
2、e procedures for digital subscriber line transceivers Amendment 1 Recommendation ITU-T G.994.1 (2017) Amendment 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
3、ALL ANALOGUE CARRIER-TRANSMISSION SYSTEMS G.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.
4、449 COORDINATION OF RADIOTELEPHONY AND LINE 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 ca
5、ble systems G.910G.919 Digital sections at 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 Dig
6、ital section and digital transmission systems 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-RELAT
7、ED ASPECTS G.1000G.1999 TRANSMISSION MEDIA 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 (2017)/Amd.1 (12
8、/2017) i Recommendation ITU-T G.994.1 Handshake procedures for digital subscriber line transceivers Amendment 1 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 incl
9、udes parameters relating to service and application requirements as 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
10、-T G.992.5, ITU-T G.993.1 and ITU-T G.993.2. It is anticipated that 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
11、revision of Recommendation ITU-T G.994.1 (version 3). It also: fixes 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
12、. The 2017 edition of this Recommendation integrates ITU-T G.994.1 (2012) and all its amendments and corrigendum. The 2017 edition does not add any new technical material. Amendment 1 includes: Codepoint for the support of ITU-T G.993.5 Annex A (Mitigating Strong FEXT) Codepoints for the support of
13、ITU-T G.993.5 Annex B (Vectored Long Reach VDSL) and ITU-T G.993.2 Annex D (Unvectored Long Reach VDSL). 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
14、2001-02-09 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-
15、13 15 11.1002/1000/7495 4.4 ITU-T G.994.1 (2003) Amd. 4 2006-01-13 15 11.1002/1000/8549 _ * 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. i
16、i Rec. ITU-T G.994.1 (2017)/Amd.1 (12/2017) 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 2009-03-22 15 11.1002/1000/9675 5.4 ITU-T G.99
17、4.1 (2007) Amd. 4 2009-06-29 15 11.1002/1000/9891 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 11.1002/1
18、000/11417 5.9 ITU-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 1
19、5 11.1002/1000/12093 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 (
20、2012) Cor. 1 2016-10-29 15 11.1002/1000/13063 6.9 ITU-T G.994.1 (2012) Amd. 8 2017-04-06 15 11.1002/1000/13062 6.10 ITU-T G.994.1 (2012) Amd. 9 2017-12-07 15 11.1002/1000/13308 7.0 ITU-T G.994.1 2017-04-06 15 11.1002/1000/13347 7.1 ITU-T G.994.1 (2017) Amd. 1 2017-12-07 15 11.1002/1000/13515 Rec. IT
21、U-T G.994.1 (2017)/Amd.1 (12/2017) iii FOREWORD The International Telecommunication Union (ITU) is the United Nations specialized agency in the field of telecommunications, information and communication technologies (ICTs). The ITU Telecommunication Standardization Sector (ITU-T) is a permanent orga
22、n of ITU. 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. The World Telecommunication Standardization Assembly (WTSA), which meets every four years, establishes the t
23、opics 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 procedure laid down in WTSA Resolution 1. In some areas of information technology which fall within ITU-Ts purview, the necessary standards are p
24、repared on a collaborative basis with ISO and IEC. NOTE In this Recommendation, the expression “Administration“ is used for conciseness to indicate both a telecommunication administration and a recognized operating agency. Compliance with this Recommendation is voluntary. However, the Recommendation
25、 may contain certain mandatory provisions (to ensure, e.g., interoperability or applicability) and compliance with the Recommendation is achieved when all of these mandatory provisions are met. The words “shall“ or some other obligatory language such as “must“ and the negative equivalents are used t
26、o express requirements. The use of such words does not suggest that compliance with the Recommendation is required of any party. INTELLECTUAL PROPERTY RIGHTSITU draws attention to the possibility that the practice or implementation of this Recommendation may involve the use of a claimed Intellectual
27、 Property Right. ITU takes no position concerning the evidence, 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, ITU had received notice o
28、f intellectual property, protected by patents, which may be required to implement this Recommendation. However, implementers are cautioned that this may not represent the latest information and are therefore strongly urged to consult the TSB patent database at http:/www.itu.int/ITU-T/ipr/. ITU 2018
29、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 (2017)/Amd.1 (12/2017) Table of Contents Page 1 Scope . 1 2 References . 1 3 Definitions 2 4 Abbreviations and acronyms 3 5 System reference
30、 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 . 10 7.1 CL Capabilities list 10 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
31、 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 ready 10 7.10 NAK-NS Negative Acknowledgement, not supported 10 7.11 NAK-CD Negative Acknowledgement, cleardown 11 7.12 REQ-
32、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 convention 11 8.2 Frame structure . 12 8.3 Frame check sequence field 12 8.4 Octet transparency 13 8.5 Inter-frame time fi
33、ll 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) 47 Rec. ITU-T G.994.1 (2017)/Amd.1 (12/2017) v Page 9.5 Non-standard information field (NS) . 872 9.6 Overall message com
34、position . 873 10 ITU-T G.994.1 transactions 873 10.1 Basic transactions . 874 10.2 Extended transactions . 875 10.3 Message segmentation 876 10.4 State transition diagrams 876 10.5 Retransmission transactions . 883 11 Start-up/cleardown procedures . 884 11.1 Duplex start-up procedures . 884 11.2 Ha
35、lf-duplex start-up procedures . 885 11.3 Cleardown procedure 886 12 Error recovery procedures 888 13 Management information base (MIB) elements . 889 13.1 Configuration parameters . 889 Annex A Support for legacy non-ITU-T G.994.1 devices 892 Annex B Operation over multiple wire pairs 893 Annex C An
36、 operating mode for use in the same cable as TCM-ISDN . 894 C.1 Scope (supplements clause 1) . 894 C.2 Signals and modulation (pertains to clause 6) 894 C.3 Start-up/cleardown procedures (pertains to clause 11) 897 Appendix I ITU-T G.994.1 sample sessions . 900 Appendix II Provider code contact info
37、rmation . 901 Appendix III Support for legacy DMT-based devices 902 Appendix IV Procedure for the assignment of additional ITU-T G.994.1 parameters . 903 IV.1 Introduction 903 IV.2 Procedure 903 Appendix V Rules for code point table numbering 904 Bibliography. 905 Rec. ITU-T G.994.1 (2017)/Amd.1 (12
38、/2017) 1 Recommendation ITU-T G.994.1 Handshake procedures for digital subscriber line transceivers Amendment 1 Editorial note: This is a complete-text publication. The modifications introduced by this amendment are shown in revision marks relative to Recommendation ITU-T G.994.1 (2017). 1 Scope Thi
39、s Recommendation defines signals, messages and procedures for exchanging these between digital 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 Reco
40、mmendation. For interrelationships of this Recommendation with other ITU-T G.99x-series Recommendations, 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 infor
41、mation between DSL equipment to identify common modes of operation; c) provisions for DSL equipment 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) provision
42、s to exchange and request service and application-related information; f) support for both duplex 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
43、the Recommendation through the use of new message type MP and its associated transactions); 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
44、 carriers in order to estimate loop characteristics. 2 References The following ITU-T Recommendations 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 Recomm
45、endations and other references are subject to revision; users of this Recommendation are therefore 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
46、published. The reference to a document within this Recommendation does not give it, as a stand-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.
47、992.1 (1999), Asymmetric digital subscriber line (ADSL) transceivers. 2 Rec. ITU-T G.994.1 (2017)/Amd.1 (12/2017) ITU-T G.992.2 Recommendation 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) (
48、except Amd.2), Asymmetric digital subscriber line transceivers 2 (ADSL2). ITU-T G.992.4 Recommendation ITU-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 (ADS
49、L) transceivers Extended bandwidth ADSL2 (ADSL2plus). ITU-T G.993.1 Recommendation ITU-T G.993.1 (2004), 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) transceivers. ITU-T T.35 R
