1、 International Telecommunication Union ITU-T G.994.1TELECOMMUNICATION STANDARDIZATION SECTOR OF ITU (06/2012) SERIES G: TRANSMISSION SYSTEMS AND MEDIA, DIGITAL SYSTEMS AND NETWORKS Digital sections and digital line system Access networks Handshake procedures for digital subscriber line transceivers
2、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.200G.299 INDIVIDUAL CHARACTERISTICS OF IN
3、TERNATIONAL 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 TELEPHONY G.450G.499 TRANSMISSION MEDIA A
4、ND 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 hierarchical bit rates based on a bit rate
5、 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 systems for customer access to ISDN G.960G.969
6、Optical fibre submarine cable systems G.970G.979 Optical line systems for local and access networks G.980G.989 Access networks G.990G.999MULTIMEDIA QUALITY OF SERVICE AND PERFORMANCE GENERIC AND USER-RELATED ASPECTS G.1000G.1999 TRANSMISSION MEDIA CHARACTERISTICS G.6000G.6999 DATA OVER TRANSPORT GEN
7、ERIC 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 (06/2012) i Recommendation ITU-T G.994.1 Handshake procedures for digital subscriber line transceivers Summary
8、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 well as parameters pertinent to various DSL transcei
9、vers. 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 future DSL Recommendations will also be able to make
10、 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 the allocation of the codepoint “Support of downstr
11、eam 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. History Edition Recommendation Approval Study Group 1.0 ITU-T G.994.1 v1 1999-07-02 15 1.1 ITU-T G.994.1 (1999) Cor. 1
12、 2000-04-04 15 2.0 ITU-T G.994.1 v2 2001-02-09 15 3.0 ITU-T G.994.1 v2 2002-07-29 15 4.0 ITU-T G.994.1 v3 2003-05-22 15 4.1 ITU-T G.994.1 (2003) Amd. 1 2004-02-22 15 4.2 ITU-T G.994.1 (2003) Amd. 2 2004-06-13 15 4.3 ITU-T G.994.1 (2003) Amd. 3 2005-01-13 15 4.4 ITU-T G.994.1 (2003) Amd. 4 2006-01-13
13、 15 5.0 ITU-T G.994.1 v3 2007-02-13 15 5.1 ITU-T G.994.1 (2007) Amd. 1 2007-11-22 15 5.2 ITU-T G.994.1 (2007) Amd. 2 2008-04-13 15 5.3 ITU-T G.994.1 (2007) Amd. 3 2009-03-22 15 5.4 ITU-T G.994.1 (2007) Amd. 4 2009-06-29 15 5.5 ITU-T G.994.1 (2007) Amd. 5 2010-04-22 15 5.6 ITU-T G.994.1 (2007) Amd. 6
14、 2010-11-29 15 5.7 ITU-T G.994.1 (2007) Amd. 7 2011-04-13 15 5.8 ITU-T G.994.1 (2007) Cor. 1 2011-10-29 15 5.9 ITU-T G.994.1 (2007) Amd. 8 2011-12-16 15 6.0 ITU-T G.994.1 v3 2012-06-13 15 6.1 ITU-T G.994.1 (2012) Amd. 1 2012-10-29 15 ii Rec. ITU-T G.994.1 (06/2012) FOREWORD The International Telecom
15、munication 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 organ of ITU. ITU-T is responsible for studying technical, operating and tari
16、ff 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 topics for study by the ITU-T study groups which, in turn, produce Recomme
17、ndations 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 prepared on a collaborative basis with ISO and IEC. NOTE In this Recommend
18、ation, 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 may contain certain mandatory provisions (to ensure, e.g., interoperabil
19、ity 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 to express requirements. The use of such words does not suggest that compl
20、iance with the Recommendation is required of any party. 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, validity
21、 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 required to
22、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 2013 All rights reserved. No part of this publication may be reproduced, by a
23、ny means whatsoever, without the prior written permission of ITU. Rec. ITU-T G.994.1 (06/2012) iii 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 .
24、8 6.3 Transmit filter characteristics . 9 7 Description of messages . 9 7.1 CL Capabilities list 9 7.2 CLR Capabilities list + request . 9 7.3 MR Mode request 9 7.4 MS Mode select . 9 7.5 MP Mode proposal 9 7.6 ACK(1) Acknowledgement, type 1 . 10 7.7 ACK(2) Acknowledgement, type 2 . 10 7.8 NAK-EF Ne
25、gative 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 10 7.12 REQ-MS Request MS message . 10 7.13 REQ-MR Request MR message 11 7.14 REQ-CLR Request CLR messag
26、e . 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 fill 13 9 Message coding format . 13 9.1 General . 13 9.2 Coding format for parameters in the
27、I and S fields 13 9.3 Identification field (I) . 16 iv Rec. ITU-T G.994.1 (06/2012) Page 9.4 Standard information field (S) 45 9.5 Non-standard information field (NS) . 857 9.6 Overall message composition . 858 10 ITU-T G.994.1 transactions 859 10.1 Basic transactions . 859 10.2 Extended transaction
28、s . 860 10.3 Message segmentation 862 10.4 State transition diagrams 862 10.5 Retransmission transactions . 869 11 Start-up/cleardown procedures . 870 11.1 Duplex start-up procedures . 870 11.2 Half-duplex start-up procedures . 871 11.3 Cleardown procedure 872 12 Error recovery procedures 874 13 Man
29、agement information base (MIB) elements . 875 13.1 Configuration parameters . 875 Annex A Support for legacy non-ITU-T G.994.1 devices 878 Annex B Operation over multiple wire pairs 879 Annex C An operating mode for use in the same cable as TCM-ISDN . 880 C.1 Scope (supplements clause 1) . 880 C.2 S
30、ignals and modulation (pertains to clause 6) 880 C.3 Start-up/cleardown procedures (pertains to clause 11) 883 Appendix I ITU-T G.994.1 sample sessions . 886 Appendix II Provider code contact information . 887 Appendix III Support for legacy DMT-based devices 888 Appendix IV Procedure for the assign
31、ment of additional ITU-T G.994.1 parameters . 889 IV.1 Introduction 889 IV.2 Procedure 889 Appendix V Rules for code point table numbering 890 Bibliography. 891 Rec. ITU-T G.994.1 (06/2012) 1 Recommendation ITU-T G.994.1 Handshake procedures for digital subscriber line transceivers 1 Scope This Reco
32、mmendation 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 Recommenda
33、tion. 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 information
34、 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) provisions to e
35、xchange 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 the Re
36、commendation 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 carri
37、ers 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 Recommendati
38、ons 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 publis
39、hed. 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.992.1
40、(1999), Asymmetric digital subscriber line (ADSL) transceivers. 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) (except Amd.2), Asymmetric digital subscriber line
41、transceivers 2 (ADSL2). 2 Rec. ITU-T G.994.1 (06/2012) 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 (ADSL) transceivers Ext
42、ended 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 (2006), Very high speed digital subscriber line transceivers 2 (VDSL2). ITU-T G.997.1 Recommendation ITU-T G.9
43、97.1 (2006) (except Amd.2), Physical layer management for digital subscriber line (DSL) 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 Telecommunication
44、s and information exchange between systems High-level data link control (HDLC) procedures 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 u
45、nit. 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 frame that contains a frame check sequence (FCS) error. 3.5 Galf: An octet of value
46、 8116, i.e., the ones complement of an HDLC flag. 3.6 initiating signal: A signal that initiates the start-up procedure of an ITU-T G.994.1 session. 3.7 initiating station: The station that initiates the start-up procedure of an ITU-T G.994.1 session. 3.8 invalid frame: A frame that has fewer than f
47、our octets between flags, excluding transparency octets. 3.9 message: Framed information conveyed via modulated transmission. 3.10 responding signal: A signal that is sent in response to an initiating signal. 3.11 responding station: The station that responds to the initiation of the start-up proced
48、ure of an ITU-T G.994.1 session. 3.12 session: An ITU-T G.994.1 session comprises a start-up procedure, one or more transactions and a cleardown procedure (except as noted in clause 12). 3.13 shaping: Application of different gain scaling (Bi, see clauses 6.1.1 and 6.2) and therefore different trans
49、mit power to individual carriers within a carrier set. 3.14 signalling family: A group of carrier sets which are integral multiples of a given carrier spacing frequency. 3.15 subcarrier: Refer to the associated xDSL Recommendation for the definition of this term. Rec. ITU-T G.994.1 (06/2012) 3 3.16 transaction: A sequence of ITU-T G.994.1 messages, ending with either a positive acknowledgement ACK(1) (except as noted in clause 7.6), a negative ack
