1、 International Telecommunication Union ITU-T G.999.1TELECOMMUNICATION STANDARDIZATION SECTOR OF ITU Corrigendum 1(04/2010) SERIES G: TRANSMISSION SYSTEMS AND MEDIA, DIGITAL SYSTEMS AND NETWORKS Digital sections and digital line system Access networks Interface between the link layer and the physical
2、 layer for digital subscriber line (DSL) transceivers Corrigendum 1 Recommendation ITU-T G.999.1 (2009) Corrigendum 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
3、 TO 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.4
4、00G.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 fibr
5、e cable 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
6、 Digital 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 Access networks G.990G.999MULTIMEDIA QUALITY OF SERVICE AND PERFORMANCE GENERIC AND USER-RELATED ASP
7、ECTS 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.999.1 (2009)/Cor.1 (04/2010)
8、 i Recommendation ITU-T G.999.1 Interface between the link layer and the physical layer for digital subscriber line (DSL) transceivers Corrigendum 1 Summary This corrigendum contains: Resolution of an inconsistency with TCI bit mapping relative to IEEE 802.1q Clarification of LENGTH field bit mappin
9、g Editorial corrections and clarifications to various clauses throughout the Recommendation History Edition Recommendation Approval Study Group 1.0 ITU-T G.999.1 2009-10-09 15 1.1 ITU-T G.999.1 (2009) Cor. 1 2010-04-22 15 ii Rec. ITU-T G.999.1 (2009)/Cor.1 (04/2010) FOREWORD The International Teleco
10、mmunication 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 tar
11、iff 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 Recomm
12、endations 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 Recommen
13、dation, 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
14、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
15、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
16、 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
17、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 2010 All rights reserved. No part of this publication may be reproduced, by a
18、ny means whatsoever, without the prior written permission of ITU. Rec. ITU-T G.999.1 (2009)/Cor.1 (04/2010) 1 Recommendation ITU-T G.999.1 Interface between the link layer and the physical layer for digital subscriber line (DSL) transceivers Corrigendum 1 1 Modifications to clause 6.1 Modify clause
19、6.1 as follows: 6.1 Fragmentation The fragmentation block (see Figure 5-1) shall fragment each data unit as shown in Figure 6-1. The fragment format is shown in Figure 6-2. G.999.1(09)_F6-1Fragment dataFragment dataFragment dataFragment dataHeaderHeaderHeaderHeader(SoF=1 and EoF=0)(SoF=0 and EoF=0)(
20、SoF=0 and EoF=0)(SoF=0 and EoF=1)Fragment 1Fragment 2Fragment n-1Fragment nData unitFigure 6-1 Data unit fragmentation LSB MSB 2 Octets TCIN octets FragmentData 000 001 EoF SoF 0 0000000LENGTH2 Octets Figure 6-2 Non-tagged fragment format The fragment header shall consist of the tag-control-identifi
21、er (TCI) field and the LENGTH field. The capability to insert the LENGTH field is mandatory. When Ethernet encapsulation is enabled, the LENGTH field shall be inserted. When Ethernet encapsulation is disabled, the LENGTH field is configurable to be used or not (see Table 7-1). When the LENGTH MODE i
22、s set to 1, the LENGTH 2 Rec. ITU-T G.999.1 (2009)/Cor.1 (04/2010) field shall be appended; otherwise the LENGTH field shall not be appended. In the TCI field, the SoF and EoF bits shall be defined as shown in Table 6-1. The remaining TCI bits shall be as defined in Figure 6-2 and partly further def
23、ined by the tag function. The LENGTH field shall contain the number of data unit octets in the fragment data field. The LENGTH field, in which the value is encoded as a 16-bit unsigned integer, shall be transmitted with the high order (i.e., most significant) octet first; where the value is encoded
24、as a 16 bit unsigned integer. Table 6-1 Definition of the data unit delimiters SoF EoF Description 0 0 Next fragment of data unit 1 0 First fragment of data unit 0 1 Last fragment of data unit 1 1 Single fragment data unit For each fragment, the value of the length field shall not exceed the maximum
25、 fragment data size (TX_MFS). If the length of a data unit is less than or equal to the TX_MFS value (see Table 7-1), then that data unit shall be transmitted as a single fragment (i.e., SoF = 1 and EoF = 1). If the length of a data unit is higher than the TX_MFS value, then that data unit shall be
26、transmitted in multiple fragments, where fragments may have the same or a different length. 2 Modifications to Annex A 2.1 Modify the first paragraph of Annex A as follows: DSL transceivers are based on transparent transport of data streams. A TPS-TC data stream is an input to a TPS-TC, where a data
27、 unit equals a 53-octet ATM cell (ATM-TC) (see clause K.2 of ITU-T G.992.3 or clause K.2 of b-ITU-T G.993.2) or a packet (PTM-TC) (see clause K.3 of ITU-T G.992.3 or clause K.3 of b-ITU-T G.993.2). In the Link/PHY interface, a data unit may, for example, contain an Ethernet frame, an Ethernet bondin
28、g fragment, one or more ATM cells or an ATM AAL5 PDU (see clause 5). A TPS-TC connects to a bearer channel. In the case of PTM-TC with pre-emption, a bearer channel may carry a high priority data stream and low priority data stream. Hence, for DSL transceivers, the stream identification (SID) shall
29、identify a particular DSL line, a particular bearer channel and a particular priority within the bearer in the DSL line. 2.2 Modify the first sentence after Figure A.1 as follows: In general, for a PHY device supporting N transceivers, there are N*4 SIDG values and N/2 =842NNoctets in the DFC field
30、of the pause unit. For example, 3 Modifications to Bibliography Delete the informative references identified as b-IEEE 802.1D and b-IEEE 802.1Q from the Bibliography. Printed in Switzerland Geneva, 2010 SERIES OF ITU-T RECOMMENDATIONS Series A Organization of the work of ITU-T Series D General tarif
31、f principles Series E Overall network operation, telephone service, service operation and human factors Series F Non-telephone telecommunication services Series G Transmission systems and media, digital systems and networks Series H Audiovisual and multimedia systems Series I Integrated services dig
32、ital network Series J Cable networks and transmission of television, sound programme and other multimedia signals Series K Protection against interference Series L Construction, installation and protection of cables and other elements of outside plant Series M Telecommunication management, including
33、 TMN and network maintenance Series N Maintenance: international sound programme and television transmission circuits Series O Specifications of measuring equipment Series P Terminals and subjective and objective assessment methods Series Q Switching and signalling Series R Telegraph transmission Se
34、ries 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, open system communications and security Series Y Global information infrastructure, Internet protocol aspects and next-generation networks Series Z Languages and general software aspects for telecommunication systems
