1、 International Telecommunication Union ITU-T G.991.2TELECOMMUNICATION STANDARDIZATION SECTOR OF ITU Amendment 3(09/2005) SERIES G: TRANSMISSION SYSTEMS AND MEDIA, DIGITAL SYSTEMS AND NETWORKS Digital sections and digital line system Access networks Single-pair high-speed digital subscriber line (SHD
2、SL) transceivers Amendment 3 ITU-T Recommendation G.991.2 (2003) Amendment 3 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 SYS
3、TEMS 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.449 COORDINATION OF RADIOTELEPHONY AN
4、D LINE TELEPHONY G.450G.499 TRANSMISSION MEDIA 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 b
5、it 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 systems for custome
6、r 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.999 QUALITY OF SERVICE AND PERFORMANCE GENERIC AND USER-RELATED ASPECTS G.1000G.1999 TRANSMISSION MEDIA CHARACTERISTICS G.6000G.6999 DATA
7、OVER TRANSPORT GENERIC ASPECTS G.7000G.7999 ETHERNET OVER TRANSPORT ASPECTS G.8000G.8999 ACCESS NETWORKS G.9000G.9999 For further details, please refer to the list of ITU-T Recommendations. ITU-T Rec. G.991.2 (2003)/Amd.3 (09/2005) i ITU-T Recommendation G.991.2 Single-pair high-speed digital subscr
8、iber line (SHDSL) transceivers Amendment 3 Summary The following text reflects the agreed modification for a third amendment to ITU-T Rec. G.991.2 (2003). Amendment 3 contains an update to ITU-T Rec. G.991.2 defining a new TPS-TC for PTM Transport based on 64/65-octet packet encapsulation. The text
9、modifications relative to ITU-T Rec. G.991.2 (2003) are shown with revision marks. Source Amendment 3 to ITU-T Recommendation G.991.2 (2003) was approved on 6 September 2005 by ITU-T Study Group 15 (2005-2008) under the ITU-T Recommendation A.8 procedure. ii ITU-T Rec. G.991.2 (2003)/Amd.3 (09/2005)
10、 FOREWORD The International Telecommunication Union (ITU) is the United Nations specialized agency in the field of telecommunications. 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
11、 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 Recommendations on thes
12、e 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 Recommendation, the expre
13、ssion “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. interoperability or applicabili
14、ty) 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 compliance with the Rec
15、ommendation 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 or applicability
16、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 implement this Rec
17、ommendation. However, implementors are cautioned that this may not represent the latest information and are therefore strongly urged to consult the TSB patent database. ITU 2006 All rights reserved. No part of this publication may be reproduced, by any means whatsoever, without the prior written per
18、mission of ITU. ITU-T Rec. G.991.2 (2003)/Amd.3 (09/2005) iii CONTENTS Page 1) Modification to Table E.22. 1 2) Change of text in clause E.10 . 2 3) Modification to Table E.34a. 2 4) Modification to title of clause E.11 2 5) Modifications to Annex E on Application-specific TPS-TC Framing 3 ITU-T Rec
19、. G.991.2 (2003)/Amd.3 (09/2005) 1 ITU-T Recommendation G.991.2 Single-pair high-speed digital subscriber line (SHDSL) transceivers Amendment 3 1) Modification to Table E.22 Modify Table E.22 as follows: Table E.22/G.991.2 Supported TPS-TCs in dual-bearer mode Type Description TPS-TCaTPS-TCb1 STM +
20、Broadband Synchronous ISDN BRA (E.8) LAPV5 Enveloped POTS or ISDN (E.13) (Note 2) STM with DSC (E.12) Clear Channel (E.1) Clear Channel Byte-Oriented (E.2) Unaligned DS1 (E.3) (Note 1) Aligned DS1/Fractional DS1 (E.4) (Note 1) Unaligned D2048U (E.5) (Note 2) Unaligned D2048S (E.6) (Note 2) Aligned D
21、2048S/Fractional D2048S (E.7) (Note 2) ATM (E.9) PTM (HDLC-based) (E.11) PTM (64/65-Octet-based) (E.15) 2 STM + Cell/Packet Unaligned DS1 (E.3) (Note 1) Aligned DS1/Fractional DS1 (E.4) (Note 1) Unaligned D2048U (E.5) (Note 2) Unaligned D2048S (E.6) (Note 2) Aligned D2048S/Fractional D2048S (E.7) (N
22、ote 2) ATM (E.9) PTM (HDLC-based) (E.11) PTM (64/65-Octet-based) (E.15) 3 STM + Clear Channel Unaligned DS1 (E.3) (Note 1) Aligned DS1/Fractional DS1 (E.4) (Note 1) Unaligned D2048U (E.5) (Note 2) Unaligned D2048S (E.6) (Note 2) Aligned D2048S/Fractional D2048S (E.7) (Note 2) Clear Channel (E.1) Cle
23、ar Channel Byte-Oriented (E.2) NOTE 1 Denotes TPS-TC modes that typically apply only in North American networks. NOTE 2 Denotes TPS-TC modes that typically apply only in European networks. 2 ITU-T Rec. G.991.2 (2003)/Amd.3 (09/2005) 2) Change of text in clause E.10 Change two occurrences of “. E.1 t
24、hrough E.9 and E.11 through E.13“ in the first sentence, and “. E.1 to E.9 and E.11 to E.13“ in the last sentence, as follows: . E.1 through E.9 and E.11 through E.13 and E.15. and . E.1 to E.9 and E.11 to E.13 and E.15 . 3) Modification to Table E.34a Modify Table E.34a as follows: Table E.34a/G.99
25、1.2 TPS-TCs from dual-bearer mode Types 1 and 2 for which DRR is supported Type Description TPS-TCaTPS-TCb1 STM + Broadband Synchronous ISDN BRA (E.8) LAPV5 Enveloped POTS or ISDN (E.13) STM with DSC (E.12) Clear Channel Byte-Oriented (E.2) Aligned DS1/Fractional DS1 (E.4) Aligned D2048S/Fractional
26、D2048S (E.7) ATM (E.9) PTM (HDLC-based) (E.11) PTM (64/65-Octet-based) (E.15) 2 STM + Cell/Packet Aligned DS1/Fractional DS1 (E.4)Aligned D2048S/Fractional D2048S (E.7)ATM (E.9) PTM (HDLC-based) (E.11) PTM (64/65-Octet-based) (E.15) NOTE See Table E.22 for the complete definitions of TPS-TC Types fo
27、r dual-bearer mode. 4) Modification to title of clause E.11 Change the title of clause E.11 to read as follows: E.11 TPS-TC for PTM transport (HDLC based) ITU-T Rec. G.991.2 (2003)/Amd.3 (09/2005) 3 5) Modifications to Annex E on Application-specific TPS-TC Framing Add the following new clause E.15
28、to Annex E defining a new TPS-TC for PTM Transport based on 64/65-octet encapsulation. E.15 TPS-TC for PTM transport (64/65-octet-based) E.15.1 Packetized data transport E.15.1.1 Functional model The functional mode of packetized data transport is presented in Figure E.19. In the transmit direction,
29、 the PTM entity obtains data packets to be transported over SHDSL from the application layer interface. The PTM entity processes each packet and applies it to the -interface for packetized data transport. The PTM TPS-TC receives the packet from -interface, encapsulates it into a special frame (PTM-T
30、C frame) and maps it into PMS-TC frame (transmission frame) for transmission over the SHDSL link. In the receive direction, the PTM-TC frame extracted from the received PMS-TC frame is directed into the PTM-TC. The PTM-TC recovers the transported packet and delivers it to the PTM entity via the -int
31、erface. The PTM path-related OAM data, including information on errored packets, shall be presented to the TPS-TC management entity providing all necessary OAM functions to support the PTM-TC. The -interface is described in E.11.3.1. The /-interfaces are application-independent and thus have the sam
32、e format as for other TPS-TCs (see E.11.3.2). E.15.2 Transport of PTM data The transport of PTM data shall be as specified in E.11.2. E.15.3 Interface description The interface description shall be as specified in E.11.3. E.15.4 PTM TPS-TC functionality The following PTM TPS-TC functionality should
33、be applied to both Rx and Tx direction. E.15.4.1 Packet encapsulation For packet encapsulation a 64/65-octet-type mechanism shall be used with detailed characteristics as specified in Annex N/G.992.3. Both a 16-bit and a 32-bit CRC are defined in Annex N/G.992.3. The STU-C shall support both of thes
34、e CRC types. The STU-R shall support at least one of these CRC types. A bit in G.994.1, CRC Type, when received by an STU-C, shall indicate which CRC type will be used in both the upstream and downstream direction. When CRC Type is set to a 1 in an MS message, it indicates the 16-bit CRC; when CRC T
35、ype is set to a 0, it indicates the 32-bit CRC. In a CL message the CRC Type bit shall always be set to a 1. In the MS message, if, and only if, both the CL and CLR indicate a 1, then the MS message indicates a 1 for the CRC Type bit. E.15.4.2 Packet error monitoring Packet error monitoring includes
36、 detection of invalid and errored frames at receive side as specified in Annex N/G.992.3. E.15.4.3 Data rate decoupling Data rate decoupling is accomplished as specified in Annex N/G.992.3. 4 ITU-T Rec. G.991.2 (2003)/Amd.3 (09/2005) E.15.4.4 Frame delineation The PTM-TC frames should be delineated
37、as specified in Annex N/G.992.3. E.15.4.5 Mapping to the SHDSL framing Packets are mapped into the SHDSL payload on a byte by byte basis as specified in E.11.4.5. Printed in Switzerland Geneva, 2006 SERIES OF ITU-T RECOMMENDATIONS Series A Organization of the work of ITU-T Series D General tariff pr
38、inciples 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 digital
39、 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 TMN
40、 and network maintenance Series N Maintenance: international sound programme and television transmission circuits Series O Specifications of measuring equipment Series P Telephone transmission quality, telephone installations, local line networks Series Q Switching and signalling Series R Telegraph
41、transmission Series 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
