1、 International Telecommunication Union ITU-T G.781TELECOMMUNICATION STANDARDIZATION SECTOR OF ITU Corrigendum 1(11/2009) SERIES G: TRANSMISSION SYSTEMS AND MEDIA, DIGITAL SYSTEMS AND NETWORKS Digital terminal equipments Principal characteristics of multiplexing equipment for the synchronous digital
2、hierarchy Synchronization layer functions Corrigendum 1 Recommendation ITU-T G.781 (2008) 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 TO ALL ANALOG
3、UE 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.449 COORDI
4、NATION OF RADIOTELEPHONY AND LINE TELEPHONY G.450G.499 TRANSMISSION MEDIA AND OPTICAL SYSTEMS CHARACTERISTICS G.600G.699 DIGITAL TERMINAL EQUIPMENTS G.700G.799 General G.700G.709 Coding of voice and audio signals G.710G.729 Principal characteristics of primary multiplex equipment G.730G.739 Principa
5、l characteristics of second order multiplex equipment G.740G.749 Principal characteristics of higher order multiplex equipment G.750G.759 Principal characteristics of transcoder and digital multiplication equipment G.760G.769 Operations, administration and maintenance features of transmission equipm
6、ent G.770G.779 Principal characteristics of multiplexing equipment for the synchronous digital hierarchy G.780G.789 Other terminal equipment G.790G.799 DIGITAL NETWORKS G.800G.899 DIGITAL SECTIONS AND DIGITAL LINE SYSTEM G.900G.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.8999ACCESS NETWORKS G.9000G.9999 For further details, please refer to the list of ITU-T Recommendations. Rec. ITU-T G.781 (2008)/Cor.1 (11/20
8、09) i Recommendation ITU-T G.781 Synchronization layer functions Corrigendum 1 Summary Corrigendum 1 to Recommendation ITU-T G.781 (2008) corrects: the quality level associated with Recommendation ITU-T G.8262/Y.1362, option II clock; a duplicate entry in Table 20; a mistake in a condition in the co
9、nsequent action in clause 8.3.1.1; a mistake in the reference to the ESMC in clause 8.9.1. Source Corrigendum 1 to Recommendation ITU-T G.781 (2008) was approved on 13 November 2009 by ITU-T Study Group 15 (2009-2012) under Recommendation ITU-T A.8 procedures. ii Rec. ITU-T G.781 (2008)/Cor.1 (11/20
10、09) 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 organ of ITU. ITU-T is responsible for
11、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 topics for study by the ITU-T study
12、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 prepared on a collaborative basis wi
13、th 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 may contain certain mandatory prov
14、isions (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 to express requirements. The use of su
15、ch words does not suggest that compliance 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 positi
16、on 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 of intellectual property, protected b
17、y 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 2010 All rights reserved. No part of this
18、 publication may be reproduced, by any means whatsoever, without the prior written permission of ITU. Rec. ITU-T G.781 (2008)/Cor.1 (11/2009) 1 Recommendation ITU-T G.781 Synchronization layer functions Corrigendum 1 Modifications introduced by this corrigendum are shown in revision marks. Unchanged
19、 text is replaced by ellipsis (). Some parts of unchanged text (clause numbers, etc.) may be kept to indicate the correct insertion points. 5.4.1.2 Option II synchronization networking QL-ST3: Traceable to stratum 3 (ITU-T G.812, type IV or ITU-T G.8262, option II). QL-SMC: Traceable to SONET clock
20、self timed (ITU-T G.813 or ITU-T G.8262, option II). 5.5.1.2 Option II synchronization networking code 1010 (quality ST3), means that the source of the trail is a stratum 3 clock (ITU-T G.812, type IV or ITU-T G.8262, option II); code 1100 (quality SMC), means that the source of the trail is a SONET
21、/Ethernet self-timed clock (ITU-T G.813 or ITU-T G.8262, option II); Table 20 Conversion of quality levels for option II synchronization networks CI_QL CI_SSF AI_QL QL-DUS False QL-DUS QL-NSUPPDUS False QL-NSUPP QL-UNC True QL-FAILED All True QL-FAILED 8.3.1.1 Type 1 P12s to SD adaptation source for
22、 station clock output supporting SSM (P12s/SD-sc-1_A_So) Consequent actions: if (MI_QLmode = dis) 2 Rec. ITU-T G.781 (2008)/Cor.1 (11/2009) then Sax1-4 = 1111 if (CI_SSF = true) then AI_AISinsert = true RI_CS = none else AI_AISinsert = false RI_CS = CI_CS fi else if (MI_SSMsupp = truefalse) then Sax
23、1-4 = 1111 if (CI_SSF = true) or (CI_QLMI_QLminimum) then AI_AISinsert = true RI_CS = none else AI_AISinsert = false RI_CS = CI_CS fi else AI_AISinsert = false if (CI_SSF = true) then Sax1-4 = 1111 RI_CS = none else Sax1-4 = SSMCI_QL RI_CS = CI_CS fi fi fi 8.9.1 ETH to SD adaptation source (ETH/SD_A
24、So) The ESSM ESMC message channel, specified in ITU-T G.8264, defines 2 types of messages, event and information ones. The generation of an event-based message is triggered by a change of the SSM code, SD_CI_QL value, within the delay times (THM, TNSM, TSM) specified in clause 5.14. The information
25、 messages are generated with a periodicity of one second. Printed in Switzerland Geneva, 2010 SERIES OF ITU-T RECOMMENDATIONS Series A Organization of the work of ITU-T Series D General tariff principles Series E Overall network operation, telephone service, service operation and human factors Serie
26、s 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 network Series J Cable networks and transmission of television, sound programme and other multimedia sig
27、nals 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 and network maintenance Series N Maintenance: international sound programme and television transmission
28、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 Series S Telegraph services terminal equipment Series T Terminals for telematic services Series U Telegraph swi
29、tching 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
