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.8273/Y.1368 TELECOMMUNICATION STANDARDIZATION SECTOR OF ITU Amendment 2 (08/2015) SERIES G: TRANSMISSION SYSTEMS AND MEDIA, DIGITAL SYSTEMS AND NETWORKS Packet over Transport aspects Synchronization, quality and availabil
2、ity targets SERIES Y: GLOBAL INFORMATION INFRASTRUCTURE, INTERNET PROTOCOL ASPECTS AND NEXT-GENERATION NETWORKS Internet protocol aspects Transport Framework of phase and time clocks Amendment 2 Recommendation ITU-T G.8273/Y.1368 (2013) Amendment 2 ITU-T G-SERIES RECOMMENDATIONS TRANSMISSION SYSTEMS
3、 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 INTERNATIONAL CARRIER TELEPHONE SYSTEMS ON METALLIC LINES G.300G.399 GENERAL CHARA
4、CTERISTICS 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 AND OPTICAL SYSTEMS CHARACTERISTICS G.600G.699 DIGITAL TERMINAL EQUIPMENTS G.700G
5、.799 DIGITAL NETWORKS G.800G.899 DIGITAL SECTIONS AND DIGITAL LINE SYSTEM G.900G.999 MULTIMEDIA QUALITY OF SERVICE AND PERFORMANCE GENERIC AND USER-RELATED ASPECTS G.1000G.1999 TRANSMISSION MEDIA CHARACTERISTICS G.6000G.6999 DATA OVER TRANSPORT GENERIC ASPECTS G.7000G.7999 PACKET OVER TRANSPORT ASPE
6、CTS G.8000G.8999 Ethernet over Transport aspects G.8000G.8099 MPLS over Transport aspects G.8100G.8199 Synchronization, quality and availability targets G.8200G.8299 Service Management G.8600G.8699 ACCESS NETWORKS G.9000G.9999 For further details, please refer to the list of ITU-T Recommendations. R
7、ec. ITU-T G.8273/Y.1368 (2013)/Amd.2 (08/2015) i Recommendation ITU-T G.8273/Y.1368 Framework of phase and time clocks Amendment 2 Summary Amendment 2 to Recommendation ITU-T G.8273/Y.1368 (2013) adds: Clause A.6 “Clocks containing Media Converters“ Appendix III “Synchronous Ethernet transient testi
8、ng methodology“. History Edition Recommendation Approval Study Group Unique ID* 1.0 ITU-T G.8273/Y.1368 2013-08-29 15 11.1002/1000/12012 1.1 ITU-T G.8273/Y.1368 (2013) Cor. 1 2014-05-14 15 11.1002/1000/12195 1.2 ITU-T G.8273/Y.1368 (2013) Amd. 1 2015-01-13 15 11.1002/1000/12394 1.3 ITU-T G.8273/Y.13
9、68 (2013) Amd. 2 2015-08-13 15 11.1002/1000/12544 _ * 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. ii Rec. ITU-T G.8273/Y.1368 (2013)/Amd.
10、2 (08/2015) 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 responsi
11、ble 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 topics for study by the ITU-
12、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 prepared on a collaborative
13、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 may contain certain mandat
14、ory 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 to express requirements. The
15、 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 Property Right. ITU takes
16、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 not received notice of intellectual property
17、, 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 2015 All rights reserved. No
18、 part of this publication may be reproduced, by any means whatsoever, without the prior written permission of ITU. Rec. ITU-T G.8273/Y.1368 (2013)/Amd.2 (08/2015) 1 Recommendation ITU-T G.8273/Y.1368 Framework of phase and time clocks Amendment 2 1) Clause A.6 Add the following clause A.6 after clau
19、se A.5: A.6 Clocks containing media converters Some clocks may use alternative physical layer technology to inter-connect to the next clock in the chain. For example, the input may be Ethernet and the output may be microwave. To simplify the measurement of these devices, the performance can be measu
20、red as a back-to-back pair, such that the measurement reference points are the Ethernet interface of the first media converter, and the Ethernet output port of the second device (as shown in Figure A.6-1). It may also be possible to measure a chain of such devices in the same way. Figure A.6-1 Demar
21、cation of measurement points for testing media converter nodes The appropriate budget allocation for a back-to-back pair, or for a chain of such devices, is for further study and will be described in the relevant clock specification. 2) Appendix III Add the following Appendix III after Appendix II:
22、Appendix III Synchronous Ethernet transient testing methodology (This appendix does not form an integral part of this Recommendation.) This appendix addresses the test method to measure the effects of a SyncE transient being received from an upstream T-BC. Note that the output signal is measured wit
23、hout a measurement filter. The timing of events in each of the test methods should be accurate to within 1%. A model for the T-BC is shown in Figure III.1; this does not imply any implementation. 2 Rec. ITU-T G.8273/Y.1368 (2013)/Amd.2 (08/2015) Figure III.1 Example NE with EEC and T-BC functions Fo
24、r all the test methods, the output performance is described in the relevant clock specification. For example, in the case of a T-BC, it is described in Annex B of ITU-T G.8273.2. Method 1 1) Input an ideal SyncE signal with QL-PRC at interface Y and an ideal IEEE 1588 signal at interface X; 2) Wait
25、for the T-BC to be fully stabilized; 3) Start the SyncE transient input signal pattern (e.g., ITU-T G.8262 transient noise) at interface Y, and send ESMC with QL-EEC at interface Y between 1800 ms and 2000 ms after the start of the transient based on the time of holdover message of b-ITU-T G.781; 4)
26、 Wait until 15 seconds (the longest duration before the second transient) after the start of the SyncE transient; 5) Send ESMC with QL restored to QL-PRC at interface Y after the 15 s mark of step 4, between 180 ms and 500 ms based on the time of the switching message of b-ITU-T G.781; 6) Wait 85 se
27、conds and end the test. The SyncE transient input signal pattern is shown in Figure III.2 Rec. ITU-T G.8273/Y.1368 (2013)/Amd.2 (08/2015) 3 Figure III.2 Method 1 SyncE Transient Input Pattern Method 2 1) Input an ideal SyncE signal with QL-PRC at interface Y and an ideal IEEE 1588 signal at interfac
28、e X; 2) Wait for the T-BC to be fully stabilized; 3) Disconnect the input SyncE link at interface Y; NOTE 1 Disconnecting the SyncE link can be accomplished by several methods (e.g., disconnecting the cable, disabling the port, etc.). 4) After 15 seconds, restore the input SyncE link at interface Y;
29、 5) Wait 85 seconds and end the test. NOTE 2 This test may not be applicable or possible in all circumstances. For example, if the SyncE and PTP messages are provided via a common physical port, the SyncE cannot be disconnected without also disconnecting the PTP. Method 3 1) Input an ideal SyncE sig
30、nal with QL-PRC at interface Y and an ideal IEEE 1588 signal at Interface X; 2) Wait for the T-BC to be fully stabilized; 3) Input ESMC with QL degraded to QL-EEC at interface Y; 4) After 15 seconds, restore the input ESMC with QL restored to QL-PRC at interface Y; 5) Wait 85 seconds and end the tes
31、t. 3) Bibliography Create a Bibliography after Annex III, with the following entry: b-ITU-T G.781 Recommendation ITU-T G.781 (2008), Synchronization layer functions. ITU-T Y-SERIES RECOMMENDATIONS GLOBAL INFORMATION INFRASTRUCTURE, INTERNET PROTOCOL ASPECTS AND NEXT-GENERATION NETWORKS GLOBAL INFORM
32、ATION INFRASTRUCTURE General Y.100Y.199 Services, applications and middleware Y.200Y.299 Network aspects Y.300Y.399 Interfaces and protocols Y.400Y.499 Numbering, addressing and naming Y.500Y.599 Operation, administration and maintenance Y.600Y.699 Security Y.700Y.799 Performances Y.800Y.899 INTERNE
33、T PROTOCOL ASPECTS General Y.1000Y.1099 Services and applications Y.1100Y.1199 Architecture, access, network capabilities and resource management Y.1200Y.1299 Transport Y.1300Y.1399 Interworking Y.1400Y.1499 Quality of service and network performance Y.1500Y.1599 Signalling Y.1600Y.1699 Operation, a
34、dministration and maintenance Y.1700Y.1799 Charging Y.1800Y.1899 IPTV over NGN Y.1900Y.1999 NEXT GENERATION NETWORKS Frameworks and functional architecture models Y.2000Y.2099 Quality of Service and performance Y.2100Y.2199 Service aspects: Service capabilities and service architecture Y.2200Y.2249
35、Service aspects: Interoperability of services and networks in NGN Y.2250Y.2299 Enhancements to NGN Y.2300Y.2399 Network management Y.2400Y.2499 Network control architectures and protocols Y.2500Y.2599 Packet-based Networks Y.2600Y.2699 Security Y.2700Y.2799 Generalized mobility Y.2800Y.2899 Carrier
36、grade open environment Y.2900Y.2999 FUTURE NETWORKS Y.3000Y.3499 CLOUD COMPUTING Y.3500Y.3999 For further details, please refer to the list of ITU-T Recommendations. Printed in Switzerland Geneva, 2015 SERIES OF ITU-T RECOMMENDATIONS Series A Organization of the work of ITU-T Series D General tariff
37、 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 digi
38、tal network Series J Cable networks and transmission of television, sound programme and other multimedia signals Series K Protection against interference Series L Environment and ICTs, climate change, e-waste, energy efficiency; construction, installation and protection of cables and other elements
39、of outside plant Series M Telecommunication management, including 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 Ser
40、ies Q Switching and signalling Series R Telegraph 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
