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 1 (01/2015) 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 1 Recommendation ITU-T G.8273/Y.1368 (2013) Amendment 1 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.1 (01/2015) i Recommendation ITU-T G.8273/Y.1368 Framework of phase and time clocks Amendment 1 Summary Amendment 1 to Recommendation ITU-T G.8273/Y.1368 (2013) adds text to clause B.4, and adds the following appendices: Appendix I Variable temperature testing meth
8、odology Appendix II Variable temperature holdover testing 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
9、2015-01-13 15 11.1002/1000/12394 _ * 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.1 (01/2015) FOREW
10、ORD 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 studying
11、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 groups wh
12、ich, 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 with ISO an
13、d 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 provisions (t
14、o 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 such word
15、s 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 no position conce
16、rning 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, protected by pa
17、tents, 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 part of this pub
18、lication may be reproduced, by any means whatsoever, without the prior written permission of ITU. Rec. ITU-T G.8273/Y.1368 (2013)/Amd.1 (01/2015) 1 Recommendation ITU-T G.8273/Y.1368 Framework of phase and time clocks Amendment 1 1) Clause B.4 Replace: “Measurement methods for transparent clocks are
19、 for further study.“ with: B.4.1 Active measurement set-up for systems with telecom transparent clocks Figure B.4-1 shows an active measurement set-up for a T-TC. Figure B.4-1 Active measurement set-up for systems with T-TC With respect to the test arrangement shown: a) One PTP impair function is us
20、ed to emulate network impairments between the SUT and the GM in order to perform stress testing, where necessary, of the PEC function of the T-TC. b) Suitable means are provided for injecting interfering traffic to mimic network loading conditions. The non-PTP traffic loading must include the ports
21、carrying the PTP traffic. c) When calculating the T-TC noise generation and noise transfer using the above set-up, the PTP impairment must be known and compared with the PTP probe measurements. 2 Rec. ITU-T G.8273/Y.1368 (2013)/Amd.1 (01/2015) B.4.2 Passive measurement set-up for systems with teleco
22、m transparent clocks Figure B.4-2 shows a passive measurement set-up for a T-TC. Figure B.4-2 Measurement setup for systems with T-TC The statements regarding the test arrangement provided in clause B.4.1 for the active measurement set-up apply to the passive measurement set-up shown in Figure B.4-2
23、. 2) Appendices Add the following appendices after Annex B: Appendix I Variable temperature testing methodology Appendix II Variable temperature holdover testing methodology. Rec. ITU-T G.8273/Y.1368 (2013)/Amd.1 (01/2015) 3 Appendix I Variable temperature testing methodology (This appendix does not
24、 form an integral part of this Recommendation.) Where variable temperature testing is required, it should be conducted using the temperature profile shown in Figure I.1. Figure I.1 Temperature profile The test should be repeated at different test reference temperatures, T, to cover the required temp
25、erature range. As a minimum the tests should be performed at nominal and temperature extremes, i.e., the reference temperature T set to Tmin + T, Tnom and Tmax T. The test stabilisation time ts should be long enough to remove start-up effects. The loop recovery time tL is dictated by the loop time c
26、onstant and should be as a minimum three times the loop time constant to allow the loop to recover. The constrained temperature excursion T and the ramp rate T/t should be aligned to the environmental profile. As an example, the constrained temperature excursion T could be set to 20C and the ramp ra
27、te T/t to 0.5C/minute, if these are the applicable environmental conditions. An additional consideration is the abruptness of the transition between ramping and constant temperature conditions. The second derivative of temperature versus time that occurs at such transitions is relevant for propertie
28、s such as the oscillator thermal control and system loop responses. If these transitions are applied too rapidly, it could cause unrealistic environmental conditions. The rate of change between ramping temperature and stable temperature conditions is for further study. 4 Rec. ITU-T G.8273/Y.1368 (20
29、13)/Amd.1 (01/2015) Appendix II Variable temperature holdover testing methodology (This appendix does not form an integral part of this Recommendation.) Appendix I describes temperature profile for generic variable temperature testing. This appendix describes details for variable temperature holdove
30、r testing methodology. For testing holdover, the duration of the test should correspond to the duration of the holdover period. The worst-case pattern is a temperature change that takes effect during the holdover period. Figure II.1 depicts negative and positive slope cases. Various starting tempera
31、tures would be used to cover the operating temperature range. Figure II.1 Variable temperature profile for holdover testing The test should be repeated at different test reference temperatures T, to cover the required temperature range. At a minimum the tests should be performed at nominal and tempe
32、rature extremes, i.e., the reference temperature T set to Tmin + T, Tnom and Tmax T. The test stabilisation time of ts period should be long enough to remove start-up effects while tH equates to the duration of the test for the corresponding period of the required holdover duration. The worst-case p
33、attern is a temperature change that remains during the holdover period. The constrained temperature excursion T and the ramp rate T/t should be aligned to the environmental profile. As an example, the constrained temperature excursion T could be set to 20oC and the ramp rate T/t to 0.5C/minute, if t
34、hese are the applicable environmental conditions. ITU-T Y-SERIES RECOMMENDATIONS GLOBAL INFORMATION INFRASTRUCTURE, INTERNET PROTOCOL ASPECTS AND NEXT-GENERATION NETWORKS GLOBAL INFORMATION INFRASTRUCTURE General Y.100Y.199 Services, applications and middleware Y.200Y.299 Network aspects Y.300Y.399
35、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 INTERNET PROTOCOL ASPECTS General Y.1000Y.1099 Services and applications Y.1100Y.1199 Architecture, access, network capabil
36、ities 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, administration and maintenance Y.1700Y.1799 Charging Y.1800Y.1899 IPTV over NGN Y.1900Y.1999 NEXT GENERATION NETWORKS
37、 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 Service aspects: Interoperability of services and networks in NGN Y.2250Y.2299 Enhancements to NGN Y.2300Y.2399 Netw
38、ork 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 grade open environment Y.2900Y.2999 FUTURE NETWORKS Y.3000Y.3499 CLOUD COMPUTING Y.3500Y.3999 For further details, p
39、lease 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 principles Series E Overall network operation, telephone service, service operation and human factors Series F Non-
40、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 signals Ser
41、ies 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 circuits
42、 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 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
