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.8275.1/Y.1369.1 TELECOMMUNICATION STANDARDIZATION SECTOR OF ITU Amendment 1 (08/2017) SERIES G: TRANSMISSION SYSTEMS AND MEDIA, DIGITAL SYSTEMS AND NETWORKS Packet over Transport aspects Synchronization, quality and avail
2、ability targets SERIES Y: GLOBAL INFORMATION INFRASTRUCTURE, INTERNET PROTOCOL ASPECTS, NEXT-GENERATION NETWORKS, INTERNET OF THINGS AND SMART CITIES Internet protocol aspects Transport Precision time protocol telecom profile for phase/time synchronization with full timing support from the network A
3、mendment 1 Recommendation ITU-T G.8275.1/Y.1369.1 (2016) Amendment 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 ANALOGUE CARRIER-TRANSMISSION SYSTEMS G.2
4、00G.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 AND LINE T
5、ELEPHONY 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 MULTIMEDIA QUALITY OF SERVICE AND PERFORMANCE GENERIC AND USER-RELATED ASPECTS G.1000G.1999 TRA
6、NSMISSION MEDIA CHARACTERISTICS G.6000G.6999 DATA OVER TRANSPORT GENERIC ASPECTS G.7000G.7999 PACKET OVER TRANSPORT ASPECTS 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 Manage
7、ment G.8600G.8699 ACCESS NETWORKS G.9000G.9999 For further details, please refer to the list of ITU-T Recommendations. Rec. ITU-T G.8275.1/Y.1369.1 (2016)/Amd.1 (08/2017) i Recommendation ITU-T G.8275.1/Y.1369.1 Precision time protocol telecom profile for phase/time synchronization with full timing
8、support from the network Amendment 1 Summary Recommendation ITU-T G.8275.1/Y.1369.1 contains the ITU-T precision time protocol (PTP) profile for phase and time distribution with full timing support from the network. It provides the necessary details to utilize IEEE 1588 in a manner consistent with t
9、he architecture described in Recommendation ITU-T G.8275/Y.1369. Amendment 1 provides the following updates: added ITU-T G.8271 to references; addition of a new definition: special port (3.2); clarification on the use of logMessageInterval in Delay_Resp messages (6.2.8); clarification on the behavio
10、ur of the T-BC Announce message contents when the T-BC has a parent clock; incremented the minor revision number of the profileVersion (Annex A); correction to the handling of the alternateMasterFlag; added informative text on the handling of the synchronizationUncertain flag (Annex E); added monito
11、ring of a PTP MASTER port by a PTP PASSIVE port (Annex G); updates to Announce message fields of currentUtcOffset and synchronizationUncertain when using PTP clock states (Appendix V); update of Appendix VII; added informative use cases for the use of the priority2 attribute (Appendix X); added cons
12、iderations on native access equipment (Appendix XI); added monitoring alternate master time information provided by a peer PTP port (Appendix XII). History Edition Recommendation Approval Study Group Unique ID* 1.0 ITU-T G.8275.1/Y.1369.1 2014-07-22 15 11.1002/1000/12197 1.1 ITU-T G.8275.1/Y.1369.1
13、(2014) Cor. 1 2015-01-13 15 11.1002/1000/12397 2.0 ITU-T G.8275.1/Y.1369.1 2016-06-22 15 11.1002/1000/12815 2.1 ITU-T G.8275.1/Y.1369.1 (2016) Amd. 1 2017-08-29 15 11.1002/1000/13329 Keywords Full timing support, IEEE 1588, phase and time synchronization, PTP, telecom profile. * To access the Recomm
14、endation, 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.8275.1/Y.1369.1 (2016)/Amd.1 (08/2017) FOREWORD The International Telecommunication Union (ITU) i
15、s 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 tariff questions and issuing
16、 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 these topics
17、. 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 expression “A
18、dministration“ 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 applicability) an
19、d 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 Recommend
20、ation 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 concerning the evidence, validity or applicability of clai
21、med 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 patents, which may be required to implement this Recomm
22、endation. 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 2017 All rights reserved. No part of this publication may be reproduced, by any means whatsoever,
23、without the prior written permission of ITU. Rec. ITU-T G.8275.1/Y.1369.1 (2016)/Amd.1 (08/2017) iii Table of Contents Page 1 Scope . 1 2 References . 1 3 Definitions 2 3.1 Terms defined elsewhere 2 3.2 Terms defined in this Recommendation . 2 4 Abbreviations and acronyms 2 5 Conventions 3 6 Use of
24、PTP for phase/time distribution 3 6.1 High-level design requirements 4 6.2 PTP modes and options 4 6.3 Protection aspects and Alternate BMCA 8 6.4 Phase/time traceability information 15 7 ITU-T PTP profile for phase/time distribution with full timing support from the network . 20 8 Security aspects
25、20 Annex A ITU-T PTP profile for phase/time distribution with full timing support from the network . 21 A.1 Profile identification . 21 A.2 PTP attribute values 21 A.3 PTP options 27 A.4 Best master clock algorithm options 27 A.5 Path delay measurement option (delay request/delay response) 27 A.6 Cl
26、ock identity format 27 A.7 Configuration management options . 28 A.8 Security aspects 28 A.9 Other optional features of IEEE 1588 28 A.10 PTP common header flags 28 Annex B Options to establish the PTP topology with the Alternate BMCA 30 Annex C Inclusion of an external phase/time input interface in
27、 a T-BC 31 Annex D Path trace (optional) 32 Annex E Synchronization uncertain indication (optional) 33 Annex F Use of stepsRemoved to limit reference chain (optional) 34 Annex G Monitoring a PTP MASTER port by a PTP PASSIVE port (optional) 35 Appendix I Considerations on the use of transparent clock
28、 36 Appendix II Considerations on the transmission of Delay_Req messages . 37 Appendix III Considerations on the choice of the PTP Ethernet multicast destination address 39 iv Rec. ITU-T G.8275.1/Y.1369.1 (2016)/Amd.1 (08/2017) Page Appendix IV Considerations on the use of priority2 40 Appendix V De
29、scription of PTP clock states and associated contents of Announce messages . 41 V.1 Purpose of the appendix . 41 V.2 Description of the states . 41 V.3 Example of mapping between PTP port states and PTP clock states for a 3-port T-BC 43 V.4 T-GM Announce message contents based on the internal PTP cl
30、ock states 44 V.5 T-BC Announce message contents based on the internal PTP clock states . 47 Appendix VI Operations over link aggregation 50 Appendix VII Relationship between clockClass and holdover specification . 51 Appendix VIII Considerations on a T-TSC connected to an end application 54 Appendi
31、x IX Calculation of offsetScaledLogVariance for T-GM timed by PRTC or ePRTC. 55 IX.1 Observation interval and TDEV noise generation 55 IX.2 Computation of PTP variance from TDEV 55 IX.3 Computation of offsetScaledLogVariance from PTP variance 56 Appendix X Description of a T-BC extended clockClass a
32、pplication 58 X.1 Purpose of T-BC extended clockClass application 58 X.2 DefaultDS data set member specifications under this extended application 58 Appendix XI Considerations on native access equipment 60 Appendix XII Monitoring alternate master time information provided by a peer PTP port 62 Bibli
33、ography. 63 Rec. ITU-T G.8275.1/Y.1369.1 (2016)/Amd.1 (08/2017) 1 Recommendation ITU-T G.8275.1/Y.1369.1 Precision time protocol telecom profile for phase/time synchronization with full timing support from the network Amendment 1 Editorial note: This is a complete-text publication. Modifications int
34、roduced by this amendment are shown in revision marks relative to Recommendation ITU-T G.8275.1/Y.1369.1 (2016). 1 Scope This Recommendation specifies a profile for telecommunication applications based on IEEE 1588 precision time protocol (PTP). The profile specifies the IEEE 1588 functions that are
35、 necessary to ensure network element interoperability for the delivery of accurate phase/time synchronization. The profile is based on the full timing support from the network architecture as described in ITU-T G.8275 and definitions described in ITU-T G.8260. This version of the profile specifies t
36、he high-level design requirements, modes of operation for the exchange of PTP messages, the PTP protocol mapping, the best master clock algorithm (BMCA) options, as well as the PTP protocol configuration parameters. NOTE The parameters defined in the first version of the profile have been chosen bas
37、ed on the case where physical layer frequency support is provided. This Recommendation also specifies some aspects necessary for use in a telecom environment that are outside the scope of, and complement the PTP profile. 2 References The following ITU-T Recommendations and other references contain p
38、rovisions which, through reference in this text, constitute provisions of this Recommendation. At the time of publication, the editions indicated were valid. All Recommendations and other references are subject to revision; users of this Recommendation are therefore encouraged to investigate the pos
39、sibility of applying the most recent edition of the Recommendations and other references listed below. A list of the currently valid ITU-T Recommendations is regularly published. The reference to a document within this Recommendation does not give it, as a stand-alone document, the status of a Recom
40、mendation. ITU-T G.781 Recommendation ITU-T G.781 (2008), Synchronization layer functions. ITU-T G.810 Recommendation ITU-T G.810 (1996), Definitions and terminology for synchronization networks. ITU-T G.8260 Recommendation ITU-T G.8260 (2015), Definitions and terminology for synchronization in pack
41、et networks. ITU-T G.8265.1 Recommendation ITU-T G.8265.1/Y.1365.1 (2014), Precision time protocol telecom profile for frequency synchronization. ITU-T G.8271 Recommendation ITU-T G.8271/Y.1366 (2016), Time and phase synchronization aspects of packet networks. ITU-T G.8271.1 Recommendation ITU-T G.8
42、271.1/Y.1366.1 (2013), Network limits for time synchronization in packet networks. ITU-T G.8272 Recommendation ITU-T G.8272/Y.1367 (2012), Timing characteristics of primary reference time clocks. 2 Rec. ITU-T G.8275.1/Y.1369.1 (2016)/Amd.1 (08/2017) ITU-T G.8273 Recommendation ITU-T G.8273/Y.1368 (2
43、013), Framework of phase and time clocks. ITU-T G.8273.2 Recommendation ITU-T G.8273.2/Y.1368.2 (2014), Timing characteristics of telecom boundary clocks and telecom time slave clocks. ITU-T G.8275 Recommendation ITU-T G.8275/Y.1369 (2013), Architecture and requirements for packet-based time and pha
44、se distribution. IEEE 1588 IEEE 1588-2008, IEEE Standard for a Precision Clock Synchronization Protocol for Networked Measurement and Control Systems. 3 Definitions 3.1 Terms defined elsewhere This Recommendation uses the following terms defined elsewhere: The terms and definitions used in this Reco
45、mmendation are contained in ITU-T G.810 and ITU-T G.8260. 3.2 Terms defined in this Recommendation This Recommendation defines the following term: 3.2.1 special port: A PTP special port is a PTP port that translates between the native timing mechanism of a medium and PTP. None. 4 Abbreviations and a
46、cronyms This Recommendation uses the following abbreviations and acronyms: AVAR Allan Variance BC Boundary Clock BMCA Best Master Clock Algorithm EEC synchronous Ethernet Equipment Clock ePRTC Enhanced Primary Reference Time Clock EUI Extended Unique Identifier FPM Flicker Phase Modulation GM Grandm
47、aster GNSS Global Navigation Satellite System LAG Link Aggregation MVAR Modified Allan Variance OC Ordinary Clock PRC Primary Reference Clock PRS Primary Reference Source PRTC Primary Reference Time Clock PSD Power Spectral Density PTP Precision Time Protocol Rec. ITU-T G.8275.1/Y.1369.1 (2016)/Amd.
48、1 (08/2017) 3 QL Quality Level SDH Synchronous Digital Hierarchy SSM Synchronization Status Message SSU Synchronization Supply Unit SSU-A primary level SSU SSU-B secondary level SSU ST2 Stratum 2 ST3E Stratum 3 Enhanced T-BC Telecom Boundary Clock TC Transparent Clock T-GM Telecom Grandmaster T-TC T
49、elecom Transparent Clock T-TSC Telecom Time Slave Clock TLV Type Length Value TVAR Time Variance VLAN Virtual Local Area Network WPM White Phase Modulation 5 Conventions Within this Recommendation, the following conventions are used: the term PTP refers to the PTP version 2 protocol defined in IEEE 1588. PTP messages used within this Recommendation are defined in IEEE 1588 and are identified using italicized text. The term
