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.8275.2/Y.1369.2 TELECOMMUNICATION STANDARDIZATION SECTOR OF ITU (06/2016) SERIES G: TRANSMISSION SYSTEMS AND MEDIA, DIGITAL SYSTEMS AND NETWORKS Packet over Transport aspects Synchronization, quality and availability targ
2、ets SERIES Y: GLOBAL INFORMATION INFRASTRUCTURE, INTERNET PROTOCOL ASPECTS AND NEXT-GENERATION NETWORKS, INTERNET OF THINGS AND SMART CITIES Internet protocol aspects Transport Precision time protocol telecom profile for phase/time synchronization with partial timing support from the network Recomme
3、ndation ITU-T G.8275.2/Y.1369.2 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.200G.299 INDIVIDUAL CHARACTERISTICS OF
4、 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 TELEPHONY G.450G.499 TRANSMISSION MEDI
5、A 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 TRANSMISSION MEDIA CHARACTERISTICS G.600
6、0G.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 Management G.8600G.8699 ACCESS NETWORKS G.9
7、000G.9999 For further details, please refer to the list of ITU-T Recommendations. ITU-T Y-SERIES RECOMMENDATIONS GLOBAL INFORMATION INFRASTRUCTURE, INTERNET PROTOCOL ASPECTS AND NEXT-GENERATION NETWORKS, INTERNET OF THINGS AND SMART CITIES GLOBAL INFORMATION INFRASTRUCTURE General Y.100Y.199 Service
8、s, 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 INTERNET PROTOCOL ASPECTS General Y.1000Y.1099 Service
9、s 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, administration and maintenance Y.1700Y.1799 Char
10、ging 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 Service aspects: Interoperability of services a
11、nd 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 grade open environment Y.2900Y.2999 FUTURE NETW
12、ORKS Y.3000Y.3499 CLOUD COMPUTING Y.3500Y.3999 INTERNET OF THINGS AND SMART CITIES AND COMMUNITIES General Y.4000Y.4049 Definitions and terminologies Y.4050Y.4099 Requirements and use cases Y.4100Y.4249 Infrastructure, connectivity and networks Y.4250Y.4399 Frameworks, architectures and protocols Y.
13、4400Y.4549 Services, applications, computation and data processing Y.4550Y.4699 Management, control and performance Y.4700Y.4799 Identification and security Y.4800Y.4899 For further details, please refer to the list of ITU-T Recommendations. Rec. ITU-T G.8275.2/Y.1369.2 (06/2016) i Recommendation IT
14、U-T G.8275.2/Y.1369.2 Precision time protocol telecom profile for phase/time synchronization with partial timing support from the network Summary Recommendation ITU-T G.8275.2/Y.1369.2 contains the ITU-T precision time protocol (PTP) profile for phase/time distribution with partial timing support fr
15、om the network (unicast mode). It provides the necessary details to utilize IEEE 1588 in a manner consistent with the architecture described in Recommendation ITU-T G. 8275/Y.1369. This Recommendation defines the PTP profile for unicast mode only. Future editions of this Recommendation may contain a
16、 separate profile for a mixed unicast/multicast case. History Edition Recommendation Approval Study Group Unique ID* 1.0 ITU-T G.8275.2/Y.1369.2 2016-06-22 15 11.1002/1000/12833 Keywords IEEE 1588, partial timing support, phase and time synchronization, PTP, telecom profile. * To access the Recommen
17、dation, 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.8275.2/Y.1369.2 (06/2016) FOREWORD The International Telecommunication Union (ITU) is the United Na
18、tions 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 Recommendation
19、s 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. The approval
20、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 “Administration“
21、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) and compliance wi
22、th 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 Recommendation is requir
23、ed 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 claimed Intellectua
24、l 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 Recommendation. Howev
25、er, 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 2016 All rights reserved. No part of this publication may be reproduced, by any means whatsoever, without the pri
26、or written permission of ITU. Rec. ITU-T G.8275.2/Y.1369.2 (06/2016) 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 PTP for phase/time distribut
27、ion 4 6.1 High-level design requirements 4 6.2 PTP modes and options 5 6.3 PTP modes 7 6.4 PTP mapping 8 6.5 Message rates 8 6.6 Unicast message negotiation 8 6.7 Alternate BMCA, telecom slave model and master selection process . 11 6.8 Phase/time traceability information 19 6.9 Use of alternate mas
28、ter flag 20 7 ITU-T PTP profile for phase/time distribution with partial timing support from the network . 21 8 Security aspects 21 Annex A ITU-T PTP profile for time distribution with partial timing support from the network (unicast mode) 22 A.1 Profile identification . 22 A.2 PTP attribute values
29、22 A.3 PTP options 26 A.4 Best master clock algorithm options 27 A.5 Path delay measurement option (delay request/delay response) 27 A.6 Configuration management options . 27 A.7 Clock identity format 28 A.8 Security aspects 28 A.9 Other optional features of IEEE 1588 28 A.10 PTP common header flags
30、 28 Annex B Options to establish the PTP topology with the Alternate BMCA 29 Annex C Inclusion of an external phase/time input interface on a PTP clock 30 Annex D TLV for PTP interface rate (optional) . 31 Annex E Synchronization uncertain indication (optional) 33 iv Rec. ITU-T G.8275.2/Y.1369.2 (06
31、/2016) Page Appendix I Considerations on the use of priority2 . 34 Appendix II Considerations on a T-TSC-A or T-TSC-P connected to an end application 35 Rec. ITU-T G.8275.2/Y.1369.2 (06/2016) 1 Recommendation ITU-T G.8275.2/Y.1369.2 Precision time protocol telecom profile for phase/time synchronizat
32、ion with partial timing support from the network 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 necessary to ensure network element interoperability for the de
33、livery of accurate phase/time (and frequency) synchronization. The profile is based on the partial timing support (PTS) from the network architecture as described in ITU-T G.8275 and definitions described in ITU-T G.8260. It is assumed that this profile will be used in well-planned cases where netwo
34、rk behaviour and performance can be constrained within well-defined limits, including limits on static asymmetry. Control of static asymmetries can be achieved in case of assisted partial timing support. Use of this profile in non-assisted mode would require careful considerations on how to control
35、static asymmetries. This version of the profile specifies the 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. Further information on th
36、e setup of the protocol in the network is planned to be included in future versions of this Recommendation. In particular, this information will be related to architectures that imply rearrangements of the synchronization direction, and to architectures that include clocks with multiple PTP ports, e
37、specially when ports not in the MASTER state provide synchronization services. At the time of publication of this profile, performance analysis, network limits, and clocks used in the profile, namely boundary and slave clocks, are for further study. This Recommendation also specifies some aspects ne
38、cessary for use in a telecom environment that are outside the scope of the PTP profile, but complement it. 2 References The following ITU-T Recommendations and other references contain provisions which, through reference in this text, constitute provisions of this Recommendation. At the time of publ
39、ication, the editions indicated were valid. All Recommendations and other references are subject to revision; users of this Recommendation are therefore encouraged to investigate the possibility of applying the most recent edition of the Recommendations and other references listed below. A list of t
40、he 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 Recommendation. ITU-T G.781 Recommendation ITU-T G.781 (2008), Synchronization layer functions. ITU-T G.810 Recommendat
41、ion 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 packet networks. ITU-T G.8265.1 Recommendation ITU-T G.8265.1/Y.1365.1 (2014), Precision time protocol telecom profile
42、 for frequency synchronization. ITU-T G.8271 Recommendation ITU-T G.8271/Y.1366 (2016), Time and phase synchronization aspects of packet networks. 2 Rec. ITU-T G.8275.2/Y.1369.2 (06/2016) ITU-T G.8272 Recommendation ITU-T G.8272/Y.1367 (2012), Timing characteristics of primary reference time clocks.
43、 ITU-T G.8273 Recommendation ITU-T G.8273/Y.1368 (2013), 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), Time and
44、 phase distribution through packet networks. ITU-T G.8275.1 Recommendation ITU-T G.8275.1/Y.1369.1 (2016), Precision time protocol telecom profile for phase/time synchronization with full timing support from the network. IEEE 1588 IEEE 1588 (2008), IEEE Standard for a Precision Clock Synchronization
45、 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 Recommendation are contained in ITU-T G.810 and ITU-T G.8260. 3.2 Terms defined in this Recommenda
46、tion None. 4 Abbreviations and acronyms This Recommendation uses the following abbreviations and acronyms: APTS Assisted Partial Timing Support BC Boundary Clock BMCA Best Master Clock Algorithm ePRTC Enhanced Primary Reference Time Clock EUI Extended Unique Identifier GM GrandMaster GNSS Global Nav
47、igation Satellite System IP Internet Protocol OC Ordinary Clock ParentDS Parent Data Set PDV Packet Delay Variation PRC Primary Reference Clock PRS Primary Reference Source PRTC Primary Reference Time Clock PTP Precision Time Protocol PTPVAR PTP Variance Rec. ITU-T G.8275.2/Y.1369.2 (06/2016) 3 PTS
48、Partial Timing Support PTSF Packet Timing Signal Fail QL Quality Level SDH Synchronous Digital Hierarchy SF Signal Fail 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-P Partial-Support Te
49、lecom Boundary Clock TC Transparent Clock T-GM Telecom Grandmaster TLV Type, Length, Value T-TC-P Partial-Support Telecom Transparent Clock T-TSC-A Assisted Partial-Support Telecom Time Slave Clock T-TSC-P Partial-Support Telecom Time Slave Clock UDP User Datagram Protocol VLAN Virtual Local Area Network 5 Conventions Within this Recommendation, the following conventions are used: the term PTP refers to the PTP version 2 protocol defined in IEEE 1588
