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 (07/2014) 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 protocol aspects Transport Precision time protocol telecom profile for phase/time synchronization with full timing support from the network Recommendation ITU-T G.8275.1/Y.1369.1 ITU-T G-
3、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 INTERNATIONAL CARRIER TELEPHONE SYSTEMS
4、 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 MEDIA AND OPTICAL SYSTEMS CHARACTERISTICS G.
5、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.6000G.6999 DATA OVER TRANSPORT GENERIC ASPE
6、CTS 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.9000G.9999 For further details, please re
7、fer to the list of ITU-T Recommendations. Rec. ITU-T G.8275.1/Y.1369.1 (07/2014) i 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 Summary Recommendation ITU-T G.8275.1/Y.1369.1 contains the ITU-T
8、 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 Std 1588-2008 in a manner consistent with the architecture described in Recommendation ITU-T G.8275/Y.1369. History Edition Recommendati
9、on 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 (2014) Cor. 1 2015-01-13 15 11.1002/1000/12397 Keywords IEEE 1588, PTP, phase and time synchronization, full timing support. _ * To access the Recommendation, type the URL http
10、:/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 (07/2014) FOREWORD The International Telecommunication Union (ITU) is the United Nations specialized agency
11、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 Recommendations on them with a view to
12、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 of ITU-T Recommendations
13、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“ is used for conciseness t
14、o 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 with the Recommendation is
15、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 required of any party. INTELLEC
16、TUAL 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 Intellectual Property Rights, whethe
17、r 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. However, implementers are caut
18、ioned 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 publication may be reproduced, by any means whatsoever, without the prior written permission of
19、ITU. Rec. ITU-T G.8275.1/Y.1369.1 (07/2014) 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 distribution 3 6.1 High-level desi
20、gn requirements 3 6.2 PTP modes and options 4 6.3 Protection aspects and Alternate BMCA 6 6.4 Phase/time traceability information 12 7 ITU-T PTP profile for phase/time distribution with full timing support from the network . 14 8 Security aspects 14 Annex A ITU-T PTP profile for phase/time distribut
21、ion with full timing support from the network . 15 A.1 Profile identification . 15 A.2 PTP attribute values 15 A.3 PTP options 20 A.4 Best master clock algorithm (BMCA) options . 20 A.5 Path delay measurement option (delay request/delay response) 20 A.6 Clock identity format 20 A.7 Configuration man
22、agement options . 20 A.8 Security aspects 20 A.9 Other optional features of IEEE Std 1588-2008 . 20 A.10 PTP common header flags 21 Annex B Options to establish the PTP topology with the Alternate BMCA 22 Annex C Inclusion of an external phase/time input interface in a T-BC 23 Appendix I Considerati
23、ons on the use of transparent clock 24 Appendix II Considerations on the transmission of Delay_Req messages . 25 Appendix III Considerations on the default PTP Ethernet multicast address . 27 Appendix IV Considerations on the use of priority2 28 Appendix V Description of PTP clock states and associa
24、ted contents of Announce messages . 29 V.1 Purpose of the appendix . 29 V.2 Description of the states . 29 iv Rec. ITU-T G.8275.1/Y.1369.1 (07/2014) Page V.3 Example of mapping between PTP port states and PTP clock states for a 3-port T-BC 31 V.4 T-GM Announce message contents based on the internal
25、PTP clock states 32 V.5 T-BC Announce message contents based on the internal PTP clock states . 33 Rec. ITU-T G.8275.1/Y.1369.1 (07/2014) 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 1 Scope
26、This Recommendation specifies a profile for telecommunication applications based on IEEE Std 1588-2008 Precision Time Protocol (PTP). The profile specifies the IEEE Std 1588-2008 functions that are necessary to ensure network element interoperability for the delivery of accurate phase/time synchroni
27、zation. 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. The first version of the profile specifies the high-level design requirements, modes of operation for the exchange of PTP messages, the PTP pr
28、otocol mapping, the best master clock algorithm options, as well as the PTP protocol configuration parameters. NOTE The parameters defined in the first version of the profile have been chosen based on the case where physical layer frequency support is provided. This Recommendation also specifies som
29、e 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 provisions which, through reference in this text, constitute provisions of this Recommendation. At the tim
30、e 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 possibility of applying the most recent edition of the Recommendations and other references listed below. A
31、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 Recommendation. ITU-T G.781 Recommendation ITU-T G.781 (2008), Synchronization layer functions. ITU-T G.810 Re
32、commendation ITU-T G.810 (1996), Definitions and terminology for synchronization networks. ITU-T G.8260 Recommendation ITU-T G.8260 (2012), 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 teleco
33、m profile for frequency synchronization. ITU-T G.8271.1 Recommendation ITU-T G.8271.1/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. ITU-T G.8273 Recommendat
34、ion 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), Architecture and requirements for
35、 packet-based time and phase distribution. 2 Rec. ITU-T G.8275.1/Y.1369.1 (07/2014) IEEE 1588 IEEE Std 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 followi
36、ng 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 Recommendation None. 4 Abbreviations and acronyms This Recommendation uses the following abbreviations and acronyms: BC Boundary Clock BMCA Best
37、Master Clock Algorithm EEC synchronous Ethernet Equipment Clock EUI Extended Unique Identifier GM Grandmaster GNSS Global Navigation Satellite System OC Ordinary Clock PRC Primary Reference Clock PRS Primary Reference Source PRTC Primary Reference Time Clock PTP Precision Time Protocol QL Quality Le
38、vel SSU Synchronization Supply Unit SSU-A primary level SSU SSU-B secondary level SSU SDH Synchronous Digital Hierarchy SSM Synchronization Status Message ST2 Stratum 2 ST3E Stratum 3 Enhanced T-BC Telecom Boundary Clock TC Transparent Clock T-GM Telecom Grandmaster T-TC Telecom Transparent Clock T-
39、TSC Telecom Time Slave Clock VLAN Virtual Local Area Network Rec. ITU-T G.8275.1/Y.1369.1 (07/2014) 3 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
40、 defined in IEEE 1588 and are identified using italicized text. The term Telecom Boundary Clock (T-BC) refers to a device consisting of a boundary clock (BC) as defined in IEEE 1588 and this Recommendation, with additional performance characteristics defined in ITU-T G.8273.2. The term Telecom Trans
41、parent Clock (T-TC) refers to a device consisting of a transparent clock (TC) as defined in IEEE 1588, with additional performance characteristics for further study. The term Telecom Grandmaster (T-GM) refers to a device consisting of a grandmaster (GM) clock as defined in IEEE 1588 and this Recomme
42、ndation, with additional performance characteristics for further study. The term Telecom Time Slave Clock (T-TSC) refers to a device consisting of a slave-only ordinary clock (OC) as defined in IEEE 1588 and this Recommendation, with additional performance characteristics defined in the Annex C of I
43、TU-T G.8273.2. 6 Use of PTP for phase/time distribution The first version of the IEEE 1588 was developed by the IEEE initially to support the timing requirements of industrial automation, and defines the Precision Time Protocol (PTP) designed to enable accurate time transfer in this context. The sec
44、ond version of IEEE 1588 (defined in IEEE 1588) contains features useful to the transport of the protocol over a wide area network, and introduces the concept of “profile“, whereby aspects of the protocol may be selected and specified for a particular use other than the originally intended industria
45、l automation. A PTP profile has been defined by ITU-T in ITU-T G.8265.1 to address applications requiring frequency synchronization only. This Recommendation defines another PTP profile, for telecom applications requiring accurate phase and time synchronization. It supports the specific architecture
46、 described in ITU-T G.8275 in order to allow the distribution of phase/time with full timing support from the network, and is based on the second version of PTP defined in IEEE 1588. In order to claim compliance with the telecom profile, the requirements of this Recommendation and the relevant requi
47、rements of IEEE 1588, as referenced in Annex A, must be met. The detailed aspects related to the telecom profile are described in the following clauses, while the profile itself is contained in Annex A. It follows the general rules for profile specification developed in IEEE 1588. This PTP telecom p
48、rofile defines the parameters from IEEE 1588 to be used in order to guarantee protocol interoperability between implementations and specifies the optional features, default values of configurable attributes and mechanisms that must be supported. However, it does not guarantee that the performance re
49、quirements of a given application will be met. These performance aspects are defined in other ITU-T Recommendations, and imply additional elements beyond the content of the PTP profile itself. 6.1 High-level design requirements IEEE 1588 states in subclause 19.3.1.1: “The purpose of a PTP profile is to allow organizations to specify specific selections of attribute values and optional features of PTP that, when using the same transport pr
