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.8265.1/Y.1365.1 TELECOMMUNICATION STANDARDIZATION SECTOR OF ITU Corrigendum 1 (04/2016) SERIES G: TRANSMISSION SYSTEMS AND MEDIA, DIGITAL SYSTEMS AND NETWORKS Packet over Transport aspects Synchronization, quality and ava
2、ilability targets 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 frequency synchronization Corrigendum 1 Recommendation ITU-T G.82
3、65.1/Y.1365.1 (2014) Corrigendum 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.200G.299 INDIVIDUAL CHARACTERISTICS
4、 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 TELEPHONY G.450G.499 TRANSMISSION M
5、EDIA 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.
6、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 Management G.8600G.8699 ACCESS NETWORKS
7、G.9000G.9999 For further details, please refer to the list of ITU-T Recommendations. Rec. ITU-T G.8265.1/Y.1365.1 (2014)/Cor.1 (04/2016) i Recommendation ITU-T G.8265.1/Y.1365.1 Precision time protocol telecom profile for frequency synchronization Corrigendum 1 Summary Recommendation ITU-T G.8265.1/
8、Y.1365.1 contains the ITU-T precision time protocol (PTP) profile for frequency distribution without timing support from 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.8265/Y.1365. Th
9、is edition of the Recommendation defines the PTP profile for unicast mode only. Future editions of the Recommendation will contain a separate profile for a mixed unicast/multicast case. Corrigendum 1 corrects the specification format of the logInterMessageInterval parameter that specified the minimu
10、m message period for the telecom profile for frequency, and corrects text to clarify that only negotiated unicast mode is used. History Edition Recommendation Approval Study Group Unique ID* 1.0 ITU-T G.8265.1/Y.1365.1 2010-10-07 15 11.1002/1000/10911 1.1 ITU-T G.8265.1/Y.1365.1 (2010) Amd. 1 2011-0
11、4-13 15 11.1002/1000/11143 1.2 ITU-T G.8265.1/Y.1365.1 (2010) Amd. 2 2012-10-29 15 11.1002/1000/11821 2.0 ITU-T G.8265.1/Y.1365.1 2014-07-22 15 11.1002/1000/12193 2.1 ITU-T G.8265.1/Y.1365.1 (2014) Cor. 1 2016-04-13 15 11.1002/1000/12811 _ * To access the Recommendation, type the URL http:/handle.it
12、u.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.8265.1/Y.1365.1 (2014)/Cor.1 (04/2016) FOREWORD The International Telecommunication Union (ITU) is the United Nations specialized agenc
13、y 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 t
14、o 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 Recommendation
15、s 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
16、 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 with the Recommendation i
17、s 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. INTELL
18、ECTUAL 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, whet
19、her asserted by ITU members or others outside of the Recommendation development process. As of the date of approval of this Recommendation, ITU had received notice of intellectual property, protected by patents, which may be required to implement this Recommendation. However, implementers are cautio
20、ned 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 prior written permission of IT
21、U. Rec. ITU-T G.8265.1/Y.1365.1 (2014)/Cor.1 (04/2016) iii Table of Contents Page 1 Scope . 1 2 References . 1 3 Definitions 1 3.1 Terms defined elsewhere 1 3.2 Terms defined in this Recommendation . 2 4 Abbreviations and acronyms 2 5 Conventions 2 6 Use of PTP for frequency distribution 2 6.1 High-
22、level design requirements 3 6.2 General description . 4 6.3 PTP modes 5 6.4 PTP mapping 6 6.5 Message rates 6 6.6 Unicast message negotiation 7 6.7 Alternate BMCA, telecom slave model and master selection process . 9 6.8 Additional protection functions 14 7 ITU-T PTP profile for frequency distributi
23、on without timing support from the network . 15 8 Security aspects 15 Annex A ITU-T PTP profile for frequency distribution without timing support from the network (unicast mode) 16 A.1 Profile identification . 16 A.2 PTP attribute values 16 A.3 PTP options 20 A.4 Best master clock algorithm (BMCA) o
24、ptions . 21 A.5 Path delay measurement option (delay request/delay response) 21 A.6 Configuration management options . 21 A.7 Clock identity format 21 A.8 Flags used by this profile 21 A.9 Control field (controlField) 22 Appendix I Use of mixed unicast/multicast mode for PTP messages 23 Rec. ITU-T G
25、.8265.1/Y.1365.1 (2014)/Cor.1 (04/2016) 1 Recommendation ITU-T G.8265.1/Y.1365.1 Precision time protocol telecom profile for frequency synchronization Corrigendum 1 Editorial note: This is a complete-text publication. Modifications introduced by this corrigendum are shown in revision marks relative
26、to Recommendation ITU-T G.8265.1/Y.1365.1 (2014). 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 d
27、elivery of frequency only. The profile is based on the architecture described in ITU-T G.8265 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 protocol mapping, the u
28、se of unicast transmission and negotiation, an alternate best master clock algorithm (BMCA), as well as the PTP protocol configuration parameters. The support for mixed unicast/multicast or static unicast modes is for further study. This Recommendation also specifies some aspects necessary for use i
29、n a telecom environment which 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 time of publication, the editio
30、ns 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 the currently valid
31、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.8260 Recommendation ITU-T G.8260 (
32、2012), Definitions and terminology for synchronization in packet networks. ITU-T G.8265 Recommendation ITU-T G.8265/Y.1365 (2010), Architecture and requirements for packet-based frequency delivery. IEEE 1588 IEEE Std 1588-2008, Standard for a Precision Clock Synchronization Protocol for Networked Me
33、asurement and Control Systems. 3 Definitions 3.1 Terms defined elsewhere This Recommendation uses the following terms defined elsewhere: 3.1.1 packet master clock ITU-T G.8260 3.1.2 packet slave clock ITU-T G.8260 3.1.3 packet timing signal ITU-T G.8260 2 Rec. ITU-T G.8265.1/Y.1365.1 (2014)/Cor.1 (0
34、4/2016) 3.2 Terms defined in this Recommendation None. 4 Abbreviations and acronyms This Recommendation uses the following abbreviations and acronyms: BMC Best Master Clock BMCA Best Master Clock Algorithm EUI Extended Unique Identifier GM Grand Master NTP Network Time Protocol OC Ordinary Clock Par
35、entDS Parent Data Set (terminology used in IEEE 1588) LSP Label Switched Path MPLS Multi-Protocol Label Switching PDV Packet Delay Variation PTP Precision Time Protocol PTSF Packet Timing Signal Fail QL Quality Level SDH Synchronous Digital Hierarchy SOOC Slave-Only Ordinary Clock SSM Synchronizatio
36、n Status Message SyncE Synchronous Ethernet TLV Type Length Value 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. The term “slave“ or “slav
37、e clock“ refers to a “slave-only ordinary clock“ (SOOC) as defined in clause 9.2.2 of IEEE 1588. A “Telecom Slave“ is a device consisting of one or more SOOCs. The term “master“ or “packet master“ or “packet master clock“ refers to a grand master as defined in IEEE 1588. PTP messages used within thi
38、s Recommendation are defined in IEEE-1588 and are identified using italicized text. 6 Use of PTP for frequency distribution IEEE 1588 has been developed by the IEEE initially to support the timing requirements of industrial automation. The IEEE 1588 standard contains the precision time protocol (PTP
39、) that was designed to enable accurate time transfer. Subsequent to the publication of the first version of the standard, work began on developing a second version of the standard which contains features useful to the transport of the protocol over a wide area Rec. ITU-T G.8265.1/Y.1365.1 (2014)/Cor
40、.1 (04/2016) 3 network. This “Version 2“ of IEEE 1588 also introduces the concept of the “profile“, whereby aspects of the protocol may be selected and specified for a particular use other than the originally intended industrial automation. This Recommendation defines the “profile for telecom“ appli
41、cations in order to support the specific architectures described in ITU-T G.8265. In order to claim compliance with the telecom profile, the requirements of this Recommendation and the relevant requirements of IEEE 1588, as referenced in Annex A, must be met. The detailed aspects related to the tele
42、com 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. The IEEE 1588 telecom profile defined within this Recommendation is intended to be used by applications that need frequ
43、ency synchronization only. It does not cover applications where there is need for phase alignment and/or time of the day. This profile addresses the case where the PTP masters and slaves will be used in networks where there is no support for the PTP protocol in any intermediate node between the PTP
44、master and the PTP slave. It is also important to note that the default PTP protocol is based on multicast. This profile uses only the negotiated unicast mode. The use of mixed unicast/multicast operation or static unicast mode is for further study. This PTP telecom profile defines the IEEE 1588 par
45、ameters 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 requirements of a given application wil
46、l be met. Those performance aspects are currently under study, and imply additional elements beyond the content of the PTP profile itself. 6.1 High-level design requirements IEEE 1588 states in clause 19.3.1.1: “The purpose of a PTP profile is to allow organizations to specify specific selections of
47、 attribute values and optional features of PTP that, when using the same transport protocol, inter-work and achieve a performance that meets the requirements of a particular application.“ For operation in the telecom network, some additional criteria are also required to be consistent with standard
48、telecom synchronization practices. With that in mind, high-level objectives for the PTP profile for frequency distribution are: 1) To allow interoperability between PTP master clocks and PTP slave clocks compliant with the profile. This means that PTP master clocks compliant with the profile must ha
49、ve the ability to serve multiple PTP slave clocks from different vendors, and slaves require the ability to derive synchronization from one or more masters from different vendors. 2) To permit operation over managed, wide-area packet-based telecom networks. This may include networks based on protocols such as Ethernet, IP and multi-protocol label switching (MPLS), and combinations thereof. 3) To define message rates and parameter values consistent with frequency distr
