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Precision Time Protocol

About: Precision Time Protocol is a research topic. Over the lifetime, 604 publications have been published within this topic receiving 6006 citations. The topic is also known as: PTP & IEEE 1588.


Papers
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Proceedings ArticleDOI
25 Oct 2010
TL;DR: The paper explains the overall design goals, details the decisions taken, and highlights the resulting software architecture, and the results achieved using the new infrastructure.
Abstract: Many distributed systems need some sort of synchronization in order to achieve their objectives. The IEEE 1588 Precision Time Protocol (PTP) was designed to achieve synchronization among distributed clocks using a non-deterministic communication medium like Ethernet. Since Linux is becoming a leading operating system in areas like distributed measurement and control or industrial automation, we found it necessary to design and implement a PTP clock infrastructure within the Linux kernel. The paper explains the overall design goals, details the decisions taken, and highlights the resulting software architecture. The case study is based on the results achieved using the new infrastructure.

25 citations

Journal ArticleDOI
TL;DR: In this article, a systematic approach to the performance evaluation of commercially available PTP devices (grandmaster, slave, transparent, and boundary clocks) from a variety of manufacturers is presented.
Abstract: New substation automation applications, such as sampled value (SV) process buses and synchrophasors, require a sampling accuracy of 1 μs or better. The Precision Time Protocol (PTP), IEEE Std. 1588, achieves this level of performance and integrates well into Ethernet-based substation networks. This paper takes a systematic approach to the performance evaluation of commercially available PTP devices (grandmaster, slave, transparent, and boundary clocks) from a variety of manufacturers. The “error budget” is set by the performance requirements of each application. The “expenditure” of this error budget by each component is valuable information for a system designer. The component information is used to design a synchronization system that meets the overall functional requirements. The quantitative performance data presented show that this testing is effective and informative. Results from testing PTP performance in the presence of SV process bus traffic demonstrate the benefit of a “bottom-up” component testing approach combined with “top-down” system verification tests. A test method that uses a precision Ethernet capture card, rather than dedicated PTP test sets, to determine the correction field error of transparent clocks is presented. This test is particularly relevant for highly loaded Ethernet networks with stringent timing requirements. The methods presented can be used for development purposes by manufacturers or by system integrators for acceptance testing. An SV process bus was used as the test application for the systematic approach described in this paper. The test approach was applied, components were selected, and the system performance was verified to meet the application's requirements. Systematic testing, as presented in this paper, is applicable to a range of industries that use, rather than develop, PTP for time transfer.

25 citations

Journal ArticleDOI
TL;DR: A phasor measurement unit (PMU) integrating the white rabbit (WR) protocol and its experimental validation with a focus on the synchrophasor phase estimation in steady state conditions is presented, by using a PMU calibrator generating the reference signals.
Abstract: Within the context of time dissemination techniques for power systems applications, this paper discusses the use of the white rabbit (WR) protocol for synchrophasor networks. Specifically, this paper presents a phasor measurement unit (PMU) integrating the WR technology and its experimental validation with a focus on the synchrophasor phase estimation in steady state conditions, by using a PMU calibrator generating the reference signals. We further compare the accuracy of the developed PMU with other state-of-the-art time synchronization technologies for PMUs, i.e., global positioning system (GPS) and precision time protocol (PTP), demonstrating applicability of WR for PMU sensing networks.

25 citations

Patent
James Aweya1
01 Oct 2013
TL;DR: In this article, a method for time offset alignment with packet delay variations (PDVs) compensation where a synchronized frequency signal is available at a slave device via Synchronous Ethernet and is used to determine the compensation parameters for the PDV is presented.
Abstract: This invention relates to methods and devices for time and frequency synchronization The invention has particular application where time and frequency synchronization over packet networks using, for example, the IEEE 1588 Precision Time Protocol (PTP) is being carried out The primary challenge in clock distribution over packet networks is the variable transit delays experienced by timing packets, packet delay variations (PDVs) Embodiments of the invention provide a method for time offset alignment with PDV compensation where a synchronized frequency signal is available at a slave device via Synchronous Ethernet and is used to determine the compensation parameters for the PDV

25 citations

Proceedings ArticleDOI
06 Nov 2014
TL;DR: R reversePTP is introduced, a clock synchronization protocol for SDN based on PTP, but is conceptually reversed; in ReversePTP all nodes (switches) in the network distribute timing information to a single node, the controller, that tracks the state of all the clocks in thenetwork.
Abstract: Accurate time can be a useful tool in Software Defined Networks (SDN), allowing to coordinate network updates and topology changes, and to timestamp events and notifications. Moreover, accurate time is used in various environments in which software defined networking is being considered, making accurate time distribution an essential feature of SDNs. Accurate timekeeping requires a clock synchronization method, such as the Precision Time Protocol (PTP). Contrary to the centralized SDN paradigm, PTP is by nature a distributed protocol, in which every node is required to run a complex clock servo algorithm. We introduce ReversePTP, a clock synchronization protocol for SDN. ReversePTP is based on PTP, but is conceptually reversed; in ReversePTP all nodes (switches) in the network distribute timing information to a single node, the controller, that tracks the state of all the clocks in the network. Hence, all computations and bookkeeping are performed by the controller, whereas the ‘dumb’ switches are only required to send it their current time periodically. In accordance with the SDN paradigm, the controller is the ‘brain’, making ReversePTP flexible and programmable from an SDN programmer's perspective. We present the ReversePTP architecture, and discuss how SDN applications that require accurate time can use ReversePTP. Our experimental evaluation of a network with 34 ReversePTP-enabled nodes shows that ReversePTP can be effectively used for coordinating events in networks at the same level of accuracy as provided by the conventional PTP.

25 citations


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Performance
Metrics
No. of papers in the topic in previous years
YearPapers
202126
202045
201936
201839
201732
201654