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Clock Synchronization in Distributed Systems Using NTP and PTP
Published in Richard Zurawski, Industrial Communication Technology Handbook, 2017
Reinhard Exel, Thilo Sauter, Paolo Ferrari, Stefano Rinaldi
PTP is a master–slave synchronization protocol defining mechanisms to find the best master in the network, and to synchronize all slave devices to the master. In the PTP nomenclature, all devices that participate in synchronization are termed clocks. Clocks can be categorized into ordinary clocks, boundary clocks, end-to-end transparent clocks, and peer-to-peer transparent clocks. The class of ordinary clocks consists of master clocks, which provide the time reference to other nodes, and slave clocks, which synchronize to a master clock. Figure 21.5 depicts the model of an ordinary clock. It consists of the local clock, the PTP control engine, the data and port data sets, timestamping functions for event messages, and application-specific functions. The latter are used, for instance, to generate timing signals, to trigger external actions, or to timestamp external signals. The core of an ordinary clock is the local clock, which contains a time indication device, depicted as watch, and a control servo, which performs adjustments in offset and skew as requested by the PTP protocol engine.
Network Synchronization in Industrial Wireless Sensor Networks
Published in V. Çağri Güngör, Gerhard P. Hancke, Industrial Wireless Sensor Networks, 2017
Network synchronization can be classified based on the strategy used to organize time dissemination. The two most fundamental strategies are: 1) Masterslave, and 2) Mutual Network Synchronization; other strategies have been derived from these two, such as hybrid master-slave, and hierarchical variants [4]. In the most fundamental master-slave approach there is a single (master) clock to which all the rest of the (slave) clocks synchronize to. The network topology can take any form, but it is typically modeled as a tree with the master clock at its root. In the mutual network synchronization approach every clock synchronizes to all of its neighbors. The mutual network synchronization approach has been investigated in the past within the context of wire line computer networks [7], and more recently within the context of wireless ad hoc networks [14]. Convergence and stability of the mutual network synchronization approach has been proved under certain scenarios. However, there are still open problems that make this an interesting research area.
Timing Synchronization System on RF-Driven Neutral Beam Injection System
Published in Fusion Science and Technology, 2022
Y. Li, C. D. Hu, Y. Z. Zhao, Q. L. Cui, X. L. Shu, Y. H. Xie, W. Liu
By contrast, the PTP defined in IEEE1588 can effectively improve the time synchronization accuracy and reach the submicrosecond synchronization accuracy through the timestamp confirmation mechanism and medium access control (MAC) layer timestamp stamping. PTP divides the synchronous network into master and slave devices. The slave will correct its own clock according to the offset and delay obtained so that the master and slave clock have the same clock benchmark. The distributed network controlled by the PTP generally has a master clock and its own clock for the whole system to provide a standard clock by exchanging messages with the master clock to get a timestamp and calculate the time deviation from the master clock and correct its own clock according to the timestamp. These slave clocks use synchronization signals to correct the clocks of all nodes in the network periodically to correct the clocks of each node and finally achieve the purpose of clock synchronization in the whole distributed network.22