Techniques are described herein for synchronizing cluster time. According to one technique, a master node is appointed in a cluster. Other “slave” nodes periodically synchronize their clocks with the master node. To synchronize its clock with the master node, a slave node sends a timestamped message to the master node, which also timestamps the message and sends the message back to the slave node, which then timestamps the message again. Based on the timestamps, the slave node is able to determine the difference between the master node's clock's time and slave node's clock's time, compensating for the message travel time between master node and slave node. Depending on various circumstances, and based on the determined difference, the slave node adjusts its clock so that the time indicated by the slave node's clock at least begins to approach more closely the time indicated by the master node's clock.

Time synchronization in cluster systems

A data communication network (1 ) may, include a first sub-network (2) and a second sub- network (3). The first sub-network (2) may include two or more two master clocks (112,122), and a synchronisation system (13) connected to the master clocks. The synchronisation system may, for determine a time-base for the master clocks and control the master clocks based on the determined time-base. The first sub-network (2) may include one or more slave synchronisation data source (1 13, 123) for generating slave clock synchronisation data derived from time information of the master clocks. The second sub-network may include one or more slave clocks (22) and a slave clock time-base controller (21 ) connected to the slave synchronisation data source. The time-base controller (21 ) may receive the slave clock synchronisation data and control one or more of the one or more slave clocks in accordance with the slave clock synchronisation data.

Network and method for setting a time-base of a node in the network

Systems and methods that efficiently simulate controlled systems are presented. A simulation management component (SMC) controls simulation of a controlled system by controlling a desired number of nodes, each comprising a controller (e.g., soft controller) and a simulated component or process, which are part of the controlled system. The simulation can be performed in a step-wise manner, wherein the simulation can comprise a desired number of steps of respectively desired lengths of time. For each step, the SMC dynamically selects a desired clock (e.g., currently identified slowest clock) as a master clock for the next step. The SMC predicts a length of time of the next step to facilitate setting a desired length of time for the next step based in part on the predicted length of time. As part of each step, components can synchronously exchange data via intra-node or inter-node connections to facilitate simulation.

Dynamically selecting master clock to manage non-linear simulation clocks

A system and a method of time information synchronization as well as related apparatuses are disclosed to improve precision of frequency synchronization or time synchronization. The application port subsystem in the information synchronization system is configured to: generate at least one local clock according to a locally running real-time clock, and provide the local clock for a core subsystem; and the core subsystem is configured to: select a best system clock according to attributes of the clock provided by the application port subsystem, and send the best system clock to the application port subsystem, where: the application port subsystem calibrates the real-time clock according to the best system clock provided by the core subsystem in order to perform frequency synchronization and/or time synchronization. The embodiments of the present invention improve the precision of frequency synchronization or time synchronization effectively.

System, method and apparatus of time information synchronization

A method and apparatus for tracking a clock source are provided by the embodiments of the present invention. The method includes: determining the best clock source which the device needs to track according to the best clock source tracked by the slave standby port of the device; distributing the best clock source which the device is tracking through the master standby port, which is in master status. According to the embodiments of the present invention, the clock source selection of the device will be converged quickly, and since the slave standby port is determined based on the network layout, the layout of the transmission network can be revealed.

A method and apparatus for tracking clock source

clock synchronization is described for a system including N clocks at least three and at most N-1 of which are master candidate clocks. A start message is broadcast from the fastest master candidate clock. From each of the master candidate clocks, a response message including the local time of receipt of the start message according to the clock in question is broadcast. Using the information representing the times of receipt of the start message, the median master clock is selected and becomes the master clock. The master clock determines the clock synchronisation error for each master candidate clock, using the information representing the times of receipt of the start message. If any such clock synchronisation error is excessive the master clock declassifies the clock in question as a master candidate clock and classifies another clock as a master candidate clock.

Geoffrey Mackintosh Allan

Papers

Fault-tolerant clock synchronisation

Fuzzy Controllers for Active Magnetic Bearings

A Smart Actuator for Fault-Tolerant Control