Clock Synchronization in Distributed Environment (original) (raw)
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Comparative Study of Clock Synchronization Algorithms in Distributed Systems
In the Distributed Systems (DS) the nodes are communicating with each other using message passing. Many real-time applications such as banking systems, reservation systems that are implemented on distributed systems, it is important to execute each transaction/event in an ordered manner. Ordering of events is essential for proper allocation of available resources and mutual allocation. This can be implemented using clock synchronization. The paper presents a comparative study of clock synchronization algorithms in distributed systems. The paper also discusses time protocol such as Network Time Protocol and Simple Network Time Protocol.
Clock Synchronization in Distributed System
In distributed systems, most of the end-to-end delay fluctuations, especially the delay fluctuations in the network, are bounded provided that the global network traffic loads are manually controlled to be light-weighted. Ethernet based communication protocols have recently gained more importance. The IEEE 1588 standard is the most widely used synchronization algorithm for Ethernet based communication protocols. The IEEE 1588 standard uses the centralized synchronization method. In this case, the malfunction of a specific node that sends the master clock can affect the performance of synchronization of every node on the network. The low synchronization performance of the nodes can cause malfunctions of the synchronous control system. For this reason, we believe the distributed synchronization method is more suitable for the industrial communication protocols.
Clock Synchronization in Distributed Systems
International Research Journal of Engineering and Technology (IRJET), 2022
Clock discrepancies are troublesome in distributed systems and pose major difficulties. To avoid mistakes, the clocks of separate CPUs must be synced. This is to ensure that communication and resource sharing are as efficient as possible. As a result, the clocks must be constantly monitored and adjusted. Otherwise, the clocks drift apart. Clock skew causes a disparity in the time values of two clocks. Both of these issues must be solved in order to make effective use of distributed system characteristics. In this study, we briefly explored the features of distributed systems and its algorithms.
Network Issues in Clock Synchronization on Distributed Database
2009
Synchronization of clocks in distributed system has been an important area of research over the last decade. There are various methods of achieving clock synchronization depending on the requirements of the situation. A clock synchronization service ensures that spatially dispersed and heterogeneous processors in a distributed system share a common notion of time. In order to behave as a single, unified computing resource, distributed systems have need for a synchronization of drifting clocks and several algorithms have been proposed on this topic. Our paper highlights total network connection between different processors (alias nodes) of the system, We provide a simple, efficient, and unified algorithm for clock synchronization that can minimize the total network connection of the system.
Improved algorithms for synchronizing computer network clocks
ACM SIGCOMM Computer Communication Review, 1994
The Network Time Protocol (NTP) is widely deployed in the Internet to synchronize computer clocks to each other and to international standards via telephone modem, radio and satellite. The protocols and algorithms have evolved over more than a decade to produce the present NTP Version 3 specification and implementations. Most of the estimated deployment of 100,000 NTP servers and clients enjoy synchronization to within a few tens of milliseconds in the Internet of today. This paper describes specific improvements developed for NTP Version 3 which have resulted in increased accuracy, stability and reliability in both local-area and wide-area networks. These include engineered refinements of several algorithms used to measure time differences between a local clock and a number of peer clocks in the network, as well as to select the best subset from among an ensemble of peer clocks and combine their differences to produce a local clock accuracy better than any in the ensemble. This paper also describes engineered refinements of the algorithms used to adjust the time and frequency of the local clock, which functions as a disciplined oscillator. The refinements provide automatic adjustment of algorithm parameters in response to prevailing network conditions, in order to minimize network traffic between clients and busy servers while maintaining the best accuracy. Finally, this paper describes certain enhancements to the Unix operating system kernel software in order to realize submillisecond accuracies with fast workstations and networks.
Performance Comparison of Physical Clock Synchronization Algorithms .
International Journal of Engineering Sciences & Research Technology, 2013
This project mainly focuses on comparing and analyzing clock synchronization algorithms in distributed system. Clock synchronization is required for transaction processing applications, This generates transmission delays and synchronization errors for processes and the clock synchronization algorithms try to synchronize the clocks in the system under the effect of these barriers. Two centralized clock synchronization algorithms are used for testing Cristian's and Berkeley clock synchronization algorithms, and the third, the distributed clock synchronization algorithm, Network time protocol for synchronization of clocks in the internet. Abstract This project mainly focuses on comparing and analyzing clock synchronization algorithms in distributed system. Clock synchronization is required for transaction processing applications, process control applications etc. This generates transmission delays and synchronization errors for processes and the clock synchronization algorithms try to synchronize the clocks in the system under the effect of these barriers. Two centralized clock nchronization algorithms are used for testing Cristian's and Berkeley clock synchronization algorithms, and the third, the distributed clock synchronization algorithm, Network time protocol for synchronization of clocks in the
Distributed Approach for Clock Synchronization in Wireless Sensor Network
2014
Time synchronization is an important service in WSNs. existing time synchronization algorithms provide on average good synchronization between arbitrary nodes, however, as we show in this paper, close-by nodes in a network may be synchronized poorly. We propose the Distributed Time Synchronization Algorithm (DTSA) which is designed to provide accurately synchronized clocks between nearest-neighbours. DTSA works in a completely decentralized fashion: Every node periodically broadcasts its time information. Synchronization messages received from direct neighbours are used to calibrate the logical clock. The algorithm requires neither a tree topology nor a reference node, which makes it robust against link and node failures.
Almost Peer-to-Peer Clock Synchronization
2007 IEEE International Parallel and Distributed Processing Symposium, 2007
In this paper, an almost peer-to-peer (AP2P) clock synchronization protocol is proposed. AP2P is almost peer-topeer in the sense that it provides the desirable features of a purely hierarchical (client/server) clock synchronization protocol while avoiding the undesirable consequences of a purely peer-to-peer one. In AP2P, a unique node is elected as a leader in a distributed manner. Each non-leader node adjusts its clock rate based on message exchanges with its neighbors, taking into consideration that neighbors that are closer to the leader have more effect on the adjustment than the neighbors that are further away from the leader. We compare the performance of AP2P with that of the Server Time Protocol (STP), which is a purely hierarchical clock synchronization protocol. Simulation results, which have been conducted on several network topologies, have shown that AP2P can provide a clock synchronization accuracy that is indistinguishable from that of STP. Furthermore, AP2P is more fault-tolerant because it can recover from certain types of failures that STP cannot recover from.
Internet time synchronization: the network time protocol
IEEE Transactions on Communications, 1991
This paper describes the Network Time Protocol (NTP), which is designed to distribute time information in a large, diverse internet system operating at speeds from mundane to lightwave. It uses a symmetric architecture in which a distributed subnet of time servers operating in a self-organizing, hierarchical configuration synchronizes local clocks within the subnet and to national time standards via wire, radio or calibrated atomic clock. The servers can also redistribute time information within a network via local routing algorithms and time daemons. This paper also discusses the architecture, protocol and algorithms, which were developed over several years of implementation refinement and resulted in the designation of NTP as an Internet Standard protocol. The NTP synchronization system, which has been in regular operation in the Internet for the last several years, is described along with performance data which shows that timekeeping accuracy throughout most portions of the Internet can be ordinarily maintained to within a few milliseconds, even in cases of failure or disruption of clocks, time servers or networks.
Time synchronization is an important issue in wireless sensor networks. Many applications based on these WSNs assume local clocks at each sensor node that need to be synchronized to a common notion of time. Some intrinsic properties of sensor networks such as limited resources of energy, storage, computation, and bandwidth, combined with potentially high density of nodes make traditional synchronization methods unsuitable for these networks. Hence there has been an increasing research focus on designing synchronization schemes. This paper contains a survey, relative study and analysis of existing clock synchronization protocols for wireless sensor networks, based on a various factors that include precision, accuracy, cost, and complexity. The design considerations presented in this paper will help the designer in structuring a successful clock synchronization system. Specifically, the comparisons presented based on various factors will provide basic guidelines to the designer in integrating various solution features to create an efficient clock synchronization scheme for the application.