The Internet Clock Synchronization And Analysis Of Stability Of NTP Servers

The internet clock synchronization is a problem from computerscience and engineering which deals with the idea that internal clocks ofseveral computers may differ. Even when initially set accurately, real clockswill differ after some amount of time due to clock drift, caused by clockscounting time at slightly different rates.At present, because applications in a distributed system are more andmore complex, so the clock accuracy requirements of each node are increased.The main purpose of the thesis is to achieve clock synchronization in theinternet. The method is to assess and compensate the clock drift rate, andadopts a model of clock drift rate and a continuous time-stamp communicationmodel to complete the clock synchronization. The entropy optimizationalgorithm is been first introduced in the clock synchronization field, and thenthe complete strategy of the internet clock synchronization is been proposed.Experiments show the strategy can adapt to the complex network environmentand avoid the occasional error, so the strategy has strong robustness and stability.In order to facilitate the experimental study, the subject developed a NTPclient software. According to the demand of the experiments, the clientsoftware can adjust the local clock, synchronize the clock using real-timedeviation or entropy optimization algorithm’s deviation, and display the graphof roundtrip delay, offset trend at real time. Using the NTP client software tocollect a large number of data, the experimental research can be carried outeasily to prove that clock adjustment based on the entropy optimizationalgorithm is superior to the clock adjustment algorithm based on real-timedeviation.In addition, the NTP server is been researched. Firstly, a NTP server isbeen set up under the windows server2008using the GPS external clocksource. The protocol is been used is NTPv4. After all these work, the thesishas a further in-depth understanding of the working principle of the NTPprotocol.Because the stability of the NTP servers have directly relationship withthe time accuracy of the distributed system nodes, so the NTP servermonitoring software is been developed. The monitoring software can scan thestatus of multiple NTP servers at the same time, including four types of NTPtime-stamps, and all of these data can be stored in the oracle database.In order to show the status of these NTP servers more clearly, the NTPserver monitoring website is been develop using the data source which were collected by the NTP server monitoring software. The purpose of the websiteis to offer NTP servers’ status for the NTP server administrator and users.Using this website, the main NTP servers’ status can be monitored directly.