Berezovska Y. Methods of Providing Functional Stability of Information Systems on the Base of Software-Defined Networking

In the dissertation work, according to the set goal, on the base of theoretical and practical research, an important scientific and technical problem was solved, namely, the development of a methods to providing functional stability of information systems (IS) on the base of software-defined networking (SDN). These studies are relevant and cost-effective in the context of the rapid development of the functioning of large IS in Ukraine and in other countries of the world. The results obtained in the dissertation have a significant scientific value and can be used at the stage of design and operation of IS in conditions of a priori uncertainty of information about the distribution function of determining random variables. They serve as grounding for the expected indicators of the functional stability of IS. In the course of theoretical and practical researches in the dissertation work the following scientific and practical results are received: 1.The conducted studies of modern IS have shown a tendency to increase the number of goals facing IS, and in turn to the functional stability of IS. The list and the complexity of tasks in IS requires the analysis and definition of requirements that must be considered when building IS. 2.The study of the state of functional stability of IS. It is shown that it is necessary to prepare alternative solutions to ensure the required level of functional stability to reduce the degree of risk in problem areas of the functioning of information networks and to predict possible events that can significantly affect the construction of the network. 3.It is determined that the foundation for such tasks in favor SDN technology, which opens up prospects for solutions to IS issues, which will allow telecommunications companies to obtain independent control of the entire network and will greatly simplify networks operation and the cost of its maintenance. 4.The mathematical model of the data transmission system has been improved, which takes into account the type of packets transmitted and allows to determine the maximum delay time of the channel and evaluate the efficiency achieved through the use of priority traffic management. 5.Mathematical models of functional stability of IS with time redundancy at moment restrictions on functions of distribution of random variables are developed. They allow to determine the guaranteed estimates of the indicators of functional stability of the IS data transmission system. 6.A method for ensuring the functional stability of IS based on SDN has been developed. The methodology is based on the definition of guaranteed estimates of indicators of functional stability of the data transmission system, takes into account the time reserve, modes of operation of IS and allows to determine the upper and lower estimates of indicators of functional stability. 7.Conducted practical realization of the developed methods to providing functional stability of IS on the base of SDN has been carried out. A virtual cloud network testing environment was developed based on the laboratory base of the State University of Telecommunications. Network testing has shown that the application of the technique can reduce the latency time in comparison with traditional techniques from 5 to 9%. 8.The results of theoretical and practical investigations have applied character and have a sufficient degree of accuracy. This allows them to be used in determining the predicted estimates of the indicators of the functional stability of the IS to substantiate the guaranteed conclusion that the IS meets the specified requirements.