Search

The rapid development, complexity of modern information systems and the growth of qualitative and quantitative characteristics of network anomalies and failures makes the task of network reliability more relevant. So, the aim of the article is to research modern problems of information systems and develop methods for its solution. For resolving of the considered problems in order to achieve the required level of network characteristics, the article contains developed the conditions for the optimal choice of network equipment, the methods for determining threshold values for detecting deviations from the normal operation of the network, the schemes of the algorithm for monitoring faults and problems.

The article is based on the monitoring faults problem of information systems and contains the mathematical model description of the process for monitoring faulty parameters for network equipment, which takes into account the probability dependence of events on a time intervals, and offers a method of probabilistic forecasting of the state of network failure.

Two mathematical models have been built to describe the behavior of an information system with a client-server architecture without and taking into account the ultimate reliability of the monitoring system and the restoration of the failed component of the system under consideration. The behavior of the information system in the presence of failures and the restoration of the performance of components is approximated by a Markov process and is described by a system of differential equations with variable coefficients. The solution of the obtained differential equations by numerical methods on computers allows the research of various characteristics of the reliability of information systems such as “client-server” in a wide range of changes in failure rates and restoration of system components.

The game task of confrontation of the attacked hardware-redundant dynamic system with an attacking enemy operating in conditions of incomplete information about the behavior of the attacked enemy in the process of conflict was posed and solved numerically and analytically. The attacking party aspires to increase the intensity of the failures of the components of the attacked system at the expense of its attack resources, up to its total failure. The attacked party, due to the corresponding strategy of redistribution of reserve blocks of the hardware-redundant dynamic system between the failed main blocks at the appropriate instants of time, strives to maximize the probability of failure-free operation of the attacked system at the end of the confrontation (game) with the attacking enemy. Behavior of the system under attack in the process of conflict is approximated by the Markov process, and the number of operable states is equal to the number of failed functional blocks that do not exceed the number of standby blocks. As a payment function in the game in question, the probability of failure-free operation of the attacked system is used by the time the game ends. The solution of the game is the vector of the system setup moments after the corresponding failures of the functional blocks and the set of reservation vectors corresponding to the instantaneous settings of the system being attacked, which maximizes the probability of system failure during the conflict. The differential game model is reduced to a multi-step matrix model with given probabilities of the states of the attacking enemy. Numerical algorithms for calculating the vector of reservation for the attacked system that maximizes the probability of its trouble-free operation by the end of the game and for solving the game problem in question are presented in a form convenient for implementation on a personal computer.

The article deals with the reliability problem of information systems and contains the developed method for assessing the fault-tolerance of data transmission systems and mathematical model that allows to obtain the probability of failure at different levels of information systems.