Dependability of Networked Computer-based Systems

by:  Ajit Kumar Verma, Srividya Ajit, Manoj Kumar

 

This book is meant for research scholars, scientists and practitioners involved with the application of computer-based systems in critical applications. Ensuring dependability of systems used in critical applications is important due to the impact of their failures on human life, investment and environment. The individual

aspects of system dependability—reliability, availability, safety, timeliness and security are the factors that determine application success. To answer the question on reliance on computers in critical applications, this book explores the integration of dependability attributes within practical, working systems. The book addresses the growing international concern for system dependability and reflects the important advances in understanding how dependability manifests in computerbased systems.

Probability theory, which began in the seventeenth century is now a wellestablished branch of mathematics and finds applications in various natural and social sciences, i.e. from weather prediction to predicting the risk of new medical treatments. The book begins with an elementary treatment of the basic definitions and theorems that form the foundation for the premise of this work. Detailed information on these can be found in the standard books on probability theory and stochastic theory, for a comprehensive appraisal. The mathematical techniques used have been kept as elementary as possible and Markov chains, DSPN models

and Matlab code are given where relevant.

Chapter 1 begins with an introduction to the premise of this book, where dependability concepts are introduced. Chapter 2 provides the requisite foundation on the essentials of probability theory, followed by introduction to stochastic processes and models in Chap. 3. Various dependability models of computer-based

systems are discussed in Chap. 4. Markov models for the systems considering safe failures, perfect and imperfect periodic proof tests, and demand rate have been derived. Analysis has been done to derive closed form solution for performancebased safety index and availability.

In Chap. 5, medium access control (MAC) protocol mechanisms of three candidate networks are presented in detail. The MAC mechanism is responsible for the access to the network medium, and hence effects the timing requirement

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