Springer Series in Reliability Engineering For furthervolumes: http://www.springer.com/series/6917 Ajit Kumar Verma Srividya Ajit • • Manoj Kumar Dependability of Networked Computer-based Systems 123 Prof.Ajit KumarVerma Dr. ManojKumar Department of ElectricalEngineering System EngineeringSection Indian Instituteof TechnologyBombay ControlInstrumentationDivision (IITB) Bhabha Atomic Research Centre (BARC) Powai, Mumbai400076 Trombay, Mumbai400085 India India e-mail: [email protected] e-mail: [email protected] Prof.Srividya Ajit Department of CivilEngineering Indian Instituteof TechnologyBombay (IITB) Powai, Mumbai400076 India e-mail: [email protected] ISSN 1614-7839 ISBN 978-0-85729-317-6 e-ISBN978-0-85729-318-3 DOI 10.1007/978-0-85729-318-3 SpringerLondonDordrechtHeidelbergNewYork BritishLibraryCataloguinginPublicationData AcataloguerecordforthisbookisavailablefromtheBritishLibrary (cid:2)Springer-VerlagLondonLimited2011 Apart from anyfair dealing for the purposes of researchor privatestudy, or criticismor review,as permittedundertheCopyright,DesignsandPatentsAct1988,thispublicationmayonlybereproduced, stored or transmitted, in any form or by any means, with the prior permission in writing of the publishers,orinthecaseofreprographicreproductioninaccordancewiththetermsoflicensesissued bytheCopyrightLicensingAgency.Enquiriesconcerningreproductionoutsidethosetermsshouldbe senttothepublishers. Theuseofregisterednames,trademarks,etc.,inthispublicationdoesnotimply,evenintheabsenceof aspecificstatement,thatsuchnamesareexemptfromtherelevantLawsandregulationsandtherefore freeforgeneraluse. The publisher makes no representation, express or implied, with regard to the accuracy of the informationcontainedinthisbookandcannotacceptanylegalresponsibilityorliabilityforanyerrors oromissionsthatmaybemade. Coverdesign:eStudioCalamar,Berlin/Figueres Printedonacid-freepaper SpringerispartofSpringerScience+BusinessMedia(www.springer.com) Dedicated to Our Parents Sri Kedar Prasad Verma & Smt Sushila Verma Sri B.C. Khanapuri & Smt Vibhavati B. Khanapuri Sri Gayanand Singh & Smt Droupdi Devi Our Gurus Bhagwan Sri Sathya Sai Baba Paramhansa Swami Sathyananda Saraswati Sri B. Jairaman & Smt Vijaya Jairaman Dr. C.S. Rao & Smt Kasturi Rao Our Teachers Prof.A.S.R.Murthy(ReliabilityEngg.,IITKharagpur) Prof.M.A.Faruqi(MechanicalEngg.,IITKharagpur) Prof. N.C. Roy (Chemical Engg., IIT Kharagpur) Foreword A compelling requirement in today’s context of the prevalent use of complex processes and systems in process and service industries, military applications, aerospace automotive and transportation, logistic, and other, is to maintain high dependability and security. The first casualty of integrated real time complex systems is dependability owing to an combinatorial like explosion of possible states, some with unacceptable probability levels and many unsafe states as well. The theoretical foundation for analytical treatment of such systems is crucial to their understanding, design and implementation. This book aims to explore the analysis, simulation and limitations in the implementation of such complex sys- tems, addressing a multitude of issues and challenges in the application of com- puter-based systems in dependability and safety critical applications. In my opinion, this book is exceptional as it fulfills a long felt need of engineers, scholars, researchers and designers for a coherent, yet effective and efficient treatmentofsuchsystemsandproblems,builtupwithaconceptualhierarchythat starts from the basics. The real-time systems also need to have an extremely important characteristic feature,timeliness.Mostofthecontemporaryresearchworkfocusesonworst-case timing guarantees. A probabilistic measure of timeliness is the new buzzword in the dependability community. A highlight of this book is its emphasis on the probabilistic measures of dependability and timeliness. System designers usually face several problems while choosing an appropriate technology (in particular, a network)foragivenproject.Thederivationofatimelinesshazardrateenablesan integrated dependability modeling of the system which in turn helps the system designer in making decisions based on specific requirements and uniform mea- sure(s).Thisbookcontainssomedetailed,wellexplainedandintuitivelyappealing examples which the practitioner may find directly applicable in the analysis and solution of his or her problems. I wish to congratulate the authors for their endeavors in bringing forth such a timely and insightful book on the dependability of networked computer-based systems. Their deep knowledge of the area, combined with vision concerning the presentandfuturechallenges,haveledtothisremarkablebook.Iamsurethatthis vii viii Foreword book will serve as an invaluable guide for scholars, researchers and practitioners interested and working in the field of critical applications where reliance on automation is indispensable. October 2010 Academician Janusz Kacprzyk Professor, Ph.D., D.Sc., Fellow of IEEE, IFSA President of the Polish Society for Operational and Systems Research, Immediate Past President of IFSA (International Fuzzy Systems Association), Systems Research Institute, Polish Academy of Sciences, Warsaw, Poland Preface Thisbookismeantforresearchscholars,scientistsandpractitionersinvolvedwith the application of computer-based systems in critical applications. Ensuring dependability of systems used in critical applications is important due to the impactoftheirfailuresonhumanlife,investmentandenvironment.Theindividual aspects of system dependability—reliability, availability, safety, timeliness and securityarethefactorsthatdetermineapplicationsuccess.Toanswerthequestion onrelianceoncomputersincriticalapplications,thisbookexplorestheintegration 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 computer- based systems. Probability theory, which began in the seventeenth century is now a well- established branch of mathematics and finds applications in various natural and social sciences, i.e. from weather predictionto predictingthe riskof new medical treatments.Thebookbeginswithanelementarytreatment ofthebasic definitions and theorems that form the foundation for the premise of this work. Detailed informationonthesecanbefoundinthestandardbooksonprobabilitytheoryand stochastic theory, for a comprehensive appraisal. The mathematical techniques used have been kept aselementaryas possibleand Markov chains, DSPN models and Matlab code are given where relevant. Chapter 1 begins with an introduction to the premise of this book, where dependabilityconceptsareintroduced.Chapter2providestherequisitefoundation on the essentials of probability theory, followed by introduction to stochastic processesandmodelsinChap.3.Variousdependabilitymodelsofcomputer-based systemsarediscussedinChap.4.Markovmodelsforthesystemsconsideringsafe failures, perfect and imperfect periodic proof tests, and demand rate have been derived. Analysis has been done to derive closed form solution for performance- based 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 ix x Preface ofmessagetransmission.Acomparisonofnetworkparametersisalsopresentedto provide an understanding of the various network protocols that can be used as primary guidelines for selecting a network solution for a given application. Methods to probabilistically model network induced delay of two field bus networks, CAN, MIL-STD-1553B and Ethernet are proposed in Chap. 6. Hazard rates are derived from discrete time process for a fault tolerant networked com- putersystem.Modelsarederivedforthethreedependabilityattributes—reliability, availability and safety, of NRT systems in Chap. 7. Timeliness hazard rate is modeled as reward rate. We hopethisbookwillbeaveryusefulreferencefor practicingengineersand research community alike in the field of networked computer-based systems. Mumbai, October 2010 Ajit Kumar Verma Srividya Ajit Manoj Kumar Acknowledgments We are indebted to Department of Electrical Engineering & Department of Civil Engineering, IIT Bombay and Control Instrumentation Division, BARC for their encouragement and support during the project. Manyofourfriends,colleaguesandstudentscarefullywentthroughdraftsand suggestedmanychangeschangedimprovingthereadabilityandcorrectnessofthe text. Many thanks to Shri U. Mahapatra, Shri G.P. Srivastava, Shri P.P. Marathe, ShriR.M.SureshBabu,ShriM.K.Singh,Dr.GopikaVinod,Prof.VivekAgarwal, Prof. Varsha Apte and Prof. P.S.V. Nataraj for their suggestions. The help by publishingstaff,especiallyofMr.Claire,intimelypreparationofthebookisalso appreciated. Mumbai, October 2010 Ajit Kumar Verma Srividya Ajit Manoj Kumar xi