Simulation of Computer Networks – Introduction1Outline• What is Simulation?• Course Objectives• Course OutlineSimulation of Computer Networks – Introduction2What is a Simulation?(Banks, Carson, Nelson and Nichol)• A simulation is the imitation of the operation of areal-world process or system over time.– May be done by computer or by hand.– Simulation involves the generation of an artificial historyof a system, and the observation of that artificial historyto draw inferences concerning the operatingcharacteristics of the real system.• The behavior of a system as it evolves over timeis studied by developing a simulation model.– Model = set assumptions about the system.– Once developed and VALIDATED, a model can be usedto investigate a wide variety of “what-if” questionsabout the real-world system.Simulation of Computer Networks – Introduction3Simulation Solutions• In some instances, a model can be developedwhich is simple enough to be solved bynumerical methods.• However, many real-world systems are socomplex that models of these systems arevirtually impossible to solve mathematically.Simulation of Computer Networks – Introduction4When to use Simulation• Simulation enable the study of, and experimentation with,the internal interactions of a complex system, or of asubsystem within a complex system.• Informational, organizational and environmental changescan be simulated, and the effect of these alterations on themodel’s behavior can be observed.• The knowledge gained in designing a simulation model maybe of great value toward suggesting improvement in thesystem under investigation.• By changing simulation inputs and observing the resultingoutputs, valuable insight may be obtained into whichvariables are most important and how variables interact.• Simulation can be used as a pedagogical device toreinforce analytic solutions.Simulation of Computer Networks – Introduction5When to use Simulation (2)• Simulations can be used to experiment with newdesigns or policies prior to implementation, so asto prepare for what may happen.• Simulation can be used to verify analyticsolutions.• By simulating different capabilities for a machine,requirements can be determined.• Simulation models designed for training allowlearning without the cost and disruption of OJT• Animation shows a system in simulated operationso that the plan can be visualized.Simulation of Computer Networks – Introduction6Simulation EngineSimulation of Computer Networks – Introduction7What is a System?• Central to any simulation study is the idea of a system.• To model a system, one must first understand what asystem is. The term system is defined in Funk andWagnall’s Standard Dictionary as “an orderly collection oflogically related principles, facts or objects.”• When used in the context of a simulation study, the termsystem generally refers to a collection of objects with awell–defined set of interactions among them.• An example is the solar system. The planets and the sunform the collection of objects (elements) of the system.• This definition of a system is general enough to allow itsapplication to many problems.Simulation of Computer Networks – Introduction8Course Objectives• Understand how, why and when to usesimulation.• Practical experience developing a simulation of acomputer network.• Improve practical knowledge of some aspect ofnetworking.• Thoroughly understand the role of verificationand validation and demonstrate ability to do V&V.• Improve research skills.• Successfully complete a publishable researchproject.Simulation of Computer Networks – Introduction9Homeworks• 9 graded homeworks– problems from the textbook– OPNET practical issues– other problems• 10 % of grade• Limited number of unannounced extra creditquizzesSimulation of Computer Networks – Introduction10Projects• 3 100 Point Projects(30% of grade)1: Literature Survey, Problem Definition andExperimental Design.2: Implementation, verification of implementationand results.3: Validation of model, analysis of results,completion of term paper.• 10% extra credit available for early submission ofpassing projectsSimulation of Computer Networks – Introduction11Exams• 3 as schedule• Open Book, Open Note• Final Exemption:– If all work completed by 6 Dec– and if grade = .90 * 750 = >