Elementary Markov Queueing Systems with Unreliable Server

In the queueing theory we usually ignore the fact that utility server is often a technical device and its breakdown can occur. Common analytic models (see for example in [1] or [2]) assume that the server works reliably without failures causing its deficit. If failures of the server occur often and we would use an analytic model of reliable queueing system for modeling studied system, reached outcomes can be inaccurate. In this case the suitable model of the unreliable queueing system should be used. This paper presents some examples of elementary Markov unreliable queueing systems models. Selected models are represented by a state transition diagram and by appropriate system of linear equations for steady state probabilities computation. Steady state probabilities are needed for performance measures computation. More information about mentioned models can be found in [3].