01240nas a2200133   4500000000100000008004100001100002400042700002000066245017500086300001400261490000900275520080800284022001401092       2011                            d1 aTadeusz Czachórski1 aFerhan Pekergin00aDiffusion Approximation as a Modelling Tool, chapter in: Network Performance Engineering, A Handbook on Convergent Multi-Service Networks and Next Generation Internet, St  a447–4760 v52333 aDiffusion theory is already a vast domain of knowledge. This tutorial lecture does not cover all results: it presents in a coherent way an approach we have adopted and used in analysis of a series of models concerning evoluation of some traffic control mechanisms in computer, especially ATM, networks. Diffusion approximation is presented from engineer`s point of view, stressing its utility and commenting numerical problems of its implementation. Diffusion approximation is a method to model the behavior of a single queueing station or a network of stations. It allows one to include in the model general sevice times, general (also correlated)input streams and to investigate transient states, which, in presence of bursty streams (e.g. of multimedia transfers) in modern networks, are of interest.  a0302-9743