The book is tightly and independently explain math and, in particular, stochastic methods to assess the performance of network systems. Part two covers the classical theory of stochastic processes (Poisson, renewal, Markov, and queuing theory), which is considered as the basic building block for performance evaluation studies. This section relates to the recent insights are obtained that are very different from many large complex networks - such as the Internet, World Wide Web, protein, utility infrastructure, social networks - to develop and behave in accordance with the laws of the more common general scale.