**8. Acknowledgment**

372 Telecommunications Networks – Current Status and Future Trends

Fig. 13. Comparison between modeled traffic 4 generated in OPNET simulation tool and

In this chapter, we present our research in the area of measurements, modeling and simulations of the self-similar network traffic. Firstly, the state of the art method for modeling and simulating of self-similar network traffic is presented. We also describe a number of facts about self-similarity, long range dependences and probability, which are used to describe such stochastic processes. Described as well are the mechanism and models to simulate network traffic in the OPNET Modeler simulation tool. The main goal of our research is to simulate measured network traffic, where we tend to minimize discrepancies between the measured and the simulated network traffic in the sense of packet-rate, bit-rate, bursts intensity, and variances. One of the big challenges in our research work was to find appropriate method to estimate parameters of data source network traffic processes that are based on measured network packet's traffic. The estimated parameters are needed during the modeling of the measured network traffic in the simulation tool. For those reasons, we have developed different methods, which allow estimation of the parameters of data source

At the end of the chapter, all phases needed for simulating the measured network traffic in the OPNET simulation tool are presented. During the analysis phase we pay attention to the self-similar property, which has become the basic model for describing today's network traffic. In the network traffic theory, the properties of short and long-range dependence are directly prescribed by the values of estimated parameter *H*. In our network traffic analysis, we prove that network traffic (test traffic 2) can exist where Hurst parameter is bigger than

For the purpose of parameters estimation of data source network traffic processes, we have used a method that mimics packet defragmentation. Through the use of this method we

network traffic processes, based on the measured network packet's traffic.

0.5, but this process does not have the property of a long-range dependence.

measured test traffic 2 in bits per second (kb/s).

**7. Conclusion** 

This work has been partly financed by the Slovenian Ministry of Defense as part of the target research program "Science for Peace and Security": M2-0140 - Modeling of Command and Control information systems, and partly by the Slovenian Ministry of Higher Education and Science, research program P2-0065 "Telematics".
