Fractal Behavior of Video and Data Traffic

A fractal is a function or a process in which an identical motif repeats itself on an ever diminishing scale. The motif of a fractal can be a feature influenced by chance. Fractals can be found in nature everywhere, for instance the surface of the moon is a fractal, where the motif of craters is repeated in a scale from inches to miles. It is created by random collisions with space objects. Fractals are also called self-similar, because they show the same picture when looking at them in different scales. Fractals can be found in the load profile of data and video traffic, too. Fractal behavior has serious consequences for the modeling, design and operation of packet switched networks like ATM. They are: 1) no smoothing effect while traffic is multiplexed and, 2) unpredictable burst lengths. This leads to difficulties in buffer dimensioning and in traffic control schemes. Understanding and modeling the fractal behavior is a new research challenge. More knowledge is needed to understand reasons for the fractal properties and to model them in order to design networks, services and even applications with regard to it. There are several methods to find out fractal properties of data and video traffic. One of them, the so called pox diagram, will be applied. We will show results achieved by application of this approach on measured video traffic. Additionally results of other measurement in data networks and in the Internet will be presented. 1. Wolfgang Frohberg is with the ALCATEL Telecom Research Division Location Stuttgart, D70430 Stuttgart, Germany