This book offers a rigorous analysis of the achievements in the field of traffic control in large networks, oriented on two main aspects: the self-similarity in traffic behavior and the scale-free characteristic of a complex network. Additionally, the authors provide a new insight into understanding the inner nature of things and the cause and effect based on the identification of relationships and behavior within a model, using the study of the influence of the topological characteristics of a network on traffic behavior. The effects of this influence are then discussed in order to find new solutions for traffic monitoring and diagnosis and for the prediction of traffic anomalies.
The international seminar “Interdisciplinary Approaches of Fractal Analysis” (IAFA) in 2003 inspired research in a new direction, which led to the writing of this book. As cochairmen of the seminar, organized by the Politehnica University of Bucharest with the kind support of Alexander von Humboldt-Foundation, Radu Dobrescu and Florin Ionescu opened a novel direction of research on the fractal analysis of information in large-scale networks, which continued and was enriched with each new edition of IAFA (held every 2 years, the last—the seventh—in 2015). Numerous scientific papers were jointly published and several PhD theses were written on the sample topic, where the research for PhD was cosupervised by the two authors, both university professors, for which research grants came through international funding. The appearance of this book is a synthesis of the results obtained so far through the expertise gained on the topic.
This book refers to complex systems that have a network-like structure. Complexity should express the level of interconnectedness and interdependencies of a system. In a complex system, it is often the case that the utility of a structure or process is expressed at the next higher level of organization relative to the process itself. This book offers a new insight into the identification of relationships and behavior of Internet traffic, based on the study of the influence of the topological characteristics of a network upon the traffic behavior. The key property to illustrate this interdependency is the self-similarity, which can be expressed both in the fractal-like topological structure of scale-free networks and in the characteristics of traffic flow in a packet-switched environment. In practice, this approach leads to developing good predictors of network performance.
The reader can follow the development, validation, and use of self-similar and multifractal models, queuing, control and performance evaluation, assessing the incremental utility of various models, hierarchical models based on aggregation, analytic approximation models for various performance metrics, tradeoff, and sensitivity analysis using a multiobjective optimization framework. Therefore, this book, aimed at undergraduates and graduate students as well as experienced researchers in the field of computer networks, is very timely and it covers topics ranging from the classical approaches right up to present-day research applications. For the experimentalist, the book may serve as an introduction to mathematical modeling topics, while the theoretician will particularly profit from the description of key problems in the context of self-similar dynamic processes. The book provides the perfect background for researchers wishing to pursue the goal of multiscale modeling in complex networks, perhaps one of the most challenging and important tasks for researchers interested in the progress of information technology and communication.
The authors are very well aware of the fact that the desire to explain the new and complicated ideas in this area, where even the terminology is hardly settled, may not be rewarding. However, the problems of optimal traffic control and the investigation of new traffic features caused by the huge users and services volume in the networks offer important insights for a wide audience (students, engineers, researchers, and academics) focused on the main idea that in future it will be impossible to analyze any complicated systems without using the fractal self-similar approach. Also, the authors hope that the bold assumption that the topological characteristics of a network influence the traffic behavior will be confirmed convincingly.
Radu Dobrescu
Florin Ionescu