This book makes the argument that performance modeling and simulation have become central issues in computer science and engineering, in part due to applications to the structures comprising the Internet. Dealing primarily with theory, tools and techniques as related to communications systems, the volume provides tutorials and surveys and relates new important research results. Each chapter presents background information, describes and analyzes important work done in the field and provides direction to the reader on future work and further readings. The topics covered include traffic models for A TM networks, simulation environments, analytical methods, interprocessor communications, and an evaluation of process architectures.