The purpose of network performance analysis is to investigate how traffic-management mechanisms deployed in the network affect the allocation of resources amongst its users and the performance they experience. This topic can be studied by the construction of models of traffic management mechanisms and observing how they perform by applying them to some flow of network traffic. This useful volume introduces concepts and principles of network performance analysis by example, using the J programming language. J is rich in mathematical functionality, which makes it an ideal tool for analytical methods. The book favours a practical approach and develops functions in J to demonstrate mathematical concepts, thereby enabling readers to explore the underlying principles behind network performance analysis. In addition, this allows the subject to become more accessible to those who, although have a mathematical background, are not pure mathematicians.