"Providing efficient IP services with support for quality of service"

A high efficiency (i.e., the ratio between the transported traffic and the costs for transporting the traffic) and a well-defined quality of service are two very important goals for IP networks. From this follows the central question of this talk: How can the efficiency and quality of service of IP networks be optimised, taking the trade-off between these two goals into account?

We show that efficiency and quality of service strongly depend on the network architecture, traffic engineering, network engineering, and the interconnections. Therefore, a system-oriented approach is employed. With this approach, all previously mentioned areas are analysed and optimised, considering their mutual influences.

In the context of network architectures, the focus of the research lies on methods for providing quality of service. Analytical models are used to determine and analyse the overprovisioning factor of a plain best-effort network compared to networks that support explicit service differentiation. Furthermore, the different IETF quality of service architectures are evaluated and compared in an experimental study. Besides the network architecture, the interconnection structure (i.e., the connections to other networks) also influences the efficiency and the quality of service of a network. Different approaches to optimise the efficiency, reliability, and quality of service of the interconnection structure are developed and evaluated, the main results are presented in this talk.They show that with these approaches, significant cost savings and quality of service improvements can be realised.

Due to the steadily increasing traffic volumes, capacity expansion is the most important traffic and network engineering task of a provider. Therefore, capacity expansion strategies are elaborated and evaluated. They also consider the influence of different network architectures and traffic engineering.