Gero Schollmeier

Improving the resilience in IP networks

Quality of service issues of IP networks are mostly related to guaranteeing bandwidth for flows. However, many interactive real-time applications also require this bandwidth in an uninterrupted fashion. The paper describes how multipath routing and local failure reaction can be employed to provide uninterrupted QoS to applications. We show how multipath route sets can be found in reasonably meshed networks and how multipath routing can be used to save on the spare capacity required in case of link failures.

Providing sustainable QoS in next-generation networks

In this article we discuss QoS from a somewhat unconventional point of view. First of all, we argue that high availability is a key ingredient in the QoS perceived by the user. High availability with extremely short interruptions in case of failure is needed for acceptable QoS in real-time dialog services such as telephony or video conferencing. Second, an even distribution of the traffic load over the network is essential to ensure efficient network utilization given that some kind of admission control for QoS traffic has to be in place for overload avoidance. Unfortunately, both these features are not adequately provided in current IP networks. We therefore introduce a new routing scheme offering a massive improvement in availability as well as efficient traffic distribution, while causing only minor computational effort. Our proposals are then evaluated for a high-speed core network. We claim that our proposed approach would be a useful basis for QoS services in an NGN.