Optimization of the bandwidth distribution scheme for handling topology changes

The bandwidth distribution scheme (BDS) was designed to combine the advantages of the integrated and differentiated services models and to provide support for scalable per-flow quality of service. In recent studies Hnatyshin et al. showed that the variation of the bandwidth distribution scheme called the exact requested bandwidth range BDS (X-BDS), can support per-flow minimum bandwidth guarantees in a scalable manner. The X-BDS achieves per-flow QoS by maintaining aggregate flow requirements in the network core and distributing these requirements as needed. Based on the obtained information the edge nodes determine the fair allocation of available bandwidth among the active flows. This paper introduces an optimization which allows the X-BDS approach to operate seamlessly in the event of network topology changes. The primary challenge of addressing this problem is determining how to correctly update the aggregate flow requirements maintained in the network core. This paper examines two instances of topology changes, link failure and link restoration, and presents an algorithm which enables the routers in the X-BDS network to properly update the aggregate flow requirements in each of these cases. This paper examines the performance of the introduced algorithm through simulation.