Congestion handling in dynamic Differentiated Services networks

Differentiated Services is a very promising approach to achieve quality of service in the Internet. However, setting up static service level agreements (SLA) between different Internet service provider domains lacks flexibility and may reduce quality of service as resource reservations cannot be adapted to the actual traffic. With the introduction of bandwidth brokers, a significant step towards a completely dynamic Differentiated Services environment has been made. Bandwidth brokers negotiate and automatically set up SLA according to network load and provider policies. Nevertheless, this automatic set-up may fail if there are bottlenecks in the network caused by physical limitations or policy issues and may lead to congestion. In this paper, we propose a scalable mechanism to handle these congestion situations, that uses four phases each solving a different level of congestion. Our mechanism does not need any destination information thus making it applicable for the majority of Internet applications.