T. Müller:
Guaranteed QoS for TCP flows in ATM-based DiffServ Networks"
ECUMN '2000, Colmar, France


We investigate the QoS which a single user observes in a DiffServ network which is based on ATM. We show that TCP flows can experience performance degradation compared to UDP flows, even if the network is well tuned. The reason for this behavior is the TCP congestion control mechanism. Individual TCP flows cannot benefit from guarantees provided by ATM on the aggregate level. We introduce a new scheme called Fair Queuing and Selective Marking (FQSM) which overcomes this problem. It is located at the network edges and requires no changes to an existing ATM network. Simulations show good performance and allow to give QoS guarantees for TCP connections.