Flow Level Modelling and Control of IP Traffic

Monday, January 12, 2004 - 11:00am - 11:50am
Keller 3-180
James Roberts (France Telecom R&D, LLC)
It proves most convenient to characterize and model IP traffic at flow level. We distinguish streaming flows, where the network requirement is to preserve the transmitted signal by limiting packet loss and delay, and elastic flows, where the requirement is to transmit a quantity of data as fast as possible. In the talk we will review recent results from stochastic flow level models for elastic traffic and for a mixture of elastic and streaming traffic. Of particular interest are the conditions under which performance measures are insensitive to precise traffic characteristics.

The modelling results enable an understanding of how performance targets can be realizable and provide guidelines for network sizing. They also suggest that current proposals for QoS differentiation do not take sufficient account of the statistical nature of traffic. This leads us to propose an alternative flow-aware architecture based on the joint use of per-flow admission control and fair queueing in routers. The resulting enhanced best effort network meets the respective performance requirements of streaming and elastic flows without the need for explicit packet marking. We describe the proposed router architecture called Cross-protect and discuss scalability issues.