Traffic monitoring in TCP/AQM networks through a time delay observer

International audienceThe use of the control theory tools for traffic control in communication networks, e.g. the congestion control in IP (Internet Protocol) routers, has given rise to challenging issues in the time-delay system framework. In this paper, we propose to design a linear time-delay observer for traffic monitoring in TCP/AQM (Transmission Control Protocol/Active Queue Management) networks. More precisely, we focus on a bottleneck topology consisting of long-lived TCP communications through a controlled router. The developed mechanism, located at the router, aims at supervising the network via TCP flow estimations as well as detecting anomalies for a class of DoS (Denial of Service) attacks. This issue is formulated as a stability problem for multiple delayed systems and appropriate robust control tools such as quadratic separation are adopted to address it. Then, some simulations via the network simulator NS-2 and an emulation experiment support the proposed methodology