When: Friday Sept. 15, 13:00
Where: Simula Research Laboratory, Oslo/Fornebu, room "Klasserommet"

Abstract: Intelligent Route Control (IRC) systems are increasingly deployed in multihomed networks. IRC systems aim to optimize the cost and performance of outgoing traffic, based on measurement-driven dynamic path switching techniques.
In this talk, we first explain how the intended usage of IRC technology in multihomed networks, and then show that IRC systems can introduce sustained traffic oscillations, causing significant performance degradation instead of improvement. This happens, first, when IRC systems do not take into account the "self-load effect", i.e., when they ignore that the performance of a path can change after additional traffic is switched to that path. Second, oscillations can take place when different IRC systems get synchronized due to significant overlap of their measurement time windows.
We propose measurement methodologies and path switching algorithms that can effectively deal with the previous two issues. The proposed IRC techniques use available bandwidth estimation to avoid the self-load effect, and they introduce a random component in the path switching decision or time scale. We evaluate the proposed techniques under diverse traffic conditions. When the background traffic is stationary, IRC systems should switch paths conservatively, only upon major traffic fluctuations. With nonstationary background traffic and congestion periods that last for a time scale T_w, IRC systems improve performance only if they can detect congestion and switch paths much faster than T_w; otherwise, they cause oscillations and hurt performance. We also show that the gradual deployment of randomized IRC systems, in the presence of traffic from deterministic IRC systems, can play a stabilizing role and benefits early adopters.

Speaker: Dr. Constantine Dovrolis is an Assistant Professor at the College of Computing of the Georgia Institute of Technology. He received the Computer Engineering degree from the Technical University of Crete (Greece) in 1995, the M.S. degree from the University of Rochester in 1996, and the Ph.D. degree from the University of Wisconsin-Madison in 2000. He was an assistant professor of Computer and Information Science at the University of Delaware from January 2001 to July 2002. His research interests include Internet protocols and technologies, network measurements and their applications, overlay and multi-homed networks, intelligent route control, router buffer sizing, service provisioning and traffic engineering, routing security, and biology-inspired network architectures. He received the NSF CAREER award in 2003.