Avoiding Oscillations Due to Intelligent Route Control Systems

CPCC Talk
Networked Systems Distinguished Speaker Series

Featuring:
Constantine Dovrolis
Georgia Tech

Thursday, May 18, 2006
2-3 PM, Refreshments at 1:45
Calit2 3008

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 paper, we first 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 then 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 non-stationary background traffic and congestion periods that last for a time scale Tw, IRC systems improve performance only if they can detect congestion and switch paths much faster than Tw; 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.

About the Speaker:

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 () 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.  His research interests include methodologies and applications of network measurements, bandwidth estimation algorithms and tools, overlay networks, service differentiation, and network problem diagnosis.  He received the NSF CAREER award in 2004.

For further information, please contact the host Prof. Athina Markopoulou at athina@uci.edu.