[CPCC] TALK: Intelligent Route Control May 18 2:00 PM

Ender Ayanoglu ayanoglu at uci.edu
Fri May 12 10:37:53 PDT 2006


	      [Networked Systems Distinguished Speaker Series]

        Avoiding Oscillations due to Intelligent Route Control Systems

  			  Constantine Dovrolis
                              Georgia Tech

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


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 nonstationary 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.

			Speaker's Biography

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.  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 at uci.edu.

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