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Home | Seminars and Symposia | Past seminars/symposia: Monday, October 20, 2003

DTC Seminar Series

Detection of Routing Loops and Analysis of Its Causes


Sue Moon
Korea Advanced Institute of
Science and Technology (KAIST), Korea

Monday, October 20, 2003
2:00 pm

402 Walter Library

Sue MoonDownload slides (pdf 444 KB) Routing loops are caused by inconsistencies in routing state among a set of routers. They occur in perfectly engineered networks, and have a detrimental effect on performance. They impact end-to-end performance through increased packet loss and delay for packets caught in the loop and through increased link utilization and corresponding delay and jitter for packets that traverse the link but are not caught in the loop. In this talk we first explain how routing loops manifest in packet traces. We characterize routing loops in terms of the packets types, loop sizes, and the loop durations. Then we present a methodology that utilizes a priori knowledge of loops to study the correlation between routing loops and routing events that could have caused them. We apply our technique to loops detected in our packet traces. Our study shows that a strong correlation exists between loop and changes in the BGP routing state while the link state protocols IS-IS is seldom responsible for such events. Joint work with: Urs Hengartner, Richard Mortier, Ashwin Sridharan, and Christophe Diot.


Sue Moon presenting

Sue Moon presenting

Sue Moon received her B.S. and M.S. from Seoul National University, Seoul, Korea, in 1988 and 1990 respectively, both in Computer Engineering. She received a Ph.D. degree in computer science from the University of Massachusetts at Amherst in 2000. From 1999 to 2003, she worked in the IPMON project at Sprint ATL in Burlingame, California. In August of 2003, she joined KAIST as an assistant professor and now teaches in Daejeon, Korea. Her research interests are in network performance measurement and monitoring: network delay, traffic scaling behavior analysis, and network anomalies.