While the AS path prepending method has been widely deployed by operators, very little is known about the impact of this method on Internet routing. In this project, we have conducted an active measurement study on a dual-homed, stub AS. We announce a route of a beacon prefix in the AS to both links, and we prepend only on the busier link. After announcing each prepending length, we observe possible route changes from a set of looking glasses and route servers.

Based on the measurement results, we have observed quite a few interesting and useful results. First of all, a very high percentage of routes to the beacon prefix have been changed. Another is that we can identify which upstream ASes are responsible for the route changes. In particular, we can classify all the upstream ASes into three categories, depending on their responses to the prepended routes: active-responsive, passive-responsive, and nonresponsive. These findings obtained from the active measurement could be very useful for operators to estimate the impact of advertising prepended routes before effecting it. A measurement-based mechanism can also be devised to compute the optimal prepending configuration.

About the Presenter
Samantha Lo is currently a Master of Philosophy student at the Department of Computing of The Hong Kong Polytechnic University. She received her BSc in Information Technology from the same university in 2005. Samatha received a Merit Award in the Charles Baggage Final-Year Project Award, and the 3rd prize in The 9th Challenge Cup Philips Competition in 2005. During 2003-2004, she was a trainee business analyst at the DBS Bank in Hong Kong. Her research interests include Internet measurement, interdomain routing, and traffic engineering. In real life, she is also a musician, playing a classical Chinese instrument. She received a number of awards and has performed in Southeast Asian countries and China.

Link to this presentation

Real Video Presentation