Detecting and Measuring Asymmetric Links in an IP Network

Jiang, Wenyu

The rapid growth of the Web has caused a lot of congestion in the Internet. Pinpointing bottlenecks in a network is very helpful in congestion control and performance tuning. Measuring link bandwidths can help identifying such bottlenecks. Existing tools for bandwidth measurement like Pathchar, Bing and Bprobe assume symmetric links. Hence their results will be incomplete or incorrect in the presence of asymmetric links. It becomes important to consider asymmetric links, as they are gaining popularity in recent years. Examples are ADSL lines, Cable modems, Satellite links, and 56K modems. In this paper, we present an algorithm that can measure each hop's link bandwidth in both directions in an IP network. Therefore, it is trivial to detect asymmetry of a link. We performed several experiments to validate our algorithm. We also discuss some factors that can adversely affect the precision and/or correctness of bandwidth measurement, and suggest possible solutions.


More About This Work

Academic Units
Computer Science
Department of Computer Science, Columbia University
Columbia University Computer Science Technical Reports, CUCS-009-99
Published Here
April 21, 2011