Netest: a tool to measure the maximum burst size, available bandwidth and achievable throughput

Distinguishing available bandwidth and achievable throughput is essential for improving network application performance. Achievable throughput is the throughput considering a number of factors such as network protocol, host speed, network path, and TCP buffer space, whereas available bandwidth only considers the network path. Without understanding this difference, trying to improve network application performance is like the "blind men feeling the elephant" problem (J. Gemmill, 2001). We define and differentiate bandwidth and throughput, and discuss which part of each is achievable and which is available. Also, we introduce and discuss a new concept, maximum burst size, that is crucial to obtaining good network performance. A new tool, netest, is introduced which is designed to help users to determine the available bandwidth. It provides information to achieve better throughput while fairly sharing the available bandwidth, thus reducing misuse of the network.