Lighter and faster simulations of high-speed IP networks

Two important factors for the realistic simulation of web-traffic are the heavy-tailed distributed file-sizes at the session level, and the transmission control protocol (TCP) at the transport level. The operation of a source that integrates both factors faces two major scalability problems: the computing resources required by each source put a limit on the total number of sources that can be simulated, and the number of discrete events in the context of high capacity networks leads to unacceptably long simulation times. We introduce a light weight traffic source (LWTS). It generates traffic statistically similar to the traffic produced by a realistic source. Similar to a realistic source, it generates heavy-tailed distributed files at the session layer. However, its transport operation is based on a pseudo-TCP (P-TCP) protocol that approximates TCP. The thin code of P-TCP makes LWTS similar to 50 times less resource hungry as compared to a realistic traffic source. To solve the second scalability problem, we introduce a novel abstraction technique at the transport level: we send a whole window of TCP packets as one big packet. This abstraction results in reducing the number of discrete events leading to similar to 28 times faster simulations. (c) 2005 Elsevier GmbH. All rights reserved.