A versatile model for TCP bandwidth sharing in networks with user heterogeneity.
Dirk Abendroth, J.L. van den Berg, Michel Mandjes · UvA-DARE (University of Amsterdam) · 2005
ABSTRACT Enabled by the emergence of various access technologies (such as ADSL and wireless LAN), the number of users with high-speed access to the Internet is growing rapidly, and their expectation with respect to the quality-of-service of the applications has been increasing accordingly. With TCP being the ubiquitous underlying end-to-end control, this motivates the interest in easy-to-evaluate, yet accurate, performance models for a TCP-based network shared by multiple classes of users. Building on the vast body of existing models, we develop a novel versatile model that explicitly captures user heterogeneity, and takes into consideration dynamics at both the packet level and the flow level. It is described how the resulting multiple time-scale model can be numerically evaluated. Validation is done by using NS2 simulations as a benchmark. In extensive numerical experiments, we study the impact of heterogeneity in the round-trip times on user-level characteristics such as throughputs and flow transmission times, thus quantifying the resulting bias. We also investigate to what extent this bias is affected by the networks' 'packet-level parameters', such as buffer sizes. We conclude by extending the singlelink model in a straightforward way to a general network setting. Also in this network setting the impact of heterogeneity in round-trip times is numerically assessed. 2000 Mathematics Subject Classification: 60K25, 68M20 Keywords and Phrases: TCP; user heterogeneity; performance; throughput; round-trip times; packet level; flow level; acyclic networks Note: The work of H. van den Berg and M. Mandjes was partially funded by the Dutch Ministry of Economic Affairs (through its agency SENTER/NOVEM) under the programme `Technologische Samenwerking ICT Doorbraakprojecten', project TSIT 2031 EQUANET. M. Mandjes is also with Korteweg-de Vries Institute, University of Amsterdam, Amsterdam, the Netherlands, and EURANDOM, Eindhoven, the Netherlands. D. Abendroth is currently with Bayerische Motor Werke, München, Germany.