University of California, Riverside

Department of Electrical and Computer Engineering

Cross-Layer Optimization in TCP/IP networks

Cross-Layer Optimization in TCP/IP networks
Jiantao Wang
California Institute of Technology

Date: November 29, 2004
Time: 11:00 am
Location: Bourns Hall A265

TCP--AQM can be interpreted as distributed primal-dual algorithms to maximize aggregate utility over source rates. We show that an equilibrium of TCP/IP, if exists, maximizes aggregate utility over both source rates and routes, provided congestion prices are used as link costs. An equilibrium exists if and only if this utility maximization problem and its Lagrangian dual have no duality gap. In this case, TCP/IP incurs no penalty in not splitting traffic across multiple paths. Such an equilibrium, however, can be unstable. It can be stabilized by adding a static component to link cost, but at the expense of a reduced utility in equilibrium. If link capacities are optimally provisioned, however, pure static routing, which is necessarily stable, is sufficient to maximize utility. Moreover single-path routing again achieves the same utility as multipath routing at optimality.


Jiantao Wang received his B.S. and M.S. degree in Automatic Control from Tsinghua University, Beijing, China, in 1997 and 1999 respectively. He is a graduate student in Control and Dynamical System in Caltech since 1999. His research interests include network congestion control, active queue management, and routing.
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