Discrete event fluid modeling of TCP

The bulk of Internet traffic is carried using variants of the TCP protocol. A realistic simulation-based performance study of any distributed application run over the Internet (e.g. reliable multicast) must therefore account for the impact that TCP background traffic has upon application behavior. Because TCP flows are shaped by other TCP flows, it is difficult to model TCP and its impact on other traffic other than by explicitly simulating it. This adds a significant computational burden to the simulation. This paper describes how we use fluid-based models of TCP to reduce the computational workload of simulating background TCP traffic. In particular we describe how a number of significant aspects of TCP can be described within a fluid formulation, how fluid models give rise to specific challenges that must be addressed by modeler and simulation kernel, and how we have addressed these in the DaSSF simulator.