Modeling feedback congestion control mechanism of TCP using fluid flow approximation and queueing theory

摘要

The Internet uses a window-based flow control mechanism in TCP (Transmission Control Protocol). In the literature, there have been a significant number of analytical studies on TCP. Most of those studies have focused on the statistical behavior of TCP by assuming a constant packet loss probability in the network. However, the packet loss probability, in reality, changes according to packet transmission rates from TCP connections. In this paper, we explicitly model the interaction between the congestion control mechanism of TCP and the network as a feedback system. In other words, we model the congestion control mechanism of TCP as a system having the input (packet loss probability) and the output (window size). We also model the network as a system having the input (window size) and the output (packet loss probability). The network is modeled as a queueing system by assuming a single bottleneck link. Using our analytic model, the transient behavior of TCP connections is quantitatively investigated with several numerical examples.