Parameter Setting and 2-D Stability Conditions for TCP/RED Networks

This paper provides parameter setting and 2-D local stability conditions for TCP/RED networks. In general, a network cannot avoid congestions due to the limit of network capacity. The RED scheme is one of the representative AQM that was proposed to avoid and alleviate network congestions. However, the issue of network stability with many TCP subscribers needs to be considered when setting the RED parameters, where the classical RED has not considered the problem. In this paper, we set up a linear time-delay system for the TCP dynamic behavior and derive some stability conditions with simple RED network parameters by utilizing the 2-D Laplace-Z transform technique. Simulation results show that the proposed stability conditions can gain the effective stability in regard to the router queue length.