Stability and TCP-friendliness of AIMD/RED systems with feedback delays

In this paper, we systematically study the stability of a class of generalized Additive Increase and Multiplicative Decrease/Random Early Detection (AIMD/RED) system. Sufficient conditions are obtained for asymptotic stability of both homogeneous-flow system and heterogeneous-flow system with or without feedback delay by using indirect Lyapunov and Lyapunov–Razumikhin method. Our study reveals the relationship between the AIMD parameters and the average window size of competing AIMD flows. Consequently, the Transmission Control Protocol (TCP)-friendly condition is derived. Numerical results with Matlab and simulation results with NS-2 are given to validate the theorems and analytical results. The analysis and the stability conditions derived can be used as a guideline to set up the AIMD/RED system parameters in order to maintain network stability and integrity, and to enhance system performance.