Abstract – In this paper the design of robust Active Queue Management (AQM) for
congestion control in computer networks is presented. The Ant Colony Optimization
(ACO) method is used to tune the parameters of PID controller subject to H-infinity
constraints. The nonlinear dynamic model for multiple TCP flows control is developed
based on fluid-flow theory. The designed controller provides good tracking performance
in the presence of wide range of system parameter uncertainty. NS2 package is used to
perform the nonlinear simulation of the system.