A new IRED (interval random early detection) congestion control algorithm is proposed for network congestion avoidance and resource management. Different to the traditional AQM (active queue management) algorithms, the control parameters of IRED are not configured statically, and is setting as a parameter interval according to the changes of network environment. By the interval parameter design, the IRED alleviates the tuning difficulty of RED (random early detection) and shows a robust performance than RED under varying network conditions. It is proved that the stability and stability margin of the IRED control system can be guaranteed. A systematic design method for the configuration of parameter interval is proposed. Simulation studies show the proposed IRED algorithm achieves a robust control performance in varying network environment, which is superior to the RED and Gentle-RED algorithm.