Using ns-2 simulations, this paper evaluates an Adaptive Explicit Congestion Notification (AECN) router. By receiving round-trip time (RTT) source hints from each TCP flow, AECN divides flows into flow groups based on RTT ranges. AECN uses distinct flow group drop probabilities and a mark front scheme to provide higher goodput and better fairness than Random Early Detection (RED) and Explicit Congestion Notification (ECN) routers.