For backward compatibility, ECN-capable networks should be capable of handling both ECN-capable and ECN-incapable TCP flows. In this letter, we present a backward congestion notification (BCN) scheme that can provide fast congestion indication delivery, while improving fairness between ECN-capable and ECN-incapable flows. Simulation results reveal that the BCN scheme is more effective than the original ECN mechanism in terms of stability, throughput, and fairness.