Abstract
Explicit Congestion Notifications are used to notify TCP when imminent congestion is about to happen. In this work we use this feature to design an error discriminator that can be added to a TCP sender to differentiate between congestion drops and drops because of wireless link failure. By distinguishing between error types, TCP can avoid unnecessary cuts of congestion window when non congestion error happens and when the retransmission of lost packets is enough and there is no need to slow down. A set of experiments were conducted to validate this solution. The results show that ECN is a good predictor of imminent congestion and can be used actively in an error discriminator over networks that suffer from low and medium congestions.