On the performance gains of TCP with ECN

We study the effect of explicit congestion notification (ECN) on TCP performance for large file transfers and compare it with other congestion avoidance mechanisms, namely drop tail and RED. In contrast to previous work, we focus on situations in which all nodes in the network operate uniformly under the same mechanism (DT or RED or ECN). We observe no significant improvement in TCP goodput when ECN is supported. On the other hand, our results show that with ECN, TCP flows benefit from lower overhead for unsuccessful transmissions, and lockouts are largely avoided.