The congestion control mechanisms used in tcp have been the focus of numerous studies and have undergone a number of enhancements. However, even with these enhancements, tcp connections still experience alarmingly high loss rates, especially during times of congestion. To alleviate this problem, the ietf is considering active queue management mechanisms, such as red, for deployment in the network. In this paper, we rst show that even with red, loss rates can only be reduced marginally in times of congestion. We then show that the solution to this problem lies in decoupling congestion notiication from packet loss through the use of explicit congestion notiication (ecn) and in understanding the traac generated by an aggregation of a large number of sources. Given this, we then propose and experiment with more adaptive active queue management algorithms (Adaptive red) and more conservative end-host mechanisms (subtcp) which can signiicantly reduce loss rates across congested links. When used together, these mechanisms can eeectively eliminate packet loss while maintaining high link utilizations under the most diicult scenarios.