Subsidized RED: an active queue management mechanism for short-lived flows

In heavily congested networks, RED using parameters that provide the best link utilization produces poor response times. In this work, we devise and study the performance of a simple active queue management mechanism called Subsidized RED (SubRED) targeted at short-lived flows or fragile flows (e.g. most HTTP flows) to keep link utilization high while reducing the average flow response time. Our simulation studies have compared the performance of RED and SubRED for a network with HTTP traffic at offered loads less, close to, and more than the link capacity. Simulations show that a subsidy given to a flow provides significantly better performance in terms of HTTP request-reply delays without sacrificing the link utilization. The new scheme is very simple to implement. Combined with our cost-effective flow table based implementation, SubRED does not impose an excessive resource overhead.