Flow-valve: Embedding a Safety-valve in RED

In this paper, we present the ow-valve, a safety-valve mechanism for RED to protect the network from misbehaving or overpumping ows and to promote end-to-end congestion control. The ow-valve can be regarded as an implementation of the concept known as a \RED penaltybox" but our focus is to protect router resources in times of congestion. The ow-valve detects a tra c increase that goes beyond the control range of RED, and protect the local resources by forcing overpumping ows to back o . The ow-valve provides an incentive for end-to-end congestion control to keep the packet drop rate low under moderate congestion, and to conservatively back o under heavy congestion. Our simulation results demonstrate that the ow-valve can e ectively protect the network from misbehaving ows and, at the same time, isolate undesirable behavior of conformant TCP. The ow-valve also has been successfully implemented onto FreeBSD.