Mark Claypool, Robert Kinicki, and Matthew Hartling
The focus in Active Queue Management (AQM) research has been on traffic that is long-lived, insensitive to delay, and often has large TCP congestion windows. However, the majority of the flows on the Internet today are Web flows, which are short-lived, more sensitive to delay, and typically have small TCP congestion windows. In particular, short-lived flows with small congestion windows frequently suffer from timeouts when encountering packet loss. This paper presents and evaluates a new AQM scheme, SHort-lived flow friendly RED (SHRED), targeted at providing better network performance for short-lived Web traffic. Using an edge hint to indicate the congestion window size in each packet sent by the flow source or by an edge router, SHRED preferentially drops packets from short-lived Web flows less often than packets from long-lived flows. A wide-range of simulation results and analysis demonstrate that SHRED protects short-lived flows from unnecessary timeouts, improving the response time characteristics for Web traffic when the router becomes congested, while not degrading overall network performance.