Why delay-based congestion control?
Delay-based congestion control has been proposed since the late 80s by Jain and many others, notably Brakmo and Peterson in TCP Vegas. We believe its advantage over loss-based approach is small at low speed, but decisive at high speed. It has been pointed out that delay can be a poor or untimely predictor of packet loss (e.g., see Martin, Nillson and Rhee’s paper in Trans. on Networking, 11(3):356-369, June 2003). This does not mean that it is futile to use delay as a measure of congestion, but rather, that using a delay-based algorithm to predict loss in the hope of helping a loss-based algorithm adjust its window is the wrong approach to address problems at large windows. Instead, a different approach that fully exploits delay as a congestion measure, augmented with loss information, is needed. Vegas and FAST explore such an approach. Delay as a congestion measure has two advantages. First, each measurement of loss (whether a packet is lost or not) provides 1 bit of congestion inform
