Performance Evaluation of Quick-Start TCP with a Linux Kernel Implementation

Quick-Start is an experimental extension of the Transmission Control Protocol (TCP) that uses explicit router feedback to speed up best effort data transfers. With Quick-Start, TCP endpoints can request permission from the routers along the path to send at a higher rate than allowed by the default TCP congestion control, which avoids the time-consuming Slow-Start. However, since Quick-Start TCP requires modifications in the protocol stacks of end-systems and routers, realization complexity is a major concern. This paper studies Quick-Start with a new implementation in the Linux protocol stack. We first show that Quick-Start support can be added to a real stack with rather limited effort, without causing much processing overhead. Second, we perform measurements with Web applications and study the impact of important parameters. These experiments with real applications demonstrate that Quick-Start can significantly speed up data transfers, and they confirm the outcome of previous simulation efforts. Our results suggest that Quick-Start is a lightweight mechanism that could be very beneficial for broadband interactive applications in the future Internet.