Abstract

The existing algorithms for detecting congestion during the slow start phase of TCP either exit too early, before loss, or too late, after loss, especially on high-latency networks like satellite links. SEARCH is a new algorithm which attempts to improve performance over those links. It attempts to detect the optimal sending rate by detecting when more data is not making it to the receiver by comparing acknowledged bytes over time. We implemented the SEARCH algorithm within a kernel congestion control module for the FreeBSD operating system. We validated our implementation by testing its components incrementally, and evaluated performance compared to the existing slow start algorithms HyStart and HyStart++. We found our implementation exited slow start at a higher goodput without inducing loss more frequently than HyStart and HyStart++.

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