  In a congested network link, synchronization effects between
bandwidth-sharing TCP flows cause wide queue length oscillations, which may
translate into poor link utilization if insufficiently buffered. We introduce
global synchronization protection (GSP), a simple extension to the ordinary
operation of a tail-drop queue that safely suppresses the flow synchronization.
Our minimalistic solution is well suited for scaling with leading-edge link
rates: it adds only few extra operations in the fast path and does not require
accelerated memory access compared to the line rate. GSP makes it easier to
provide advanced control of TCP congestion in high-speed links and in low-power
packet processing hardware. Using experiments with a Linux prototype of GSP, we
show that, despite its exclusive focus on removing global synchronization, the
new scheme performs as well as far more complex active queue management (AQM)
schemes like CoDel and PIE.
