Vladimir

Zoomed-out we see a repeating pattern of slow in-flight ramp up with rapidly increasing RTTs because of a queue at the slow WAN interface. When the queue fills (usually ~100KB but sometimes less) we get losses and SACK/retrans recovery. Repeat pattern. Server RWIN never filled.

Here's a great 1Mbps egress queue example. Bottom part shows in-flight data ramping up with red "ticks" showing that losses always began at ~100KB. Black squares are individual measured RTTs. They neatly increase as queue time is added, flattening when the queue is full.