I have a throughput issue on high latency (175ms) link and need help to understand why throughput growth transitions out of slow start. At first the server sends data in batches of 10 and throughput increases after each ACK but then transitions to a different mode for a reason that I do not understand.
It happens after an 11th, valid, segment is received 1ms after the main batch:
It's a long way from filling the receive window, the previous segments have been ACK'd, there is no packet loss, so why does the arrival of the highlighted segment seem to cause a change in behaviour, or is it a symptom of a change at the server end?
I'm going to get a server side pcap for a complete view of what is going on, but does this make sense to anyone?