Hi there Been using Wireshark for a few years but I'm now in deep, and hopefully someone can help. I am using iperf3 (TCP) to test uploads on a symmetrical 1Gb/sec connection-the client is an Odroid C2, with the server being a hosted Ubuntu box on Digital Ocean. Using 4 threads and an RTT of 14ms, downloads are coming through fine, at 940Mb/sec-but uploads are poor-by poor, I mean it starts well in the first few seconds-and then drops off, ending at about 250Mb/sec (10 second test). Looking at the pcap trace on one of the streams (all 4 look the same), TCP slow start is in play-after about 2 seconds in, with a bytes in flight of just over 1MB, a fast retransmission is seen-as a result, the calculated window size of the receiver (which is the Ubuntu server) drops from 2.08MB to 1.19MB-fair enough,TCP doing what it should and it (window size) recovers back to >2MB within a few ms. But here's the bit I dont get-the sender (Odroid) never recovers back to 1MB bytes in flight-as a result, the speeds remain at a stubbornly low level. I have played about with window sizes and memory buffers on both machines but to no avail-the bit I dont get is after that Fast Rx, why doesn't the upload recover, now that the window size being advertised by the receiver recover? This receiver works ok with other tests-and if there was an inherent problem, I would expect the downloads to be poor as well-but they are always great.
I have the pcap at hand and happy to upload it but I dont know if I can/am allowed as this is my first post?
Thanks
cabs
