I have been running some tests with the iPerf speed tester feature that is built into the iOS net toolbox app which I wrote a review of a while back. The servers that I have used are in France and the USA - the latter being pretty useless for a uk user.
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ping6.online.net — France?
Upload sent: 1.78 / received: 1.3
Download sent: 10.45 / received 9.85
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iperf.he.net — USA
Upload sent: 1.37 / received 1.17
Download sent: 6.88 / received 5.18
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In these results, where it talks about sent and received, I presume that is is what it appears to be but if the received count does not match the sent count, then why not ? Is this a home brew TCP-like application, which can count lost packets or retransmissions or both and include them into the totals? If it is a normal application above a normal TCP implementation then it would have to be talking about TCP SDUs’ byte counts and so how could anything that has been sent not be ‘received’? (As it’s a reliable transport.) the only thing I can think of in the latter scenario is that some stuff has not been ‘received’ because the experiment was terminated too soon and there is still stuff in transit or sitting in buffers waiting on lost or withheld ACKs. That would mean that the test is rubbish because it’s far too short a duration and it would be far more accurate if it were longer - for the above reasons and also because of the bad effects of TCP slow start.
You see that these sent vs received counts don’t match up, in fact some are a long way off? So what are we supposed to make out of that?