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Test result metrics question
05-20-2016, 07:11 AM
Post: #2
RE: Test result metrics question
If you haven't already, you may want to run your test again and maybe from a different location. From looking at the tcpdump you provided, I am seeing some retransmitted data both to and from the WPT machine.

During connection ID 25 specifically, the HTTP GET for that URL from the WPT machine doesn't seem to get to the server because no response ever comes. WPT resends the request after the retransmission timer and the server responds with the data.

After that, it looks like about 11KB of data was sent by the server that WPT never got initially because WPT starts requesting for them, and subsequently gets them. So the server must have sent them, but WPT never got them, which suggests that they got lost along the way. This explains the extra time for the content download.

The bandwidth may be a bottleneck, but you shouldn't be having retransmissions. A bandwidth bottleneck should just slow things down by data taking longer to get to and from WPT. This should not lead to dropped packets on the network. Also, the retransmissions aren't a whole lot; only around 1 or 2%. However, in your case, specific URL requests are being retransmitted that's affecting your WPT results.

Since I see the retransmissions both to and from WPT, you may want to test from other locations just in case.

Also, whenever there are retransmissions, you always want to capture some data on the server side, if possible, to verify that you can see the same retransmissions from the server directly.

Jean Tunis
Principal Consultant, RootPerformance Consulting
Author, Analyzing HTTP
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Messages In This Thread
Test result metrics question - sluong88 - 05-19-2016, 06:44 PM
RE: Test result metrics question - beyondstop - 05-20-2016 07:11 AM
RE: Test result metrics question - pdibona - 05-27-2016, 04:58 AM

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