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We are currently testing some network equipment (consumer routers with 1 Gbit/s ports) with Jpef 2.0. All kinds of connection parameters are tested: wired and wireless, different wireless standards, TCP/UDP, etc.
When not specifying a TCP window size, the performance is low (300 mbit/s). If you enter a high value, the throughput is much better (900 mbit/s). Google tells that Windows uses TCP Window Scaling, there is no "standard" TCP Window size.
What should we use as the TCP Window size in Jperf?
Robert
Posted 2012-06-05T13:51:48.987
Reputation: 826
The only option allowed on Jperf is a fixed value? – Diogo – 2012-06-05T14:01:26.893
Nope, you can manually choose a Window size. edit: yes, it is one fixed value you can enter – Robert – 2012-06-05T14:02:16.020
As far I know it is an automatic algorithm, Windows adjust this value depending on the internet speed. I will try to find the theory behind it, but I think on your case you must set a value due to the speed of the network that you are testing... – Diogo – 2012-06-05T14:07:48.773
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Tried to find a good reference, but the best one that I found was this. On my opinion Jperf leaves this value "open for edit" only because this way be a parameter important to test networks in some specific way. I mean, this should be a choice of the tester so you could find the best value for your network. I just reccomend you to read most of everything you could find about this and try to test different values until you reach the best one for you.
– Diogo – 2012-06-05T14:19:43.687Thanks! I think I have enough information for now. I'm can't accept a comment as an answer, so could you post it as an answer? – Robert – 2012-06-06T07:47:30.800
Yes, I will paste it as an asnwer. Thank you. – Diogo – 2012-06-06T11:59:02.327