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Old 01-03-2015, 05:25 PM   #1
trafikpolisen
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Iperf test - slow in one direction


I have a closet where i keep my network equipment including a server on which i store everything. Tonight i installed a new cable between my computer and the switch next to the server (the old cable was kind of abused). Apart from accidentally hitting a nail right through the new cable (fucking shit...) everything went fine. The cable luckily escaped reasonably undamaged though.
When finished I thought I'd run an iperf test just to see if everything was according to expectation. When running iperf server on the server (which happens to be an old Windows server) and the client on my computer, I get around 820 Mbit. Now, in the opposite direction I get just around 270 Mbit. Any idea why? I have tried with another cable with basically the same result.
 
Old 01-04-2015, 10:05 AM   #2
Keruskerfuerst
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Which type of cable are you using? (cat xx).
 
Old 01-04-2015, 09:49 PM   #3
trafikpolisen
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5e. Though the loose cable i also tried with was Cat6.
 
Old 01-07-2015, 02:32 AM   #4
Keruskerfuerst
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Can you try the cable with a another networking card?
 
Old 01-10-2015, 10:59 PM   #5
trafikpolisen
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Ok, booted the server from a USB stick with Linux Mint and ran iperf. Now I get 880 Mbit (270 Mbit before) when sending from that machine and about 850 Mbit when sending traffic to it. So I think it's safe to say that it's not a problem with hardware or cables, but rather with Windows or a setting with the NIC. Any ideas? The NIC in question is an Intel Pro PCI card.
 
Old 01-10-2015, 11:57 PM   #6
ferrari
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Is the NIC negotiating correctly with whatever device it is connected to? For Linux, it is useful to observe using 'ethtool'. For Windows, it can be a bit more tricky (depending on the hardware concerned).

http://forums.hexus.net/networking-b...ml#post1421629
 
  


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