I used iperf to measure the max throughput for TCP connection between two ubuntu machines. Both the machines were directly connected be means of a 1Gbps cable. When I performed iperf tests i obtained a bandwidth of 845 Mbps on an average. But when i tried reversing the direction (i.e changed server to client and viceversa) the results went down to 185 Mbps.These results are an average of ten readings and the max i was able to obtain was 370Mbps. I then decided to set the same value for parameters such as rmem_max, wmem_max, tcp_rmem, tcp_wmem but even after setting same parameters i got similiar results. i.e(845Mbps in one direction and 185Mbps in the other direction). I don't know what the possible cause could be. Is there something important that i have missed?

  • I just made a similar observation: In a similar setup, iperf -c ... is much faster for me compared to iperf -r -c .... I have no explanation for this behavior either. – bluenote10 May 14 '14 at 11:45

Your Answer

By clicking "Post Your Answer", you acknowledge that you have read our updated terms of service, privacy policy and cookie policy, and that your continued use of the website is subject to these policies.

Browse other questions tagged or ask your own question.