Poor IPERF file transfer performance between two back-to-back Windows 7 Dell laptops
I work for an ISP, and our WAN install process for enterprise business customers requires us to install a laptop at the customer's premise to run IPERF tests to measure average file transfer throughput between different offices. I've been using Dell D830 laptops running Windows XP Pro, but I recently purchased two brand new Dell Precision M4400 laptops running Windows 7 because many of my customers plan to upgrade. Before deploying them for WAN tests, I wanted to get an idea of what to expect in a low-latency LAN environment, so I connected the two Windows 7 laptops back-to-back with a crossover Ethernet cable and installed IPERF on both boxes. I disabled Windows Firewall and I don't have any other firewall or anti-virus apps installed. The NICs are set to 1G full duplex, flow control is disabled. So I ran the IPERF tests and found that TCP-based file transfers aren't bad...I can average 910 mbps after tuning the TCP Window Size. However, UDP-based file transfers are absolutely horrible. The best I can get is 150 mbps and I drop a lot of packets. It appears there's a UDP rate limiter built into the operating system, perhaps to smooth out audio and video performance (as those packets are typically UDP). Can someone tell me how to disable this rate limiting so I can get better UDP packet transfer test results? Thanks!
March 18th, 2010 3:09am

Hi, Considering this is related to a third party tool and we have limited recourses about how it is designed and how it works, it is recommended that you contact the support of IPERF for help since they are familiar with their products: IPERF Note: Microsoft provides third-party contact information to help you find technical support. This contact information may change without notice. Microsoft does not guarantee the accuracy of this third-party contact information. Thanks. Nicholas Li - MSFT
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March 19th, 2010 1:15pm

Hi, I was testing a local network and had similar problems. On UDP try to put 1000 Mbps/sec UDP bandwidth and increase the UDP packet size. I used 1000 Mbps/sec and 63 UDP packet size. Thanks StephanosCF
July 19th, 2010 7:53pm

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