Microsoft network engineers advise users not to use iPerf3 tool because it is not good on Windows

iPefr is a well-known network testing tool launched and maintained by ESnet. Windows network and debugging engineer James Kyle posted a post in the Microsoft TechNet community today, suggesting that users should not use iPefr3, but should use ntttcp or ctsTraffic developed and maintained by Microsoft.

Why not recommend users to use iPerf3? Microsoft engineers gave three reasons. Simply put, iPerf3 is not directly compatible with Windows systems, so the actual performance is not good.

Reason one: Windows is not supported

ESnet does not recommend users to use iPerf3 on Windows because the tool itself does not support Windows. ESnet recommends that users should use iPerf2 if they really need it.

iPerf3 is mainly developed based on CentOS Linux, FreeBSD and macOS, which are also the main platforms officially supported by ESnet.

For the same reason of unsupport, Microsoft does not recommend users to use iPerf3 on Windows systems.

Reason two: Windows API is not supported

iPerf3 does not call the Windows native API, as it is mainly called through Linux/POSIX, and the iPerf3 community uses Cygwin as an emulation layer to allow iPerf3 to run on Windows.

When the call is sent to Cygwin, the latter converts it to the Windows API. Only in this way can the network stack be detected on Windows. Although this works, some advanced functions do not perform well, such as reduced performance, operational delays, etc. .

The most important thing is that iPerf3 uses the unusual winsock (Windows Socket) option, which is fine for general throughput testing, but for testing applications, winsock cannot simulate the operation of real-world Windows software.

Reason 3: Users are still using the old version of iPerf3

The latest version of iPerf3 provided by ESnet is version 3.16, but when users search for iPerf3 for Windows on search engines (including Bing), the first one listed is the iPerf.fr website, which provides version 3.1.3, and This version was released 8 years ago, and there is a difference of 15 versions from version 3.16.

These 15 versions contain a large number of bug fixes and functional improvements, but because users are using old versions, and the version provided by iPerf.fr contains cygwin1.dll, this will cause the winsock buffer to be limited to 1MB. Poor performance on latency and high-bandwidth networks because not enough data can be transferred causing inaccurate testing.

Therefore, if users really need to use iPerf3, please download it from the ESnet official website.

It is recommended that users use the testing tools maintained by Microsoft:

James Kyle recommends ntttcp and ctsTraffic to developers and network engineers. Both are comprehensive network benchmark testing tools maintained by Microsoft. The latest version of ntttcp is open source on GitHub and is compatible with Windows and Linux systems, which means that it can test different System combinations such as Windows – Windows, Windows –Linux, Linux – Windows, and Linux – Linux.

ctsTraffic is Windows only – Windows testing, focusing on end-to-end good throughput scenarios, developers can choose according to their needs.

Original address: https://techcommunity.microsoft.com/t5/networking-blog/three-reasons-why-you-should-not-use-iperf3-on-windows/ba-p/4117876