Microsoft does not want you to use iPerf3 to measure network performance on Windows

iPerf is a fairly popular cross-platform tool that is used by many to measure network performance and diagnose any potential issues in this area. The open-source utility is maintained by an organization called Energy Sciences Network (ESnet) and officially supports Linux, Unix, and Windows. However, Microsoft has now published a detailed blog post explaining why you should not use the latest version, iPerf3, on Windows installations.

iPerf 3 isn’t really supported on Windows

Microsoft has highlighted three key reasons to discourage the use of iPerf3 on Windows. The first is that ESnet does not support this version on Windows, and recommends iPerf2 instead. On its website, ESnet has emphasized that CentOS 7 Linux, FreeBSD 11, and macOS 10.12 are the only supported platforms.

Another very important reason not to use iPerf3 on Windows is that it does not make native OS calls. Instead, it leverages Cygwin as an emulation layer, which obviously comes with a performance penalty. This alone means that iPerf3 on Windows isn’t really an ideal candidate for benchmarking your network. While Microsoft has praised the maintainers who are trying to get iPerf3 to run on Windows via emulation, another flaw with this approach is that some advanced networking options simply aren’t available on Windows or may behave in unexpected ways.

The final reason deals with the fact that Windows customers are likely using older copies of iPerf3 without even realizing it. The official latest version maintained by ESnet is 3.16, but if you search for “iPerf3 on Windows” in your browser, you’ll likely be directed to download version 3.1.3, which was last updated eight years ago. This implementation also utilizes the Cygwin emulation layer and even contains a bug which limits the socket buffer to 1MB. Even ESnet recommends using other unofficial builds of iPerf3 if you are really eager to run the software on your Windows installation.

What does Microsoft recommend instead?

Microsoft is strictly against the idea of using iPerf3 to measure network performance on Windows. It has instead urged users to try out ntttcp (Windows NT Test TCP) and ctsTraffic; both pieces of software are maintained by Microsoft. The company has emphasized the use of the right tool when performing synthetic testing of your network’s health. If you compare the three tools, you’ll notice massive differences in network performance, further underscoring the need to ditch iPerf3 in favor of other tools on Windows.