Don't Use Iperf3 on Windows
Microsoft’s warning against using the popular iperf3 network benchmarking tool on Windows and its promotion of proprietary alternatives like ntttcp and ctsTraffic draws skepticism from engineers who rely on cross‑platform interoperability. Commenters argue that iperf3 is “good enough” in real‑world scenarios, is widely available on routers and Linux systems, and that Microsoft would be better served by contributing proper native Windows support rather than pushing Windows‑centric tools with poor packaging, awkward CLIs, and limited ecosystem reach. Broader concerns surface around Microsoft’s culture, app‑store and search practices, and the trade-offs between centralized package management, openness, and usability on Windows versus Linux.
Context and main reactions
- Many agree the article correctly highlights that popular Windows iperf3 builds are outdated Cygwin ports and can underperform, but several note that for typical LAN / 10 Gbps use they see little or no practical issue.
- Some argue Microsoft would be better off improving/maintaining a native iperf3 for Windows instead of pushing its own tools (ntttcp, ctsTraffic).
Interoperability and real-world usage
- A recurring objection: Microsoft’s tools assume Windows on both ends, while iperf is ubiquitous on routers, ISP test endpoints, and assorted Linux/BSD systems.
- Commenters stress that a network testing tool must be cross‑platform and interoperate; single‑platform or non–wire‑compatible tools are seen as non‑starters.
- ntttcp packages are limited (Debian/Ubuntu/NetBSD); not available on common router OSes like OpenWRT or commercial network gear, limiting its practicality.
Performance and technical points
- Some report iperf3 on Windows achieving near‑line‑rate 10 Gbps with a single TCP stream, contradicting the article’s more pessimistic numbers.
- Others accept that Cygwin/syscall translation adds overhead but question why Microsoft doesn’t contribute a native implementation or wire‑compatible tool.
- Discussion notes that Microsoft’s newer tools target advanced scenarios (high‑latency/high‑bandwidth, QUIC and offload testing) that iperf doesn’t cover well.
- There is debate over whether performance gaps could be closed with iperf flags (e.g., parallel streams) versus needing entirely new tooling.
WSL and platform behavior
- WSL is seen as unsuitable for “pure” benchmarking because it introduces emulation/virtualization layers, even if it may outperform the old Cygwin iperf3.
- Some mention that enabling WSL2 can itself put Windows into a more virtualized mode, further complicating measurements.
CLI UX, packaging, and app distribution
- Microsoft’s benchmarking tools are criticized for verbose, unfriendly command lines compared to
iperf3 -sstyle UX. - Centralized package managers (winget, choco, Linux repos) are praised for simplicity and safety, but there is pushback against a single Microsoft‑controlled store and against app‑store bureaucracy.
- One thread notes Linux distro packages can be feature‑reduced (e.g., VLC without non‑free components), so “official repo” does not always mean “best binary.”
iperf2 vs iperf3
- Clarification that iperf2 and iperf3 are separate, non‑interoperable projects, both actively developed, with different strengths.
- iperf2 on Windows is reported to perform similarly to Linux in localhost tests, suggesting Cygwin overhead may not always be significant.