How to use iPerf3 to test network bandwidth: A step-by-step guide

Learn to install, configure, and execute iPerf3 for effective network performance measurement across various systems and environments.

iPerf3 is an open-source benchmarking tool used to measure the speed of data transfers over a network, ensuring everything works efficiently. This guide will explain downloading, installing, and using iPerf3 on Windows and Linux systems.

Important considerations

System compatibility: iPerf3 works on many devices, including Windows, Mac, Linux (like Ubuntu, Debian, Mint, Fedora, Red Hat, CentOS, openSUSE, Arch Linux), FreeBSD, Android phones, iPhones/iPads, and Microsoft apps.
Testing environment: Run iPerf3 tests when fewer people use the network because it uses a lot of internet speed, which might slow down others.
Comprehensive testing: iPerf3 tests both the upload and download speeds to provide a complete picture of your network’s performance.

Step-by-step instructions for Windows

Step 1: Download iPerf3

Visit the iPerf3 download page.
Download the ".zip" file for Windows.

Step 2: Extract the ".zip" file

Navigate to your "Downloads" folder.
Right-click the downloaded ".zip" file (e.g., iperf-3.1.3-win64.zip or iperf3.17_64.zip) and select "Extract All..." (see Fig. 1).

Fig. 1. Extracting the iPerf3 ".zip" file.
Choose a destination folder for the extracted files (see Fig. 2).

Fig. 2. Selecting a destination folder for the extracted files.

For this tutorial, we will use "C:\Users\cherry\Downloads\iperf3" (replace "cherry" with your actual username).

Step 3: Navigate to the iPerf3 directory

Open Command Prompt or PowerShell as an Administrator:
- Command Prompt: Search for "cmd" in the Start menu, right-click Command Prompt, and select "Run as administrator".
- PowerShell: Search for "PowerShell" in the Start menu, right-click Windows PowerShell, and select "Run as administrator".
Use the "cd" command to navigate to the directory where iPerf3 was extracted. Replace "cherry" with your actual username and "x.x" with the version number:
```
$ cd C:\Users\cherry\Downloads\iperf3\iperfx.x_64
```

Step 4: Run iPerf3

To test the bandwidth, run the following command:

$ .\iperf3.exe -c paris.testdebit.info -p 9215 -P 10

Explanation of flags:

-c: Specifies the client mode and the server address to connect. In this case, it connects to paris.testdebit.info.
-p: Specifies the port number to connect to on the server. Here, it uses port 9215.
-P: Specifies the number of parallel client threads to use. Here, it uses 10 threads.

Step-by-step instructions for Linux

Step 1: Install iPerf3

For Debian/Ubuntu-based systems:

$ sudo apt install iperf3

For CentOS/RHEL-based systems:

$ sudo yum install iperf3

For Fedora operating systems:

$ sudo dnf install iperf3

For Arch Linux-based systems:

$ sudo pacman -S iperf3

For openSUSE operating systems:

$ sudo zypper install iperf3

Step 2: Run iPerf3

Run the following command:

$ iperf3 -c paris.testdebit.info -p 9215 -P 10

Explanation of flags:

-c: Specifies the client mode and the server address to connect. In this case, it connects to paris.testdebit.info.
-p: Specifies the port number to connect to on the server. Here, it uses port 9215.
-P: Specifies the number of parallel client threads to use. Here, it uses 10 threads.

Testing network speed between two servers

To test the speed between two servers using iPerf3, you must set up one server as an iPerf3 server and the other as a client.

Step 1: Set up the iPerf3 server

On the first server, start iPerf3 in server mode:
```
$ iperf3 -s  
```
This command will start iPerf3 in server mode, listening for incoming connections on the default port - 5201.

Step 2: Set up the iPerf3 client

On the second server, run iPerf3 in client mode and connect to the first server. Replace <server_ip> with the IP address of the first server:
```
$ iperf3 -c <server_ip> 
```

Step 3: Exit iPerf3 server mode

To exit iPerf3 server mode, press Ctrl + C in the terminal where iPerf3 runs.

Reviewing test results

iPerf3 displays the test results in the terminal (see Fig. 3).
Results show the total bandwidth for both client-to-server and server-to-client directions.

Example output:

Fig. 3. Example output of iPerf3 test results.

Additional resources

List of iPerf3 servers: For a comprehensive list of public iPerf3 servers, visit GitHub iPerf3 Servers.
iPerf3 documentation: Detailed documentation and various test options are available at the iPerf3 Documentation.
iPerf3 server locations: Find a list of servers, their locations, and available ports at iPerf3 Server Locations.

Summary

By following these steps, you can successfully set up and use iPerf3 to measure the speed of your network connections. Ensure your test environment is configured correctly to avoid interference or inaccurate test results.