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An often-overlooked challenge : simulating real-world network conditions

May 09, 2023

Every AV engineer encounteres their fair share of live streaming challenges. While AV engineers often focus on bandwidth and signal strength, there’s one subtle yet significant factor that tends to slip through the cracks: accurately emulating real-world network conditions.

Why would you want to emulate network conditions?

Real-world network conditions are a complex mix of latency, bandwidth fluctuations, packet loss, and other factors. Accurately emulating these conditions during testing is essential to ensure a seamless streaming experience for your viewers.

I’ve come to fully understand and appreciate the importance of a well-rounded testing routine when I got myself into some trouble. It was the day of a pretty anticipated product launch, and I was responsible for ensuring a flawless live streaming experience. I thought I had covered all bases, testing bandwidth and signal strength extensively. 

As the event began, viewers started complaining about video stuttering, buffering, and even disconnects. I was perplexed and frustrated, feeling the weight of the situation. That’s when I realized : I hadn’t considered other network conditions during testing.

Okay, but what exactly are these tests for?

Emulating real-world network conditions during testing helps identify potential issues that might arise during live streaming. By accounting for these conditions, you can optimize your streaming setup to minimize delays and buffering, resulting in a better experience for your viewers.

In simple terms, testing your set up against different network conditions works like a crash test. The goal is to spot any potential issues and account for them before they ruin your event.

My preferred solution: WANem

WANem (Wide Area Network emulator) is an open-source software tool that I’ve found invaluable for emulating network conditions during testing. With WANem, you can introduce latency, packet loss, bandwidth restrictions, and more to your testing environment, simulating real-world network conditions.

How you can use WANem

Here’s a step-by-step guide to using WANem for network condition emulation:

1. Download WANem: Visit the WANem website ( and download the latest version of the application.

2. Create a bootable USB drive: Follow the instructions on the WANem website to create a bootable USB drive containing the WANem software.

3. Boot your system with WANem: Restart your computer, booting from the WANem USB drive.

4. Configure WANem settings: Once WANem has loaded, use the web-based interface to configure the desired network conditions for your test. You can set latency, packet loss, and bandwidth limitations, among other parameters.

5. Test your live streaming setup: With WANem running, perform your usual streaming tests to see how your setup handles the emulated network conditions.

6. Adjust your streaming setup accordingly: Based on your test results, make the necessary adjustments to your streaming setup to optimize for the emulated network conditions. This may involve tweaking encoding settings, using a different streaming protocol, or adjusting buffering settings.

Alternative Network Condition Emulation tools

While WANem works for me, I understand the importance of having alternatives up your sleeve. Here are a couple of other network emulation tools you might consider:

  1. tc (Traffic Control) — A cross-platform network emulator available on Linux and macOS. It allows you to introduce latency, packet loss, and other network conditions to your testing environment.
  2. Clumsy — A Windows-based application that offers a graphical interface for emulating various network conditions, including latency, packet loss, and bandwidth limitations.

I’ll never forget the day I overlooked the importance of emulating real-world network conditions during live streaming tests. That experience taught me a valuable lesson and transformed the way I approach testing. By incorporating tools like WANem, tc, or Clumsy into your testing workflow, you can ensure that your streaming setup is optimized for real-world network conditions, and avoid the headaches I once faced.

Emulating network conditions is an essential yet often overlooked aspect of live streaming testing. Don’t let network conditions catch you off-guard; include them in your testing routine and deliver the best possible streaming experience to your viewers.