What is network stress testing?

What is network stress testing_

What is network stress testing?

Network stress testing is the practice of putting your network under a heavy load to discover breaking points and areas for improvement.

By using network testing tools, you can determine the limits of your hardware, and help get an understanding of how much traffic you can take on before you need to expand your resources.

Here is our list of the best network stress testing tools for 2020:

  1. SolarWinds WAN Killer Traffic Generator (FREE TRIAL) – An easy to use and feature-rich toolkit ideal for stress testing the networks of medium to large-sized businesses.
  2. Nping – Free open-source command-line tool for packet crafting and network testing.
  3. Packet Sender – Free network stress tester with a graphical interface.
  4. Ostinato – Provides API integrations, support, and reporting.
  5. NetScanTools Pro – A bundle of tools that includes a Packet Generator and Packet Flooder to perform stress tests.

Why is network stress testing important?

Network stress testing is important when planning network expansions, as well as when looking to upgrade equipment such as switches and firewalls.

Knowing exactly what your network can and cannot handle will keep you prepared for growth, and help avoid any outages based on hardware limitations. In addition to growth, there are a few other reasons why a business or sysadmin would want to stress test their network.

If you’re an MSP, or service provider that guarantees a certain SLA, you’re going to want to ensure that your network can not only keep your business running but keep your client’s services running as well. Network stress testing can help find unconventional ways end-users could accidentally overload the network and cause service outages that directly impact productivity.

Stress tests can also help identify weaknesses that an attacker could use to overwhelm your infrastructure. DDOS attacks have evolved in complexity over the years, so testing the limits of your network both internally and externally can give you an idea of what it would take to bring down your network.

On the flip side, not all floods of traffic are malicious. In the age of viral content, a successful marketing campaign could drive massive amounts of traffic to a  website or service. Not having a plan for these types of events could lose new customers or bring down services that existing customers use in the process.

What causes network stress for businesses?

Network stress can be caused by several factors and can be divided into two segments: internal and external.

Internally on the LAN, most causes of network stress are found to be caused by unregulated traffic taking up too much bandwidth. A great example of this that you may have experienced yourself is when multiple people are streaming Netflix or Hulu and everything grinds to a halt. This can also happen if too many people are moving large files across the intranet or parts of your LAN.

From externally on the WAN, malicious traffic can attempt to overload services that may impact outward-facing products your customers use such as websites and online tools. Attacks could be thwarted with a simple CAPTCHA, but sometimes it’s not that simple. Attackers can create malformed packets and send them to your exposed ports at incredible volumes. Being able to not just stop, but withstand this type of attack is critical for any business that relies on the internet.

How do I fix network stress?

So what can be done to regain control of your network? It all starts with the Quality Of Service (QoS). QoS is available in nearly all-business-class firewalls and routers and allows you to set limits on how much resources a specific source of traffic can use.

Say you’d still like to allow employees to listen to music at work, but don’t want the network getting overloaded by music streaming packets. You can set the QoS to limit music streaming services so that it doesn’t interfere with day to day operations. Ideally, it’s a win-win for everyone. QoS allows you to get as granular as you’d like. You can even set rules based on individual ports and set exclusions based on certain IP addresses.

Of course, all of this would be in vain if you had a legitimate physical bottleneck in your network, like old wiring or a failing switch that brought down your speeds. That’s when running a thorough network stress test can help you map out what parts of your network need improving, and just how much traffic it can take.

How to stress test a network

Stress testing a network can be as simple as sending packets to a machine, or as complex as running an automated tool to report back it’s findings. On a very simple scale running a ping check across your network can give you an idea if a device is dropping packets or experiencing high latency.

For instance, if you know a device is behind a specific firewall or switch, you can ping another device that isn’t behind that switch to help get a better idea of where the bottleneck is coming from. The downside of this is that it’s tedious, and doesn’t provide much insight into what is causing the problem.

Alternatively, you can move a 1GB file across the LAN to another workstation, VLAN or server, and measure the speed. The file size doesn’t have to be 1GB but should be large enough to take some time. This will give you a rough idea of what the speeds are on your LAN to that destination.

A proper network test would involve a bit more detail. With network stress testing tools you can craft specific packets of any size, and control the exact amount of times a device is sent traffic. This level of customization gives you better flexibility.

Most sysadmins will agree that having a proper network stress testing tool saves tons of time, and is a valuable part of their everyday toolkit.

The best network stress testing tools

1. SolarWinds WAN Killer Traffic Generator (FREE TRIAL)

SolarWinds WAN Killer

WAN Killer Traffic Generator is one of the many tools you can find in the SolarWinds Engineer’s Toolkit. This tool enables you to go beyond basic stress testing by creating specific packets tailored to your specified protocols inside of any Windows environment.

This opens up near-limitless possibilities when it comes to testing how your servers, applications, and overall network will behave under certain conditions. Through the traffic dashboard, you can control the size, protocol, and destination of your traffic before sending it. This allows you to simulate certain applications, or how your end users are likely to behave in a real-life scenario.

While most network stress testing tools simply blast out traffic, WAN Killer gives you the option to customize traffic patterns to replicate human behavior and set random intervals. This method of testing gives you a more realistic set of data to analyze, and better reflect a live environment.

The true value in WAN Killer comes from its ability to mimic your network over time. As you configure WAN Killer you can create traffic patterns that reflect how your network usually functions. As you test new applications you can use this traffic flow as a baseline to better understand how your live environment will react to bandwidth changes and limited network access.

Lastly, WAN Killer gives you tools to measure SLA levels as well as using performance metrics to ensure that not just speeds are met, but that productivity isn’t impacted as well.

You can test out WAN Killer as well as the other 60+ tools in the Engineer’s Toolkit completely free for 30 days.

SolarWinds WAN Killer Start 30-day FREE Trial

2. Nping


Nping is an open-source tool used to test response times while targets on a network are under heavy traffic loads. Through a simple command-line interface you can craft packets and set their destination for a wide variety of load balancing and stress testing purposes.

Users of Nping will have full control over every aspect of the traffic sent. Configurations such as custom header, protocol type, size, and speed can all be set up through the terminal interface. Just like WAN Killer, you can specify a target for either multiple hosts or even multiple ports.

In addition to network stress testing, this utility can also prove useful in different security checks as well. Simulate and test for ARP poisoning vulnerabilities by crafting fake ARP messages over your network, or recreate common Distributed Denial Of Service (DDoS) attacks to see how your network holds up.

Nping also comes with an echo mode that gives you a first-hand look at how traffic is changed or manipulated in real-time as it moves through the network. This is an important feature to have, especially if you utilize network address translation across your firewalls or suspect traffic might be getting manipulated.

While Nping is a powerful tool, it does lack official support which is critical for business environments that rely on high up times. There is also no graphical interface for Nping, which could be considered a downside to some sysadmins.

Nping is completely free and available for Windows, Linux, or macOS.

3. Packet Sender

packet sender dashboard

Pack Sender is an open-source packet traffic generator that was developed for testing how networked devices react to specific traffic.

Similar to Nping, Packet Sender can issue multiple types of traffic to any given device, or port on your network and comes with both a command-line interface as well as a GUI. All data can be defined as either ASCII or HEX and this data can be shared either through the Packet Sender Cloud or through an exported report.

While Packet Sender may look simple, it’s still a powerful and free tool that you can use to stress-test your network. Packet Sender is available for Windows, Linux, and macOS.

4. Ostinato

Ostinato packet generator

Ostinato is a paid packet sending tool that can be used to stress test devices on your network. Ostinato has a simple and easy to use interface that gives you an overview of your current traffic speeds, volume, port, and device.

On the backend, Ostinato comes with a full API library to allow for integrations into your custom tools or plugins. Traffic tests can be configured to fire randomly, in a pattern, or in a constant stream.

You can set up Ostinato to record data and provide simple reporting on the overall performance or the test, or on how an individual target handled specific traffic. Pricing for Ostinato starts at $19.00 (£14.75) and is available for Windows, Linux, and macOS.

5. NetScanTools Pro

NetScanTools Pro network stress tester

Last but not least is NetScanTools Pro, which contains a bundle of network testing tools that include a Packet Generator, as well as a Packet Flooder.

With Packet Generator, you can craft any type of packets you’d like and send them across your network. You’ll have the full ability to specify how those packets are built, as well as replay captured packets that come across your network. Packets can either be imported from a WinPcap file or captured live on the network in real-time.

The NetScanTools bundle runs on modern Windows environments, is available for testing through a 30-day demo, and starts at $249 (£193.18) per license.


We’ve determined that network stress testing is an important part of keeping your environment running smoothly, as well as planning for expansions. So which network stress testing software is right for you?

If you’re managing a medium to large-sized company SolarWinds WAN Killer will give you the best mix of features, ease of use, and support. The ability to craft customized stress tests and produce data-rich reports so conveniently puts WAN Killer at the top of our list.

For departments on a budget or home hobbyist networks, Pack Sender is a great free software that will provide plenty of packet crafting and traffic flooding features you’d need to test your environment. The main downside to these free tools is that if you run into a problem, you’re on your own when looking for support.

Do you stress test your network? Do you think it’s an important part of network testing? Let us know in the comments below.

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