Simulate Your Network Devices And Configuration Using NetEmul

Ryan Dube 10-05-2012

simulate network trafficIt wasn’t until I started working in the IT field that I realized just how complex it can be to troubleshoot networking issues. If  certain devices on a network aren’t wired right or the IP settings for your network cards have a typo, a lot can go wrong fast.


When it’s time to lay out a network, whether it’s on a large scale at a corporation or on a small scale at your house, wouldn’t it be nice to lay out all of your network devices, their IP settings, and then simulate whether or not your network will work as expected?

We like simulators here at MakeUseOf.  I recently covered how you can simulate building a model rocket Simulate Building & Launching A Model Rocket With OpenRocket We love making models here at MUO. But one problem with tweaking a model design in the real world is that to test it, you have to rebuild a rocket with new parameters, do a... Read More , and even further back, simulating a model train layout How To Create Simulated Model Train Layout Plans & Control Train With Your PC Read More . But what about simulating something that’s even more applicable to the field of IT, like simulating computer networks?

That’s exactly what you can do with the open source network simulator called NetEmul.

Simulating Networks with NetEmul

It’s a pretty cool concept, and when I first heard about it I didn’t really think it was possible. I know when I do network troubleshooting, there’s not a lot that’s simple or straightforward. So many things can go wrong to mess up a good line of data transfer, whether it’s a poorly wired port, a bad switch, or bad network settings for the network device.

However, when I started playing around with NetEmul, it really surprised me. The software lets you realistically set up a proposed network layout using things like hubs, switches, routers and computers. By copying the different layouts for the network you’re planning out, you can test whether or not the network settings and configuration will work.


simulate network traffic

The top menu is where you select what devices you want to add to the design grid. Above, I’ve added 3 PCs and a router. I later decided to switch the router for a hub. Then drawing connections just involves clicking the “Create connection” button and drawing a line between the devices that you want to connect. You choose the “LAN” port that you want to plug the computer into the hug, switch or router, and move on to the next.

Here I have three groups of computers all linked to their own central hub.

simulate network load


To complete my hypothetical network, I then toss a switch between all of the hubs and connect them together. Thinking that I’ve got everything under control, I decide to go ahead and do a test “data send” over the network from the first computer. To do this, you click the “Send data” button, and you’ll see a choice to select what protocol you want to use for the transfer.

simulate network load

You’ll also need to select what network card you want to send those packets out of. In this case I only gave each computer one network card, so that’s the one I go with.

simulate network load


It didn’t take long for me to realize that something was wrong. The dead giveaway should have been the fact that the indicator lights on all of the PCs were yellow. A good comm link will give you a green light. Obviously I forgot something.

After a few seconds it dawned on me, the network settings…duh!  Just right click on the computer, select Netcard” from the list, and type in the appropriate IP settings for this node on your simulated network.

simulate network

If you want to set a gateway, you can do that by right clicking on the computer and choosing Properties. The pop-up will let you type the default gateway. Once I went through and configured six PCs to use a common subnet, all of their status lights turned green.


simulate network

You can also check on the Properties of the network hardware like the switches, hubs and routers by right clicking and choosing “Properties”.  This gives you the Mac address and lets you expand its capacity with a greater number of ports (I wish it was that easy in real life!)

simulate network

This time, when you send out the test data packet, you’ll see the test data flowing through the network as highlighted red dots traveling along the network lines.

Simulate Your Network Devices And Configuration Using NetEmul netemul10

Right click on any network device and choose “Show log” to watch incoming and outgoing network communications at that point in the network. This is also a cool way to see what changes you’ve made to your simulated network actually work, and what changes don’t. You can see what devices are talking and which aren’t, and then test out different network settings to get things to talk.

simulate network traffic

The ability to test out network settings in a simulated network like this would actually save a whole lot of headache in the real world, where people often just throw devices onto a network, or build entire networks in office areas, without really giving much thought into how devices need to be configured to talk. And in an environment where you have virtual LANs, things can get even more complicated.

So if you’re a network manager, or you’re just a networking geek in general, download NetEmul and try your hand at building networks of different complexities. Do you think the software might help you test out or troubleshoot your own networks? Share your reviews and thoughts in the comments section below.

Image Credit:3d Cloud Computing via Shuttertock

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  1. dragonmouth
    October 29, 2012 at 3:34 pm

    Is NetEmul for Windows only, like most of the stuff on MakeUseOf site, or is there a Linux version? Seems like a useful program but I don't do Windows.

  2. vishu
    May 21, 2012 at 4:20 pm

    well seem to intersting