Adding Cisco router in GNS3 simulator

GNS3 is virtual simulator that emulates various network equipment. It is mainly used for learning purposes because with this program you can create various kinds of network topologies and labs without requisite for real hardware appliances. Also you can use it for testing potential solutions before implementing it in production network.

In this tutorial I will show you how to properly create virtual router inside of GNS3 simulator.

From the upper left menu, click Edit, then Preferences:


Under Dynamips and then IOS routers, select New to add new Cisco IOS router:


Then, browse your machine for Cisco IOS image. In this tutorial, I’m using IOS version 12.4 for Cisco 7200 Series routers:


Here you should specify name for router and it’s platform. I set both values as default ones (C7200):


On this step you should specify amount of RAM memory for virtual router. Although minimum requirement for this Cisco IOS is 256MB, I set 512MB:


This is where you should specify which network modules you need for your router. You have plenty of options, which includes modules with Ethernet interfaces (PA-4E, PA-8E), modules with Fast Ethernet interfaces (PA-FE-TX, PA-2FE-TX), modules with serial WAN interfaces (PA-4T+, PA-8T) etc:

Under this option should specify Idle PC value. It’s purpose is to prevent Dynamips from taking all of your CPU resources. It’s best to skip this option at this moment, because better option is to calculate this value when router is functional:


On the summary page, check your settings, then click Apply and OK:


After this process, you should be able to pick your router from Router menu on the left side of GNS3 window.


GNS3 simulator you can download from this location.

I hope that this tutorial was informative to you and thank you for visiting this website.

Ivan Sasic

Ivan Sasic

Ivan is IT professional and System Engineer for more then 7 years with experience in financial institutions and education sector. Passionate about computer networks, football and running.

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