One day, I was intently searching for a method to emulate a router or switch in Oracle VirtualBox After a long search, I didn’t find a method but I found another virtualizing software called GNS3. GNS3 is a network emulation software which can be really helpful to someone preparing for CCNA,CCNP,CCIE,JNCIA,JNCIS and JNCIE. It can emulate Cisco IOS’s, Junos routers and also complex networks functioning as close as possible to the real networks without needing the network hardware like routers and switches. The best part of it is that it is open source. However we will have to download Cisco IOS and Junos separately.
GNS3 is available for Windows, Linux and MacOS X. In this article, I am going to show you how to install GNS3 in Windows step by step.
Download the software suitable for your Windows from here. The all-in-one download is recommended.
Click on the executable file downloaded. The welcome message pops up. Click on “Next”.
Then the License Agreement is displayed. Click on “I Agree”.
Then you are asked to choose the start menu folder in which your program’s shortcuts will be stored. If you choose the default folder, click “Next”. You can also create a new folder if you want.
Then you can choose which components you want to install from the components shown. I suggest you to choose all the options. Click on “Next”.
Then you are asked to choose where you want to install your program. you can choose a different folder if you want but the default folder should be OK. Click on “Install”.
Then the WinPcap installation wizard starts. WinPcap is an opensource library for packet capture and network analysis for Win32 platforms. Click on “Next”.
Click on “Next”.
On the WinPcap License Agreement, click on “I Agree”.
On the review WinPcap installation options, Click on “Install”.
The installation starts.
After the installation is finished, Click on “Finish”.
Then the Wireshark installation wizard” opens (only if you selected the component for installation above). Wireshark is a network sniffer. Click on “Next”.
You are shown the License Agreement of Wireshark. Click on “I Agree”.
Then you are prompted to select the components of Wireshark you want to install. Choose all and Click on “Next”.
Then you are prompted to select which shortcuts you want to create. The choice is yours. Click on “Next”.
Then choose the directory in which you want to install Wireshark and click on “Next”.
Then Wireshark starts installing.
After the installation is completed, Click on “Next”.
Then Completion of Wireshark installation Wizard appears. You are prompted to choose if you want to run Wireshark. Don’t make any selection. Click on “Finish”.
Then the installation of GNS3 starts.
After the installation is completed, click on “Next”.
Completion of GNS3 wizard appears. Click on “Finish”.
Start GNS3. The following window appears when we start GNS3 for the first time. Click on 1(the space enclosed in a red box).
This is to check whether path to Dynamips and the path to its working directory are valid or not. Dynamips is the core program that allows IOS simulation. Click “OK”.
Let’s go to Step 2. Here we configure path to our IOS image directory. We have to store all our images in this directory. Make changes to the path if you want otherwise click on “OK”.
Step 3: In this step, we will add one or more uncompressed IOS images of a router or switch. As already said, IOS images should be downloaded separately due to license agreements.
Browse to the folder where your IOS image is. I am adding a CISCO c3700 router for example. Click on Save and your window should like this.
Click on “Close” and your GNS3 windows appears.
In the Node Types section, click on C700 (the type we just added) and drag it to the right to see if our router has been added or not. If it is like below, then your installation is success. Happy practicing.