Disclaimer: This post is intended only for educational purposes only. I take no responsibility is a person after viewing this article participates in activities beyond the boundary of Laws. Do not scroll down and move away from this page if you believe that this is not for you.

Today, I will show you how to set up your own Cisco lab without expending too much money. If you are studying for a CCNA certification, you need a lab environment for practicing your networking skills before taking the actual exam. If this is your plan, you have three options to put in practice your knowledge doing hands on labs.

The first option is to build a hardware lab. A complete Cisco hardware lab could be something cool for learners but, its main drawback is the cost. Building a CCNA Lab is an expensive option for most people. Based on my personal experience you need at least three router (1760), two switch (2960), one router acting as Frame Relay cloud (2520), six serial WIC and six V.35 serial cables. Building a lab like this could cost a lot of money without including books, workbooks and reference materials.

The second option is to install a simulator. A simulator is a computer software running on computer pretending to simulate the functions of some sort of hardware or software. In this case, Packet Tracert is a network simulator made by Cisco. It is another option people have to put in practice networking skills. The main drawback of simulators is that they are not 100% accurate. So often, functions and commands are missing so students are not able to manage highly complex network environments. Advanced Cisco IOS commands and functions are not available under this type of solution.

The third option is to use a software emulator. An emulator is a piece of software written to emulate the functions of certain primary hardware in a separate second hardware platform. The second hardware behaves like if it were the primary device.

GNS3 is the most popular Cisco hardware emulator. It is free and open source software. You can install it on your Windows PC or Linux. GNS3 allows students to interact directly with a Cisco IOS. Students can install and deploy large and complex networks without expending a fortune buying Cisco equipments.

GNS3 allows anyone to run Cisco router on PC platform. The only requirement is to get the Cisco IOS images legally which is only available through the Cisco web site for those with partner access. If you have access to a physical Cisco router, you can download the IOS image from a router via TFTP protocol and, run it under GNS3. Unfortunately, GNS3 is not capable to simulate Cisco Switch, only routers.

GNS3 emulator is composed by two software components. The first component is the GNS3 software which is a graphical front end for drawing network connections, configuring and managing Cisco IOS images. The second component is Dynamips which is the software used for emulating Cisco hardware.

Obviously, GNS3 development has improved substantially so now it can be integrated to a different  emulator platform like Qemu and VirtualBox. This integration allow users to build a more realistic network environments using different operating systems combined in the same environment.

The following is a procedure to install GNS3 on Linux Fedora 16. This method has been tested on 32 bits Linux version. I do not know if it works on 64 bits.

Step 1: Install Python

#yum install python3-PyQt4

Step 2: Install PyQt4

#yum install PyQt4

Step 3: Install Putty

#yum install putty

Step 4: Make a directory called “gns3”

#mkdir gns3

Step 5: Change to gns3 directory

#cd gns3

Step 6: Download gns3

#wget http://sourceforge.net/projects/gns-3/files/GNS3/0.7.4/GNS3-0.7.4-src.tar.bz2

Step 7: Download dynamips

#wget http://sourceforge.net/projects/gns-3/files/Dynamips/0.2.8-RC2/dynamips-0.2.8-RC2-x86.bin

Step 8: Uncompress GNS3

#tar -jxvf GNS3-0.7.4-src.tar.bz2

Step 9: Change access permissions to dymanips executable file

#chmod 755 dynamips-0.2.8-RC2-x86.bin

Step 10: Move Dynamips to GNS3 directory

#mv dynamips-0.2.8-RC2-x86.bin GNS3-0.7.4-src

Step 11: Change to GNS3-0.7.4-src directory

#cd GNS3-0.7.4-src

Step 12: Running GNS3

#./gns3

Step 13: Setting up GNS3 preferences

a) Click on edit, preferences, General, Terminal Setting

/usr/bin/putty -telnet %h %p

b) Click on edit, preferences, Dynamips

Executable Path = /home/$user/gns3/GNS3-0.7.4-src/dynamips-0.2.8-RC2-x86.bin

Working Directory = /home/$user/gns3/GNS3-0.7.4-src

Step 14: Finally, load your Cisco IOS images into GNS3

Click on Edit, IOS Images and Hypervisors, Select your IOS according to its hardware models and press Save button.

For those of you who are Windows users and, want to know how to install GNS3 on Windows, I encourage you to watch the following video:

I hope you enjoyed this post! And if you did, please feel free to share it! Cheers, and all the best.