GNS3 is a graphical network simulator that allows simulation of complex networks. GNS3 is an excellent complementary tool to real labs for network engineers, administrators and people wanting to pass certifications such as CCNA, CCNP, CCIP, CCIE, JNCIA, JNCIS, JNCIE.
It can also be used to experiment features of Cisco IOS, Juniper JunOS or to check configurations that need to be deployed later on real routers.
This project is an open source, free program that may be used on multiple operating systems, including Windows, Linux, and MacOS X.
Features overview
- Design of high quality and complex network topologies.
- Emulation of many Cisco IOS router platforms, IPS, PIX and ASA firewalls, JunOS.
- Simulation of simple Ethernet, ATM and Frame Relay switches.
- Connection of the simulated network to the real world!
- Packet capture using Wireshark.
On Fedora
Installing dynamips & other dependencies
Go to dynamips & download latest version of dynamips from its website.
mkdir /tmp/network cd /tmp/network wget http://www.ipflow.utc.fr/dynamips/dynamips-0.2.8-RC2-x86.bin chmod 777 dynamips-0.2.8-RC2-x86.bin yum install -y qt python sip PyQt PyQt4 xterm telnet |
Downloading GNS3
Go to GNS3 website and download the latest version
cd /tmp/network wget http://downloads.sourceforge.net/project/gns-3/GNS3/0.7.2/GNS3-0.7.2-src.tar.bz2 tar zxvf GNS3-0.7.2-src.tar.bz2 |
Runing GNS3
cd /tmp/network/GNS3-0.7.2-src ./gns3 |
Go to edit > preference & select Dynamips from left hand side menu.
Adjust parameters as per below screenshot.
On Ubuntu
Installation
apt-get install gns3 |
Running GNS3
just run “gns3″ on terminal(without quotes)
You also have to provide IOS image of Cisco (use google).
My name is Vidyadhar Sarmalkar & I work as a consultant and have done RHCE & CCNA. 
