GNS3

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Introduction to GNS3

Graphical Network Simulator (GNS3) is an open source software, Which allow to simulate complex network. It works on windows, Linux and Mac OS based machines.GNS3 has a graphical front end product called Dynagen.Dynamips is the core program to emulate the Router OS. A user can design their own network topology with the help of GNS3. GNS3 can also be liked with Qemu and virtualBox. Qemu is general open source processor emulator. VirtualBox is a free virtualizaion software.


In this tutorial we are using GNS3 0.7.3 which is under GPL v2 license. GNS3 work better on Linux (Ubuntu) based OS, So it is recommended to use any Linux based OS. The Tutorial use Ubuntu 11.04 OS. In the following tutorials we will create some basic network topology to learn GNS3 and to understand the network issue before they deployed to real networks.

GNS3 is an excellent complementary tool to real labs for network engineers, administrators and people wanting to study for certifications.It allow to run Router OS like JUNOS and Cisco IOS in a virtual environment on your machine. JUNOS is FreeBSD based Juniper Router OS. IOS is Internetwork Operating System for Cisco Routers.It can also be used for experimental purpose to check the configuration of the network before being deployed in real network.

GNS3 has a simulation of various network devices, A user can create network topology by using them. We can design a complex network topology to test and troubleshoot before being implemented in real network. GNS3 can also be connected with physical network and virtual OS like VirtualBox, Qemu, and Virtual PC Simulator (VPCS).


Users are expected to familiar with basic networking concept, Ubuntu OS and VirtualBox.

The Spoken Tutorial effort for GNS3 has been contributed by Amit Shrivastava IIT Bombay.


Basic Level

  1. Introduction to GNS3    
    • Introduction and use of GNS3
    • Introduction to VPCS
    • Download VPCS to create virtual machine for GNS3
    • Extract VPCS zip file
    • Install VPCS in Ubuntu OS
    • Configure VPCS clouds in GNS3
    • Design network topology involving only three nodes
    • Add nodes to work space
    • Connect network devices using links
    • Example: Simulate the two node network using ping
  2. Introduction to Qemu in GNS3    
    • Introduction to Linux Microcore Kernel
    • Introduction to Qemu (Patch Installation Steps)
    • Download Linux micorecore kernel
    • Test the Qemuwrapper setting in GNS3
    • Configure Linux microcore kernel image in Qemu host settings
    • Add two Qemu and a switch network node in work space
    • Connect nodes with links to complete the topology
    • Running Linux microcore kernel Qemu
    • Configure IP settings on Qemu
    • Example: Simulate the communication between the Linux microcore kernel using the ping and ARP commands
  3. Configuring Vyatta network OS in GNS3    
    • Introduction to a Vyatta network OS
    • Download Vyatta OS
    • Configure Vyatta OS in Qemu host settings
    • Design network topology by adding Router, Linux microcore kernel Qemu and switch to work space
    • Connect nodes with links to complete the topology
    • Run Vyatta Router
    • Configure Basic router commands on Vyatta
    • Configure Interface IP of vyatta
    • Configure Telnet setting in Vyatta
    • Run Linux microcore kernel Qemu
    • Configure IP settings in Linux microcore kernel Qemu
    • Example: Simulate the communication between Vyatta Router and Qemu using ping and Telnet commands

Intermediate Level

  1. Routing protocol in Vyatta using GNS3
    • Introduction to Routing Protocol
    • Create Network topology using two Routers, two Switches, and two VPCS virtual machine
    • Add Vyatta Qemu nodes to workspace
    • Add Clouds and Switches nodes in workspace
    • Connect all nodes using links
    • Start Vyatta Routers
    • Run VPCS on terminal and configure IP settings
    • Configure Interface on Vyatta Router
    • Configure Routing protocol RIP on Vyatta Router
    • Check communication between two different network using Ping and Traceroute command
    • Save network topology in GNS3
  2. Analysis the data packet in network using Wireshark in GNS3
    • Introduction to Wireshark
    • Download and Install Wireshark
    • Open the saved topology
    • Use add a note for naming topology
    • Run network devices and check connectivity
    • Capture link to analysis packet flow
    • Start Wireshark in GNS3
    • Use command Ping Telnet and ARP in Qemu and VPCS
    • Check flow of packet in Wireshark
    • Draw a conclusion for the flow of packet in the network

Contributors and Content Editors

Minal