Simulate networks with GNS3

Graphical Network Simulator-3 (GNS3)¹⁾ is a network software emulator. The first release dates back to 2008. GNS3 allows the combination of virtual and real devices to simulate complex networks. Cisco IOS images can be integrated with the help of Dynamips emulation. GNS3 is used by many large companies, including Exxon, Walmart, AT&T and NASA. Many network admins also use GNS3 to prepare for professional exams such as the Cisco Certified Network Associated (CCNA). vorzubereiten.²⁾³⁾

Hardware requirements of GNS3

A GNS platform is available on the server side at Rafisa. If you want to install GNS3 on your local computer, make sure that your device fulfils the following requirements:

The GNS3 environment of Rafisa

The Rafisa GNS3 platform can be found at the URL http://gns3.rafisa.org:

To start a new project, click on Add blank project and give the project an appropriate name [topic, initials]. Click on the newly created project to open the GNS3 desktop. The device templates can be displayed using the + symbol at the top of the screen and then dragged onto the desktop.

Then right-click on the newly created object and press Startto start the device. Depending on the device type, various consoles are available for connecting to the device, which can be selected via the menu with Console in the menu:

• Telnet
• Spice
• VNC

The available console can be defined in the device settings. To do this, right-click on the object and select Configure. You can then go to General Settings the Console type can be defined. Depending on the console selected, the device must be called up with the correct connection string. GNS3 provides a web launcher that takes care of the manual input. Task 1 consists of installing and setting up this programme.

Task 0 - Getting to know the architecture of GNS3

In task 0 you will learn the basics of the architecture of GNS3 v2.0. The four components of GNS3 are presented: 1) the user interface (GUI) (gns3-gui or gns3-web); 2) the controller (gns3-server); 3) the computer (gns3-server); 4) the emulators (Qemu, Dynamips, Virtualbox etc.).

Task 1 - Setting up the GNS3 WebLauncher

In Task 1 install the GNS3 WebLauncher. This programme allows you to open virtual devices from the GNS3 platform directly with a mouse click. These instructions describe how to install the WebLauncher under Windows and Linux.

Task 2 - Installing GNS3 and setting up a basic topology

In task 2 a simple topology is to be set up with a switch and two test PCs. The GNS3 environment provided on the server side can be used for this task. The document also describes how to install GNS3 locally on a Windows 10 PC.

Task 3 - Setting up a topology with firewall and virtual Cisco switch

In task 3 a complex topology with a pfSense firewall and a virtual Cisco switch is to be set up.

Task 4 - Setting up VLANs on pfSense firewall and Cisco switch

In Task 4 the network is to be segmented using VLANs on the basis of the existing topology from task 3.

Task 5 - Rebuilding, analysing and suggesting improvements for the Rafisa network

In task 5 the existing Rafisa network in GNS3 is to be reconstructed and analysed (actual topology). Based on the analysis, suggestions for improvement (topology, technologies used, etc.) should then be made (TARGET topology).