Free graphical network simulator
GNS3 is a graphical network simulator that allows users to create visual representations of virtual topologies. This software is quite flexible and it can be employed to configure a single workstation or a complex Cisco enterprise-level router. There is no charge to download this package and as it is an open-source framework, updates tend to take place on a frequent basis.
Primary Purpose and Uses
GNS3 is a tool that is primarily deployed by network developers and similar IT professionals. The primary benefit associated with this system is that it provides a graphical representation of the nodes within a system. This top-down perspective clearly illustrates real-time operations and therefore, any changes can be made within a relatively short amount of time. While boasting the ability to perform complex operations, the layout itself is quite straightforward. The user is presented with a menu found on the left-hand side of the page. This highlights any existing routers and switches that may be present.
GNS3 also employs an emulation mode; useful when bench testing a new system or when troubleshooting an existing network. Of course, the programmer also has the ability to display and modify any source code (while observing the output). All files are available in a ZIP format for easy installation.