GNS3

GNS3 (Graphical Network Simulator-3) is a powerful open-source network simulation tool used for communication testing and network design.

It allows users to build, configure, and test complex network topologies in a virtual environment. GNS3 supports the simulation of real devices and integrates with various network hardware, enabling testing and troubleshooting without needing physical equipment.

It’s widely used by network engineers and IT professionals for testing communication protocols, training, and research.