GNS3 - GNS3 is a graphical network simulator that allows simulation of complex networks.

ns-3 - a discrete-event network simulator for internet systems

Mininet - Mininet is a robust and inexpensive Instant Virtual Network designed to function on standard PCs like Laptops and Desktops.

NetSim - NetSim software was created to simulate various Cisco systems. Cisco software is known around the world as being one of the best network, routing and switch systems for businesses and private use. Read more about NetSim.

Ranplan Wireless - Ranplan Wireless is a leading platform that has revolutionized itself with innovative wireless tools and software based on extensive technology.

FlexSim - Simulation software to model, simulate, predict, and visualize systems in manufacturing, material handling, healthcare, warehousing, mining, etc.