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

MATLAB - A high-level language and interactive environment for numerical computation, visualization, and programming

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

Wolfram Mathematica - Mathematica has characterized the cutting edge in specialized processing—and gave the chief calculation environment to a large number of pioneers, instructors, understudies, and others around the globe.

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.

GNU Octave - GNU Octave is a programming language for scientific computing.