Simulating Network Architectures with GNS3

A network simulator is a software program, free or paid, which is used to create virtual representations of IT networks. In the context of networks, simulation refers to the reproduction of the architecture of a network without using any physical equipment. The interest of the simulation lies in its ability to test the features and operation of a network architecture at no cost. Network simulators enable an architect or network engineer to build and assess an experimental model of a network. This chapter introduces graphical network simulator‐3 (GNS3) which is a graphical network emulator that is free to use, open source and reliable. GNS3 is based on three concepts: simulation, emulation and virtualization. Emulation does not allow modeling, but actually identically reproduces the behavior of a software program and its hardware architecture. The chapter discusses the functionalities and limitations of GNS3. It also describes the installation and operating procedures of GNS3.