Abstract:Computer networks technology is subject to constant change and innovation. New ideas and concepts regarding the usage of internet networks demand new network protocol and technologies. Due to its complexity many challenges arise from developing, implementing, testing and understanding these technologies. This is where simulation comes into play. Network Simulator is used to evaluate the performance of different wired and wireless networks and their topologies without real world implementation. Network Simulators are widely used by the research community to evaluate new theories and hypothesis. NS-3(network simulator 3) has a number of helper objects that assist in execution and analysis of simulation. The main focus of this paper is to study the Wi-Fi (wireless fidelity) performance when implemented on NS-3. This paper is offering a closer look on network simulation by describing NS-3, its core functionality and Wi-Fi implementation in NS-3.