In the network research area, establishing of network in a real time scenario is very difficult. A single test takes a large amount of time and cost. So implementation of a whole network in real world is not easily possible and very costly too. The simulator helps the network developer to check whether the network is able to work in the real time. Thus both the time and cost of testing the functionality of network have been reduced and implementations are made easy. This paper introduces the main features of different simulator.