In the network research area, establishing of network in a real time scenario is very difficult. A single test bed takes a large amount of
In the network research area, implementation of a whole network in real world is not easily possible because establishing of network in a real world is very difficult. A single test bed containing multiple networked computers, routers and data links to validate and verify a certain network protocol or a specific network algorithm that needed a large amount of time and cost. The simulator help
s the network developer to check whether the network is able to work in the real world. Thus both the time and cost of testing the functionality of the network have been reduced and implementations are made easy. Network simulators are also particularly useful in allowing the network designers to test new networking protocols or to change the existing protocols in a controlled and reproducible manner. In this paper, we discuss on different open-source simulators, present a comprehensive survey on current open-source network simulators and introduce the main features of different open- source network simulator and consider their advantages and disadvantages. We hope this survey for those people who feel difficult to select the appropriate open-source network simulators for their research.