Network simulator

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A network simulator is a piece of software that simulates a network, without an actual network being present.

Network simulators serve a variety of needs. Compared to the cost and time involved in setting up an entire test bed containing multiple networked computers, routers, infrastructure, network simulators are relatively fast and inexpensive. They allow engineers to test scenarios that might be particularly difficult or expensive to simulate using real hardware- for instance, simulating the effects of a sudden burst in traffic or a DoS attack on a network service. Networking simulators are particularly useful in allowing designers to test new networking protocols or changes to existing protocols in a controlled and reproducible environment.

Network Simulators, as the name suggests are used by researchers to design various kinds of networks, simulate and then analyze the effect of various parameters on the network performance. A typical network simulator like NS2[1] encompasses a wide range of networking technologies and help the users to build complex networks from basic building blocks like variety of nodes and links. With the help of simulators one can design hierarchical networks using various types of nodes like computers, hubs, bridges, routers, optical cross connects, multicast routers, mobile units, MSAUs etc. Various types of Wide Area Network (WAN) technologies like packet, circuit, burst switching etc and Local Area Network (LAN) technologies like Ethernet, token rings etc. can all be simulated with a typical simulator and the user can test, analyze various standard results apart from devising some novel protocol or strategy for routing etc.

There are a wide variety of network simulators, ranging from the very simple to the very complex. Minimally, a network simulator must enable a user to represent a graph of a network, specifying the nodes on the network and the links between those nodes. More complicated systems may allow the user to specify everything about the protocols used to handle network traffic. Graphical applications allow users to easily visualize the workings of their simulated environment. Text-based applications may provide a less intuitive interface, but may permit more advanced forms of customization. Others, such as GTNets, are programming-oriented, providing a programming framework that the user then customizes to create an application that simulates the networking environment that he or she wishes to test.