An introduction to network simulation
Network simulation is the process by which a computer network is modelled by identifying, analysing and quantifying the interaction between various network devices and software. Mathematical modelling is used to study the behaviour of a computer network rather than using actual data. There are many advantages of doing this. Network behaviour under extreme conditions can be analysed very easily using a simulator. For example, consider a node (network simulation jargon to refer to a computer system) with mobility in a wireless network. We can very easily study the behaviour of a node having high velocity, using a simulator. In a physical network, achieving high velocity for mobile nodes is a very difficult task, and varying the velocity of mobile nodes for analysis purposes is time consuming and difficult.
Another situation where simulation becomes the natural choice is when the number of nodes in the network is very high. For example, if you want to study the working of a network with, say, a 1000 nodes, then simulation is the ideal choice, at least till you are sure about the results. Simulators are also suitable for network analysis if you have a limited budget, limited time, or you are not sure about the success of your proposed method or protocol.
While the previous paragraph lists out a few scenarios where network simulation is warranted, don’t assume that network simulation is an easy task. Simulating networks is difficult and developing a network simulator is an almost impossible task. Very often, I have lamented that it is far better to set up a network in hardware than use these simulators (at least, I used to in my younger days). To crown it all, sometimes the data obtained from the actual physical network may not corroborate the results obtained from the simulator. Having discussed all the many negative aspects of network simulators, I still believe they are excellent tools and all researchers should arm themselves with these potent tools.
Even though the ns class of simulators is the most widely used, there are other options in this field. There are QualNet, NetSim, OMNeT++, etc, which also are useful network simulators. If there are so many alternative network simulators,