In the world of rapidly growing technology, recent update demands robust, reliable, and evaluated network protocols. The behavior of protocols needs to be examined thoroughly. There are numerous methods available for evaluating and analyzing the behavior of protocols. The most famous are cloud computing and network simulation. A simulation tool named network simulator2 is discussed in detail with the help of 6-node simulation example consisting of the details about Awk script (for performance analysis) and Xgraph (for plotting graph). Moreover, comparison of different versions of network simulator and comparison between NS2 and NS3 are discussed which suggests that NS3 has more advantageous features than NS2. Experimental results of Ad hoc Distance Vector Routing protocol (AODV) and Dynamic State Routing protocol (DSR) in both, NS2 and NS3, are also included with respect to throughput and end-to-end delay for 25 nodes.