NS2 is a widely recognized and utilized open-source event-driven simulator for developing simulation models in wired and wireless networks. The primary purpose of the NS2 simulator is to study the behavior of network protocols and evaluate their performance. NS2 has tremendously attracted many researchers from the network community in the industry as well as academia. NS2 is decomposed into a set of modules to manage Physical, MAC, Routing, Transport, and Application layer protocols. It is an ideal tool to configure the network components and validate the results. It can be easily extended to support new protocol design, and a wide range of extensions this efficient tool facilitates effective investigation of the performance of the Research Work already available as open source components. Unfortunately, the recent network protocol developments are not included in the NS2 modules. Undoubtedly, future releases of NS2 certainly contain the latest protocols to support the next generation of network research..