Abstract
Computer simulation is becoming increasingly popular among computer network researchers for performance modeling and evaluation of computer and telecommunication networks. This popularity is due to the availability of various sophisticated and powerful simulators, and also because of the flexibility in model construction and validation offered by simulation. While various network simulators (both open source and commercial) exist for modeling and performance evaluation of communication networks, OPNET is becoming popular network simulator as the package is available to academic institutions at no cost, especially OPNET IT Guru. This chapter aims to provide a tutorial on OPNET focusing on the simulation and performance modeling of IEEE 802.11 wireless local area networks (WLANs). Results obtained show that OPNET provides credible simulation results close to a real system.
TopLiterature Review
Computer network design and implementation involves interaction of various networking devices including Servers, network interface cards (NICs), switches, routers, and firewalls. In most cases it is ineffective with respect to time, money, and effort to test the performance of a live network. Computer network simulators are often used to evaluate the system performance without building a real network. However, the operation of a network simulator relies on various stochastic processes, including random number generators. Therefore the accuracy of simulation results and model validation is an important issue. A main concern in wireless network simulations or any simulation efforts is to ensure a model is credible and represents reality. If this can’t be guaranteed, the model has no real value and can’t be used to answer desired questions (McHaney, 1991; Sargent, 2004). For selecting an appropriate network simulator for a particular application, it is important to have good knowledge of the simulator tools available, along with their strengths and weaknesses.
Key Terms in this Chapter
OPNET IT GURU: OPNET is a discrete event, object-oriented, general purpose network simulator (commercial simulation package). OPNET IT GURU is a smaller version of OPNET Modeler which is available at no costs under OPNET academic program.
IEEE 802.11: A family of wireless local area network (LAN) standards. The IEEE 802.11b is the wireless LAN standard with a maximum data rate of 11 Mbps operating at 2.4 GHz. The IEEE 802.11a is the high-speed wireless LAN with a maximum data rate of 54 Mbps operating at 5 GHz. The IEEE 802.11g is backward compatible with the IEEE 802.11b, with a maximum data rate of 54 Mbps operating at 2.4 GHz.
GUI: GUI stands for Graphical User Interface. Most of the modern operating systems provide a GUI, which enables a user to use a pointing device, such as a computer mouse, to provide the computer with information about the user’s intentions.
NIC: NIC stands for Network Interface Card which is the hardware interface that provides the physical link between a computer and a network.