ABSTRACT
Building a network topology as described in Chapter 2 is only the rst and usually one of the simplest steps in developing a simulation study. The subsequent steps include such tasks as conguring individual links and network devices, setting up and deploying protocols and applications, and dening the proles of users in the network. In OPNET, every network element is represented as an object. Characteristics or properties of the network elements are specied through object attributes. Conguration of network devices is performed by modifying the attribute values of the corresponding objects in the simulation model. The accuracy of a simulation study depends not only on how precisely the placement of various nodes and their connecting links matches the real-life network but also on correct conguration of the devices in the created network topology. The closer the OPNET-created representation of the simulated network is to the real network, the more accurate the simulation results will be. OPNET provides device and link models to support most of the common networking protocols. However, you do not need to specify the values of all attributes of all the protocols and technologies used in your simulation study, as each protocol is usually precongured with the most frequently used default values. Most of the time, you only need to change some of those default values.
