Networking technologies and concepts are often difficult to explain, even through careful description and well thought out examples. One method for making this information 'stick' is to create an environment where networking professionals and students can visualize how networks work by utilizing a software tool that simulates the functions within a network. The tool provides a virtual environment for an assortment of desirable features such as modeling a network based on specified criteria and predicting its performance. "The Network Simulation Experiments Manual" takes this instructional tool a step further and provides detailed experiments on core networking topologies for use in this simulation environment. Various scenarios are presented within each topology: review questions, suggested readings, a lab report, and exercises accompanying each assignment. This manual also comes with directions for downloading the free and easy-to-install OPNET IT Guru Academic Edition software. This software provides a virtual environment for modeling, analyzing, and predicting the performance of IT infrastructures, including applications, servers, and networking technologies. Prepared by Professor Emad Aboelela of the Taibah University, Saudi Arabia, the experiments in the manual are closely tied to the organization of "Computer Networks: A Systems Approach, Fifth Edition" and, when used together, serve as a complete tool for understanding how and why computer networks function as they do. It is updated and expanded by an instructor who has used OPNET simulation tools in his classroom for numerous demonstrations and real-world scenarios. Software download based on an award-winning product made by OPNET Technologies, Inc., whose software is used by thousands of commercial and government organizations worldwide, and by over 500 universities. It includes useful experimentation for professionals in the workplace who are interested in learning and demonstrating the capability of evaluating different commercial networking products, i.e., Cisco routers. It covers the core networking topologies and includes assignments on Switched LANs, Network Design, CSMA, RIP, TCP, Queuing Disciplines, Web Caching, etc.