Student Network Design Projects using OPNET

To provide students with a practical knowledge of networking, the K.U.Leuven organizes design projects, complementary to the theoretical courses. Master students in Electrical Engineering (Telecommunications option) design a network for a specific service in a specific environment. During the academic year 2000-2001, students worked on one of the following topics: voice traffic on leased lines, VoIP on an Ethernet, or file sharing on an office LAN. Every project consists of four different parts: traffic load measurements, analytic performance calculations, simulations, and a practical lab implementation. The simulations are performed with the OPNET Modeler and are discussed in this paper. Introduction Graduate education in the field of networking is far from evident in our present-day ICT society. New inventions and technologies are developed in rapid succession. Networks constantly grow in size and complexity. More and more people and companies connect to the information highway. To offer students the opportunity to get acquainted with modern communication networks, the TELEMIC (Telecommunications and Microwaves) research group of the Electrical Engineering department (ESAT) organizes design projects. These projects are supplementary to the advanced lectures on networking, taught in the final Master's year. They provide students not only with a clear understanding of networking but also with practical design and project skills. To make the projects as interesting as possible, real-life problems and challenges are presented to the students. The subjects dealt with during the academic year 2000-2001 are the following: voice traffic on leased lines between two remote campuses of the university, VoIP on a student dorm network, and file sharing on the LAN of our research group. Previous topics examined are the impact of videoconferencing on the university network, VoIP replacing the ISDN network of our research group, and cable access networks using the DOCSIS protocol. The assignment consists of different parts. After a study of the problem, students determine the current network load statistics. This ranges from measuring packets on the specific network infrastructure to analyzing call records. Some precautions are taken to avoid violating users' privacy. The aim of the project is to predict whether a new service can be added to the existing infrastructure. Both analytical calculations based on simplified models and simulations are used to determine the quality of service the network can offer. A comparison of both methods will indicate their respective strength and weakness. Finally, some practical experience is gained from a lab implementation. The last year Master students in Electrical Engineering (Telecommunications option) are grouped in teams of two. Each team works on one of the three subjects. Teams, working on the same subject, have a slightly different assignment and are encouraged to cooperate where possible. The total project is credited a study load of 150 hours and should result in a report summarizing the major results. The students are coached by a team of assistants, each responsible for one part of the assignment. In this paper, we will focus on the use of the OPNET Modeler for simulations in the projects. In [1] we comment on the other parts of the assignment. This paper is organized as follows: for each subject we summarize the results of one team. We start with an outline of the problem followed by a description of the simulations. We go deeper into the simulated network topology and the definitions of the different tasks and applications. Possible problems and difficulties encountered are also mentioned. Finally we conclude with an evaluation of the projects and of the simulations in particular. More information on the design projects, together with all reports, can be found on the homepage [2]. Voice traffic on leased lines In this chapter we summarize the results obtained in [3]. The complete report can be found on the homepage [2] together with the reports of two other groups working on the same subject. Problem outline The University in Leuven (K.U.Leuven) has a smaller campus in Kortrijk (KULAK). Both sites are located more than a 100 km apart and are interconnected by a 2 Mbps full duplex leased line. Until now this line is only used for data traffic. The aim of this project was to examine whether the current phone traffic between the two campuses can go via this line instead of using the PSTN and paying a telecom operator for every call.