Dimensioning of an European backbone network in OPNET WDM Guru

Master courses lab sessions at Ghent University use OPNET WDM Guru to evaluate dimensioning of an optical European backbone network. The low connectivity of optical networks increases consequences of single defects. Therefore, an availability analysis was performed, starting from a ring network. Additional links improve reliability and routing cost, but increase installation cost. An evaluation finds the best compromise. A network topology must be designed for a traffic forecast consisting of voice, business IP and residential IP traffic components. Because of high optical equipment prices, different design alternatives concerning grooming and protection/restoration are evaluated to find the most costeffective solution. Introduction The importance of network reliability has increased even more in the last decades, mainly because of the development and acceptance of optical fiber technology in backbone networks. This transmission medium has an almost infinite amount of lowcost, reliable bandwidth. However, this has lead to the fact that optical networks typically operate with a lower connectivity than networks with traditional transmission media, such as copperbased networks, which are usually heavily meshed. The low connectivity seen in optical networks implies that the occurrence of a defect can potentially cause catastrophic consequences for a very large number of users. Providing sufficient backup capacity and equipment is of crucial importance during the design of optical networks. Obviously, this reliability constraint may clash with cost considerations. One has to evaluate availability against cost, and find the best compromise. Often certain minimal demands are required from the topology (e.g. availability service levels), and against those demands one then tries to achieve minimal costs. Once an appropriate network topology is found, this network must be designed for a particular traffic pattern. By using the grooming operation, the SDH traffic demands will be mapped into optical wavelength demands. This grooming procedure first designs the logical layer, i.e. the SDH layer. Then, the physical layer, i.e. the optical layer, is designed. Finally, the capacity that is requested by the demand for the physical layer is made available in the network. The grooming procedure will result in a combined SDH-optical channel network design with the lowest possible network cost. In optical network design, cost is a primary factor. Due to the high prices of optical equipment, a network designer strives for the most cost-effective solution. In addition, the network design is also influenced by the traffic pattern. This paper gives an overview of two master courses lab sessions at Ghent University that use OPNET WDM Guru 8.5 [1]. The goal of the Availability Analysis lab session is to gain insight into network reliability related problems, using some specific examples. We will use WDM Guru to determine availability results, routing costs and installation costs for certain candidate network topologies. As a starting point, the European backbone ring network is considered. The goal of the Transport Network Design lab session is to design the pan-European backbone network for particular traffic patterns, consisting of voice, business IP and residential IP traffic components. Two grooming alternatives, namely link-by-link and end-to-end grooming are considered and the impact of the traffic demand, cost parameters and recovery strategy on their performance is investigated. This paper is organized as follows. First the general settings for the lab sessions are discussed. Afterwards, the Availability Analysis lab session and the Transport Network Design lab session are described in detail. OPNET WDM Guru settings for the lab sessions