Computer networking is an important subject in the computer science curriculum. However, owing to its constant evolutionary nature and inherent complexity, learning and teaching new paradigms in computer networking can be difficult. The design and implementation of a fully operational SDN (software defined networking) network is practically illustrated using a virtualisation environment, which is aimed at learning the fundamentals of routing management of SDN networks. We describe the virtualisation environment, software tools, SDN controllers, and programming details of networking equipment for the implementation of an SDN network. For educational purposes, a detailed description of the network configuration process in also presented. The level of details presented in this paper can be useful for both instructors and students to grasp the fundamental concepts of SDN routing management at an educational level in a friendly manner. A virtualised environment, as the one described in this paper, can also be useful for understanding other advanced computer networking concepts.