With the evolution of wireless communication system, especially the increasing demanding of services and applications, fitting different scenarios with the same physical network infrastructure became infeasible and inefficient. Furthermore, the typical usage scenarios, such as eMBB, URLLC and mMTC, require more and more divergent needs in terms of bandwidth, latency and reliability. Hence, to fulfil the market requests, network programmability and virtualization becomes fundamental. A key enabler for networks customization is Network Slicing, that allows to overlay the physical infrastructure with multiple virtual networks sharing resources efficiently. A cost-efficient way of testing new solutions is by deploying open-source testbeds with functionalities close to real networks.