The fifth generation of mobile networks (5G) promises to improve network utilization by allowing operators to create virtual networks for their tenants with different Quality of Service (QoS) requirements. This technology is also referred to as network slicing. To guarantee physical isolation for virtual networks and no interference between different slices, it is possible to rely on the Flex Ethernet (FlexE) technology. It isolates different slices by allocating resources in a TDMA-fashion. In this demo, we will present our algorithmic framework, based on a Column Generation routine, and we will showcase how the configuration of FlexE interfaces to guarantee hard isolation between slices.