Despite increasing deployment of software-defined networks (SDN), little is yet known about how to actually manage such kind of networks. When service degradation (generically termed here “trouble”) happens, the first step is to localise under-performing network paths (“troubleshooting”). SDN-RADAR gives a novel approach to ease large network troubleshooting by leveraging SDN features and incorporating distributed monitoring of network traffic. The demo shows how the SDN-RADAR tool can help network administrators understand which is the most likely faulty network link.