The present invention is related to verifying an installed lighting system (300), in particular an Ethernet-based lighting system (300), without it being necessary to employ a designated lighting controller and without it being necessary to completely commission the installed lighting system (300). According to an aspect of the invention, this is achieved by providing a network switch (200) that comprises a plurality of ports for coupling luminaires (312A, 312B, 312C, 312D) and sensors and/or actuators (314A, 314B) of the lighting system (300) to the network switch (200); and by setting the network switch (200) such that a signal received at a first port (e.g. port 4) of the plurality of ports is only forwarded to pre-selected ports (e.g. ports 2,3,5,6 and 7) of the plurality of ports.