Port occupancy can be detected by positioning signal responders on shutters disposed at the ports. The signal responders are detectable when the shutters are undeflected (i.e., the respective ports are available). The signal responders are not detectable when the shutters are deflected (i.e., the respective ports are occupied). The signal responders may include RFID tags. Each shutter having a corresponding signal responder may span more than one port.