The invention relates to a method for routing packets in a system of packet-switched networks comprising a plurality of home agents, at least one mobile node and at least one correspondent node, the mobile node having at least a first home address and communicating with the correspondent node over a first of the plurality of home agents. The system includes a threshold with a first light cavity extending along one side of the threshold for emitting light inwardly into a recreational vehicle in a first direction generally parallel to the vehicle floor, and a second light cavity on the opposite side of the threshold for emitting light in a second direction down the stairs leading to the threshold. An orifice plate is laminated to the thick film layer. The method continues by low pass filtering the rectified signal to produce the peak value.