Methods and apparatus are described for routing data traffic in a network having a plurality of layers including physical, data link, and network layers. The edge switch includes: a join message identification unit; and a marking unit. The subscriber station then transmits a channel quality indicator feedback message to the wireless network. In a mode of the invention, a cylindrical concave reflector 2 whose section taken vertical to a linear light source 1 is a part of an ellipse 2e having a first focus F1 at the linear light source 1 and a second focus F2 at an irradiation plane 3.