A wireless local area network for data communications between a computer and mobile units is provided with at least two cell controllers connected to the computer and one or more rf ports each connected to a primary interface of one cell controller and to a backup interface of another cell controller. A control program in the cell controller monitors data communications between the other cell controller and the rf port by a backup interface. The program is arranged to cause the second cell controller to assume primary communications functions for the rf port in the event primary communications functions between a first cell controller and the rf port are inoperative.