A networking system architecture includes a plurality of main devices, one of the main devices acts as a master main device, and the other main devices act as slave main devices. If the master main device malfunctions, one of the slave main devices substitutes for the master main device to act as a new master main device. Priorities are set to the main devices, respectively. If a current master main device malfunctions, the current master main device may be replaced by a new master main device having the highest priority among the other main devices.