Abstract: A power over Ethernet (PoE)-based redundant power management method manages a redundant power supply electrically connectable to plural network devices through plural twisted pairs respectively, so as to transmit first electricity and digital information to each network device. The redundant power supply receives a power demand message from, and is informed of the electric power needed by, each network device electrically connected to the redundant power supply. In response to determining the second electricity each such network device has been receiving is interrupted, the redundant power supply outputs to each such network device the corresponding first electricity equal to the electric power needed by the network device through a corresponding Ethernet port. In response to receiving a power-off request message from any such network device, the redundant power supply stops outputting to that network device the corresponding first electricity.