The application pertains to a method for an Ethernet power sourcing equipment to provide electric power to one or more Ethernet powered devices. A controlling apparatus determines a power supply mode of the Ethernet power sourcing equipment, and determines high-power Ethernet powered device(s) and low-power Ethernet powered device(s) among the Ethernet powered devices. The controlling apparatus sets a power supply priority for each of the Ethernet powered devices. In one power supply mode, the power supply priority of a high-power Ethernet powered device is same as or lower than the lowest priority of the low-power Ethernet powered device(s). When a new Ethernet powered device is connected to the Ethernet power sourcing equipment, the controlling apparatus determines whether to supply electric power to the new Ethernet powered device according to its power supply priority.