US Patent 10027494 POE-based power supply method and PSE

A PoE-based power supply method and PSE. The method includes: after PSE supplies power to a PD, determining, by the PSE, a line voltage drop across a network cable between the PSE and the PD; and when the line voltage drop across the network cable is greater than a line voltage drop threshold, sending, by the PSE, a first Ethernet packet to the PD, so that the PD decreases load of the PD according to instruction information instructing the PD to decrease load power consumption and included in the first Ethernet packet. This ensures that a voltage received by the PD can satisfy a power requirement of the load of the PD, and further ensures that the PD can work normally.