Power supply

A Power Sourcing Equipment (P S E), comprising:

• a first port group, comprising a plurality of PSE ports, wherein the PSE ports in the first port group are connected in parallel and connected with a first line pair and a second line pair in an Ethernet cable;
• a second port group, comprising a plurality of PSE ports, wherein the PSE ports in the second port group are connected in parallel and connected with a third line pair and a fourth line pair in the Ethernet cable;
• a detecting and classifying module, configured to perform feature detection for a Power Device (PD) connected with the Ethernet cable;
• and
• a power sourcing module, configured to output a working voltage from the first port group to supply power for the PD via the first line pair and the second line pair and output the working voltage from the second port group to supply power for the PD via the third line pair and the fourth line pair when the PD passes the feature detection.