What is PoE - 802.3af Standard in Brief
802.3af, also known as Power over Ethernet, defines a way to build Ethernet power-sourcing equipment and powered terminals.
The specification involves delivering 48 volts of DC power over unshielded twisted-pair wiring.
It works with existing cable plant, including Category 3, 5, 5e or 6.
The technology supports a point-to-multipoint power distribution architecture, parallel to the data network.
The total amount of continuous power that can be delivered to each node is 12.95 watts. (max. load power 15.4W, after counting cable lost left 12.95W)
802.3af power sourcing equipment contains a detection mechanism to prevent sending power to noncompliant devices.