Power over Ethernet (PoE) is an optional standard that provides direct current electrical power over Ethernet twisted-pair cabling. This makes it possible for an Ethernet switch port to provide both...
After 802.3at made it possible to provide roughly 30 watts over two pairs of wires, it was a relatively straightforward process to extend the standard to provide power over four pairs simultaneously.
To manage these power loads, vendors of switches typically program the switches to provision power one port at a time, this is PoE Port Management.
The PoE standard specifies the way that power is injected into the Ethernet cable pairs, and which pairs should be used.
Understanding how PoE works. The idle state and three operational states: detection, classification, and operation.
For those who want to delve into the details of the Power over Ethernet technology, here we discuss PoE devices roles and type parameters.