Power over Ethernet (PoE) is a revolutionary technology that extends the already ultra-broad functionality of Ethernet by supplying reliable DC power over the same twisted-pair cable that currently carries Ethernet data. PoE, modeled after the technology used by the telecommunications industry to supply reliable power to telephones, enables lifeline quality power for IP telephones (VoIP) as well as many other low power Ethernet network devices like wireless access points (WAP) and security cameras.

When locating access points, system designers often use the availability of AC (alternating current) electrical outlets to base decisions on where to install access points. In some cases, companies only locate access points near AC outlets and within reach of a typical six foot electrical cord. Or, they'll look for a convenient location to install new outlets at points where it's suitable to run conduit and mount outlet boxes. All of these situations limit the location of access points and can incur significant costs if new outlets must be installed.

Power-over-Ethernet (PoE) solves these problems. A PoE solution only requires technicians to run one Ethernet cable to the access point for supplying both power and data. With PoE, power-sourcing equipment detects the presence of an appropriate "powered device" (e.g., an access point or Ethernet hub) and injects applicable current into the data cable. An access point can operate solely from the power it receives through the data cable.