Power over Ethernet refers to the existing Cat.5 Ethernet cabling infrastructure does not make any changes in the situation, for some IP based terminal (such as IP telephone, wireless LAN access point AP network camera, etc.) for the transmission of data signals at the same time, can also provide DC power supply technology for this kind of equipment.
The PoE standard defines two methods for delivering DC to POE compatible devices using Ethernet transmission cables:
1, Mid -Span. Not use Ethernet cable in idle line to transmission DC applied between Poe switches and network terminal equipment, can through the network cable to the terminal equipment of power supply network.
2, the End-Span transmits DC at the same time on the core line used to transmit data, and the transmission uses a frequency different from the Ethernet data signal.