POE+ SERIES SWITCHESTECHNICAL WHITE PAPER
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1. PoE Power Supply Principle
1.1 PoE Power Supply Principle Introduction
PoE (Power over Ethernet) refers to the technology that can transmit data signals for some IP based terminals (such as IP phone, Wireless LAN
access point AP, webcam, etc.) while provides DC power supply technology for such equipment under the circumstances that the existing
Ethernet Cat.5 cabling infrastructure has no changes. PoE technology can ensure the security of the existing structured cabling while the
operation of the existing network is normal and the cost is minimum.
In PoE system, the equipment providing power is called Power Supply Equipment (PSE), and the equipment using power is called Powered
Device (PD). As shown in the figure below, PoE switch is PSE, other IP phones, indoor AP, cameras, etc. are PD.
PoE technology is widely used in home applications, wireless networking, security protection, retail, entertainment and other scenes because of
its easy installation, easy management, security and stability. Currently, PoE based on 802.3af standard can provide up to 15.4W power, and
PoE+ based on 802.3at standard can provide up to 30W power.