Power over Ethernet is injected onto the cable at a voltage between 44 and 57 volts DC, and typically 48 volts is used. The PoE switch voltage output directly affects device compatibility, stability, and application range, making it a crucial parameter to consider during selection. In normal PoE equipment there is no danger in connecting a non-PoE device to any PoE port. Wikipedia has a some nice. Power over Ethernet (PoE) describes any of several standards or ad hoc systems that pass electric power along with data on twisted-pair Ethernet cabling. This allows a single cable to provide both a data connection and enough electricity to power networked devices such as wireless access points. The UniFi Switch is a fully managed, PoE+ Gigabit switch, delivering robust performance and intelligent switching for growing networks. The UniFi Switch offers the forwarding capacity to simultaneously process trafic on all ports at line rate without any packet loss.
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