The Power over Ethernet feature -- the IEEE 802.3af standard -- lets Ethernet cables supply the power for network devices, at the same time as transmitting data in the normal way. Typical PoE users are businesses adding to their network or adding VoIP phones in buildings where new power lines would be expensive or inconvenient.

• Products using the standard send or receive power to another PoE product following the standard.
• A device can send or receive, but not both.
• The sender is a Power Sourcing device (PSE), while device that is powered is a Powered Device (PD).
• The PSE supplies 15.4 watts, which can be divided between several PDs.