Passed away, this makes still every good reading: [Wayback/Archive] PoE Secret Strengths – Danny Thorpe.
I wish both Danny and his site were still alive.
Power over Ethernet (PoE) is a standard (802.3af) for powering devices using voltage carried on “spare” wires in the Ethernet cable. For devices that support being powered by PoE, it means you only need one cable to the device to connect it to network and provide power. Only one cable to snake through walls and attics, and the device can be placed without regard to access to a power outlet.
PoE is rightfully marketed to business IT and is particularly well suited to devices such as IP security cameras, wireless access points, and IP phones. Unfortunately, targeting the business IT audience meant the devices tended to be a lot more expensive than consumer equivalents.
That is now changing. I’m finding a fair number of PoE PSE switches (PSE = Power Source Equipment, that supply power on the Ethernet wire) and PoE PD devices (PD = Powered Device) in the consumer price range. They’re still listed under “business networking” rather than “home networking”, but at least they exist.
He mainly used Netgear PoE switches; I like the MikroTik ones better.
Note there are many Power over Ethernet standards and they have evolved over time. See Source: Power over Ethernet: Standard implementation – Wikipedia
–jeroen
The Wiert Corner - irregular stream of stuff 