Key Product Features
5
IEEE 802.3af
The IEEE 802.3af-2003 Power over Ethernet standard defines
terminology to describe a port that acts as a power source (PSE) to
a powered device (PD). The IEEE 802.3af standard states that
power may be delivered by an end-point PSE, using either the
active data wires of an Ethernet port or the spare wires, to a
powered device. An end-point PSE, such as a Power over Ethernet
capable Ethernet switch, may implement either scheme. If a
mid-span PSE is used, then the mid-span PSE can only implement
power delivery over the spare pairs of the copper cabling and
cannot be used to deliver Power over Ethernet over 1000BASE-T
connections. It should be noted that even if a device supports both
methods of providing power, only one mechanism may be used to
deliver power to a powered device.
The first mechanism is to use the data pairs (pins 1, 2 & 3, 6) to
transmit power, which is sometimes referred to as "phantom"
power. The second power delivery mechanism is to use the unused,
from a 10/100BASE-T perspective, pairs (pins 4, 5 & 7, 8) to deliver
power that is supported within mid-span power delivery.
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