Allied Telesis AT-S101 - Manual (Page 180)

Chapter 17: Power over Ethernet (PoE)
180
Overview
The four of the twisted pair ports on the AT-GS950/8POE switch feature
Power over Ethernet (PoE) which is a mechanism for supplying power to
network devices over the same twisted pair cables used to carry network
traffic. This feature can simplify network installation and maintenance by
allowing you to use the switch as a central power source for other network
devices.
A device that receives its power over an Ethernet cable is called a
powered device. Examples of such devices can be wireless access points,
IP telephones, web cams, and even other Ethernet switches. A powered
device connected to a port on the switch receives both network traffic and
power over the same twisted pair cable. In order to use the PoE feature,
you must connect a powered device to one of the four PoE ports on the
switch.
There are several advantages that the PoE feature of the AT-GS950/
8POE switch adds to the installation and maintenance of your network.
First of all, the switch acts as the central power source for your powered
devices. Adding an uninterruptible power source (UPS) to the switch
increases the protection to the switch from possible power source
problems and to all of the powered devices connected to the switch. In
addition, the PoE feature can increase the reliability of your network by
minimizing the impact to network operations from a power failure.
A port on the switch connected to a powered device can supply up to 15.4
Watts of power to the device and, simultaneously, furnishing standard 10/
100 Mbps Ethernet functionality. A PoE port that is connected to a network
node that is not a powered device (that is, a device that receives its power
from another power source) functions as a regular Ethernet port, without
PoE. In this case, the PoE feature remains enabled on the port, but no
power is delivered to the device.