Allied Telesis FS970M Series - Manual (Page 39)

FS970M Series Installation Guide
39
Power Over Ethernet
The AT-FS970M/8PS, AT-FS970M/8PS-E, AT-FS970M/24PS, and
AT-FS970M/48PS Switches feature Power over Ethernet (PoE) on the 10/
100Base-TX ports. PoE is used to supply power to network devices over
the same twisted pair cables that carry the network traffic.
The main advantage of PoE is that it makes it easier to install a network.
The placement of network devices is often limited by whether there are
power sources nearby. This often limits equipment placement or requires
the added time and cost of having additional electrical sources installed.
But with PoE, you can install PoE-compatible devices wherever they are
needed without having to worry about whether there are power sources
nearby.
A device that provides PoE to other network devices is referred to as
power sourcing equipment (PSE). The AT-FS970M/8PS,
AT-FS970M/8PS-E, AT-FS970M/24PS, and AT-FS970M/48PS Switches
act as PSE units by adding DC power to the network cable, thus
functioning as a central power source for other network devices.
Devices that receive their power from a PSE are called powered devices
(PD). Examples include wireless access points, IP telephones, webcams,
and even other Ethernet switches.
The switch automatically determines whether or not a device connected to
a port is a powered device. Ports that are connected to network nodes that
are not powered devices (that is, devices that receive their power from
another power source) function as regular Ethernet ports, without PoE.
The PoE feature remains activated on the ports but no power is delivered
to the devices.
PoE Standards The AT-FS970M/8PS, AT-FS970M/8PS-E, AT-FS970M/24PS, and
AT-FS970M/48PS Switches support these PoE standards:
 PoE (IEEE 802.3af): This standard provides up to 15.4 watts at the
switch port to support powered devices that require up to 12.95
watts.
 PoE+ (IEEE 802.3at): This standard provides up to 30.0 watts at
the switch port to support powered devices that require up to 25.5
watts.
Powered Device
Classes
Powered devices are grouped into the five classes listed in Table 10 on
page 40. The classes are based on the amount of power the devices
require. The switches support all five classes.