Allied Telesis AlliedWare Plus AT-GS980M/52, Installation Manual, Page: 26 / 94

Chapter 1: Overview
26
Power Over Ethernet on the AT-GS980M/52PS Switch
The AT-GS980M/52PS Switch features PoE on all forty eight 10/100/
1000Mbps ports. With PoE, the switch can supply DC power to network
devices over the same twisted pair cables that carry the network traffic.
PoE can make it easier to install networks. The selection of a location for a
network device is often limited by whether there is a power source 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 such as the AT-GS980M/52PS Switch that provides PoE to
network devices is referred to as
power sourcing equipment (PSE). It
functions 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 devices connected to
its ports are powered devices. 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-GS980M/52PS Switch supports these PoE standards:
 PoE (IEEE 802.3af): This standard provides up to 15.4 watts at the
switch port for 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 for powered devices that require up to 25.5 watts.
Powered Device
Classes
Powered devices are grouped into the five classes listed in Table 4 on
page 26. The classes are based on the amount of power the devices
require. The switches support all five classes.
Table 4. IEEE Powered Device Classes
Class
Maximum Power
Output from a Switch
Port
PD Power Range
0 15.4W 0.44W to 12.95W
1 4.0W 0.44W to 3.84W