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Chapter 10 PoE
PoE (Power over Ethernet) technology describes a system to transmit electrical power along with
data to remote devices over standard twisted-pair cable in an Ethernet network. It is especially
useful for supplying power to IP telephones, wireless LAN access points, cameras and so on.
Composition
A PoE system usually consists of PSE and PD.
PSE: Power sourcing equipment (PSE) is a device such as a switch that provides power on the
Ethernet cable to the linked device.
PD: A powered device (PD) is a device accepting power from the PSE and thus consumes energy.
PDs falls into two types, standard PDs and nonstandard PDs. Standard PDs refer to the powered
devices that comply with IEEE 802.3af and IEEE 802.3at. Examples include wireless LAN access
points, IP Phones, IP cameras, network hubs, embedded computers etc.
Advantage
Cheap cabling: The remote device such as cameras can be powered by PSE in no need
of prolonging its power cord additionally and Ethernet cable is much cheaper than AC
wire or power cord.
Easy to connect: PoE uses only one Ethernet cable with no need of external power
supply.
Reliable: A powered device can be either powered by PSE using Ethernet cable or
powered through the provided power adapter. It is very convenient to provide a backup
power supply for the PDs.
Flexibility: In compliance with IEEE 802.3af and IEEE 802.3at, global organizations can
deploy PoE everywhere without concern for any local variance in AC power standards,
outlets, plugs, or reliability.
Wide use: It can be applied to wireless LAN access points, IP Phones, IP cameras,
network hubs, embedded computers etc.
T1500-28PCT is a Power Sourcing Equipment (PSE). All the Auto-Negotiation RJ45 ports on the
switch support Power over Ethernet (PoE) function, which can automatically detect and supply
power for those powered devices (PDs) complying with IEEE 802.3af and IEEE 802.3at. The
maximum power T1500-28PCT can supply is 180W and the maximum power each PoE port can
supply is 30W.
PoE function can be configured in the two sections, PoE Config and PoE Time -Range.
10.1 PoE Config
All the RJ45 ports on the switch can be configured to supply power for the powered devices that
comply with IEEE 802.3af and IEEE 802.3at. As the power every port or the system can provide is
limited, some attributes should be set to make full use of the power and guarantee the adequate
power to the linked PDs. When the power exceeds the maximum power limit or the power is
inadequate to power the device, the switch may disconnect the power supply to the PD linked to
the port with lower priority. When detecting a PD is unplugged, the switch will stop supplying the
power to the PD.
PoE Config, mainly for PoE attributes configuration, is implemented on PoE Config and PoE
Profile pages.
