HP FlexNetwork NJ5000, User Manual

Page: 442 / 475

430
Configuring PoE
Overview
Power over Ethernet (PoE) enables a power sourcing equipment (PSE) to supply power to powered
devices (PDs) through Ethernet interfaces over straight-through twisted pair cables. Examples of
PDs include IP telephones, wireless APs, portable chargers, card readers, Web cameras, and data
collectors. A PD can also use a different power source from the PSE at the same time for power
redundancy.
The HPE NJ5000 5G PoE+ switch can operate as a PSE or a PD. This chapter focuses on the PoE
configuration when the switch operates as a PSE.
PoE system
As shown in Figure 472 , a PoE system contains the following elements:
•
PoE power
—The entire PoE system is powered by the PoE power.
•
PSE
—The PSE supplies power for PDs. A PSE can examine the Ethernet cables connected to
PoE interfaces, search for PDs, classify them, and supply power to them. When detecting that a
PD is removed, the PSE stops supplying power to the PD.
•
PI
—An Ethernet interface with the PoE capability is called PoE interface. A PoE interface can
be an FE or GE interface.
•
PD
—A PD receives power from the PSE. You can also connect a PD to a redundant power
source for reliability.
In Figure 472 , the switch is operating as a PSE.
Figure 472 PoE system diagram
Power supplying modes
The PSE supplies power over category 3/5 twisted pair cable in the following two modes:
•
Over signal wires
—The PSE uses data pairs (pins 1, 2 and 3, 6) to supply DC power to PDs.
•
Over spare wires
—The PSE uses spare pairs (pins 4, 5 and 7, 8) to supply DC power to PDs.
The switch supplies power over signal wires. To ensure correct power supplying, make sure the PD
also supports power supply over signal wires. If the PD does not support this power supply mode,
you must change the order of the lines in the twisted pair cable to supply power to the PD.