3com 2928 User Guide
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3Com Baseline Switch 2920-SFP Plus is a single PSE device, as so .this manual introduces the device
with a single PSE only.
with a single PSE only.
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 unplugged, the PSE stops supplying power to
the PD.
PI
An Ethernet interface with the PoE capability is called PoE interface. Currently, a PoE interface can be
an FE or GE interface.
The PSE supplies power for a PoE interface in the following two modes:
an FE or GE interface.
The PSE supplies power for a PoE interface in the following two modes:
z
Over signal wires: The PSE uses the pairs (1, 2, 3, 6) for transmitting data in a category 3/5 twisted
pair cable to supply DC power while transmitting data to PDs.
pair cable to supply DC power while transmitting data to PDs.
z
Over spare wires: The PSE uses the pairs (4, 5, 7, 8) not transmitting data in a category 3/5 twisted
pair cable to supply DC power to PDs.
pair cable to supply DC power to PDs.
3Com Baseline Switch 2920-SFP Plus only support for signal mode.
PD
A PD is a device accepting power from the PSE, including IP phones, wireless APs, chargers of portable
devices, POS, and web cameras.
The PD that is being powered by the PSE can be connected to another power supply unit for
redundancy power backup.
devices, POS, and web cameras.
The PD that is being powered by the PSE can be connected to another power supply unit for
redundancy power backup.
Protocol Specification
The protocol specification related to PoE is IEEE 802.3af.
Configuring PoE
Before configure PoE, make sure that the PoE power supply and PSE is operating normally; otherwise,
you cannot configure PoE or the configured PoE function does not take effect.
you cannot configure PoE or the configured PoE function does not take effect.