3Com Switch 7757, Configuration Manual

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64
P
O
E C
ONFIGURATION
PoE Overview
Introduction to PoE Power over Ethernet (PoE) uses 10BaseT, 100Base-TX, and 1000Base-T twisted
pairs to supply power to the remote powered devices (PD) in the network and
implement power supply and data transmission simultaneously.
Advantages of PoE
■
Reliability: The centralized power supply provides backup convenience, unified
management, and safety.
■
Easy connection: Network terminals only require an Ethernet cable, but no
external power supply.
■
Standard: PoE conforms to the 802.3af standard and uses a globally uniform
power interfaces;
■
Bright application prospect: PoE can be applied to IP phones, wireless access
points (APs), chargers for portable devices, module readers, cameras, and data
collection.
PoE components
■
Power sourcing equipment (PSE): PSE is comprised of the power and the PSE
functional module. It can implement PD detection, PD power information
collection, PoE, power supply monitoring, and power-off for devices.
■
PD: PDs receive power from the PSE. PDs include standard PDs and
nonstandard PDs. Standard PDs conform to the 802.3af standard, including IP
phones, WLAN APs, network cameras and so on.
■
Power interface (PI): PIs are RJ45 interfaces which connect PSE/PDs to network
cables.
PoE Features Supported
by the Switch 7750
The Switch 7750 supports PoE. Equipped with external power supply and
PoE-enabled modules, Switch 7750 can provide -48 VDC power to remote
powered devices (PDs) through twisted pairs.
■
The Switch 7750 support IEEE802.3af standard. While they can also supply
power to PDs noncompliant with the standard.
■
The power supply of the Switch 7750 is administered by the main control
module; each PoE module on the switch can be viewed as a power sourcing
equipment (PSE) and administers the power supply of all the ports on it
independently.
■
The Switch 7750 can deliver data and current simultaneously through data
wires (1, 3, 2, and 6) of category-3/5 twisted pairs.