Chapter 3 Installing And Managing Power Over Ethernet (Poe) - Alcatel OmniSwitch 7700 Hardware User's Manual

3 Installing and Managing
Power over Ethernet (PoE)
Power over Ethernet (PoE) is supported on OmniSwitch 7700 and 7800 switches and provides inline
power directly from the switch's Ethernet ports. Powered Devices (PDs) such as IP phones, wireless LAN
stations, Ethernet hubs, and other access points can be plugged directly into the Ethernet ports. From these
RJ-45 ports—provided on Alcatel's OS7-ENI-P24 modules—the devices receive both electrical power
and data flow.
Because the feature reduces devices' dependence on conventional power sources, PoE eliminates many
restrictions that traditional electrical considerations have imposed on networks.
In a PoE configuration, power source equipment (PSE) detects the presence of a PD and provides an elec-
trical current that is conducted along the data cable. The PD operates using the power received via the
Ethernet data cable; no connection to an additional power source (e.g., an AC wall socket) is required.
Note on Terminology. There are several general terms used to describe this feature. The terms Power
over Ethernet (PoE), Power over LAN (PoL), Power on LAN (PoL), and Inline Power are synonymous
terms used to describe the powering of attached devices via Ethernet ports. For consistency, this chapter
and the OmniSwitch CLI Reference Guide refer to the feature as Power over Ethernet (PoE).
Additional terms, such as Powered Device (PD) and Power Source Equipment (PSE) are terms that are not
synonymous with PoE, but are directly related to the feature:
PD refers to any attached device that uses a PoE data cable as its only source of power. Examples
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include access points such as IP telephones, Ethernet hubs, wireless LAN stations, etc.
PSE refers to the actual hardware source of the electrical current for PoE. In the case of OS7700 and
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OS7800 switches, the PSE is the peripheral power shelf unit, which contains up to four 52V hot-
swappable power supplies.
OmniSwitch 7700/7800 Hardware Users Guide April 2005 page 3-1