Linksys LGS308 User Manual page 60

PoE capabilities:
• Eliminates the need to run 110/220 V AC power to all devices on a wired LAN.
Removes the necessity for placing all network devices next to power sources.
•
• Eliminates the need to deploy double cabling systems in an enterprise, significantly
decreasing installation costs.
Power over Ethernet can be used in any enterprise network that deploys relatively low-
powered devices connected to the Ethernet LAN:
• IP phones
• Wireless access points
IP gateways
•
• Audio and video remote monitoring devices
PoE Operation
PoE implementation stages:
Detection—Sends special pulses on the copper cable. When a PoE device is located at the
•
other end, that device responds to these pulses.
Classification—Negotiation between the Power Sourcing Equipment (PSE) and the
•
Powered Device (PD) commences after the Detection stage. During negotiation, the PD
specifies its class, which is the amount of maximum power that the PD consumes.
• Power Consumption—After the classification stage completes, the PSE provides power to
the PD. If the PD supports PoE, but without classification, it is assumed to be class 0 (the
maximum). If a PD tries to consume more power than permitted by the standard, the PSE
stops supplying power to the port.
Power Modes
Power per port can be limited depending on the Power Mode:
• Port Limit—Power is limited to a specified wattage. For these settings to be active, the
system must be in PoE Port Limit mode. That mode is configured in the PoE Feature
Configuration page. When the power consumed on the port exceeds the port limit, the port
power is turned off.
Class Limit—Power is limited based on the class of the connected PD. For these settings
•
to be active, the system must be in PoE Class Limit mode. That mode is configured in the
PoE Feature Configuration page. When the power consumed on the port exceeds the class
limit, the port power is turned off.
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