Allied Telesis AT-GS950/16PS, Руководство пользователя

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Chapter 22: Power Over Ethernet (PoE)
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Overview
The AT-GS950/16PS switch features Power over Ethernet (PoE) on the
10/100Base-Tx ports on ports 1 - 16. PoE is used to supply power to
network devices over the same twisted pair cables that carry the network
traffic.
The main advantage of PoE is that it can make installing a network easier.
The selection of a location for a network device is often limited by whether
there is a power source nearby. This constraint limits equipment
placement or requires the added time and cost of having additional
electrical sources installed. However, with PoE, you can install PoE-
compatible devices wherever they are needed without having to worry
about whether there is power source nearby.
Power Sourcing
Equipment (PSE)
A device that provides PoE to other network devices is referred to as
power sourcing equipment (PSE). The AT-GS950/16PS switch is a PSE
device which provides DC power to the network cable and functions as a
central power source for other network devices.
Powered Device
(PD)
A device that receives power from a PSE device is called a powered
device (PD). Examples include wireless access points, IP phones,
webcams, and even other Ethernet switches.
PD Classes
PDs are grouped into five classes. The classes are based on the amount
of power that PDs require. The AT-GS950/16PS PoE switch supports all
five classes listed in Table 6.
Power Budget
Power budget is the maximum amount of power that the PoE switch can
provide at one time to the connected PDs. The AT-GS950/16PS can
supply up to 855 Watts maximum.
Table 6. IEEE Powered Device Classes
Class
Maximum Power Output
from a Switch Port
Power Ranges of the PDs
0 15.4W 0.44W to 12.95W
1 4.0W 0.44W to 3.84W
2 7.0W 3.84W to 6.49W
3 15.4W 6.49W to 12.95W
4 34.2W 25.5W to 38.9W