User manual

C HAPTER 4 | Configuring the Switch
Power over Ethernet
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on the amount of cables attached to each device. Once configured to
supply power, an automatic detection process is initialized by the switch
that is authenticated by a PoE signature from the connected device.
Detection and authentication prevent damage to non-compliant devices
(IEEE 802.3af or 802.3at).
◆ This switch supports both the IEEE 802.3af PoE and IEEE 802.3at-2009
PoE Plus standards. To ensure that the correct power is supplied to
powered devices (PD) compliant with these standards, the first
detection pulse from the switch is based on 802.3af to which the
802.3af PDs will respond normally. It then sends a second PoE Plus
pulse that causes an 802.3at PD to respond as a Class 4 device and
draw Class 4 current. Afterwards, the switch exchanges information
with the PD such as duty-cycle, peak and average power needs.
◆ All the RJ-45 ports support both the IEEE 802.3af and IEEE 802.3at
standards. The total PoE power delivered by all ports cannot exceed the
maximum power budget of 375W.
◆ The switch’s power management enables individual port power to be
controlled within the switch’s power budget. Port power can be
automatically turned on and off for connected devices, and a per-port
power priority can be set so that the switch never exceeds its power
budget. When a device is connected to a switch port, its power
requirements are detected by the switch before power is supplied. If
the power required by a device exceeds the power budget of the port or
the whole switch, power is not supplied.
◆ Ports can be set to one of four power priority levels, critical, high,
medium, or low. To control the power supply within the switch’s budget,
ports set at critical to medium priority have power enabled in
preference to those ports set at low priority. For example, when a
device connected to a port is set to critical priority, the switch supplies
the required power, if necessary by denying power to ports set for a
lower priority during bootup.
N OTE : For more information on using the PoE provided by this switch refer
to the Installation Guide.
PATH
Advanced Configuration, PoE
PARAMETERS
These parameters are displayed:
◆ Reserved Power determined by - There are three modes for
configuring how the ports or attached Powered Devices (PD) may
reserve power:
■
Class – Each port automatically determines how much power to
reserve according to the class to which the connected PD belongs,