3Com 4210G Series, Руководство по настройке, Страница: 1122 / 1133

29-5
z
19 watts guard band is reserved for each PoE interface on the device to prevent a PD from being
powered off because of sudden increase of the power of the PD. When the remaining power of the
interface is lower than 19 watts and no priority is configured for a PoE interface, the PSE does not
supply power to the new PD; when the remaining power of the interface is lower than 19 watts, but
priority is configured for a PoE interface, the interface with a higher priority can preempt the power
of the interface with a lower priority to ensure the normal working of the higher priority interface.
z
If the sudden increase of the power of the PD results in PSE power overload, power supply to the
PD on the PoE interface with a lower priority will be stopped.
If the guaranteed remaining PSE power (maximum PSE power – power allocated to the critical PoE
interface, regardless of whether PoE is enabled for the PoE interface) is lower than the maximum
power of the PoE interface, you will fail to set the priority of the PoE interface to
critical
. Otherwise,
you can succeed in setting the priority to
critical
, and this PoE interface will preempt the power of
other PoE interfaces with a lower priority level. In the latter case, the PoE interfaces whose power is
preempted will be powered off, but their configurations will remain unchanged. When you change the
priority of a PoE interface from critical to a lower level, the PDs connecting to other PoE interfaces will
have an opportunity of being powered.
Configuration prerequisites
Enable PoE for PoE interfaces.
Configuration procedure
Follow these steps to configure PD power management:
To do… Use the command… Remarks
Enter system view
system-view
—
interface interface-type
interface-number
Configure the power
priority for the PoE
interface in PoE
interface view
poe priority
{
critical
|
high
|
low
}
poe-profile profile-name
[
index
]
Configure
the power
priority for
a PoE
interface
Configure the power
priority for the PoE
interface in PoE
configuration file view
poe priority
{
critical
|
high
|
low
}
Use either
command.
By default, the
power priority of a
PoE interface is
low
.
Configure a PD power management
priority policy
poe pd-policy priority
Optional
By default, no PD
power management
priority policy is
configured.
Configuring the PoE Monitoring Function
The PoE monitoring function involves monitoring of PoE power, PSE and PD.
z
Monitoring PoE power means monitoring the voltage of the PoE power.