H3C Technologies H3C S7500E Series Switches - Manual (Page 109)

5-10
Configuring PoE Interface Power Management
The power supply priority of a PD depends on the priority of the PoE interface. The priority
levels of PoE interfaces include critical, high and low in descending order. Power supply to a PD
is subject to PoE interface power management policies.
All PSEs implement the same PoE interface power management policies. When a PSE supplies
power to a PD,
z If the PoE interface power management is not enabled, no power will be supplied to a new
PD if the PSE power is overloaded.
z If the PoE interface power management priority policy is enabled, the PD with a lower
priority is first powered off to guarantee the power supply to the PD with a higher priority
when the PSE power is overloaded.
z 19 watts guard band is reserved for each PoE interface on the device to prevent a PD from
being powered off because of a sudden increase of the PD power. When the remaining
power of the PSE where the PoE interface resides is lower than 19 watts and no priority is
configured for the PoE interface, the PSE does not supply power to the new PD; when the
remaining power of the PSE where the PoE interface resides is lower than 19 watts, but
priority is configured for the 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 PD power results in PSE power overload, power supply to the
PD on the PoE interface with a lower priority will be stopped to ensure the power supply to
the PD with a higher priority.
If the guaranteed remaining PSE power (the maximum PSE power minus the 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 PoE interface power management:
To do… Use the command… Remarks
Enter system view system-view —