poe power-reserved
Function
The poe power-reserved command sets the percentage of the reserved PoE power against the total PoE power.
The undo poe power-reserved command restores the default percentage of the reserved PoE power against the total PoE power.
By default, the percentage of the reserved PoE power against the total PoE power is 20%.
Format
poe power-reserved power-reserved [ slot slot-id [ mcu mcu-id ] ]
undo poe power-reserved power-reserved slot slot-id
undo poe power-reserved [ slot slot-id [ mcu mcu-id ] ]
Only the S5720I-28X-PWH-SI-AC supports the mcu mcu-id parameter.
Parameters
Parameter |
Description |
Value |
|---|---|---|
power-reserved |
Specifies the percentage of the reserved PoE power against the total PoE power. |
The value is an integer that ranges from 0 to 100, in percentage. The default value is 20. |
slot slot-id |
Specifies a slot ID. |
The value depends on the device configuration. |
mcu mcu-id |
Specifies an MCU ID. |
The value is 1 or 2. |
Usage Guidelines
Usage Scenarios
The device can dynamically allocate power to each interface according to the power consumption of each interface. The power consumption of a PD keeps changing when the PD is running. The system periodically calculates the total power consumption of all the PDs. If the total power consumption exceeds the upper threshold of the device, the system powers off the PDs on the interfaces of low priority. If interfaces have the same priority, the system powers off the PD on the interface with a larger port number.
Sometimes, however, the power consumption increases sharply and the available power of the system cannot support the burst increase of power. At this time, the system has not calculated and found that the total power consumption exceeded the upper threshold; therefore, the system does not cut off power low-priority interfaces in time. As a result, the PoE power supply is shut down for overload protection, and all PDs are powered off.
This problem can be solved by running the poe power-reserved command to set proper reserved power. When there is a burst increase in power consumption, the reserved power can support the system running. Then the system has time to power off interfaces of low priority to ensure stable running of other PDs.
Precautions
- The reserved power should not be set greater than 20%. If the reserved PoE power is greater than 20% of the total PoE power, the power capacity of the device is affected.
- To set the maximum output power of a device, run the poe max-power command. In this case, the device calculates the reserved power based on the set maximum output power. If the maximum output power is not set, the available PoE power is the power provided by the PoE power module.