1-5Configuring PoE Power ManagementConfiguring PD Power ManagementThe power priority of a PD depends on the priority of the PoE interface. The priority levels of PoEinterfaces include critical, high and low in descending order. Power supply to a PD is subject to PDpower management policies.All PSEs implement the same PD power management policies. When the PSE supplies power to a PD,z By default, no power will be supplied to a new PD if the PSE power is overloaded.z Under the control of a priority policy, the PD with a lower priority is first powered off to guarantee thepower supply to the new 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 beingpowered off because of sudden increase of the power of the PD. When the remaining power of theinterface is lower than 19 watts and no priority is configured for a PoE interface, the PSE does notsupply power to the new PD; when the remaining power of the interface is lower than 19 watts, butpriority is configured for a PoE interface, the interface with a higher priority can preempt the powerof 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 thePD 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 PoEinterface, regardless of whether PoE is enabled for the PoE interface) is lower than the maximum powerof the PoE interface, you will fail to set the priority of the PoE interface to critical. Otherwise, you cansucceed in setting the priority to critical, and this PoE interface will preempt the power of other PoEinterfaces with a lower priority level. In the latter case, the PoE interfaces whose power is preemptedwill be powered off, but their configurations will remain unchanged. When you change the priority of aPoE interface from critical to a lower level, the PDs connecting to other PoE interfaces will have anopportunity of being powered.Configuration prerequisitesEnable PoE for PoE interfaces.Configuration procedureFollow these steps to configure PD power management:To do… Use the command… RemarksEnter system view system-view —
