Configuring PoE Power Management
Context
The maximum output power of the device is determined by the PoE-capable module quantity, type, and input voltage. You can configure the maximum power, percentage of PoE power to be reserved, PoE power alarm threshold, and maximum power on each interface. Setting power parameters based on the requirements of PDs connected to the device helps effectively use PoE power and ensures device stability.
Procedure
- Configure the PoE power supply mode.
The S5720I-28X-PWH-SI-AC has two built-in power modules for 1+1 power redundancy. To improve system stability, set the PoE power supply mode of the S5720I-28X-PWH-SI-AC to the backup mode.
- Run poe-power backup-mode backup-mode [ slot slot-id ]
The PoE power supply mode of the S5720I-28X-PWH-SI-AC is configured.
By default, the PoE power supply mode is the high-power mode.
Changing the PoE power supply mode will power off the PDs connected to all ports.
- Run poe-power backup-mode backup-mode [ slot slot-id ]
- Configure the maximum output power of the device.
If the power that the network provides for the PoE device is unstable, for example, the mains voltage fluctuates, the power that the PoE device provides for PDs is affected and begins to fluctuate. As a result, PDs are not provided with sufficient power and some PDs are powered off. You can configure the maximum output power of the device to ensure power stability for a PD.
- Configure the maximum output power for an interface.
The PD power negotiation result may be different from the power required by non-standard PDs or PDs that cannot be classified. You can configure the maximum output power of an interface to prevent power overload for PDs and save energy.
An interface provides 15400 mW power to PDs based on the power class 0 if non-standard PDs are connected to the interface or forcible power supply is configured on the interface of the switches except the S5720-16X-PWH-LI-AC, S5720-28X-PWH-LI-AC, S5720I-SI, S5735-L, S5735S-L, S5735S-L-M, S5735-S, S5735-S-I, S5730-HI, S5730-SI, S5730S-EI, S5731-H, S5731-S, S5731S-S, S5732-H, and S6720-SI.
- Configure the percentage of PoE power to be reserved.
The power of a PD continually changes while the PD is running. Sometimes, the power consumption increases sharply and the available power of the device cannot support the burst increase of power. If the device does not detect this problem and cuts off PDs on low-priority interfaces, all PDs will be powered off due to overload. You can configure reserved power to solve the problem. When power consumption increases sharply, the reserved power can support the running of the system. The device can immediately power off PDs on low-priority interfaces to ensure that other PDs continue to run stably.
- Configure the alarm threshold for the percentage of power consumption.
When power consumption increases sharply, the reserved power can often satisfy power requirements. However, if power consumption exceeds the safe range, some PDs will still be powered off. To solve this problem, configure an alarm threshold for the percentage of power consumption. When power consumption exceeds this threshold, the system generates an alarm, alerting administrators to take measures to reduce power consumption.
- Enable power auto-negotiation for interfaces.
By default, the switch supplies power to the APs connected to interfaces in compliance with IEEE 802.3at (the maximum output power is 30 W). Some APs support both IEEE 802.3at and 802.3af. The switch can supply power to these APs in accordance with IEEE 802.3af (the maximum output power is 15.4 W). When the APs connected to the switch support both IEEE 802.3at and 802.3af, enable power auto-negotiation on the interfaces connected to these APs. When the total available power of the switch is less than 30 W and the switch detects that the current power supply standards of an AP are IEEE 802.3at, the switch can send an LLDP packet to the AP to enable the AP to set its power supply standards to IEEE 802.3af. Power auto-negotiation changes only the power supply standards of APs but not the interfaces to which the APs are connected.
Enabling power auto-negotiation on interfaces will change the power supply standards of the APs connected to the interfaces, reduce the power consumption of the APs, and enable the switch to supply power to more APs when the rated output power of the switch is fixed.
Only the S5731-H, S5731-S, S5731S-S, S5735-L, S5735S-L, S5735S-L-M, S5735-S, S5735-S-I, S5720-12TP-PWR-LI-AC, S5720-28TP-PWR-LI-AC, S5720-28TP-PWR-LI-ACL, S5720-28P-PWR-LI-AC, S5720-52P-PWR-LI-AC, S5720-28X-PWR-LI-AC, S5720-28X-PWR-LI-ACF, S5720-52X-PWR-LI-AC, S5720-52X-PWR-LI-ACF, S5720S-12TP-PWR-LI-AC, S5720S-28TP-PWR-LI-ACL, S5720S-28P-PWR-LI-AC, S5720S-52P-PWR-LI-AC, S5720S-28X-PWR-LI-AC, and S5720S-52X-PWR-LI-AC support this function.
- Run poe power auto-neg enable
Power auto-negotiation is enabled for interfaces.
By default, power auto-negotiation is disabled for interfaces.
- The lldp dot3-tlv power 802.1ab force command is mutually exclusive with the lldp dot3-tlv power 802.3at command and cannot be configured together.
- Only AP6050 and AP4051TNN support power auto-negotiation.
- When the total available power of the switch is less than 30 W, the power supply standards of all the APs connected to the interfaces that have power auto-negotiation enabled will be set to IEEE 802.3af. When the total available power of the switch is more than the larger value of 60 W and reserved power, the power supply standards of the APs connected to the interfaces will be restored to IEEE 802.3at based on the power supply priority configured on the interfaces. That is, the power supply standards of the AP connected to the interface with a higher priority are restored to IEEE 802.3at. If the power supply priority of these interfaces is the same, the power supply standards of the AP connected to the interface with a smaller interface number are restored to IEEE 802.3at first.
- Disabling power auto-negotiation on an interface will restore the power supply standards of the AP connected to the interface to IEEE 802.3at. This operation will power off the APs connected to some interfaces if the total power of the switch is insufficient.
- Run poe power auto-neg enable