User's Manual

80-4
Configuration Steps:
Globally enable PoE:
Switch(Config)# power inline enable
Globally set the max power to 370W:
Switch(Config)# power inline max 370
Globally enable the priority policy of power management:
Switch(Config)# power inline police enable
Set the priority of Port 1/0/2 to critical:
Switch(Config-Ethernet1/0/2)# power inline priority critical
Set the max output power of Port 1/0/6 to 9000mW:
Switch(Config-Ethernet1/0/6)#power inline max 9000
80.4 PoE Troubleshooting Help
If problems occur on using PoE, please check:
When the global value of Power Remaining is less than 15W, due to the power source protection mechanism,
the power supply to new PDs will be cut off in first-come-first-serve mode, while the existing low-priority
devices will also be disconnected in priority policy mode. If the Power Remaining is over 15W, say 16W, any
newly connected device with a power no more than 15W can get its power supply normally, without affecting
other devices. Such a power supply buffer of 15W is designed for power source protection, and calls for
special attention.
The displayed value of Power might over the value of Max. This involves the relationship between the
displayed power and the actual power, for instance:
The power set on the port: A, represents the actual output PoE power
The displayed power: B, represents the total power of the port (total current × total voltage)
The power loss set on the port: C, represents power loss of the internal Sensor ohmic resistance,
MosFet etc.
Then: B=A+C
If the power is set as A=500mW, according to the following table, the compensating current will be I=2.44mA
(500mW/50V＝10mA assuming the current working voltage is 50V), plus the compensating power C=50V×
2.44mA＝122mA
B=A+C=500+122=622mW. So, only when the displayed power reaches 622mW, the PD will be
disconnected
Table:
Max Working Current (mA)
Compensating Current (mA)
50
2.44
100
4.88
150
9.76
200
17.08
250
24.41
350
31.73