If there is a continuous, intermittent, or reoccurring alarm related to
power, replace the power supply if possible it is a field-replaceable unit.
Otherwise, replace the switch.
If the problem is on a consecutive group of ports but not all ports, the
power supply is probably not defective, and the problem could be related to
PoE regulators in the switch.
Use the show log privileged EXEC command to review
alarms or system messages that previously reported PoE conditions or status
If there are no alarms, use the show interface
status command to verify that the ports are not shut down
or error-disabled. If ports are error-disabled, use the
shut and no shut
interface configuration commands to reenable the ports.
Use the show env power and show power
inline privileged EXEC commands to review the PoE status
and power budget (available PoE).
Review the running configuration to verify that power inline
never is not configured on the ports.
Connect a nonpowered Ethernet device directly to a switch port. Use only a
short patch cord. Do not use the existing distribution cables. Enter the
shut and no shut
interface configuration commands, and verify that an Ethernet link is
established. If this connection is good, use a short patch cord to connect a
powered device to this port and verify that it powers on. If the device
powers on, verify that all intermediate patch panels are correctly
Disconnect all but one of the Ethernet cables from switch ports. Using a
short patch cord, connect a powered device to only one PoE port. Verify the
powered device does not require more power than can be delivered by the
Use the show power inline privileged EXEC command
to verify that the powered device can receive power when the port is not
shut down. Alternatively, watch the powered device to verify that it powers
If a powered device can power on when only one powered device is connected
to the switch, enter the shut and no
shut interface configuration commands on the remaining
ports, and then reconnect the Ethernet cables one at a time to the switch
PoE ports. Use the show interface status and
show power inline privileged EXEC commands
to monitor inline power statistics and port status.
If there is still no PoE at any port, a fuse might be open in the PoE
section of the power supply. This normally produces an alarm. Check the log
again for alarms reported earlier by system messages.