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Catalyst 2928 Switch Software Configuration Guide
OL-23389-01
Chapter 33 Troubleshooting
Troubleshooting Tables
No PoE on all ports or a group of ports.
Trouble is on all switch ports.
Nonpowered Ethernet devices cannot
establish an Ethernet link on any port, and
PoE devices do not power on.
If there is a continuous, intermittent, or reoccurring alarm related to power,
replace the power supply if possible it is a field-replacable 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 changes.
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 re-enable the ports.
Use the sh
ow 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 connected.
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 switch port.
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 on.
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.
For more information, see
No PoE On Any Port or a Group of Ports
on
Cisco.com.
Figure 33-1
Power Over Ethernet Troubleshooting Scenarios (continued)
Symptom or problem
Possible cause and solution
