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Catalyst 3750-X and 3560-X Switch Software Configuration Guide
OL-21521-01
Chapter 51 Troubleshooting
Troubleshooting Tables
No PoE on all ports or a group of ports.
Trouble is on all switch ports. Nonpowered
Et
hernet 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
po
wer, 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
po
wer supply is probably not defective, and the problem could be related
to PoE regulators in the switch.
Use the sho
w 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 sho
w 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 sho
w 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 po
wer inline never is
not configured on the ports.
Connect a nonpowered Ethernet device directly to a switch port. Use
o
nly 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 fro
m 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 sho
w 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
co
nnected 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
secti
on 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 51-1 Power Over Ethernet Troubleshooting Scenarios (continued)
Symptom or problem Possible cause and solution