Cisco Catalyst 3560-X Series, Software Configuration Manual

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Catalyst 3750-X and 3560-X Switch Software Configuration Guide
OL-25303-03
Chapter 1 Troubleshooting
Troubleshooting Tables
Cisco IP Phone disconnects or resets.
After working normally, a Cisco phone or
wireless access point intermittently reloads
or disconnects from PoE.
Verify all electrical connections from the switch to the powered device.
Any unreliable connection results in power interruptions and irregular
powered device functioning such as erratic powered device disconnects
and reloads.
Verify that the cable length is not more than 100 meters from the switch
port to the powered device.
Notice what changes in the electrical environment at the switch location
or what happens at the powered device when the disconnect occurs?
Notice whether any error messages appear at the same time a disconnect
occurs. Use the
show log privileged EXEC command to review error
messages.
Verify that an IP phone is not losing access to the Call Manager
immediately before the reload occurs. (It might be a network problem
and not a PoE problem.)
Replace the powered device with a non-PoE device, and verify that the
device works correctly. If a non-PoE device has link problems or a high
error rate, the problem might be an unreliable cable connection between
the switch port and the powered device.
For more information, see Cisco Phone Disconnects or Resets on
Cisco.com.
Non-Cisco powered device does not work on
Cisco PoE switch.
A non-Cisco powered device is connected to
a Cisco PoE switch, but never powers on or
powers on and then quickly powers off.
Non-PoE devices work normally.
Use the show power inline command to verify that the switch power
budget (available PoE) is not depleted before or after the powered device
is connected. Verify that sufficient power is available for the powered
device type before you connect it.
Use the show interface status command to verify that the switch detects
the connected powered device.
Use the show log command to review system messages that reported an
overcurrent condition on the port. Identify the symptom precisely: Does
the powered device initially power on, but then disconnect? If so, the
problem might be an initial surge-in (or
inrush ) current that exceeds a
current-limit threshold for the port.
For more information, see Non-Cisco PD Does Not Work Correctly on
Cisco PoE Switch on Cisco.com.
Figure 1-1 Power Over Ethernet Troubleshooting Scenarios (continued)
Symptom or problem Possible cause and solution