Cisco Systems 3560 Manual De Usuario

No PoE on only one port.

Trouble is on only one switch port. PoE and 
non-PoE devices do not work on this port, but do 
on other ports. 

Verify that the powered device works on another PoE port. 

Use the show run, show interface status, or show power inline detail 
user EXEC commands to verify that the port is not shut down or error 
disabled. 

Most switches turn off port power when the port is shut down, 
even though the IEEE specifications make this optional. 

Verify that the Ethernet cable from the powered device to the switch port 
is good: Connect a known good non-PoE Ethernet device to the Ethernet 
cable, and make sure that the powered device establishes a link and 
exchanges traffic with another host.

Verify that the total cable length from the switch front panel to the 
powered device is not more than 100 meters. 

Disconnect the Ethernet cable from the switch port. Use a short Ethernet 
cable to connect a known good Ethernet device directly to this port on 
the switch front panel (not on a patch panel). Verify that it can establish 
an Ethernet link and exchange traffic with another host, or ping the port 
VLAN SVI. Next, connect a powered device to this port, and verify that 
it powers on. 

If a powered device does not power on when connected with a patch cord to 
the switch port, compare the total number of connected powered devices 
to the switch power budget (available PoE). Use the show inline power 
and show inline power detail commands to verify the amount of 
available power.

For more information, see 

No PoE On One Port

 on Cisco.com.