Scenarios for Troubleshooting the Software Configuration Scenarios to Troubleshoot Power over Ethernet (PoE) Table 4: Power over Ethernet Troubleshooting Scenarios Troubleshooting the Software Configuration Scenarios for Troubleshooting the Software Configuration Symptom or Problem Possible Cause and Solution Only one port does not have PoE. 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, or show interface status user EXEC commands to verify that the port is not shut down or error-disabled.
Note Most switches turn off port power when the port is shut down, even though the IEEE specifications make this optional. Verify that power inline never is not configured on that interface or port. 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. Note Cisco powered device works only with straight cable and not with crossover one. 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 power inline command to verify the amount of available power. Troubleshooting the Software Configuration 25