Configuration Examples for Troubleshooting Software Example: Pinging an IP Host This example shows how to ping an IP host: Device# ping 172.20.52.3 Type escape sequence to abort. Sending 5, 100-byte ICMP Echoes to 172.20.52.3, timeout is 2 seconds: !!!!! Troubleshooting the Software Configuration Configuration Examples for Troubleshooting Software Symptom or Problem Possible Cause and Solution Cisco pre-standard powered device disconnects or resets. After working normally, a Cisco phone 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. IEEE 802.3af-compliant or IEEE 802.3at-compliant powered devices do 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.
Troubleshooting the Software Configuration 27