Use the show interfaces privileged EXEC command to see if the port is error-disabled, disabled, or shutdown. Reenable the port if necessary. The LEDs on the front panel provide troubleshooting information about the switch. You can also get statistics from Device Manager, from the CLI, or from an SNMP workstation. POST failures are usually fatal. Contact. The table describes the LED status indicators for Ethernet modules or fixed-configuration switches: Ensure that both sides have a link. Whether you are dealing with a no link light, intermittent connectivity (link flapping), or a transceiver not detected error, the root cause is often not immediately obvious.