Did you ever have the problem that your switch didn’t learn the MAC-addresses of the connected devices on one of its switchport? All cabling seems all right – Link is UP – Port is connected.
But show mac address-table won’t show you the MAC of your device although it is sending packets.
Check your VLAN-config!
If your switchport is configured to a VLAN thet doesn’t exists on your switch – then the switch won’t learn anything on this port. This could only happen if your switch is in VTP mode “client”.
Otherwise the VLAN will be created automatically.