Oct 212009

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.

 Posted by at 14:06