Removing a device from the “authorized” list for a port
This command option removes unwanted devices (MAC addresses) from the Authorized Addresses list. (An Authorized Address list is available for each port for which Learn Mode is currently set to “Static”. See the Command syntax listing under Configuring port security.
When learn mode is set to static, the Address Limit (address-limit) parameter controls how many devices are allowed in the Authorized Addresses (mac-address) for a given port. If you remove a MAC address from the Authorized Addresses list without also reducing the Address Limit by 1, the port may subsequently detect and accept as authorized a MAC address that you do not intend to include in your Authorized Address list. Thus, if you use the CLI to remove a device that is no longer authorized, it is recommended that you first reduce the Address Limit (address-limit) integer by 1, as shown below. This prevents the possibility of the same device or another unauthorized device on the network from automatically being accepted as “authorized” for that port.
To remove a device (MAC address) from the “Authorized” list and when the current number of devices equals the Address Limit value, you should first reduce the Address Limit value by 1, then remove the unwanted device.
You can reduce the address limit below the number of currently authorized addresses on a port. This enables you to subsequently remove a device from the “Authorized” list without opening the possibility for an unwanted device to automatically become authorized.
For example, suppose port A1 is configured as shown below and you want to remove 0c0090-123456 from the Authorized Address list:
The following command serves this purpose by removing 0c0090-123456 and reducing the Address Limit to 1:
switch(config)# port-security a1 address-limit 1 switch(config)# no port-security a1 mac-address0c0090-123456
