The port security feature is a dynamic Catalyst switch feature that secures switch ports, and ultimately the CAM table, by limiting the number of MAC addresses that can be learned on a particular port or interface. With the port security feature, the switch maintains a table that is used to identify which MAC address (or addresses) can access which local switch port. Additionally, the switch can also be configured to allow only a certain number of MAC addresses to be learned on any given switch port. Port security is illustrated below in Figure 6-1: