Description: A port security feature which controls the address learning capability. When number is given said N, which allows N addresses to be learned on this VLAN from the special port, the first N learned addresses are locked at this VLAN from the special port as static entries. When the learned addresses number reaches N, any incoming packet without learned source addresses are discarded (e.g. dropped) and no more new addresses can be learned on this VLAN from the special port.