A network switch including a port, a memory, and a controller. The port has a port identifier and receives a packet (including an address of the source device) transmitted from a source device to the network switch. The memory is configured to store entries, each entry including (i) an identifier of a port of the network switch and (ii) an address of a network device. The controller is configured to (i) determine whether the address of the source device and the port identifier of the packet are stored in the memory and (ii) send a message to a processor requesting approval of the packet. The controller is configured to send the message when (i) the address of the source device is not stored in the memory or (ii) the port identifier of the packet is not stored with the address of the source device as one of the entries.