Like a hub, a switch is designed to repeat packets. However, unlike a hub, rather than broadcasting data to every port, a switch sends data to only the computer for which the data is intended. Switches store the layer 2 address of every connected device in a CAM table, which acts as a kind of traffic cop. When a packet is transmitted, the switch reads the layer 2 header information in the packet and, using the CAM table as reference, determines to which port(s) to send the packet. Switches send packets only to specific ports, thus greatly reducing network traffic.