How a Switch Forwards Frames

A switch is the modern device that connects devices in a LAN, and it is far smarter than a hub. Instead of blindly repeating data, a switch reads addresses and forwards each frame only to the port where the destination actually is. This single change dramatically improves speed, efficiency, and security. This lesson explains exactly how a switch makes those forwarding decisions.

A switch works at the data link layer (Layer 2 of the OSI model). At this layer, data is organized into frames, and each device has a unique MAC address (Media Access Control address) burned into its network card. The switch reads the MAC addresses inside frames to decide where to send them, which is why it is called a Layer 2 device.