A switch is a device connecting devices within a network. It receives data from one device and sends it to another. Unlike a hub, which broadcasts to all devices, a switch sends data only to the intended recipient. That makes networks faster and more secure. Switches work at the data link layer.

Switches learn which devices are on which ports. They build a MAC address table. When a frame arrives, the switch looks up the destination MAC address and forwards it to the correct port. If the address is unknown, it floods the frame to all ports. The table is built dynamically.

Types of switches

• Unmanaged: plug and play, no configuration
• Managed: configurable, VLANs, monitoring
• Layer 3: routing between VLANs
• PoE: provides power over Ethernet
• Stackable: multiple switches as one

Switches are the workhorses of local networks. They connect computers, printers, and access points. They are cheap and reliable. They are not glamorous. But without them, LANs would not function. The switch is the traffic director of the local network.