What does a layer 2 switch use to direct packets?

A layer 2 switch uses the MAC address to direct packets. MAC addresses, or Media Access Control addresses, are unique identifiers assigned to network interfaces for communications at the data link layer. When a switch receives a frame of data, it reads the MAC address contained in the frame to determine the appropriate outgoing port.

The switch maintains a MAC address table, which maps each MAC address to the port through which the device associated with that address is reachable. By looking up the destination MAC address in this table, the switch can efficiently forward the frame only to the relevant port, minimizing unnecessary traffic on the rest of the network. This function is integral to the operation of a switch, enabling it to create a more efficient and effective local area network by reducing collisions and managing bandwidth.

While IP addresses are used at layer 3 (the network layer) for routing between different networks, and port numbers are specific to transport layer protocols like TCP and UDP, and destination addresses might refer to various types of addresses depending on the context, the specific mechanism a layer 2 switch employs for directing packets is specifically based on MAC addresses.