Which device operates at Layer 3 of the OSI model?

A router operates at Layer 3 of the OSI model, which is the Network layer. This layer is responsible for routing packets of data from one network to another, determining the best paths for those packets, and managing the logical addressing of devices within a network. Routers use IP addresses to make forwarding decisions, allowing them to direct traffic across different networks or subnets.

For instance, when data is sent from a device in one network to a device in another network, the router inspects the destination IP address of the data packet and decides the optimal route for that packet to reach its destination. This functionality is essential for the operation of the internet and is key to facilitating communication between different networks.

In contrast, repeaters, switches, and hubs operate at different layers and do not have the capability to route packets based on IP addresses. Repeaters function at Layer 1 (the Physical layer), primarily for amplifying signals to extend transmission distance. Hubs also work at Layer 1, acting as basic connection points that simply broadcast incoming traffic to all ports without consideration of addressing. Switches, on the other hand, operate primarily at Layer 2 (the Data Link layer), where they use MAC addresses to forward frames within the same local network