Which device operates at the network layer of the OSI model?

The device that operates at the network layer of the OSI model is a router. The network layer is responsible for the logical addressing and routing of packets across different networks, which includes determining the best path for data to travel from the source to the destination. This is where routers come into play, as they are designed to forward data packets based on their IP addresses.

Routers manage traffic between different networks, establishing paths for information to travel based on factors like network topology or congestion. They also perform functions such as packet forwarding and filtering based on the destination address, and they can connect dissimilar networks.

In contrast, other devices mentioned operate at different layers of the OSI model. A switch operates primarily at the data link layer, responsible for forwarding frames based on MAC addresses. A hub functions at the physical layer, simply transmitting data signals to all connected devices without filtering or intelligence. A bridge operates at the data link layer as well, filtering traffic based on MAC addresses and connecting different network segments within the same LAN.

Understanding the roles of these devices and their respective layers is crucial for effective networking and troubleshooting, highlighting why the router is fundamentally linked to functions at the network layer.