At which OSI layer does routing primarily operate?

Routing primarily operates at Layer 3, the Network Layer of the OSI model. This layer is responsible for logical addressing and the routing of packets across different networks. It determines how data is sent from the source to the destination by selecting the most efficient paths through the network.

Routers, which facilitate the routing process, examine the packet headers to determine the best route based on IP addresses, enabling communication between devices on different networks. The routing process involves determining the next hop for the packet, managing traffic, and ensuring that data reaches its destination accurately and efficiently.

The other layers mentioned—Data Link, Transport, and Session—do not handle routing in the same way. Layer 2 focuses on the physical transmission of frames between devices on the same local network, Layer 4 manages end-to-end communication and data flow control, and Layer 5 deals with the session establishment and management between applications. Each of these layers has specific functions that are distinct from the routing tasks conducted at the Network Layer.