1. Role of a Switch

• A switch operates mainly at the Data Link Layer (Layer 2) of the OSI model, although some advanced switches also work at Layer 3.

• Its primary job is to connect multiple devices (computers, printers, servers) within the same Local Area Network (LAN) and forward data based on MAC addresses.

• When a switch receives data, it checks the MAC address table to see which port the destination device is connected to and forwards the frame only to that port.

👉 Example with a Switch:
Imagine you are in a university lab where 10 computers are connected to one switch. When Computer A sends a file to Computer B, the switch looks at B’s MAC address and sends the data directly to B’s port without disturbing the other 8 computers. This reduces unnecessary traffic and increases efficiency.

2. Role of a Router

• A router works at the Network Layer (Layer 3) of the OSI model.

• Its job is to connect different networks together (for example, your home network to the Internet) and forward data based on IP addresses.

• Routers make decisions about the best path to send packets using routing tables and protocols (like RIP, OSPF, BGP).

• A router also performs Network Address Translation (NAT), which allows multiple devices in a LAN to share a single public IP when accessing the Internet.

👉 Example with a Router:
In the same university, suppose the lab network, library network, and administrative office network all need Internet access. A router connects each of these LANs to the wider Internet. If Computer A in the lab wants to access an educational website, the router uses the IP address of the website’s server and forwards the request through the Internet.