Packets and Routing

Sending a whole video as one giant blob would be fragile. One glitch could ruin everything. Instead, data is cut into packets, small blocks with labels saying where they came from and where they should go.

Packets from the same message can travel different paths. Routers along the way read the label and pass each packet to the next router closer to the destination.

Use the packet route lab to watch one message split apart, move through routers, and meet again at the end.

A router is like a crossing guard with a map. It does not know the whole journey, but it knows a good next step. If one road is crowded, it may send packets another way.

That is why ping times change and why video may buffer when many people use the network at once. The packets still arrive, just slower.

Lost packets can be sent again. Higher layers of the internet check that the full message rebuilt correctly.

Your browser request for a page becomes packets going out. The server’s answer comes back as packets too. The browser waits until it has enough pieces to show text and images.

This design lets the internet grow. New routers can join without rebuilding the whole system, as long as they follow the same forwarding rules.

Next you will see how websites use HTTP and HTTPS, and why the padlock icon matters when packets carry private information.