Congestion, Queues and Collapse
What happens when everybody sends at once, and how to get out of it
About 50 minutesAdvancedThe Internet and Search
What your child can do at the end
Explain queueing delay and why it grows non-linearly near saturation
The brief
Congestion is not a broken cable. It is arithmetic: if packets arrive at a router faster than they can leave, the queue grows, delay grows with it, and once the queue is full the router throws packets away. Worse, naive senders respond to loss by sending more, which is how congestion collapse happens. In this lab you build a jam on purpose, measure queueing delay, and then get a full transfer through a saturated network.
Skills it develops
predictionstatistics basicsdebugging
How it is assessed
3 graded challenges inside the lab, and 8 questions at the end that check the idea rather than the clicks. Every attempt is saved, so a retry after a mistake counts as the learning it is.