How Data TravelsCongestion Control

The Internet's Traffic Jam

Networks slow themselves down on purpose to avoid collapse

In 1986, a link between two buildings a short walk apart slowed almost a thousandfold. Nothing was broken. What went wrong?

You'll find out

  • Why a full router throws packets away
  • The rule every sender follows unasked
  • How halving ends up sharing fairly

Why it matters

Every video call and download you make is throttled by this rule, many times a second, with nobody in charge.

About 3 min6 interactive slides · 5 questionsLesson 151 · Zone 17

Play this lesson

Free to play in your browser or on iPhone

More in this zone

  1. 145Exponential GrowthRice on a ChessboardDouble a grain on every square and you'd bankrupt a kingdom
  2. 146Quantum MechanicsSchrödinger's Cat Was a JokeThe famous cat was meant to show how absurd the idea sounded
  3. 147Exponential GrowthThe Lily Pad RiddleIf lilies double daily and cover the pond on day 30, when was it half full?
  4. 148Electrical EngineeringThe Cooktop That Stays ColdInduction heats the pan directly with a changing magnetic field
  5. 149Search EnginesHow Google Ranked the WebA page matters when pages that matter point to it
  6. 150Text EncodingA Is 65Every letter you type is secretly a number
  7. 152Game DesignWhy Mario Has a MoustacheIn a 16×16 sprite, a moustache was easier to draw than a mouth
  8. 153AlgorithmsTwice the Data, Four Times the WaitHow fast a method slows down is what matters