Data communication
What if…
What if senders waited for every ACK?
What if every sender had to wait for an ACK before the next frame?
Quick check · tap an answer to continue
Lesson notes
Key points
- Only one frame would be in flight, so the link sits idle during each round trip.
- Efficiency would collapse as distance grows, because utilisation is roughly one over one plus two a.
- Satellite links with huge delays would crawl, using a tiny fraction of their bandwidth.
Takeaway: Sliding windows keep many frames in flight to fill long pipes.
Quick check: Why does stop-and-wait perform badly on long-delay links?
- Frames get bigger
- The link idles each round trip
- Bits travel slower
Only one frame is outstanding, so the link waits empty for every ACK.
Stop-and-waitUtilisationSatellite delay
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