Free The transport layer lessonsThe transport layer · Stage 1 · Reliability and speed · Step 3

Congestion control

Watch TCP probe for capacity with slow start and additive increase, and cut back when it loses a packet. About 15 minutes.

Quick check

TCP Reno receives three duplicate ACKs when cwnd is 20. What does it do?

AHalves cwnd to 10, sets ssthresh to 10, and continues in congestion avoidance
BDrops cwnd to 1 and restarts slow start
CDoubles cwnd

Show the answer

Halves cwnd to 10, sets ssthresh to 10, and continues in congestion avoidance. Fast recovery: packets are still getting through, so there's no need to restart.

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