TCP: congestion control

• Detects packet losses:

  • three duplicate ACKs
  • retransmission timeouts

• Assumes that losses are due to network congestion.

• Congestion control:

  • congestion window size (cwnd) decreases
  • amount of data sent into network decreases
    • sending window = min (cwnd, rwnd)
  • throughput decreases.

rwnd: receiver’s advertised window

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