Summary.

TCP round trip time, timeout

Seq and Ack #s cover error to cover packet loss we need a timer.

$$ EstimatedRTT = (1-\alpha)*EstimatedRTT + \alpha*SampleRTT $$

Explicit congestion notification (ECN)

TCP deployments often implement network-assisted congestion control:

  • two bits in IP header marked by network router to indicate congestion
    • policy to determine marking chosen by network operator
  • congestion indication carried to destination …