Chapter 24 Congestion Control 1 Slow Start initialize

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Chapter 24 Congestion Control 1

Chapter 24 Congestion Control 1

Slow Start initialize: cwnd = 1 (one maximum segment size); For each segment that

Slow Start initialize: cwnd = 1 (one maximum segment size); For each segment that is acknowleged cwnd = cwnd + 1 until min(cwnd, awnd) 9

Congestion Avoidance n n TCP는 timeout될 때까지 ACK을 받지 못하면 congestion avoidance를 수행한다. Congestion

Congestion Avoidance n n TCP는 timeout될 때까지 ACK을 받지 못하면 congestion avoidance를 수행한다. Congestion Avoidance If (segment timeout) 1. Set threshold = cwnd/2 2. Set cwnd = 1 and restart “slow-start” until (cwnd = threshold) 3. If (cwnd threshold) cwnd = cwnd + 1 every roundtrip time 10

Slow Start와 Congestion Avoidance 20 Time out occurs cwnd 15 10 Threshold 5 1

Slow Start와 Congestion Avoidance 20 Time out occurs cwnd 15 10 Threshold 5 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 Round-trip times 11

Fast Retransmit와 Fast Recovery n 동일한 ACK을 3개 받을 경우 n Fast Retransmit n

Fast Retransmit와 Fast Recovery n 동일한 ACK을 3개 받을 경우 n Fast Retransmit n n Timeout되기 전이라도 바로 재전송한다. Fast Recovery n n Cwnd를 현재의 Cwnd의 반으로 줄인다. 그리고 줄인 Cwnd에서부터 linear하게 증가시킨다. 12

Fast Retransmit와 Fast Recovery 13

Fast Retransmit와 Fast Recovery 13

Congestion Control 1 Principles of Congestion Control CongestionCongestion Control 1 Principles of Congestion Control Congestion
Congestion Control 1 Principles of Congestion Control CongestionCongestion Control 1 Principles of Congestion Control Congestion
Initialize 1 Private Sub Initialize Dim i aInitialize 1 Private Sub Initialize Dim i a
Typical Program Structure Initialize Window GLUT Initialize EventTypical Program Structure Initialize Window GLUT Initialize Event
Congestion Control Quality of Service Internetworking Congestion CongestionCongestion Control Quality of Service Internetworking Congestion Congestion
Improving Slow Start In Kwan Yu Slow StartImproving Slow Start In Kwan Yu Slow Start
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Applet init Initialize start start stop stop destroyApplet init Initialize start start stop stop destroy
Congestion Control TCP implements congestion control at theCongestion Control TCP implements congestion control at the
CONGESTION CONTROL 1 Congestion Control When one partCONGESTION CONTROL 1 Congestion Control When one part
Congestion Control Algorithms General Principles of Congestion ControlCongestion Control Algorithms General Principles of Congestion Control
TCP Congestion Control Networks TCP Congestion Control 1TCP Congestion Control Networks TCP Congestion Control 1
Endend congestion control windowbased congestion control Sending transportEndend congestion control windowbased congestion control Sending transport