15-441 Computer Networking Lecture 19- TCP Performance
15-441 Computer Networking Lecture 19 – TCP Performance
Outline TCP congestion avoidance ·TCPs| ow start TCP modeling Lecture 19: TCP Congestion Control
Lecture 19: TCP Congestion Control 2 Outline • TCP congestion avoidance • TCP slow start • TCP modeling
Additive Increase/decrease Fairness line Allocation Efficiency Line User 1s Allocation X, Lecture 19: TCP Congestion Control
Lecture 19: TCP Congestion Control 3 Additive Increase/Decrease T0 T1 Efficiency Line Fairness Line User 1’s Allocation x1 User 2’s Allocation x2
Multiplicative Increase/Decrease °Both×1andX2 increase by the same factor over Fairness line time User 2s Extension from Allocation origin -constant fairness Efficiency Line User 1s Allocation X, Lecture 19: TCP Congestion Control
Lecture 19: TCP Congestion Control 4 Muliplicative Increase/Decrease • Both X1 and X2 increase by the same factor over time • Extension from origin – constant fairness T0 T1 Efficiency Line Fairness Line User 1’s Allocation x1 User 2’s Allocation x2
What is the right choice? · Constraints limit us to aIMD Fairness Line X Improves or keeps fairness User 2s constant at Allocation each step AIMD moves towards optimal Efficiency Line point User 1s Allocation x, Lecture 19: TCP Congestion Control
Lecture 19: TCP Congestion Control 5 What is the Right Choice? • Constraints limit us to AIMD • Improves or keeps fairness constant at each step • AIMD moves towards optimal point x0 x1 x2 Efficiency Line Fairness Line User 1’s Allocation x1 User 2’s Allocation x2