Instead of md cwnd for aimd timeouts are suciently

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Unformatted text preview: closed loop, host- driven, and window- based 279 36 11/4/13 Addi7ve Increase Mul7plica7ve Decrease •  AIMD is a control law hosts can use to reach a good alloca7on –  Hosts addi7vely increase rate while network is not congested –  Hosts mul7plica7vely decrease rate when conges7on occurs –  Used by TCP •  Let’s explore the AIMD game … 281 AIMD Game •  Hosts 1 and 2 share a bokleneck –  But do not talk to each other directly •  Router provides binary feedback –  Tells hosts if network is congested Host 1 Host 2 1 1 Bokleneck Router 1 Rest of Network 282 37 11/4/13 AIMD Game (2) •  Each point is a possible alloca7on Host 1 1 Congested Fair Op7mal Alloca7on Efficient 0 1 Host 2 283 AIMD Game (3) •  AI and MD move the alloca7on Host 1 1 Addi7ve Increase Mul7plica7ve Decrease 0 Congested Fair, y=x Op7mal Alloca7on Efficient, x+y=1 1 Host 2 284 38 11/4/13 AIMD Game (4) •  Play the game! Host 1 1 Congested Fair A star7ng point Efficient 0 1 Host 2 285 AIMD Game (5) •  Always converge to good alloca7on! Host 1 1 Congested Fair A star7ng point Efficient 0 1 Host 2 286 39 11/4/13 AIMD Sawtooth •  Produces a “sawtooth” pakern over 7me for rate of each host –  This is the TCP sawtooth (later) Host 1 or Mul7plica7ve Addi7ve 2’s Rate Decrease Increase Time 287 AIMD Proper7es •  Converges to an alloca7on that is efficient and fair when hosts run it –  Holds for more general topologies •  Other increase/decrease control laws do not! (Try MIAD, MIMD, AIAD) •  Requires only binary feedback from the network 288 40 11/4/13 Feedback Signals •  Several p...
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