30 lines
935 B
Markdown
30 lines
935 B
Markdown
# lec11
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## TCP Congestion CControl
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Additive increase & Multiplicative decrease
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Sender increases window size until a loss happens.
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* Additively: increase by 1 every round-trip-time until a loss is detected.
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* Multiplicative decrese: cut window size in half
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Sender limits the transmission by changing the size of it's congestion window.
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The sender detects loss with one of two methods:
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* Timeout
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* Triple Duplicate ACK's
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## General Fairness
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### TCP Fairness
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Say we have two competing sessions:
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* additive increase slope of 1, as throughput increases
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* multiplicative decrease lowers throughput proportionally
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### UDP Fairness
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Certain types of applications won't be be rate limited by TCP fairness.
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Streaming video for instance won't since we just want to _throw_ data across as much as possible.
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This also means we have to account for loss and tolerate it when it does happen because UDP doesn't account for loss anyway.
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