net: lec11

cst311/lec/lec11.md

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