Transport Layer
	Internet Transport Layer
		Click here for subtitle 
		multiplexing/demultiplexing
		port numbers
			well-known ports
			dynamic binding
		UDP: unreliable datagram transport
		TCP: reliable stream transport
	UDP: User Datagram Protocol
		unreliable, connectionless service
		uses IP
		checksum
		allows to distinguish among multiple destinations within a given host
	TCP: Transmission Control Protocol
		stream transport
			connection oriented service (~ virtual circuit)
			unstructured stream
		reliable transport
			positive acknowledgment with retransmission
			sliding window
				Go-back-N
		end-to-end flow control
			buffering
		full duplex
	TCP (cont.)
		segments vs. IP packets
			maximum segment size
				MTU discovery
		checksum
		windows
			octet/byte-based
			3 pointers
				ack-ed bytes
				transmitted but not ack-ed bytes
				"transmittable" but not yet transmitted bytes (vs. bytes that cannot be transmitted until acks are received and the window slides)
	variable window size
		windows serve for
			error control
			flow control
				window advertisement
			congestion control
				congestion window
					window = min{rx advertisement, congestion window}
				slow-start
				multiplicative decrease, additive increase
		adaptive retransmission timeout
		silly window syndrome
			avoidance: receiver and sender heuristics
	TCP Connections
		3-way handshake
		SYN, FIN msgs