Chapter 3 Concepts
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Connection-oriented (TCP) and connectionless (UDP)
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Layer functionality
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multiplexing and demultiplexing (TCP and UDP)
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error checking (TCP and UDP)
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segmentation and reassembly (TCP only)
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reliable data transfer (TCP only)
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congestion control (TCP only)
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Multiplexing
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headers: source and destination ports
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TCP: source and destination, port and IP address
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UDP: destination only, port and IP address
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Using UDP
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short simple messages (e.g. DNS), or
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do-it-yourself connections (multimedia, telephony)
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Reliable data transfer protocols
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mechanisms
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checksum
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acks and nacks
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sequence numbers
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timers
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windowing/pipelining
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advantage of windowing/pipelining
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protocols
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alternating bit
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go back n (pipelined, single timer)
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selective repeat (pipelined, multiple timer)
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TCP reliable data transfer protocol charateristics
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pipelined
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cumulative acknowledgement
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single timer
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Congestion
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end host and network
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congestion aggravates itself
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retransmissions (lost, timed out packets)
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upstream propagation
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choke packets
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drawback of transport layer congestion control