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Data Link Control
ผศ . ดร. อนั�นัต์ ผลเพิ่��มAsst. Prof. Anan Phonphoem, Ph.D.
[email protected]://www.cpe.ku.ac.th/~anan
Computer Engineering DepartmentKasetsart University, Bangkok, Thailand
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Physical characteristics of interface
Stream of Bits (e.g., 001010100100)
Line config. (e.g., point-to-point)
Topology (e.g., bus, star)
Transmission mode
(e.g., half-duplex, full-duplex)
Encoding
Error detection (and correction)
TCP/IP Protocol Suite
Application5
4 Transport
3 Network
2 Data Link
1 Physical
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Line Discipline
Flow Control
Error Control
TCP/IP Protocol Suite
Application5
4 Transport
3 Network
2 Data Link
1 Physical
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Data Link Control
Line Discipline
Flow Control
Error Control
Who Should send data and When ?
How much data may be sent?
How can errors be Detected and correct?
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Data Link Control
Line Discipline
Flow Control
Error Control
ENQ / ACK
Poll / Select
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Line Discipline: ENQ/ACK
Peer-to-peer communication
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Line Discipline: ENQ/ACK
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Line Discipline:Poll/Select
Primary-secondary communicationMultipoint Discipline
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Select
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Poll
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Data Link Control
Line Discipline
Flow Control
Error Control
Stop-and-wait(one frame at a time)
Sliding window(several frames at a time)
a set of procedures used a set of procedures used to restrict the amount of to restrict the amount of data that the sender can data that the sender can sendsend
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Stop-and-wait
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Sliding window
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Sender sliding window
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Receiver sliding window
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Example of sliding window
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Control variable
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Example of sliding window
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Data Link Control
Line Discipline
Flow Control
Error Control
Stop-and-wait ARQ
Sliding window ARQ• Go-back-n• Selective-reject
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Stop-and-wait ARQ: Normal Operation
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Stop-and-wait ARQ: Damaged frame
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Stop-and-wait ARQ: Lost data frame
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Stop-and-wait ARQ: Lost ACK frame
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Stop-and-wait ARQ: Delay ACK
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Stop-and-wait ARQ: Piggybacking
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Sliding WindowGo-back-n: Normal Operation
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Sliding WindowGo-back-n: Damaged data frame
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Sliding Window Go-back-n: Lost Data Frame
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Sliding Window Go-back-n: Lost ACK
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Sliding Window Selective-reject: Damaged data frame
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Sliding window ARQ Comparison
Go-back-n Simple More practical
Selective-reject Complex (sorting, storage, extra select frame
logic) Better performance
