3 - switching and performance

3 - switching and performance - Last Lecture Nuts-and-bolts...

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SUNY AT BUFFALO; CSE489/589 – MODERN NETWORKING CONCEPTS; Fall 2010; INSTRUCTOR: HUNG Q. NGO 1 Last Lecture Nuts-and-bolts description of the Internet ! The topology ! The core ! The edge ! The communication links
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SUNY AT BUFFALO; CSE489/589 – MODERN NETWORKING CONCEPTS; Fall 2010; INSTRUCTOR: HUNG Q. NGO 2 This Lecture ! How to send data from end to end: two switching methods ! Circuit switching ! Packet switching ! Packet loss and delay in a packet switched network
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How is data transferred through a network? SUNY AT BUFFALO; CSE489/589 – MODERN NETWORKING CONCEPTS; Fall 2010; INSTRUCTOR: HUNG Q. NGO 3 Two switching methods: 1. Circuit Switching : dedicated physical circuit is established, maintained, and terminated over a communication session (e.g. ISDN) 2. Packet Switching : data are transferred in packets (chunks of data of a fixed size), possibly go through different paths to reach the destination (e.g. ATM, X.25, Frame Relay, Internet)
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1. Circuit Switching SUNY AT BUFFALO; CSE489/589 – MODERN NETWORKING CONCEPTS; Fall 2010; INSTRUCTOR: HUNG Q. NGO 4 Three step process o Source establishes connection to destination " Find path " Reserve resources o Data exchanged (no need for destination address) o Connection torn down " Resources released
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SUNY AT BUFFALO; CSE 489/589 – MODERN NETWORKING CONCEPTS; Fall 2010; INSTRUCTOR: HUNG Q. NGO 5 Sharing a Link: Multiplexing ! To combine multiple signals (analog or digital) for transmission over a single line or medium. ! Multiplexing technologies: ! Frequency Division Multiplexing ( FDM ) : each signal is assigned a different frequency range (e.g. FM radio). ! Time Division Multiplexing ( TDM ) : each signal is assigned a fixed time slot in a “fixed” rotation. ! Statistical Time Division Multiplexing ( STDM ): time slots are assigned to signals dynamically to make better use of bandwidth. ! Wavelength Division Multiplexing ( WDM ) : each signal is assigned a particular wavelength; used in optical fiber.
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SUNY AT BUFFALO; CSE 489/589 – MODERN NETWORKING CONCEPTS; Fall 2010; INSTRUCTOR: HUNG Q. NGO 6 Circuit Switching: FDMA and TDMA FDMA frequency time TDMA frequency time 4 users Example:
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SUNY AT BUFFALO; CSE 489/589 – MODERN NETWORKING CONCEPTS; Fall 2010; INSTRUCTOR: HUNG Q. NGO 7 2. Packet Switching
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Packet Switching: Statistical Multiplexing Packets SUNY AT BUFFALO; CSE 489/589 – MODERN NETWORKING CONCEPTS; Fall 2010; INSTRUCTOR: HUNG Q. NGO 8
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SUNY AT BUFFALO; CSE 489/589 – MODERN NETWORKING CONCEPTS; Fall 2010; INSTRUCTOR: HUNG Q. NGO 12 Packet Switching vs. Circuit Switching: In Theory ! Packet Switching ! CS wastes bandwidth when data is sporadic ! PS is statistically more efficient and less costly ! CS takes time to establish the circuit ! PS is simpler to implement ! Side Question: what about packet sizes? Small or Large? ! Circuit Switching ! PS is not suitable for real time application !
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  • Fall '10
  • hungngo
  • Networking, Time-division multiplexing, Multiplexing, Statistical multiplexing, Hung Q. Ngo

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