Lecture 5- Data Communcations

Lecture 5- Data Communcations - Chapter 5 Data...

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Chapter 5 Data Communications and Networking
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A collection of computers electronically connected so that data ( and sometimes programs ) may be shared over a distance . Communication Network Computer
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Uses of Computer Communications Most commonly used communication services…….
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Basic Communication Model
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Individual bundles of data are called “ packets .” Communication CHANNEL uses media and other devices to transport data between computers . channel Communication MEDIA is an electronic highway that transports data…such as wire pair, coaxial cable, fiber optics, microwave, infrared, satellite, radio frequency Computers are connected through Communication Channels… modem modem sender receiver
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Communication Channel - -sending / receiving data The communication channel carries data Data usually flows over the communication channel in both directions Bi-directional (walkie talkie) Full-duplex (telephone-talking at same time) Data flows in both directions at same time The channel is shared Data Data Data Data Data Data Always have the set of rules to follow for communicating! …. Protocols!
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Bandwidth— the measure of a Channel’s Capacity to transmit data— measured in bps (bits per second) Think of bandwidth as a MEASURE of how much traffic a road” can carry at one time. The higher the bandwidth the greater amount of data that passes through the channel….but higher speed is more expensive !
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Wire pair Coaxial cable Fiber optics Microwave Satellite Radio Frequency Infra-Red Guide Media : “physical” and “wire-like” Wireles s Media: no wires or cables Media Types: two groups…
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Media Types : Guide Media speed ??– security?? – cost ?? TWISTED PAIR CABLE (Wire Pair) Ordinary telephone wire Not expensive Slow Susceptible to interference Not secure COAXIAL CABLE (Cox Cable) Broadband • Often used for cable television wiring High transmission speed • Quite free from outside noise Less susceptible to interference Secure FIBER OPTICS CABLE (Verizon Fios) Carries light waves in a glass Very fast Very secure Big bandwidth Expensive to deploy Less expensive in terms of cost per bps
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Media Types : Wireless Infra-Red Similar to microwave – with line of sight restrictions Light signals rather than radio signals Short range medium—like remote controls devices ( remote control car; TV Microwave Based on radio signals sent over the air in “straight”
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This note was uploaded on 01/26/2012 for the course IT 108, 103, taught by Professor Bruno during the Spring '11 term at George Mason.

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Lecture 5- Data Communcations - Chapter 5 Data...

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