Chapter 1. Chapter 1. IntroductionIntroduction

Data CommunicationsData CommunicationsThe term telecommunication

means communication at a distance. The word data refers to information presented in whatever form is agreed upon by the parties creating and using the data. Data communications are the exchange of data between two devices via some form of transmission medium such as a wire cable.

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Five Components of Data Five Components of Data CommunicationCommunication

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Five Components of Data Five Components of Data CommunicationCommunication

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Message: ◦text, number, images, audio, and video

Sender and Receiver◦devices that send/receive data message◦Computer, workstation, telephone, TV, etc.

Transmission medium◦Physical path thru which the message

travels Protocol

◦Set of rules governing data communications

Data flow (simplex, half-Data flow (simplex, half-duplex, and full-duplex)duplex, and full-duplex)

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NETWORKSNETWORKSA network is a set of devices

(often referred to as nodes) connected by communication links. A node can be a computer, printer, or any other device capable of sending and/or receiving data generated by other nodes on the network.

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Network CriteriaNetwork CriteriaPerformance

◦Mostly measured by throughput and delay

Reliability◦The frequency of failure◦Recovery time from a failure

Security◦Protecting data from

unauthorized access Damage

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Type of ConnectionType of ConnectionPoint-to-PointMultipoint (multi-drop)

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Physical TopologyPhysical TopologyMesh topologyStar topologyBus topologyRing topologyHybrid topology

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Mesh TopologyMesh TopologyAdvantage v. DisadvantageConnection of telephone regional

offices

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Star TopologyStar TopologyAdvantage v. DisadvantageHigh speed LAN

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Bus TopologyBus TopologyAdvantage v. DisadvantageEarly Ethernet

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Ring TopologyRing TopologyAdvantage v. DisadvantageIEEE 802.5 Token Ring, MAN

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Hybrid TopologyHybrid TopologyCombination of two or more

network topology

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Categories of NetworksCategories of NetworksLocal Area Network (LAN)Wide Area Network (WAN)Metropolitan Area Network (MAN)Personal Area Network (PAN)

WANs: a switched WAN v. a WANs: a switched WAN v. a point-to-point WANpoint-to-point WAN

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Heterogeneous NetworkHeterogeneous Network

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The InternetThe InternetThe Internet has revolutionized

many aspects of our daily lives. It has affected the way we do business as well as the way we spend our leisure time. The Internet is a communication system that has brought a wealth of information to our fingertips and organized it for our use.

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PROTOCOLS AND PROTOCOLS AND STANDARDSSTANDARDSProtocols

◦ A set of rules to define What is communicated How it is communicated When it is communicated

Standards◦ To guarantee national/international

interoperatibility of data and telecommunication technology

◦ Regardless of equipment manufacturers◦ ISO, ITU, ANSI, IEEE, …◦ Internet standards are maintained by IETF

for publishing RFC (Request for Comments) http://www.ietf.org/rfc.html

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