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Chapter 4Chapter 4

IntroductionIntroductionByBy

Mohammed Altaf AhmedMohammed Altaf Ahmed

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DATA COMMUNICATIONSDATA COMMUNICATIONS

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

Components of Data CommunicationData Flow

Topics discussed in this section:Topics discussed in this section:

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Five components of data communication

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

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NETWORKSNETWORKS

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

Types of ConnectionsNetwork TopologiesCategories of NetworksInterconnection of Networks: Internetwork

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Types of connections: point-to-point and multipoint

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Categories of topology

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A fully connected mesh topology (five devices)

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A star topology connecting four stations

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A bus topology connecting three stations

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A ring topology connecting six stations

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A hybrid topology: a star backbone with three bus networks

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An isolated LAN connecting 12 computers to a hub in a closet

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WANs: a switched WAN and a point-to-point WAN

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A heterogeneous network made of four WANs and two LANs

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