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Page 1: Sm1 Computer Networks

Computer Networks

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Networks

• A computer network is any system of two or more computers that are linked together.

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Networks

Why is networking important ?

Networks enable people to share computer hardware resources, to share data and software and allow people to collaborate in ways that other wise difficult.

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Network Classification

• LAN

• WAN

• MAN

• PAN

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Network Classification

LAN (Local Area Network)

• Computers are physically close to each other, usually in the same building.

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Network ClassificationLAN hardware

Each computer or peripheral in a LAN is called a node; nodes are connected through hubs or switches.

Hubs broadcast messages to all devices connected to a network but one at a time. A switch broadcast the messages only to a destination node and it can carry multiple messages simultaneously.

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Network ClassificationMAN (Metropolitan area network)• Links two or more LANs within a city

(WAN) Wide area network• Extends over a long distance.• Each network site is a node on the network.• WANs are possible thanks to telephone lines,

microwave towers, satellites and fiber-optic cables

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Network ClassificationMAN/WAN hardware

• Bridges: hardware devices that connect segments of a network. They often translate messages so they can be understood by networks that obey different protocols.

• Routers: hardware devices or software programs that route messages as they travel between networks.

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Network Classification(PAN) Personal Area Network

• It is a network that links a variety of personal electronic devices so they can communicate with each other, generally through bluetooth technology.

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Wireless Technologies

Is the transfer of information through the air rather than through cables. Wireless communication may be via:

• radio frequency communication • microwave communication• infrared

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Modems

• A modem is a device that converts digital signals from a computer's serial port to the analog signals required for transmission over traditional telephone lines, and vice versa.

• Conversion is necessary because telephone lines were initially designed to handle the analog nature of the human voice, not data.

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Protecting the NetworkThe creation of bigger networks,

has increased security risks

• Firewalls: are hardware and software barriers that execute an access control policy among networks.