sm1 computer networks

Computer Networks

Networks

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

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.

Network Classification

• LAN

• WAN

• MAN

• PAN

Network Classification

LAN (Local Area Network)

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

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.

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

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.

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.

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

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.

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.