Living Online ModuleLesson 23 — Networks and

Telecommunication

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Objectives

Describe a network. Explain the benefits of a network. List and describe the types of networks. Explain the advantages and disadvantages

of networked computing. List and describe communications media.

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Objectives (cont.)

Describe communications hardware. Describe network architecture. Describe communications software.

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Vocabulary

Bridge Client Client/server

network Communications

channel

Extranet Gateway Hub Intranet

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Vocabulary (cont.)

Modem Network interface

cards (NICs) Peer-to-peer

network

Router Server Transmission

media

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Networks

A network is a group of two or more computers linked together.

Most networks have a server that manages the network resources.

Most networks have multiple clients, which are computers that access the server.

An endpoint of a network connection, such as a computer terminal, server, or printer, is called a node.

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Networks (cont.)

A network confined to a limited geographical area is called a local area network (LAN).

A network spread over a wide area is called a wide area network (WAN).– Most WANs are made up of several LANs.

The transmission of data from one location to another is called data communications.

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Components Required for Data Communications

A sending device, which is generally a computer A communications device, such as a modem, that

converts the computer signal into signals supported by the communications channel

A communications channel or path, such as telephone lines, cable, or a wireless transmission link, over which the signals are sent

A receiving device that accepts the incoming signal, which is generally a computer

Communications software

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Communications Components

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Network Benefits

Networks provide almost instant communication with other users on the network.

Users can share information. Users can share hardware. Users can share software. Users can work on group projects.

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Communications Media

Sending data from one computer to another requires a channel, the link through which the message is sent.– A phone line or cable serves as a channel.

You also need a device on each end of the channel to convert the computer signal to a signal type that the channel can send.– A modem is a conversion device.

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Transmission Media

Sending a message through the channel requires a transmission media, which can be physical or wireless.

Examples of physical media include twisted-pair cable, coaxial cable, and fiber-optic cable.

Examples of wireless media include radio signals, microwave signals, and satellite transmissions.

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Types of Physical Media

Twisted-pair cable

Coaxial cable

Fiber-optic cable

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Types of Wireless Media

Microwave towers

Satellite transmissions

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Network Hardware

Most networks consist of a server and multiple client computers.

They also include two other categories of hardware:– Communications hardware to facilitate the

transmitting and receiving of data– Network transmission hardware to connect

the cabling and amplify signals as they travel across the network.

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Communications Hardware

A modem converts analog signals to digital and vice versa.– Modems enable a computer to send data over a

standard phone line.– The sending computer and the receiving computer

must both have modems. Cable modems use coaxial cable to send data

over cable television lines.– These have much faster transmission rates than a

standard telephone line modem.

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Communications Hardware:A Computer with Attached Modem

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Network Transmission Hardwarefigure

Network Interface Cards (NICs): All computers in a LAN must have a NIC, which enables and controls the sending and receiving of data between the computers.

Hub: Receives and sends signals back out Bridge: Connects one LAN to another LAN Gateway: Links networks using different protocols Router: Connects multiple networks and determines

the fastest route for sending data over the network

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Network Transmission Hardware:Computers Connected to a Hub

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Local Area Networks

Local area networks (LANs) are usually confined to a limited area.

Most LANs connect computers and peripherals, such as printers or scanners.

The two most popular LANs are– Client/server– Peer-to-peer

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A Client/Server Network

A computer (or more than one computer) called a server manages the network resources for all of the devices on the network.

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A Peer-to-Peer Network

All of the computers on a peer-to-peer network are equal—there is no server, and people on the network each deter-mine what files they will share with others on the network.

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Wide Area Networks

Wide area networks (WANs) cover a large geographical area such as a city, a state, a country, or the world.

Most WANs consist of two or more LANs connected by routers.

Two types of WANs are– Intranets– Extranets

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Intranets

An intranet is designed for the exclusive use of people within an organization.

Many businesses have intranets that they use to make files, such as handbooks and employee manuals, newsletters, and employment forms, available to company employees.

An intranet may use HTML files and browsers to create and view documents on the network.

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Extranet

An extranet is similar to an intranet, but it allows specified users outside of the organization to access internal information systems.

Like the Internet, extranets utilize and support Web technologies, such as hyperlinks and Web pages, coded in hypertext markup language (HTML).

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Network Operating Systems

Networks require a network operating system (NOS) and a desktop operating system.

The NOS runs on the server and provides– Network administration tools– Print services– Client services– Security services

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Summary

A network is a group of two or more computers linked together.

A local area network is generally confined to a limited geographical area.

A wide area network is made up of several connected local area networks.

Data communications is the transmission of data from one location to another.

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Summary (cont.)

The Internet is the biggest network of all. You can use a network for information

sharing, hardware sharing, software sharing, and as a collaborative environment.

The link through which data is transmitted is the communications channel.

Transmission media can be either physical or wireless.

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Summary (cont.)

Physical media includes twisted-pair cable, coaxial cable, and fiber-optic cable.

Wireless media includes radio signals, microwaves, and satellite transmission.

Most networks consist of a network server and computer clients.

A modem is a type of communication device.

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Summary (cont.)

Network interface cards enable the sending and receiving of data between PCs in a LAN.

A hub is a device that controls the incoming and forwarding of data.

A bridge connects one LAN to another. A gateway links two different types of

networks.

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Summary (cont.)

A router directs traffic on the Internet or on multiple connected networks.

The two popular types of LANs are the client/server network and the peer-to-peer network.

Networks require network operating system software.

Vocabulary

Bridge :Connects one LAN to another LAN Client: Is a computer on the network that

request and shares the resources from the server.

Client/Server n/w: It is a network that has one/more server and user computers known as clients.

Communication :A link through which the data can be transmitted.

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Extranet: An extranet is similar to an intranet, but it allows specified users outside of the organization to access internal information systems.

Gateway: Links networks using different protocols.

Hub: Receives and sends signals back out. Intranet: An intranet is designed for the

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Modem: A communications device, that converts the computer signal into signals supported by the communications channel.

NIC(Network Interface card): enables sending and receiving of data between PC’s in a LAN.

Peer to Peer Network: on a peer-to-peer network are equal—there is no server, and people on the network each deter-mine what files they will share with others on the network

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Router: A router directs traffic on the Internet or on multiple connected networks.

Server: Is a centralized computer that manage network resources.

Transmission media: Sending a message through the channel requires a transmission media, which can be physical or wireless.

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NICMICROWAVERouter

Communication Hardware

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