Networks

Mr Hewitt

Objectives

By the end of this lesson you will be able to:

Compare stand alone, networked and laptop computers

Define a Network Explain the terms LAN and WAN Understand network topology

Types of computer

Stand alone PC Network

A PC that is not connected to any other computer

Laptop PC

A lightweight portable computer

A collection of computers linked together

CAN YOU GIVE A DEFINITION OF EACH?

What is a Network?

What is a Network ‘A collection of

computers are linked together so they can communicate’

‘Networked computers can share hardware software and data’

Stand alone PC Network

What is a LAN

LAN stands for a ‘Local Area Network’ The School network is a LAN All computers are in the same building Computers are permanently connected Each computer is a workstation There is a server with applications software,

a list of users and passwords Lans users need a password to log on

What are the advantages of LAN’s?

Shared software and peripherals e.g. printers

Workstations can be lower spec Centralised information storage Users can communicate & share data

What are the disadvantages of LAN’s?

Security is needed to protect programs A network technician is needed Faults can affect all users

What is a WAN?

WAN stands for Wide Area Network Computers are spread over a large

area Computers are linked by phone lines

radio or satellite links The Internet is one big WAN Computers are not permanently

connected

What are the advantages of WAN’s

Ease of communication Access to information Work from home Advertising and E-business

What are the disadvantages of a WAN?

Viruses - need firewall Lack of face to face interaction Costly Risk of data being intercepted

Line or Bus Networks

All data is sent to and from the file server along a central line of cable. All terminals are connected to the central line

Good Points:

Cheap – doesn’t use much cable

Bad Points:

Can be slow as all data goes down the central line

If the central cable fails, the whole network goes down

Ring Networks

Terminals are linked in a ring, data flows around the network in one direction only

Good Points

Cheap to add computers

Fast as data only flows one way

Bad Points

The system gets slow when there are lots of users

If the central cable fails the whole network goes down

Star NetworksIn a Star Network, a large number of computers are directly connected to the server

Good Points

If one computer or a cable fails, the others will be unaffected

This is the fastest network

Bad Points

If the central computer fails, the whole network will go down

Uses lots of cable so is expensive

Wireless NetworksIn a wireless network, there are no wires!

Computers have a wireless network card

The server will act as a base station which will be able to receive wireless transmission of data