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