Transcript Theme 1: Let`s start with the basics

Module 3.1 Networks
Overview
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What is a network?
Reasons for having a network
Disadvantages of having a network
Components of a network
Types of networks
Client-server VS Peer-to-peer LAN
Network access control
What is a network?
When two or more
computers/devices are connected
to each other we have a ‘network’
To share printers, scanners and
other devices and files.
Reasons for having a network
Fast, efficient communication
•Make communication among
users possible
•To enable users to share
resources such as information,
hardware and software
Reasons for having a network
Sharing of hardware resources
Cutting costs
Equipment can be shared
amongst many users on
the network.
Reasons for having a network
Centralisation of data
• Data is stored centrally for easier access
• Data integrity is maintained
• Backups are easy to do from one central
location
Reasons for having a network
Transfer of files
The files on a CD can be transferred using the
network.
Reasons for having a network
Leisure
LAN Parties
Reasons for having a network
Increased control and security
Reasons for having a network
Flexible access
In a network, users can access
their information from any
computer on the network
Internet banking.
Disadvantages of having a network
network administrator needed
 A high level of security needed to keep information
confidential
 Harmful software can spread quickly
 If the network develops a problem,
potentially no users can work, print or access
their data.
 Server crashing can cause a loss of data
Components of a network
Components of a network
• Hardware
– Computers and
peripherals
– Network Interface
Controller (NIC)
– Switch
Switches
Fibre cable
Components of a network
• Communication
media
– Wired
• UTP
• Fibre
– Wireless
• Network operating
software
Weaknesses of communication
media
• Attenuation
• EMI
• Eavesdropping
• Crosstalk
Weaknesses of communication
media
Comparison of weaknesses between UTP and Fibre optic cables
UTP
Attenuation
Eavesdropping
Electromagnetic interference
UTP is susceptible to
attenuation therefore the
maximum cable length that can
be used without having to boost
the signal is 100m.
UTP is sensitive to
eavesdropping although the
twisting does help reduce the
sensitivity.
UTP is sensitive to EMI and
power surges although the
twisting does help reduce the
sensitivity.
Fibre optic
Fibre has much lower
attenuation than UTP. It can
transmit over distances
measured in kilometres.
Fibre is immune to
eavesdropping. If the signal was
tapped, the flow of light would
be broken and the tapping would
be detected.
Fibre is not affected by
electromagnetic interference
and power surges. It can be
used in areas such as factories
and oil refineries where
electromagnetic fields can affect
communication.
Fibre optic cables
Types of networks
Local Area Networks
Wide Area Networks
Types of networks
• WLAN
• Intranet
• Extranet
Activity
Activity1
Written
Client-server VS Peer-to-Peer
Clients
Clients are computers (PCs or workstations) that use but
do not provide network resources. They rely on servers for
resources such as files and printing.
Servers
Servers are computers that only provide network
resources. They are powerful computers with large hard
drives and are never used as normal users' PCs.
Peers
Peers are those computers that both use and provide
network resources.
Client-server LAN
• Network resources
are managed by
the server
• Used for large
networks
• High level of
security
Peer-to-peer LAN
• Network resources
are shared amongst
the computers
• Home or very small
network
• Printers, Internet
access and files can
be shared
Peer-to-peer
All computers are peers (equals) and
perform the same communication
functions.
No server is necessary.
Client server
Each computer in the network is either a
client or a server.
A server is required.
All the computers have high
specifications
The rest of the computers in the network
do not have to have a large disk capacity
and can have a less powerful processor.
Can only be used with a small number of More suitable for a larger number of
computers.
computers.
Can be installed by a person with
reasonably low technical skills
Has to be installed by a person with high
technical skills
Can have a slow performance.
Faster performance.
Access control when logging into a
network
• Network security refers to policies put in
place to ensure the security of a network
by preventing unauthorised access and
misuse of the computer network.
• Username and password is used to control
access to a network
• Security and confidentiality of data is
important
Example of folder permissions
Rules to follow for a ‘strong’
password
• At least 8 characters long.
• Contains a mixture of upper and lowercase letter,
numbers and special characters.
• Do not use your name, you girlfriend or boyfriend’s
name, your pet’s name or anything else that is easy to
guess about you.
• Change your password at least every 2 months.
• Passwords should not follow a pattern such as asdf.
• Be creative!
• The following would be an example of a ‘good’, secure
password: q&F1oP%*>41z
How do you know that you are
connected to a network?
Presence of extra (logical / shared) drives
How do you know that you are
connected to a network?
• Presence of other
computers in “My
Network Places”.
• Access to devices such
as printers not directly
attached to the computer
is possible.
• Indicator showing
network activity in the
system tray.
Activity
Activity2
Written
Glossary
Clients
Clientserver
network
E-mail
servers
Extranet
Internet or
proxy
server
Intranet
Network
NIC
Network
operating
system
Network
security
Peers
Peer-topeer
network
Print
servers
Server
Switch
Thin
Clients
WAN
WLAN
Fat clients
LAN