Module 3.1 Networks

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Module 3.1 Networks
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Overview

• 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

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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.
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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

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Reasons for having a network
Sharing of hardware resources
R
R
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Equipment can be shared amongst many users on the
network.
Cutting costs
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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

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Reasons for having a network
Transfer of files
The files on a CD can be transferred using the
network.
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Reasons for having a network
Leisure
LAN Parties
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Reasons for having a network
Increased control and security
Keep data safe in secure location
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Reasons for having a network
Flexible access
In a network, users can access their information
from any computer on the network
Internet banking.
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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
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Components of a network
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Components of a network

• Hardware
• Computers and peripherals
• Network Interface Controller (NIC)
• Switch

Switches
Fibre cable
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Components of a network

• Communication media
• Wired
• UTP
• Fibre
• Wireless
• Network operating software

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Weaknesses of communication media

• Attenuation
• EMI
• Eavesdropping
• Crosstalk

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Weaknesses of communication media
Comparison of weaknesses between UTP and Fibre optic cables Comparison of weaknesses between UTP and Fibre optic cables Comparison of weaknesses between UTP and Fibre optic cables
UTP Fibre optic
Attenuation UTP is susceptible to attenuation therefore the maximum cable length that can be used without having to boost the signal is 100m. Fibre has much lower attenuation than UTP. It can transmit over distances measured in kilometres.
Eavesdropping UTP is sensitive to eavesdropping although the twisting does help reduce the sensitivity. Fibre is immune to eavesdropping. If the signal was tapped, the flow of light would be broken and the tapping would be detected.
Electromagnetic interference UTP is sensitive to EMI and power surges although the twisting does help reduce the sensitivity. 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.
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Fibre optic cables
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Types of networks
Local Area Networks
Wide Area Networks
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Types of networks

• WLAN
• Intranet
• Extranet

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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.

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Client-server LAN

• Network resources are managed by the server
• Used for large networks
• High level of security

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Peer-to-peer LAN

• Network resources are shared amongst the
  computers
• Home or very small network
• Printers, Internet access and files can be shared

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Peer-to-peer Client server
All computers are peers (equals) and perform the same communication functions. Each computer in the network is either a client or a server.
No server is necessary. 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 computers. More suitable for a larger number of 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.
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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

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Example of folder permissions
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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
  boyfriends name, your pets 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 qF1oPgt41z

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How do you know that you are connected to a
network?
Presence of extra (logical / shared) drives
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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.

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Glossary