Download - IGCSE Networks Presentation
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NetworksBy the end of this session, you will:
• Define and describe a LAN and WAN.
• Understand the hardware required.
• Know the 3 LAN topologies.
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Networks• What is a Network?
• What is a LAN? What hardware do you need to make one?
• What is a WAN? What hardware do you need to make one?
• What are the advantages and disadvantages of a network?
• Draw a star, ring and bus network – give advantages and disadvantages of each.
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NetworksA network is two or more computers connected together so they can communicate which each other.
There are 2 main types of network…
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Networks: LANsLAN stands for:
LOCAL AREA NETWORK
LANs are networks that are found where computers within a building need to communicate.
They are Small and Local!
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Networks: LANs
•File Server : Runs software, stores files.
•Terminals : Workstations that give network access.
•Print Server : Queues up all print jobs from users in network.
•Cables (wire/optic) : Sends data.
What hardware do you need for a LAN network?
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Networks: WANsWAN stands for:
WIDE AREA NETWORK
WANs are networks that are found where computers in different areas or countries need to communicate.
They are long range and not local!
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Networks: WANsWhat extra hardware do you need for a WAN network? •Modems : To connect up to
a telephone system (instead of cable).
How a modem works…
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Networks: Ad/DisadSome advantages of a
network are:• Resources (Hardware and Software) can be shared.
• Allows more effective communication between users e.g. via e-mail.
• Networks are cheaper than “stand-alone PCs.”
• Information held on the network can be accessed by all users with authorised access.
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Networks: Ad/DisadSome disadvantages of a
network are:• The set-up and maintenance costs can be expensive.
• A fault with the network server can cause difficulties with the organisation.
• Networks need security measures to restrict access to users.
• WANs are vulnerable to hackers and viruses.
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NetworksAs well as knowing the advantages and disadvantages of a network…
You need to know the advantages and disadvantages of 3 network topologies…
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Network TopologiesThere are 3 main types of network
topologies:
The Ring Network
The Bus Network
The Star Network
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Network TopologiesThe Ring
Network: Computers are connected together to form a ring shape so that none of them is more important than any of the others.
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Network TopologiesThe Ring
Network:Advantages:
•They are cheap to expand.
•The data flows around the network in one direction so it is fast.
•There is no reliance on a central computer.
Disadvantages:
•If there are a lot of users on the network, it could slow down as all the data is sent along a single line.
•If one computer in the ring stops working, the whole network stops.
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Network TopologiesThe Bus (or line) Network:
Computers are connected like bus stops on a main road. None of them is more important than any of the others.
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Network TopologiesThe Bus (Line) Network:
Advantages:
•It is cheap as it uses the least amount of cable.
•More computers can be added without disruption.
Disadvantages:
•With a lot of users, the network will be slow as data has to travel through the same central cable.
•Failure of the central cable will stop the network from working.
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Network TopologiesThe Star Network:
Computers are connected like a star to a central computer such as a mainframe. This is also called the “host” computer.
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Network TopologiesThe Star Network:
Advantages:
•If a cable fails, it will only affect one workstation.
•More computers can be added without disruption.
Disadvantages:
•It is more expensive as it uses the most cabling.
•Failure of the central computer will stop the network from working.
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Networks: SecurityBecause networks are almost vital to an organisation’s daily activities, they must be kept safe and secure…
There are 3 main types of network security…
Physical, Access and Data.
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Networks: SecurityPhysical security means that the hardware of the network is protected from theft and kept safe.
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Networks: SecurityAccess security means that there is a limit to the amount of access a user has to the information held on the network.
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Networks: SecurityData security means that there are measures taken to prevent the loss of data held on the system.