LAN Topologies (AQA GCSE Computer Science)
Revision Note
Written by: Robert Hampton
Reviewed by: James Woodhouse
LAN Topologies
What is a network topology?
A network topology is the physical structure of the network
It defines how the network hardware will be arranged to create the network
Two popular topologies to understand for the exam are:
Star Topology
Bus Topology
Star Network Topology
What is a star topology?
A star topology has a central switch which all other devices connect to
A switch is an intelligent device which ensures that traffic only goes to the intended device
A star topology is commonly seen in most homes, businesses, organisations and schools
What are the advantages of a star topology?
If any single cable stops working, the rest of the network will continue to work
An example you may have experienced would be in school when one computer won't log on to the network, but all other classmates can get logged on
This is important because in other topologies if a cable was broken, all computers on the network would stop working which would have a negative impact on learning in schools and businesses completing their daily tasks
What are the disadvantages of a star topology?
The central switch is a single point of failure
This means that if the switch stops working, all of the devices connected to it will not be able to connect to the network or any of its facilities and resources
Bus Network Topology
What is a bus topology?
A bus topology is all devices connected by one single ‘bus’ cable, terminated at each end
The terminators stop the signal bouncing back and causing errors
A bus topology works by each device:
‘Listening’ to electrical signals
Checking data packets for their specific address
Ignoring data packets it does not recognise
A bus topology has been replaced by much more efficient network topologies such as the star topology
What are the advantages of a bus topology?
Easy and cheap to set up as only one cable is required
Does not rely on any other network hardware such as a central server/switch
What are the disadvantages of a bus topology?
Low security as data is seen by all devices on the network
Slow data transfer and prone to data collisions
If the cable breaks, the whole network is affected (central point of failure)
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