Year 9 Bandwidth and Latency

Open Ended

What are the three main types of network transmission media?

​Twisted copper cable - electrical signals
​Fibre optic cables - light pulse signals
​WiFi - radio waves (microwave)

Open Ended

What does bandwidth mean in computer networks?

​Bandwidth is how much data can be sent on the medium per second e.g. 3Mbs = 3 million bits per second

Open Ended

A) Define the term ‘contention ratio (1 mark)

B) Explain how the contention ratio might affect the performance of the school network (3 marks)

Open Ended

What causes latency?

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Open Ended

What is the difference between high and low latency?

Open Ended

Write down the gap words in order.

Open Ended

How does bandwidth affect performance?

How does bandwidth affect performance?
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Bandwidth measure the maximum amount of data that can be transferred per second.
A higher bandwidth means files can be downloaded (or uploaded) more quickly, or high quality video can be viewed

Open Ended

How does latency affect network performance?

How does latency affect performance?

Latency is a measure of how long it takes data to be sent and is due to delay in a server sending data, or data being delayed in routers computers along the path of data transfer.
It causes slow starts to downloads and lag in games and video
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Open Ended

How does number of users (contention ratio) affect network performance?

​How does number of users (contention ratio) affect network performance?
Each user has to share the available bandwidth limited the amount of data per second each can receive (or send).

Servers that are responding to many users may not be able to respond quickly causing latency issues.

More users increases data collisions (especially with WiFI) slowing data transfer and increasing latency

Open Ended

How does data transmission media effect network performance?

​How does data transmission media effect network performance?
Twisted copper cable has reasonable high bandwidth for good data download/upload speeds. Normally data collision will not to be frequent so latency will be down to distance to servers, and speed of server response to requests.
Optical fibre cables have very high bandwidth for very good data transfer speeds which will be limited by how much data servers can send. Data collisions are rare so latency will be down to distance to servers, and speed of server response to requests.
Wifi has lower bandwidth and may limit data transfer speeds. High collision and lost packets from signal noise will increase latency

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