Lesson video

Hello, my name is Mrs. Holbrook and welcome to computing.

I'm so pleased you've decided to join me for the lesson today.

In today's lesson, we are going to be exploring the factors that can affect network performance.

For example, how long does it take to transfer data and what can slow this down? Welcome to today's lesson from the unit, network fundamentals.

This lesson is called network performance, and by the end of today's lesson, you'll be able to explain the factors affecting network performance.

Shall we make a start? We will be exploring these key words in today's lesson.

Let's take a look at them now.

Bandwidth.

Bandwidth, a measure of how much data can be transferred in specific amount of time.

Routing.

Routing, the process where routers select the best path for data to travel across a network using rules called routing protocols.

Look out for these keywords throughout today's lesson.

Today's lesson is split into two sections.

We'll start by describing the factors affecting network performance, and then we'll move on to calculate network transmission times.

Let's make a start by describing the factors affecting network performance.

Network performance affects the speed and reliability of data transfer.

Several factors can influence this performance, and understanding them can support better decisions when designing or managing a network.

The key factors that can affect network performance are bandwidth, latency, range, and the number of devices.

Bandwidth is a measure of how much data can be transferred in a specific amount of time.

Bandwidth is limited to the type or types of transmission media that are used across the network.

The higher the bandwidth, the more data than transmission media can transmit at once.

Think of bandwidth as the number of lanes available on a motorway.

If a motorway has four lanes, then four cars can pass through the road network at the same time.

You could say that the bandwidth of this motorway is four cars per second.

If three of the lanes close, then this lowers the bandwidth of the motorway.

Now only one car can pass through the network at a time.

The bandwidth of the motorway is now just one car per second.

Note that this is an analogy.

In reality, the cable doesn't get thicker when bandwidth is increased.

Bandwidth isn't just used for downloads, it also includes uploads.

Typically, more bandwidth is given for downloads, but this can be changed if required.

Okay, time to check your understanding.

I have a question for you.

In the context of network performance, what does bandwidth measure? Is it A, the physical distance between two connected devices? B, the delay before data begins to transfer? Or C, how much data can be transferred in a specific amount of time? Pause the video.

What do you think about your answer? Did you select C? Well done.

Bandwidth is how much data can be transferred in a specific amount of time.

Bandwidth is typically measured in megabits per second, or Mbps, or gigabytes per second, Gbps.

Each transmission media type has a maximum bandwidth.

Here are some common transmission media types and their typical bandwidth measurements.

So, copper ethernet cable has typical bandwidth measurements of a hundred megabits per second to one gigabit per second, or up to 10 gigabits per second with Cat six, seven, or eight ethernet cable.

Fibre optic cable has bandwidth of one gigabit per second all the way up to a hundred gigabits per second.

Radio signals using wifi has up to 9.

6 gigabits per second with Wi-Fi six or six E in that case, and Bluetooth has up to two to three megabits per second.

Fibre optics has the highest maximum bandwidth making it an excellent option for networks with high amounts of traffic.

Latency is the delay from the time a signal is sent to when it is received.

Data travels across a network using signals such as light pulses, radio waves, or electrical currents.

Each type of transmission media has a maximum effective distance.

This is how far the signal can travel before its quality begins to drop.

This distance is known as the range.

The range needs to be considered carefully when deciding which transmission media to use in a network.

Copper ethernet cable has a typical range of a hundred metres, fibre optic cable has a range of 40 kilometres, radio signals using Wi-Fi has a range of 50 metres, and Bluetooth has a range of 10 metres.

Fibre optics has the highest range, making it an excellent option for networks spread over large geographical areas.

The number of devices connected to a network will affect the network performance.

This is because each device will take a share of the bandwidth available and the network traffic.

You might have noticed this, if you've ever tried to use free internet or mobile data in a crowded area, like a concert.

With each new device that tries to access the free internet connection, the data transfer rate reduces.

Eventually, there are so many devices trying to share the same network that it becomes almost impossible to download or upload any data.

When creating a new network, it's important to consider the maximum number of devices that will use the network.

It's also a good idea to future proof the network in case more devices are added on later.

Time to check your understanding.

I have a question for you.

How does an increasing number of devices connected to a network generally affect its performance? Is it A, it significantly increases the network's maximum range.

B, it causes the data transfer rate for each device to speed up.

Or C, it reduces the available bandwidth per device, which can slow down data transfer.

Pause the video whilst you think about your answer.

Did you select C? Well done.

Increasing number of devices connected to a network generally affects the available bandwidth per device, which can slow down data transfer.

Okay, we're moving on to our first task of today's lesson.

Name and explain four key factors that affect network performance.

Pause the video here whilst you complete the task.

How did you get on with the task? Did you manage to come up with four factors that can affect network performance? Well done.

Let's have a look at some sample answers together.

So one, bandwidth.

Bandwidth is a measure of how much data can be transferred in a specific amount of time.

Higher bandwidth means more data can be transmitted at once, leading to faster speeds.

Latency, this is the delay from the time a signal is sent until it is received.

Lower latency means quicker responses and less lag, which is crucial for things like online gaming.

Range, this is the maximum effective distance a signal can travel before its quality drops.

If devices are too far from a network access point, their connection quality will drop.

Number of devices.

The more devices connected to a network, the more they share the available bandwidth and contribute to network traffic.

This can slow down data transfer rates for everyone if the network becomes too crowded.

Did you have some of these factors? Well done.

Remember, if you need to pause the video and make any amendments to your answer, you can do that now.

So, we've described the factors affecting network performance, let's now move on to calculate network transmission times.

It is possible to calculate how long a file will take to transmit from one location to another on a network.

To do this, you need to know the size of the file in bits, the speed of the network in bits per second, and then you can calculate the time that it will take.

This is the formula you can use.

Time is equal to size of file in bits divided by networks speed in bits per second.

So let's have a look at an example.

If the size of the file is a hundred bits and the network speed is two bits per second, then the formula will be time is equal to a hundred divided by two.

So the time will be 50 seconds.

50 seconds to transmit a hundred bits of data is very slow with today's technology.

Most speeds are measured in megabits or gigabits per second, and file sizes can be extremely large.

Time to check your understanding.

I have a true or false statement for you.

The formula to calculate transmission time is time is equal to network speed in bits per second divided by size of file in bits.

Is this true or false? Pause the video whilst you have a think.

That's right, it's false.

The correct formula is time is equal to the size of file in bits divided by network speed in bits per second, so we just have them the wrong way round.

Modern networks can include many nodes or devices and connections between them.

Nodes can be devices such as routers, switches, or computers, and the connections between them may use different types of transmission media such as fibre optic cables or wireless links.

One of the main functions of a network is to allow devices to share data and resources efficiently.

To do this, data must be sent to the correct destination and take an efficient path to get there.

This is where routing plays an important role.

Routing is the process of selecting the best path for data to travel across a network.

To do this, networks use routing protocols, which are sets of rules that routers follow to find the most efficient route for the data.

Each possible path through a network has a cost.

This cost is a measure of how suitable the route is.

It can depend on factors like time delay, which is latency, bandwidth availability, reliability of the connection, and network congestion.

Routing algorithms calculate the total cost for different routes and choose the one with the lowest cost.

So let's have a look at some examples.

Route one here is equal to five plus five, which is equal to 10.

Route two is five plus three plus six, which is equal to 14.

Route three is equal to three plus six, which is equal to nine, so this is the lowest and will be the path that is selected.

Route three has the lowest cost, so this route will be used to transmit the data.

Efficient routing reduces network congestion.

It ensures faster data transfer and improves network performance.

It also helps make better use of available resources.

Routing ensures that network traffic is managed in a way that keeps the network reliable and responsive, even as demands grow and maybe more users are added to the network.

Okay, time to check your understanding.

I have a question for you.

What is the primary purpose of routing in a computer network? Is it A, to store data files on a central server? B, to select the best path for data to travel across a network? Or C, to physically connect computers using cables? Pause the video whilst you think about your answer.

Did you select B? Well done.

The primary purpose of routing is to select the best path for data to travel across the network.

Okay, we are moving on to our second task of today's lesson, task B.

For part one, to calculate the time it takes to transmit a file, you can use the formula time is equal to size of file in bits divided by network speed in bits per second.

A file has a size of 50,000 bits.

If the network speed is a thousand bits per second, calculate how long it will take to transmit the file.

For part two, explain what routing is in a network and describe two benefits of efficient routing.

Pause the video here whilst you complete the task.

How did you get on? Did you manage to complete the task? Well done.

Let's have a look at some sample answers together.

For part one, you were asked to calculate the time it takes to transmit a file.

So we had a file with a size of 50,000 bits and a network speed of a thousand bits per second.

So our calculation is equal to time is equal to 50,000 bits divided by a thousand bits per second, which is equal to 50 seconds.

It will take 50 seconds to transmit the file.

For part two, you were asked to explain what routing is in a network and describe two benefits of efficient routing.

Routing is the process of selecting the best path for data to travel across a network.

It uses routing protocols, which are sets of rules that routers follow to find the most efficient route for data.

Two benefits of efficient routing are it reduces network congestion, which means less traffic and fewer slowdowns on the network, it ensures faster data transfer as data takes the quickest available path to its destination.

Other benefits you could have included in your answer are improves network performance and helps make better use of available resources.

Remember, if you need to add any corrections or detail to your answer, you can pause the video now.

Okay, we've come to the end of today's lesson, network performance, and you've done a great job, so well done.

Let's summarise what we've learned in this lesson.

Network performance is influenced by several key factors, including bandwidth, signal range, latency, and the number of connected devices.

The time it takes to transmit data also depends on the file size and the data transfer rate.

Efficiently managing this network traffic is crucial, a task primarily handled by routing.

I hope you've enjoyed today's lesson and I hope you'll join me again soon.

Bye.