Lesson video

Hi, I'm Allen, your computing teacher for this network unit.

And this is lesson three of six.

And this one is called basic networks.

You'll need a pencil and a piece of paper and a rule for this lesson as you'll be needing to draw a network diagram in the activity later on.

Turn off any notifications on mobile phones that are nearby and remove any distractions that are around you.

You can pause the video until you're settled and when you're ready, we can make a start.

Okay, in this lesson, will list and describe the different types of networks, including personal, local, and wide area networks.

And we'll also list, describe, and compare different network topologies, such as ring, star, and bus.

Okay, so let's define some of these networks to start with.

So local area network, that's normally known as a LAN network, and that's a network of computers that are connected together over a small locality.

Next, we have a wide area network or WAN, and this is a network that covers a large or a wide geographical area.

Then lastly, we have a personal area network or PAN.

So this is a network within the kind of locality of a person.

So for instance, personal devices on yourself like a phone or a watch.

Okay, so got a bit of a quiz for you.

So I'm going to give a couple of seconds to look at each one of the pictures I'm going to show you now.

And you've got to decide whether it's a LAN, a WAN, or a PAN.

Remember, LAN is local area network, WAN is wide area network, and PAN is personal area network.

So this first one is a mobile phone mast, so a mobile phone network.

Is that a LAN, WAN, or a PAN? That is a WAN, so wide area network, for instance, mobile phone operators in the UK, they're prime examples of a wide area network.

Next one is a router.

Router, would that be a LAN, a WAN, or a PAN? Yeah, hopefully you've realised that that's a LAN, a local area network.

You may have one of these in your home.

And this network only extends to the boundaries of your home.

So it's a local area network.

Next one is a city-wide CCTV system, city-wide CCTV system.

It's a LAN, a WAN, or a PAN? Okay, that's a wide area network.

And it's kind of in the clue, in the title city-wide CCTV system.

So therefore, a smaller CCTV system in a business premises would be a LAN, but obviously one that covers a whole city would be a WAN.

Okay, you got smartwatch.

Is that a LAN, WAN, or a PAN? Ooh.

Yeah, easy that one.

That's a personal area network.

The network connection between the smartwatch and the smartphone is designed to operate around your body if you've got the watch on your wrist and your phone in your pocket or your bag.

So that's a personal area network.

The internet, is that a local area network, wide area network, or a personal area network? That is a wide area network.

So the internet is the largest network of computers in the world and it covers the whole world.

So it's very, very wide indeed.

We've now got a GPS, so a global positioning system.

LAN, WAN or PAN? Yeah, that's a wide area network.

The GPS is used in your car satellite navigation, cover a number of satellites.

So it connects to a number of satellites around the world.

So that's probably a wider network than the internet in terms of how far it spreads.

Okay, so thinking in terms of a school network, so classrooms, and you've got a classroom there full of computers.

Is that a LAN? Is it a WAN or is it a PAN? Yeah, that one's a LAN.

A school or campus network is an example of a LAN.

It exists within a single building or a collection of buildings on the same site.

Okay, so let's take a look at a home versus business network.

Okay, so you've got a diagram there.

And in the middle we've got our home gateway or which would be the equivalent of our modem or our router that's plugged into the telephone line.

And then from there, you can see a yellow connection of diamonds.

Well, that's a power line connection.

So you can run an Ethernet cable through to your power lines with a special adapter.

And that can plug, give you Ethernet connectivity in other rooms as well with the right adapters, of course.

And in this instance, it's connected to a printer, a hub which is connected to a printer, a network webcam, and a Wi-Fi extender.

The home gateway is also connected via wireless or Wi-Fi to some PCs and some smartphones and tablets.

And it has a wired connection to a drive, a NAS drive, so a storage device at the bottom there, and a set-top box which is then connected to the television.

So that would be an example or a diagrammatical example of a home network.

Okay, so let's compare that to a business network.

Well, a business network would have some connectivity coming into the building via Ethernet or fiber-optic cable.

So that would obviously be much faster.

And then in terms of devices that are connected to it, so things like PCs, tablets, photocopiers, CCTV cameras may be around the perimeter of the building, and you could have door locks that are connected to the network around that building too.

As opposed to having one router in the home that performs things like you switching your wireless access point for your devices and your firewall, you would draw only one device.

In a business network, you'd have separate hardware devices to do those functions.

So for instance, you have a separate firewall and a separate switch to do those functions.

So task one, as we saw on that slide there, you've got a typical business network.

And in this task, what we've got is you've got a worksheet with a scenario.

And this scenario explains what devices a business has and where they want them to be located.

Your job is to read the scenario carefully and read the requirements.

And then your job is to map out that network, either drawing the icons that I provided for you or you can print out the icons and cut them out if you wish.

That might be a bit easier, but it obviously depends if you've got a printer to be able to do that.

You're going to mark the connections between each component on the paper with a straight line.

Okay? And you can decide whether it is a dotted line for wireless or a straight line, just straight solid line in a wired connection.

And make sure it meets the requirements.

So make sure you read the scenario really carefully.

There's a lot of requirements in the there for you to be able to look at and see what devices they need connecting in what locations of the building.

If you're ensure, you can go back to that first diagram and take a look.

You can pause the video and complete the task.

Okay, how did you get along? Well, here's one possible solution.

I guess the first thing we'd have to do is make sure we've got the different locations.

So we've got an admin office on the left there and we've got the manufacturing plant on the right.

So they have got two separate buildings.

And then within the admin office, they said they had a server room.

So the servers are going to go in there where the internet connection comes in.

And then we have a switch that is then connected to PCs within that building and another switch that links to the manufacturing plant.

We also have one wireless access point within the admin office and that connects the mobile phone.

And there are CCTV cameras and door locks, or one door lock, two door locks, yeah, one inside, one outside on the admin office as well.

Within the manufacturing plant, we've got a couple of printers in there.

We've also got door locks and CCTV again.

And we've got lots of, we've got two wireless access points 'cause there's lots of tablets to be connected in there as well.

As long as you've got those things in the right rooms and you've got the right amount of those, then you've met the requirements of that task.

So well done.

Doesn't matter if it's laid out a little bit different, as long as you've got the right things in the right locations and the right number of them.

So good job.

Okay, so let's take a look at network topologies.

Well, a typology is just an arrangement of the links and the nodes within a network.

And a node is any device that's connected to that network.

So my mobile phone is connected to this network.

There we go, it's over there.

I thought it was here.

That is classed as a node on my network.

This laptop I'm using to create this video would be a node on my network.

So topology diagram shows nodes as dots, so little circles, and the links between them as lines, a little bit like you did in the previous activity.

Okay, so the main topologies are bus, ring, star, and mesh.

And they're just different ways of configuring your network.

And I'll show you an example of each one of those now.

So this one is a bus network and I've got a little diagram there for you to kind of diagrammatically show what it would be laid out like.

So for instance, each one of those green circles would be a machine or a PC on the network.

And then they'd be connected to a central line.

The advantage of this is it's quite cheap to set up because you don't need a lot of cable.

You've just got the one central line and then machines just jump onto that bus along the way.

Disadvantages of it, well, we can have a single point of failure.

So if there was a damage somewhere along that central line, that bus line running across the middle, then all machines would lose connectivity.

It's not very secure as all machines can see all the data that's passing through it.

So the next typology we're going to look at is a ring topology.

So data travels around the ring in one direction.

And when the data receipt gets to one node, it then boosts it and passes it on to the following node in the circuit.

It performs better than a bus topology when under heavy load.

And that's one of the advantages of it.

And there's no need for any network service, okay? It does have some disadvantages as well.

Again, single point of failure.

If there's one point of failure in there, then it stops the machines being able to communicate.

And again, it's not very safe because all nodes see all the data because it's passing through each node as it travels around the ring.

And the whole network, despite it performing better than a bus network, it's as slow as the slowest link between any two nodes.

Okay? So you may have a really fast connection between most of the nodes, but if you've got a really slow connection between a couple of them, then that's going to slow down the whole system.

The next topology we're going to look at is a star topology.

So all of the networks connect through a central node, okay? So you can easily add new nodes to this design just by attaching one to the centre again and adding them on via cable that way.

And it is the most common network topology.

The advantages of this, well, the good thing is if a machine is, if a link to a machine is damaged, it only affects that one machine.

Okay, so that's the biggest advantage.

It doesn't bring the network down.

It doesn't force all the other machines to be offline.

You can easily add new nodes like I said at the beginning.

It works well into heavy load, especially when using a switch for the central node because everything's connected to that central switch.

And then that will obviously determine what information is going where.

Disadvantages of that though, the central node now becomes the central point, the single point of failure.

So if that central node, where a machine or a switch goes down, then communication would be lost.

And as you can see from the diagram, it requires a lot more cable than a bus network or a ring network would need.

And obviously because of that, that makes it more expensive.

The last network to look at, the last network topology is a mesh.

So nodes are connected to multiple nodes.

So in a partial mesh topology, not all are connected, but in a full mesh, they are.

So every node is connected to every other node.

As a result, there's no single point of failure.

So that's a great advantage.

And data is then transferred via the most direct route because it can get straight to a machine.

As a result of that too, it works well under heavy load because you've got lots of different paths for the data to go between machines.

Disadvantages, well, that requires a lot of cable.

Okay, you can see with the six nodes on the screen there, all connected to each other, then that is a lot of cable to be able to do that.

And as a result, it becomes difficult to manage and troubleshoot should something go wrong Don't forget there is a quiz at the end of this lesson.

And that will include some questions on network topologies.

If you'd like to share your work with Oak National, I'd love to see some of the network diagrams you've done.

So please ask your parent or carer to share it on Instagram, Facebook, or Twitter, tagging @OakNational and #LearnwithOak.

I'll see you next time.