1.4 - Wired and Wireless Networks
In this section (click to jump):
Networks - definition
"It looks like you're about to learn another definition..."
Whether you realise it or not, you are surrounded by networks and make use of them on a daily basis. Some are obvious and others less so. Some networks are physical and you can see the connections they make, like a rail network - you can physically see the tracks connecting up each station. Whereas other networks could be described as "virtual" - things that are connected but not physically, like a group of friends would be connected but it's not like they are constantly holding hands to stay together.
Just so we're clear, some examples of networks might be:
What do they all have in common?
They connect things together.
The dictionary definition of a network is:
"A group or system of interconnected people or things."
or, if you like the verb "to network" means:
"to interact with others to exchange information and develop professional or social contacts."
But for the love of god please never use the word network as a verb. "Darling, I've had such a productive day networking at very important meetings, running ideas up the flag pole, blue sky thinking, vis-a-vis the conference down in London about the new corporate identity and marketing lead strategy. I really am very important."
Please. No.
But back to the story, these definitions all point to the same thing - when we talk about networking we are talking about joining things together for a reason. That reason is always to either share something or to communicate in some way. When we have a resource, be it knowledge or something useful like electricity its usually much better when we share it with others. By networking we allow other people to build on our knowledge or services, to enable people to work together and inevitably to be more productive. Its usually all a good thing.
So in computing, our definition of a network is as follows:
A network is: two or more devices connected together for the purpose of sharing and communicating.
We do this because (advantages):
So it's a pretty good idea, right?!
However there are one or two disadvantages you should be aware of:
Having said all that, the benefits of networking usually far outweigh any negatives.
Just so we're clear, some examples of networks might be:
- Telephones (land lines)
- Mobile phone networks
- The national power grid
- Post or parcel delivery services
- Railways
- Bus routes
- Social Media (Facebook, Twitter, Instagram)
- A computer network! (wooooohhhh)
What do they all have in common?
They connect things together.
The dictionary definition of a network is:
"A group or system of interconnected people or things."
or, if you like the verb "to network" means:
"to interact with others to exchange information and develop professional or social contacts."
But for the love of god please never use the word network as a verb. "Darling, I've had such a productive day networking at very important meetings, running ideas up the flag pole, blue sky thinking, vis-a-vis the conference down in London about the new corporate identity and marketing lead strategy. I really am very important."
Please. No.
But back to the story, these definitions all point to the same thing - when we talk about networking we are talking about joining things together for a reason. That reason is always to either share something or to communicate in some way. When we have a resource, be it knowledge or something useful like electricity its usually much better when we share it with others. By networking we allow other people to build on our knowledge or services, to enable people to work together and inevitably to be more productive. Its usually all a good thing.
So in computing, our definition of a network is as follows:
A network is: two or more devices connected together for the purpose of sharing and communicating.
We do this because (advantages):
- It enables us to communicate (obviously) via email or instant messaging
- We can work collaboratively on projects
- We can share files, data and information that other people may need
- We can share expensive resources such as printers and the internet (you do this all the time on your home wireless) which saves money.
- We can share software
- We can look after everything in one place - control the network centrally
- We can back up work all in one place - on a server
So it's a pretty good idea, right?!
However there are one or two disadvantages you should be aware of:
- Adding computers to a network reduces the security of your data
- There is a cost involved - you have to buy equipment such as cables, switches and access points if you're going wireless
- It will also cost you to install all the equipment - networking is a skilled job.
- You may need to employ an administrator to look after your network
Having said all that, the benefits of networking usually far outweigh any negatives.
LAN's
"what are we going to do?!""...about 25 years I think!"
Now we know what a network is, we should look at how they are categorised in terms of their physical size.
LAN stands for Local Area Network and the name itself gives the game away really, doesn't it?
We need a few facts for the exam to be able to discuss these properly, and you need to use the word "geographic area/location" in your answers.
A LAN is:
Characteristics of a LAN are:
LAN stands for Local Area Network and the name itself gives the game away really, doesn't it?
We need a few facts for the exam to be able to discuss these properly, and you need to use the word "geographic area/location" in your answers.
A LAN is:
- A network confined to a small geographic area or location. For example a house, an office or a school.
Characteristics of a LAN are:
- It usually makes use of dedicated equipment, such as cables and switches
- They are internal networks
- Dedicated equipment means that the company, person or organisation owns or is responsible for all equipment
- This also means that connections should be reliable and fast as they are not shared with other users/organisations
WAN's
Whatever happened to Trigger Happy TV?
If I told you WAN stood for Wide Area Network you should be able to work the rest out for yourself, right?
Weirdly, OCR seem to have lost their mind when it comes to WAN's and don't seem to want to accept the definition of a WAN which has been the same since before the dinosaurs. If only we could feed an OCR examiner to a dinosaur every time they change their mind for no other reason other than they feel like it.
So what is the definition of a WAN that we need to learn? Well, usually it is:
What characteristics do we need to know about?
The biggest example of a WAN is clearly, the internet.
Weirdly, OCR seem to have lost their mind when it comes to WAN's and don't seem to want to accept the definition of a WAN which has been the same since before the dinosaurs. If only we could feed an OCR examiner to a dinosaur every time they change their mind for no other reason other than they feel like it.
So what is the definition of a WAN that we need to learn? Well, usually it is:
- A network which covers a large geographic area, such as a country or internationally.
- The computers are physically far apart, at least over a mile or more.
- How odd they are.
What characteristics do we need to know about?
- A WAN makes use of external communications equipment, meaning we no longer had dedicated connections everywhere on the network
- We do not own all the equipment, we make use of rented or leased lines (think about it, you don't own your internet connection, you rent it monthly through a provider like Virgin, BT or Sky for example)
- This means we are not in control of traffic on all parts of the network and may have different levels of service/bandwidth
The biggest example of a WAN is clearly, the internet.
How data is sent - packets
Who comes up with the ideas for stock photos?!
Before we can go any further into networks, we need to learn what happens at the very lowest level - how does data actually get from one place to another. This makes sense, we can't expect to design road networks without first understanding that they'll be filled with cars, buses, lorries and those odd people who jog down the road even when there's a nice, safe pavement right next to them. Odd.
To understand how data travels in a network, let's look at an example.
I want to make a healthy, nutritious breakfast so I go on YouTube and start streaming the latest episode of Kay's Good Cooking. Everything is good, I've got plenty of lard in, plenty of tins of things to mash up together and I'm ready to knock up some serious gourmet action in my kitchen.
So how does that video make its way from YouTube to my phone or computer?
The first thing to understand is that data is not sent all at once as one big chunk. This web page was not sent to your device all at once, not even the small pictures dotted about the place. Absolutely everything that gets sent through a network ends up being broken into many little pieces first.
If you've ever watched Charlie and the Chocolate Factory, you're going to get this without a problem. The way networks work is pretty much the same as Wonka Vision (click the link to see for yourself!)
Now, let's make life easy and focus on how one single frame of the video is sent. All video works by showing still pictures, one after the other, very quickly to fool us in to thinking it's a moving image. So, to simplify this massively, when a video is sent to your device you are actually just receiving a stream of pictures one after the other.
Here's the frame we're going to send:
To understand how data travels in a network, let's look at an example.
I want to make a healthy, nutritious breakfast so I go on YouTube and start streaming the latest episode of Kay's Good Cooking. Everything is good, I've got plenty of lard in, plenty of tins of things to mash up together and I'm ready to knock up some serious gourmet action in my kitchen.
So how does that video make its way from YouTube to my phone or computer?
The first thing to understand is that data is not sent all at once as one big chunk. This web page was not sent to your device all at once, not even the small pictures dotted about the place. Absolutely everything that gets sent through a network ends up being broken into many little pieces first.
If you've ever watched Charlie and the Chocolate Factory, you're going to get this without a problem. The way networks work is pretty much the same as Wonka Vision (click the link to see for yourself!)
Now, let's make life easy and focus on how one single frame of the video is sent. All video works by showing still pictures, one after the other, very quickly to fool us in to thinking it's a moving image. So, to simplify this massively, when a video is sent to your device you are actually just receiving a stream of pictures one after the other.
Here's the frame we're going to send:
"I've saved a lot of money in lard since I've been using this spray, but I can tell you it's worse for you and that's scientific."
There's our Kay with two banging "all day" breakfasts, enough to give you furry arteries for life.
The first thing that happens is that this image is split into equal chunks:
The first thing that happens is that this image is split into equal chunks:
This is done so that:
To enable us to put the picture back together again at the other end, we then number each piece:
- Each piece of data sent through the network is small
- This makes it quick to send
- Most importantly, if one piece gets lost, we do not lose the entire image and we don't have to re-send the entire image. This is a huge time saver.
To enable us to put the picture back together again at the other end, we then number each piece:
This is another top idea, because not only does it mean we know what order the pieces go in when we put it back together, it also means that we do not need to receive the data in order. If all the pieces arrive in a random order, it doesn't matter, we just look at the numbers an put them the right way round again. Bonus.
Once we've done all this, we package the data up to create something called a packet. If this sounds like we're sending things through the post then... that's because it's almost identical. Indeed, why not go all out for a truly retro experience and have an "offline Instagram day." Simply take and print out endless pictures of food, pets, selfies and "hilarious memes." Then, spend an afternoon snipping pictures into thousands of pieces and then post them in individual envelopes to your friends. It should only set you back a thousand pounds or so in stamps and think of all the fun they'll have with the sellotape when they arrive! Awesome.
Packets are they key to how data is sent through a network. Absolutely everything - web page, songs you stream, videos, apps, your latest social media update about your dinner... everything is sent as a series of packets through a network.
What does a packet contain, then? Well, just like a letter you'd send in the post, it needs some information on it to help it reach its destination.
A packet consists of:
Once the data is neatly packaged up in a packet, we can then actually send it down a wire on its way to its destination.
The job of getting a packet from one place to another is taken care of by devices called routers and switches which we look at in far greater detail later on.
Packets are they key to how data is sent through a network. Absolutely everything - web page, songs you stream, videos, apps, your latest social media update about your dinner... everything is sent as a series of packets through a network.
What does a packet contain, then? Well, just like a letter you'd send in the post, it needs some information on it to help it reach its destination.
A packet consists of:
- The actual data you are sending (in this case, a bit of a picture)
- A header containing:
- The destination address (these are IP addresses, more on those later)
- The source address (so you know where it came from)
- Some checksum/error correction data (because its a wild place out there and data can get damaged in transit and we'd like to be able to fix that if it happens)
Once the data is neatly packaged up in a packet, we can then actually send it down a wire on its way to its destination.
The job of getting a packet from one place to another is taken care of by devices called routers and switches which we look at in far greater detail later on.
Eventually, the packets will make their way to their destination and it is very likely that, as in the picture above, these packets arrive out of order. Not to worry, the receiving device simply waits until all the packets arrive and then just rearranges them in to the correct order to recreate the original data.
Should a packet not arrive, after a certain amount of time the receiving device can just ask for the packet to be sent again.
If data arrives corrupted for some reason, then the device has two options - first it can use the checksum/error correction data to try and fix the problem itself. If this fails, then it will have to ask for the packet to be sent again.
It is incredibly easy for data to become corrupted in transit, and if this happens then as we've just seen, it results in the data having to be sent again. Imagine if we had not split our data in to packets - you could be in the position of having to repeatedly just send and re-send a huge file over and over again until it arrives intact. The chances of this happening get smaller and smaller as the amount of data we send gets bigger. This is why packets are so important - without them your data may, quite literally, never arrive.
Should a packet not arrive, after a certain amount of time the receiving device can just ask for the packet to be sent again.
If data arrives corrupted for some reason, then the device has two options - first it can use the checksum/error correction data to try and fix the problem itself. If this fails, then it will have to ask for the packet to be sent again.
It is incredibly easy for data to become corrupted in transit, and if this happens then as we've just seen, it results in the data having to be sent again. Imagine if we had not split our data in to packets - you could be in the position of having to repeatedly just send and re-send a huge file over and over again until it arrives intact. The chances of this happening get smaller and smaller as the amount of data we send gets bigger. This is why packets are so important - without them your data may, quite literally, never arrive.
Packets - a summary
Data is split in to equal sized chunks before it is sent through a network.
A packet of data is one of these chunks of data, wrapped up with other data that ensures it can be delivered to its destination.
A packet contains:
The advantages of using packets are:
The disadvantages of packets are:
A packet of data is one of these chunks of data, wrapped up with other data that ensures it can be delivered to its destination.
A packet contains:
- some data
- a checksum or error correction data
- the source address
- the destination address
- a packet number - x out of x (e.g. 5 of 100) so it can be put back together in the right order on arrival
- a "time to live" counter which counts how many "hops" through switches or routers it has taken and will result in the packet being discarded if this number is reached
The advantages of using packets are:
- Smaller pieces of data are less likely to be involved in collisions
- If data is corrupted or lost, then a small amount of data takes much less time to re send
- If a packet is lost it can be re-sent, rather than needing the whole file to be re-sent. This is much quicker.
- Packets may all take different routes through the network, meaning they can all take the best/most efficient path at the time they are sent. This makes efficient use of the network and enables errors/problems to be avoided (like a diversion on a road)
The disadvantages of packets are:
- Making packets and re-assembling data has an overhead (it uses processing time). This isn't usually a problem as virtually all network cards have dedicated hardware chips that do the processing of packets instead of the main CPU.
Networking Hardware - NIC's and WAP's
One thing many people forget about when talking about networks and how they work, is that you actually need some specific hardware to actually connect to a network in the first place. This can be done using either a wired connection or wireless, but either way you will need either a:
- NIC - Network Interface Card
- WNIC - Wireless Network Interface Card
- WAP - Wireless Access Point
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As you can see, these can come in many different form factors depending on the type of device being used. In most cases, devices come with some form of network card built in - it'd be a bit weird if you had to screw a bit of circuit board to the side of your new phone to make it work on your home wifi, wouldn't it?
The job of a NIC is:
The job of a WAP is:
When asked the question in an exam "what hardware would be needed to create a network" or "what additional hardware does a device need in order to connect to a network" remember to mention some form of wired or wireless NIC!
The job of a NIC is:
- To enable a device to connect to a network using either a cable (wired) or radio waves (wireless)
- To turn data in to packets
- To receive packets and reassemble them in to data
- To manage the sending and receiving of packets
The job of a WAP is:
- To allow a network to have wireless access
- To allow devices to connect wirelessly to the network
- To implement wireless security and encryption
- To allow devices to send data
- To send data to devices that they have requested.
When asked the question in an exam "what hardware would be needed to create a network" or "what additional hardware does a device need in order to connect to a network" remember to mention some form of wired or wireless NIC!
Networking Hardware - Hubs, Switches and Routers
Hubs
You don't actually need to know about hubs as OCR have sensibly taken them off the specification for this course. However, I'm going to tell you about them anyway... Why? Mainly as a little bit of networking history and also so you can see clearly the problems that excess traffic can cause on a network.
A hub is designed to be a central point on a network - it connects devices together. So far, so good. The problems start when we look at how this device works.
If you look at the picture, you can see it's possible to connect up to four computers to the hub. Now imagine that computer 1 wants to send a message to computer 4. How do you think the hub handles this?
You'd be wrong.
The hub gets the packets from port 1 (computer 1) and then.... sends them out to all the devices connected to it. Yes. that's right, it literally spams packets all over the shop.
This type of behaviour is called "broadcasting" and a hub is simply a "broadcast device." What is sent in on one port will be copied and sent out on all other ports. This is the equivalent of me wanting to send a package to someone in the UK, so I make 65 million packages and just send it to every person in the country, safe in the knowledge that my package will definitely make it to the intended recipient. What happens to the other packages? Just stick them in the bin, of course!
Why did we ever do this?
As if I needed to explain, here's the bad points:
Now we understand how not to do things, lets have a look at a more sensible way of working, with switches.
A hub is designed to be a central point on a network - it connects devices together. So far, so good. The problems start when we look at how this device works.
If you look at the picture, you can see it's possible to connect up to four computers to the hub. Now imagine that computer 1 wants to send a message to computer 4. How do you think the hub handles this?
You'd be wrong.
The hub gets the packets from port 1 (computer 1) and then.... sends them out to all the devices connected to it. Yes. that's right, it literally spams packets all over the shop.
This type of behaviour is called "broadcasting" and a hub is simply a "broadcast device." What is sent in on one port will be copied and sent out on all other ports. This is the equivalent of me wanting to send a package to someone in the UK, so I make 65 million packages and just send it to every person in the country, safe in the knowledge that my package will definitely make it to the intended recipient. What happens to the other packages? Just stick them in the bin, of course!
Why did we ever do this?
- Cost - there is no cheaper way of networking
- Guaranteed delivery - if the computer you want to send to is connected to the hub, it'll certainly get your packets.
As if I needed to explain, here's the bad points:
- The network quickly becomes flooded with traffic, meaning computers are constantly causing collisions on the network when they try to send data themselves
- Did I mention the collisions?
- Does not work if someone is sending large amounts of data - you'll see huge slow downs
- Really poor security - everyone gets your packets!
- Does not work for more than 3 or 4 computers connected together
Now we understand how not to do things, lets have a look at a more sensible way of working, with switches.
Switches
It might not look like it, but switches are properly awesome.
As before a switch is:
Switches are used on internal networks. If you think about a classroom of computers, each one will have a cable which goes somewhere... but where? The answer is to a switch somewhere. Those switches may be connected to other switches, and all of them will eventually be connected to either a server or to a router which allows access to the internet. So lets be clear, when we talk about switches, these are the devices which allow our computers to communicate on an internal network.
A switch will keep a record of the MAC addresses (more on this in section 1.5, click to jump) of each computer connected to it. When a packet arrives at the switch, it will look at the packet to determine who it is for. If the device is connected to the switch, then it will deliver it to the destination computer. This makes for efficient networking and doesn't fill the network full of unnecessary traffic.
A switch then:
Disadvantages
A switch is NOT used to connect a network to the internet. Please don't mention the internet when talking about switches.
As before a switch is:
- A central point on a network.
- A device which connects computers together in a LAN.
Switches are used on internal networks. If you think about a classroom of computers, each one will have a cable which goes somewhere... but where? The answer is to a switch somewhere. Those switches may be connected to other switches, and all of them will eventually be connected to either a server or to a router which allows access to the internet. So lets be clear, when we talk about switches, these are the devices which allow our computers to communicate on an internal network.
A switch will keep a record of the MAC addresses (more on this in section 1.5, click to jump) of each computer connected to it. When a packet arrives at the switch, it will look at the packet to determine who it is for. If the device is connected to the switch, then it will deliver it to the destination computer. This makes for efficient networking and doesn't fill the network full of unnecessary traffic.
A switch then:
- Connects devices together on an internal network (LAN)
- Delivers packets only to their destination
- Uses MAC addresses to know whether a device is connected or not
- Does not generate excess traffic on the network - efficient.
- Switches can be quite large - up to 40 devices can connect to a single switch.
Disadvantages
- Switches are expensive to buy
- They will need some setting up initially on larger networks
- You may need to have an administrator employed who can look after them/set them up.
A switch is NOT used to connect a network to the internet. Please don't mention the internet when talking about switches.
Routers
Virgin Media Super "hub"
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A Sky Q "hub"
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A Cisco Router
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Unfortunately there is a lot of misunderstanding and poor branding of networking hardware from many popular companies. If you look at the pictures above, two popular home routers are actually sold and marketed as hubs. Clearly, these devices are not hubs at all - they do not just broadcast traffic around the network to all connected devices.
In the case of home routers, such as the Virgin Super Hub and the Sky Q Hub or any other router provided by a broadband supplier, they are actually four devices in one:
So next time you hear a company advertising their latest "home hub" you'll know it's not a hub at all, so please don't confuse these types of network devices. However, the most important part of any of these devices is the router part, so what is a router exactly?
A stand alone router has one job - to connect networks together and route packets between them.
Now there's quite a lot going on in that definition so lets break things down:
The internet is a network of networks, so it makes sense that routers are the devices in between all of these networks - being as their job is to connect networks, right?! This is just like a roundabout in the road network - lots of roads come together and we can pick a direction to continue on our journey. So, we can conclude our first deduction - routers are used to connect networks to the internet.
Next we need to understand that the internet consists of thousands of networks and this means, just like the roads we use every day, there is more than one way to a destination. Think about it, if there are roadworks on your usual route to school, you can just take another way. This is the same on the internet. This also explains why packets will travel through many routers on the way to their destination. So a router often is just forwarding packets closer to their destination.
This also means that:
Routers, then, can be seen as "intelligent" networking devices, capable of talking to each other to coordinate the delivery of packets to their destination via the best path possible. Should a problem occur on the network, they will automatically find another path to the destination.
In the case of home routers, such as the Virgin Super Hub and the Sky Q Hub or any other router provided by a broadband supplier, they are actually four devices in one:
- A Router (to connect you to the internet)
- A Modem (to convert signals from one form to another for transmission and receiving)
- A Wireless Access Point (to enable you to connect wirelessly to the device)
- A Switch (to enable multiple wired devices to be connected to your network)
So next time you hear a company advertising their latest "home hub" you'll know it's not a hub at all, so please don't confuse these types of network devices. However, the most important part of any of these devices is the router part, so what is a router exactly?
A stand alone router has one job - to connect networks together and route packets between them.
Now there's quite a lot going on in that definition so lets break things down:
The internet is a network of networks, so it makes sense that routers are the devices in between all of these networks - being as their job is to connect networks, right?! This is just like a roundabout in the road network - lots of roads come together and we can pick a direction to continue on our journey. So, we can conclude our first deduction - routers are used to connect networks to the internet.
Next we need to understand that the internet consists of thousands of networks and this means, just like the roads we use every day, there is more than one way to a destination. Think about it, if there are roadworks on your usual route to school, you can just take another way. This is the same on the internet. This also explains why packets will travel through many routers on the way to their destination. So a router often is just forwarding packets closer to their destination.
This also means that:
- The internet is robust - if one route breaks then another can be used
- Routers can sense changes in the network like this and work round them
- Routers communicate with each other to notify other routers about changes to the network
- Routers can then, and this is the really important bit, select the best path for a packet to take to reach its destination.
Routers, then, can be seen as "intelligent" networking devices, capable of talking to each other to coordinate the delivery of packets to their destination via the best path possible. Should a problem occur on the network, they will automatically find another path to the destination.
Transmission Media
Transmission media can be simplified to: how does data physically travel from one place to another? We have two options for sending data from one computer to another:
Types of wired media:
- Wires
- Wireless (radio waves)
Types of wired media:
Cat 5 or "ethernet" cable
Inside a cat 5 cable
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Telephone cable - for ADSL
Coaxial - "cable" internet connections
Fibre Optic cable
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The internet is really rather big. Who'd have thought? As a result it is made up of many different types of transmission media, each one has advantages and disadvantages that you need to understand so you can discuss each type and explain why a certain type of cable might have an impact on performance. We'll start with the best first:
Fibre Optic
What is it? Fibre Optic cable is made up of either glass or plastic strands and data is transmitted as light signals. This is by far the fastest form of transmission media - think about it, nothing in the known universe is faster than light (unless you're some kind of God reading this and you know better, in which case, give us a nudge, it'd be really useful to know about something faster than light. Unless it would break the universe, in which case you might as well keep it to yourself. P.S. It's nice to know that even God needs to revise computer science).
Advantages:
Disadvantages:
Advantages:
- The fastest type of transmission media
- Has the highest bandwidth of any media (make sure you know what bandwidth actually means)
- Multiple signals can be sent down a single strand of optical fibre
- Cables can be very, very long without suffering signal degradation, interference or loss
- Incredibly useful for transferring huge amounts of data over really long distances (under sea cables are all fibre optic)
Disadvantages:
- More expensive to manufacture and install than copper based cables
- Can be fragile / have a limit to how far you can bend the cable
Cat 5 or 6 (or "Ethernet" cable)
What is it? Twisted pairs of copper cables inside an insulated casing. This is the single most common type of cable used in a network. Have a look behind a computer in school if you don't know what it is... did you look? What a fascinating world it is we live in.
Some clever person discovered that by twisting wires together in pairs you drastically reduce any interference or errors that occur during data transmission. The more twists, the better this effect is (cat 6 is more twisted than cat 5 (and therefore get's arrested more often)).
MASSIVE EXAM WARNING!!
If you are asked what "ethernet" is, you cannot say "It is a cable." Ethernet is NOT a cable (which is confusing, considering we just called this Cat 5 cable Ethernet Cable). Ethernet is a PROTOCOL which defines how data is physically sent as electrical signals down a cable. Be careful, you have been warned!
Advantages:
Disadvantages:
Types of Ethernet cable (fastest to slowest)
Some clever person discovered that by twisting wires together in pairs you drastically reduce any interference or errors that occur during data transmission. The more twists, the better this effect is (cat 6 is more twisted than cat 5 (and therefore get's arrested more often)).
MASSIVE EXAM WARNING!!
If you are asked what "ethernet" is, you cannot say "It is a cable." Ethernet is NOT a cable (which is confusing, considering we just called this Cat 5 cable Ethernet Cable). Ethernet is a PROTOCOL which defines how data is physically sent as electrical signals down a cable. Be careful, you have been warned!
Advantages:
- Relatively cheap, widely available
- Easy to customise or make cables of any desired length
- A "standard" cable type - all computers with a network card and an RJ45 connector will expect a cat5 or 6 cable to be plugged in to it
- High bandwidth
- Fairly robust, you can route it almost anywhere without worrying.
Disadvantages:
- Suffers signal degradation on long lengths of cable. Generally a maximum of 100m at a time is recommended.
Types of Ethernet cable (fastest to slowest)
- Cat 6
- Cat 5e
- Cat 5
Coaxial
What is it? Robust, shielded and insulated copper cable used to transmit TV signals (aerial cable) as well as satellite and broadband data. Versatile and robust.
Advantages:
Disadvantages:
Advantages:
- Robust, reliable cabling suitable for indoor and outdoor use
- Higher bandwidth than telephone cable
- Well shielded (insulated) from interference
Disadvantages:
- Requires different types of connectors than "standard" Ethernet
- Cable can be of varying quality, quality will affect bandwidth and data transmission rates
Telephone Cable
What is it? A standard of cable that has been around seemingly since the dawn of time. The main reason we find it used in networks is because the telephone network reaches virtually all locations in a country, whereas dedicated networking infrastructure such as fibre optic or coaxial cable is only available in certain areas. Standards and bandwidth has vastly improved in recent years but internet connections through a phone line will never reach the levels that dedicated fibre or coaxial internet connections can.
Advantages:
Disadvantages:
Advantages:
- Enables network connectivity even in remote areas
- Simple to install and maintain
- Cheap
Disadvantages:
- Suffers significant signal degradation over long distances (ADSL speeds get slower the further from an exchange you are)
- Not suited to high bandwidth applications
Wireless Transmission
Wireless transmission of network data really did change the entire way we look at computer devices and how we use them. Without wireless we wouldn't have any of the portability we take for granted today and you certainly wouldn't be able to update the world on important, life changing events on social media no matter where you were, such as next time you notice it's snowing and decide to tell everyone else in case they hadn't noticed, even though they too have eyes and can experience such crazy phenomena as weather by just looking out of the window into the dark, dangerous real world outside...
Wireless, or WiFi (wireless fidelity) is a set of standards for transmitting data using radio waves to computer devices in the place of a physical cable. It is designed to work using the same networking methods as a wired connection.
Wireless standards are all in the 802.11 standard set and each one defines how the sending and receiving of data should work and also how fast that transmission can happen.
Standards:
Before we go any further, we unfortunately need to understand a little bit more about radio waves so we can talk about some issues we face when using wireless networks and transmission.
Wireless, or WiFi (wireless fidelity) is a set of standards for transmitting data using radio waves to computer devices in the place of a physical cable. It is designed to work using the same networking methods as a wired connection.
Wireless standards are all in the 802.11 standard set and each one defines how the sending and receiving of data should work and also how fast that transmission can happen.
Standards:
- 802.11b - 11mbps (very slow)
- 802.11g - 54mbps
- 802.11n - 600mbps
- 802.11ac - 1300mbps (stupidly fast)
Before we go any further, we unfortunately need to understand a little bit more about radio waves so we can talk about some issues we face when using wireless networks and transmission.
A wave. See, how scary can it get...? Er...
Without bending your mind with science too much, lots of things in the universe are a form of electromagnetic waves:
The only thing which differentiates this electromagnetic energy is.... the wavelength .or frequency of the waves
- X-Rays
- Microwaves
- Visible Light
- Radio Waves
The only thing which differentiates this electromagnetic energy is.... the wavelength .or frequency of the waves
Here's a diagram I stole from Google Images.
Frequencies:
This frequency stuff does present us with a little bit of a problem. WiFi is fairly clever in that you can have multiple networks all transmitting and receiving on the same frequency. If you did this with radio, it'd sound really weird because you'd be listening to two completely different stations at exactly the same time!
Your wireless card is clever enough to be able to filter out some of the "noise" of other networks it is not currently connected to, however, even computers can't handle this beyond a certain point. This explains why if there are a lot of wireless networks in a small space then it can actually have a drastic effect on performance and make things go very slowly - this also goes some way to explain why you can never, ever get 4G on your phone working in a football stadium during a game...
To mitigate this interference, there are multiple WiFi channels:
Channels:
- Radio waves cover a broad spectrum of frequencies. The frequency of a radio wave transmission refers to how quickly the wave oscillates or changes
- This oscillation for WiFi is measured in Gigahertz (Ghz)
- To receive data your wireless card literally "tunes in" to a frequency and listens to it in almost exactly the same way you tune your radio to a station to receive it.
- And just like there are many radio stations on many different frequencies, there are many different frequencies that WiFi can be transmitted on.
This frequency stuff does present us with a little bit of a problem. WiFi is fairly clever in that you can have multiple networks all transmitting and receiving on the same frequency. If you did this with radio, it'd sound really weird because you'd be listening to two completely different stations at exactly the same time!
Your wireless card is clever enough to be able to filter out some of the "noise" of other networks it is not currently connected to, however, even computers can't handle this beyond a certain point. This explains why if there are a lot of wireless networks in a small space then it can actually have a drastic effect on performance and make things go very slowly - this also goes some way to explain why you can never, ever get 4G on your phone working in a football stadium during a game...
To mitigate this interference, there are multiple WiFi channels:
Channels:
- The frequencies that WiFi can used are split down into smaller ranges - each one becomes a "channel"
- If several networks are using the same channel then data will be subject to interference and this causes slow downs
- However, most wireless Routers or Access Points are now intelligent enough to switch channels if interference is bad...
- ...this reduces interference and should improve performance.
- The downside is... they overlap so there are actually only ever 3 channels in any given area that are completely separate. See below:
WiFi Channels in the 2.4Ghz Spectrum. Looks like a load of jellies.
That was heavy going... Lets shave off our radio engineer beards and go for some vanilla advantages and disadvantages therapy.
Advantages of WiFi
Disadvantages of WiFi
Advantages of WiFi
- Devices can be located anywhere
- Allows portable devices to connect to a network without cabling
- Allows devices to easily join a network
- Cheaper to install a wireless access point than run cables to every device that needs to connect
Disadvantages of WiFi
- Security - anyone can intercept data should they wish, although it should be encrypted if you are using a secure connection
- Physical Objects - The more walls, floors, steel beams, buildings or any other physical objects you can think of, the weaker the signal gets. Think about it, you always get a worse mobile signal inside the house than compared to outside for the same reason.
- Distance - The further you want to send a radio signal, the more power you need. WiFi signals have a limited range and suffer degradation over long distances
Network Performance
People that look after networks are odd people. I once convinced a student that every network had a guardian figure called the Server Room Urchin, a being that only existed in networking and server rooms. Their sole existence revolved around massaging data through the cables and overseeing the safe transmission of packets through the network. Unfortunately, putting this down as an answer to an exam question on how networks work won't get you any marks. Still, it'd make the examiner smile after seeing the same wrong answer 500 times in a row. If you're going to fail, go out in style.
So what does affect the speed at which data can travel around a network? The answer is:
Bandwidth
Bandwidth is a measure of capacity in a connection or cable. It is not, necessarily, a measure of speed.
How does that work? Consider the roads:
So what does affect the speed at which data can travel around a network? The answer is:
- Available bandwidth
- The types of cables used
- The number of users on the network
- The amount and type of traffic being sent through the network
- Distance that data is travelling
- Whether the connection is wired or wireless
- Interference
Bandwidth
Bandwidth is a measure of capacity in a connection or cable. It is not, necessarily, a measure of speed.
How does that work? Consider the roads:
A dual carriage way has a maximum speed limit of 70 mph. It has two lanes. Let's presume that we stand on a bridge over the road - how many cars can pass under the bridge every second? Lets say 2 cars in each lane, that's 4 cars per second. The "bandwidth" of this road is 4 cars per second.
Now lets add another lane:
Now lets add another lane:
Let's do the same experiment again - how many cars can now pass under our bridge every second? Well, using the same estimate as before, it doesn't take a genius to work out we can now fit 6 cars per second. This road, then, has a bandwidth of 6 cars per second.
So, we can now get more cars down our road per second. But wait... the important thing here is we did not increase the speed limit. The speed limit on this road is still 70mph. All we did was increase the capacity of the road. This is why bandwidth is not really a measure of speed - yes you will get more stuff to you quicker, but it's as a result of increased capacity and not increased speed.
So lets look at networks:
Definition: Bandwidth is a measure of the amount of data that can be sent per second through a transmission media (cable/wireless)
So, we can now get more cars down our road per second. But wait... the important thing here is we did not increase the speed limit. The speed limit on this road is still 70mph. All we did was increase the capacity of the road. This is why bandwidth is not really a measure of speed - yes you will get more stuff to you quicker, but it's as a result of increased capacity and not increased speed.
So lets look at networks:
Definition: Bandwidth is a measure of the amount of data that can be sent per second through a transmission media (cable/wireless)
- We measure bandwidth in Bits Per Second (Bps) or these days, its Megabits (Mbps) or Gigabits (Gbps) per second.
- The higher the bandwidth, the greater volume of data that can be sent every second down a cable
- It is not a measure of how fast the data travels
Type of Cable
If you scroll up you'll see the types of cables have been discussed in detail, so just flick up the page if you're still not sure which is which. It should be fairly obvious, for example, that a network connected up with optical cables is clearly going to work faster than one connected up with cat 5 cables.
Number of Users
As more users are connected to a network, there is more traffic being sent and received. This in turn places more burden on the switches and routers being used, servers may take longer to respond at peak times (a whole class logging on together maybe) and more of the available bandwidth will be used up at any one time.
Amount and Type of Traffic
Not all traffic is created equal. Indeed if you're an American ISP you're currently rubbing your hands as Mr Trump has decided to sign an executive order allowing them to charge different amounts depending on the kind of data you send. If this sounds naughty to you then you'd be right, it is. The internet works on the principle of "net neutrality" which means all data is treated equally regardless of its type. This ensures that the internet is a "fair" place where things are not deliberately slowed down because you haven't paid enough...
Some types of activity, however, clearly create more traffic than others. When you send an email, a message on your phone or send a snapchat or similar, you are not using up a massive amount of bandwidth. These are things that do not cause large amounts of data to be sent as packets across the network. However, if you start streaming a song or watching a video then this places a different kind of demand on a network. Streaming requires lots of bandwidth, reliably, for a long period of time - otherwise you get the dreaded swirly circles of buffering doom.
As a result, network providers have to ensure they have sufficient bandwidth to provide a stable service when thousands of people all start watching YouTube at the same time and this can cost a significant amount of cash. If there isn't sufficient bandwidth to cope with demand, packets start to get lost, buffering happens or users notice the network being slower than they would normally expect.
Distance
Physics. It always has to throw a spanner in the works, doesn't it? The fact is that electric signals suffer from two things:
Interference can happen at any point in a data transmission - the most obvious example of this would be during a thunder storm
If you scroll up you'll see the types of cables have been discussed in detail, so just flick up the page if you're still not sure which is which. It should be fairly obvious, for example, that a network connected up with optical cables is clearly going to work faster than one connected up with cat 5 cables.
Number of Users
As more users are connected to a network, there is more traffic being sent and received. This in turn places more burden on the switches and routers being used, servers may take longer to respond at peak times (a whole class logging on together maybe) and more of the available bandwidth will be used up at any one time.
Amount and Type of Traffic
Not all traffic is created equal. Indeed if you're an American ISP you're currently rubbing your hands as Mr Trump has decided to sign an executive order allowing them to charge different amounts depending on the kind of data you send. If this sounds naughty to you then you'd be right, it is. The internet works on the principle of "net neutrality" which means all data is treated equally regardless of its type. This ensures that the internet is a "fair" place where things are not deliberately slowed down because you haven't paid enough...
Some types of activity, however, clearly create more traffic than others. When you send an email, a message on your phone or send a snapchat or similar, you are not using up a massive amount of bandwidth. These are things that do not cause large amounts of data to be sent as packets across the network. However, if you start streaming a song or watching a video then this places a different kind of demand on a network. Streaming requires lots of bandwidth, reliably, for a long period of time - otherwise you get the dreaded swirly circles of buffering doom.
As a result, network providers have to ensure they have sufficient bandwidth to provide a stable service when thousands of people all start watching YouTube at the same time and this can cost a significant amount of cash. If there isn't sufficient bandwidth to cope with demand, packets start to get lost, buffering happens or users notice the network being slower than they would normally expect.
Distance
Physics. It always has to throw a spanner in the works, doesn't it? The fact is that electric signals suffer from two things:
- Interference
- Resistance
Interference can happen at any point in a data transmission - the most obvious example of this would be during a thunder storm
I knew a guy who got hit by lightening. The moral of the story was "don't play football in the rain."
You don't need lightening to strike something for it to be a real issue - just the build up of static in the air can be enough to really knacker electronic devices. I've had many things that have given up the will to live after a storm has passed over.
Another example is something called "cross talk" which is where wires that are bundled together actually start to interfere with each other. This doesn't seem possible but is a genuine problem, which was partially resolved when someone realised you could twist wires round each other and for some odd reason it really reduced interference.
Resistance is easily explained. If I try to shove you down a pipe that's just wide enough for you to fit in, it's going to be a bit of a struggle. You're likely to get stuck against the sides and the friction of your clothing won't help either. Don't worry, though, I'm nothing if not persistent so I stick at it and drag you through the pipe by your feet and we all agree the experience was a life changing one.
Another example is something called "cross talk" which is where wires that are bundled together actually start to interfere with each other. This doesn't seem possible but is a genuine problem, which was partially resolved when someone realised you could twist wires round each other and for some odd reason it really reduced interference.
Resistance is easily explained. If I try to shove you down a pipe that's just wide enough for you to fit in, it's going to be a bit of a struggle. You're likely to get stuck against the sides and the friction of your clothing won't help either. Don't worry, though, I'm nothing if not persistent so I stick at it and drag you through the pipe by your feet and we all agree the experience was a life changing one.
The ladies love the rich, masculine aroma of used engine oil. Just a dab behind the ears is enough to make heads turn everywhere you go.
However, during the ordeal, you got rather hot because of the friction inside the pipe and one or two bits and pieces fell off you on the way through. Not the best outcome - your resistance was too high, so we decide to have another go.
This time I cover you in grease and chuck a bit of Castrol GTX over you for good measure. Now you slip through the pipe without any problems and not a single thing falls off you. Success - we reduced your resistance and now you can travel through a pipe without the risk of losing important bits of you.
Every type of physical transmission media has some kind of resistance and as electricity travels down a cable, energy is lost in the form of heat. In a data cable this results in the signal strength becoming weaker and weaker. There are ways around this - thicker cable for example has much less resistance but costs more, is physically bigger so takes up more room and isn't ideal. This explains why a run of Cat 5 Ethernet cable has a maximum length of 100m before you need to use a repeater or another networking device to boost the signal before transmitting it again.
This time I cover you in grease and chuck a bit of Castrol GTX over you for good measure. Now you slip through the pipe without any problems and not a single thing falls off you. Success - we reduced your resistance and now you can travel through a pipe without the risk of losing important bits of you.
Every type of physical transmission media has some kind of resistance and as electricity travels down a cable, energy is lost in the form of heat. In a data cable this results in the signal strength becoming weaker and weaker. There are ways around this - thicker cable for example has much less resistance but costs more, is physically bigger so takes up more room and isn't ideal. This explains why a run of Cat 5 Ethernet cable has a maximum length of 100m before you need to use a repeater or another networking device to boost the signal before transmitting it again.
Client - Server Networks
This section is all about who has control over the network and how the devices are connected together. In a Client - Server network, there is a clearly defined structure to the network and it can be easily controlled from a central point. Its important you can discuss the advantages and disadvantages of these networking structures and also avoid one or two common pit falls.
You will often see diagrams of Client - Server networks that look something like this:
You will often see diagrams of Client - Server networks that look something like this:
"Hello, Dell? Yes I'd like to buy a server please... How many network cards? Well... lets see... 500?"
This makes my brain hurt. A lot.
Why? Because all the devices on the network are shown as having a direct connection to the server. This is just nuts - if we did this then we'd need the server to have one network card for every device connected to it! This is absurd. Also I don't understand why on all diagrams the computers appear to be 100% up to date, blazingly fast 16mhz 386 machines from 1992.
What should it look like? Something a bit more like this:
Why? Because all the devices on the network are shown as having a direct connection to the server. This is just nuts - if we did this then we'd need the server to have one network card for every device connected to it! This is absurd. Also I don't understand why on all diagrams the computers appear to be 100% up to date, blazingly fast 16mhz 386 machines from 1992.
What should it look like? Something a bit more like this:
Its not a great diagram but it serves a purpose. Can you see that all the devices are first connected to a switch. The server then has one connection to a switch and can still communicate with all devices on the network. Any new devices simply have to be connected to a switch.
So, a client server network is one which has:
A server is simply a machine which has a dedicated purpose on a network such as:
The advantages of networking in this way are:
The disadvantages of the Client - Server model are:
So, a client server network is one which has:
- Some kind of central point that devices are connected to - a switch
- One or more servers which are in control or have authority over the network
- Some devices that connect to the central switch (clients)
A server is simply a machine which has a dedicated purpose on a network such as:
- Authenticating log in attempts
- Storing users files (file server)
- Sending, receiving and storing email (mail server)
- Storing and processing web pages (web server)
The advantages of networking in this way are:
- You can manage the users and connections to your network
- Security - you can set "policies" centrally that apply to anyone that logs in to a machine
- Backup - you only need to copy data from one place - the servers.
- You can centrally manage software and configuration - you don't need to go to each machine, just set it centrally and roll it out to devices.
- More secure and reliable than a P2P network
The disadvantages of the Client - Server model are:
- They usually require some kind of administrator to set up and maintain the servers, switches etc.
- All internet traffic is usually coming through a single connection, so you may need to pay for higher bandwidth than in a P2P model.
- You will need to buy server and switch equipment which is expensive.
Peer to Peer Networks
Peer to Peer (or P2P) networks work on the idea that every device is equal. They are unique in that no one single computer has control of the network, resources are shared between all devices on the network and devices can join and leave the network at any time.
Peer to Peer technology is usually used for file sharing and it grew in popularity significantly for this kind of activity (mainly people downloading music and films from Pirate Bay (which is a lesson in how the internet works in itself - the government blocked it and so now there are literally hundreds of mirrors. Yep, that stopped the pirates! You showed them...)) although more recently Peer to Peer technology is being used to share and roll out system updates, enable smoother media streaming and even to solving scientific and medical problems through distributed processing.
A Peer to Peer network is:
The advantages of Peer to Peer networks are:
The disadvantages are:
Peer to Peer technology is usually used for file sharing and it grew in popularity significantly for this kind of activity (mainly people downloading music and films from Pirate Bay (which is a lesson in how the internet works in itself - the government blocked it and so now there are literally hundreds of mirrors. Yep, that stopped the pirates! You showed them...)) although more recently Peer to Peer technology is being used to share and roll out system updates, enable smoother media streaming and even to solving scientific and medical problems through distributed processing.
A Peer to Peer network is:
- One where each device has equal status on the network
- Each device offers up some resources to share on the network. This could be:
- Bandwidth
- Processing time/power
- Storage
- There is no central control - all devices must co-operate for the network to use.
The advantages of Peer to Peer networks are:
- Cheap to set up - you don't need any servers or new infrastructure
- No need for an administrator
- Reduces the amount of bandwidth used/data that each device must send and receive
- Complex tasks can be split amongst many machines to distribute the work load
The disadvantages are:
- There is no easy way to ensure security
- There is no way to back up data easily on either individual devices or the network as a whole
- They are generally less reliable when compared to Client - Server networks as devices with important data on them can drop out of the network at any time. They also tend to use standard desktop PC hardware which can be less reliable than server hardware.
The Internet
The internet is, to coin a phrase, pretty big. It's also incredibly misunderstood and we need to kill the biggest myth/misunderstanding before we even start:
The internet is NOT Google.
Now that we have that out of the way - what actually is it?
The Internet is a network of computer networks. What that means in reality is that it is thousands of devices, and networks of devices, all connected together through some common, public and private transmission media.
Some people have tried to map out what the internet looks like, and it comes out as something like this:
The internet is NOT Google.
Now that we have that out of the way - what actually is it?
The Internet is a network of computer networks. What that means in reality is that it is thousands of devices, and networks of devices, all connected together through some common, public and private transmission media.
Some people have tried to map out what the internet looks like, and it comes out as something like this:
The internet is simply something that enables traffic to travel from one place to another. So this means the internet is NOT web pages, applications, YouTube or anything like that. The way to understand this if it confuses you is that the Internet is like the roads - they're just tarmac that connect places together.
One important thing to understand is the difference between the World Wide Web (WWW) and the Internet. The difference is that the internet is a network, whereas the WWW is a collection of resources, usually in the form of web pages that are linked together by hyperlinks.
What do you need to know for an exam?
One important thing to understand is the difference between the World Wide Web (WWW) and the Internet. The difference is that the internet is a network, whereas the WWW is a collection of resources, usually in the form of web pages that are linked together by hyperlinks.
What do you need to know for an exam?
- Internet = a global network of networks.
- WWW = some of the data that can travel on the internet, usually in the form of web pages.
- The internet operates a principle of net neutrality - all data packets are treated equally.
- Routers are used to join networks to other networks and forward packets between them
- Data travels in the form of packets (if you haven't understood these then scroll up!)
DNS
DNS is all to do with how a your computer ends up connecting to a web server to fetch a site that you want to visit.
When you go to a website, you will type in to a browser the address of the site, for example:
www.interesting-but-weird-shaped-vegetables.com
This address is formally known as a URL, which stands for Uniform Resource Locator. This is a posh way of saying "an easy way to make and remember website addresses."
Websites usually belong to some form of domain. A domain can indicate where a site is located or what type of site it is. Some examples are:
The problem here is that a web server has no understanding of these addresses. URL's are designed so we can easily understand and remember website addresses. As you may already have guessed, a web server simply has an IP address and this is how it can be found on the internet.
DNS stands for Domain Name Services (or server) and it is a server on a network which has one job - to translate a URL into an IP address.
DNS servers are in a hierarchical system and therefore your local DNS (maybe the one your ISP provides) will not know the IP address for every website in the world. This is sensible - DNS servers are getting lots of traffic all the time (think about it - every time someone visits a site) and the load is distributed amongst many, many different servers. If for some reason the DNS you are connected to does not know the IP address you are looking for, it can pass it up the chain to another server to see if that has it instead.
To summarise DNS:
When you go to a website, you will type in to a browser the address of the site, for example:
www.interesting-but-weird-shaped-vegetables.com
This address is formally known as a URL, which stands for Uniform Resource Locator. This is a posh way of saying "an easy way to make and remember website addresses."
Websites usually belong to some form of domain. A domain can indicate where a site is located or what type of site it is. Some examples are:
- .co.uk (a UK website)
- .org (an organisation)
- .gov (government websites)
- .sch.uk (schools)
- .ac.uk (universities)
The problem here is that a web server has no understanding of these addresses. URL's are designed so we can easily understand and remember website addresses. As you may already have guessed, a web server simply has an IP address and this is how it can be found on the internet.
DNS stands for Domain Name Services (or server) and it is a server on a network which has one job - to translate a URL into an IP address.
DNS servers are in a hierarchical system and therefore your local DNS (maybe the one your ISP provides) will not know the IP address for every website in the world. This is sensible - DNS servers are getting lots of traffic all the time (think about it - every time someone visits a site) and the load is distributed amongst many, many different servers. If for some reason the DNS you are connected to does not know the IP address you are looking for, it can pass it up the chain to another server to see if that has it instead.
To summarise DNS:
- You type a URL in to your web browser
- This is sent to a DNS server
- The server looks up the URL in its database and IF a match is found, it returns this to your device
- If it is not found it passes the request to a higher DNS server.
- If it is then found the IP is passed back and a local copy cached in the DNS server you first used.
- If it is not found then an appropriate message is sent back to your device.
Virtual Networks
A physical network is connected together, as we know, using cables, switches, servers and so on.
A virtual network is a network which exists inside a physical network. What this means in simple terms is that you can make switches, servers and devices think they are on completely separate networks, even though they are all connected to the same cables and switches. Virtual networks are used to logically organise your network for easier management and better security (if you are on one VLAN you cannot access another, for example.)
As an example, a network may have the following virtual networks, all existing on the same physical network:
By splitting these up we can:
Advantages of creating a virtual network are:
A virtual network is a network which exists inside a physical network. What this means in simple terms is that you can make switches, servers and devices think they are on completely separate networks, even though they are all connected to the same cables and switches. Virtual networks are used to logically organise your network for easier management and better security (if you are on one VLAN you cannot access another, for example.)
As an example, a network may have the following virtual networks, all existing on the same physical network:
- Students
- Staff
- Office Staff (Admin)
- Finance
- Printers
- Wireless
By splitting these up we can:
- Manage security efficiently
- Ensure efficient use of bandwidth
- Contain users or devices to one specific area
Advantages of creating a virtual network are:
- Increased security
- Data is sent over only the virtual network which needs access to it - users on other virtual networks cannot access it
- You may need to log in to a virtual network
- People without the correct credentials should not be able to access virtual networks they have not been allowed access to (think public wifi)
- Cost saving - you do not have to set up several separate, physical networks if you want to separate data/users in your organisation.
