Now if we're going to talk about networking we should really define what a network is.
So what is a network?
No I'm not talking about a social media network.
I'm not talking about your contacts. Let's say on Facebook or Linked In or Twitter or tick-tock or whatever
your social media platform of choice is.
We're not talking about a social media network.
In this case we're talking about a computer network.
So what is a computer network?
Here’s a challenge
I'm going to ask the robots what a computer network is.
See how much you understand by this definition.
Alexa, what is a computer network? A computer network is a digital telecommunications network for sharing
resources between nodes which are computing devices that use a common telecommunications technology.
Data transmission between nodes is supported over data links consisting of physical cable media such
as twisted pair of fiber optic cables or by wireless methods such as Wi-Fi microwave transmission or
free-space optical communication. OK, so there's the course.
We're finish now.
We all understand what computer networking is.
Yeah.
If only.
Now if you're a robot you may be able to understand everything about computer networking just by listening
to those two paragraphs.
But I think for us we need to spend quite a bit more time to really understand what a computer network
is and understand how computer networks work.
Let's start firstly with the why? Why do we have computer networks?
What's the whole point of the Internet.
What's the whole point of all this infrastructure that's been built around the world.
And the big reason to have a network as per this definition is to share resources.
We want to share information or share some kind of resource with someone else.
Now what is a resource in the old days.
A common example of a resource would be a printer.
If you had an office with 100 people in the office you could buy a printer for every workstation or
for every PC
And that's what they had to do before the days of networking.
They either had to have a printer for every computer or have no printers or what they had to do is do
something like this where they copy a file onto a floppy disk and then go over to the printing station
and then print it manually.
It's not cost-effective to buy a printer for every workstation or for every person.
It makes much more sense to have a centralized resource in this case a printing resource and share that
resource amongst the people in the office.
So rather than having let's say 100 printers for 100 people you only let's say have 10 printers.
So you've reduced the cost by creating a shared resource a resource that can be shared by what are called
clients.
So we have client devices or PCs in this example that are sharing a resource in this case a printer.
Another example is file sharing.
This is very common.
I want to share a file with you.
So how do I do that?
Now in the old days the way to do that was to get a floppy disk like this.
The problem with these floppy disks is in the old days they're only supported one point for four megabytes.
It's not a very big drive but there you go really old example.
So they'd have to if they wanted to share a photograph or a file with someone else they'd have to copy
it to this floppy disk then walk using what we would call sneakernet.
So they'd firstly have to copy the photo or the file onto this disk then walk using sneakernet across
the office put it into the other computer and then access the file.
So that's how they would share a resource.
In this case a file or a photograph.
Now today we still use this kind of technology by using USB thumb drives.
So if I wanted to share a resource with you like a photograph or a file I could copy it onto this USB
drive and then give it to you and then you'd copy it to your computer.
So sneakernet the original type of networking if you like is where a human being would take a resource
copy of file or a photograph into this USB drive.
I'd walk to your computer and then give it to you and share the resource with you.
But that's not very effective.
It's not scalable doesn't work that well.
You, let's be honest, most humans would be too lazy to have to walk around the office to share files.
It's much easier just to share files using a digital transmission mechanism or medium and they're different
types of digital transmission mechanisms.
Why are we doing this?
We are trying to share a resource between what in this definition is called a node and they define that
as a computing device.
So a node is a computing device.
And there are many types of computing devices.
We could have Windows laptops.
We could have Mac books.
We could have phones.
We could have servers.
Those are often the devices that most consumers will think about.
And I've mentioned printers already has another one.
But in networking, we have specialized devices such as hubs, switches, routers and firewalls to name a
few.
So stepping back a second.
Why do we have a computer network?
We want to share resources which could be a printer, could be a file, could be a video.
So videos are very popular these days.
You watching this video through a computer network I'm sharing this information with you using a data
link in the Wikipedia definition.
They talk about a data link being a physical cable such as twisted pair, fiber optic cables, Wi-Fi or
some type of data link where I'm sharing information with you.
So the big idea here is I'm sharing a resource with you and I need a way to get that to you.
You need a device that can receive the resource, we need some kind of transmission media which could
be physical cables or it could be wireless.
So the idea is rather than having to physically transport a file on a USB drive or in the very
very old days using a floppy disk we use a cable or some kind of mechanism to transmit data from one
device to another or from one device to many devices.