Poodle.
What is this supposed to draw from?
It's a bridge for cars to drive over, isn't it?
Actually an ethnic bridge?
Ethnic bridge.
Well done.
What is this?
Oh, FUB.
What is this, then?
That's what this is all about.
It looks like a switch, doesn't it?
These two hubs for pub apps for a pub are like that.
What is this?
Aurora, Aurora.
What is this one, this is a funny one, but a repeater, it repeats signals, stories and repeat stories.
What is this one?
You know?
This one switch like in the room.
It's a switch that turns on the light in the roof.
Well done.
And what about this one?
Switch to switch to a better switch?
Yeah, we have a whole bunch of networking devices.
And in this video, we're going to learn about network devices.
Oh, you've got a book, Kelly Linux hacking.
You love to hack.
Well, then putto thing to remember is basic definition routing, switching, dumb device.
So no intelligence here.
Intelligence based on MAC addresses, intelligence based on IP addresses.
I'll go through this in more detail later.
Let's just look briefly at some of the devices that we had in the past and then some modern devices.
The original Ethernet was 10 by five using this really big yellow cable.
So this cable was restricted and distance.
The signal would attenuate from one end of the cable to the other.
And what they developed were repeaters.
This is an example of a very early repeater.
This would repeat the signal from one port to another.
We could use 10 base five here or 10 base two.
So this amplified the signal.
Basically didn't understand the actual signal, but it just amplified the signal from one place to another.
Now you'll notice it doesn't have many ports on it.
We've only got two ports.
So it was simply repeating from one put to another example of a repeater.
They then developed what was called a multi port repeater.
This is a Cisco Fossicked Hub 400 series.
So we've got Oduye 45 Connectors on the front.
We've got power on the back.
But the idea is a hub is essentially a multi port repeater.
We've got multiple ports and we are simply repeating the signal we would connect all 45 unshielded twisted
as an example to these ports.
And what a hub does is once again, it simply repeats the signal without understanding what's going
on.
So it doesn't understand the frames that it receives, all the information that it receives, it's simply
amplifies it.
So a repeat here would amplify the signal amplified from one port another.
Here we've got a multiple repeater.
It's repeating the signal from one port to multiple other ports.
So if traffic was received on Port one on this hub, it would simply amplify the signal out of all of
those ports.
So repeats the signal out of every other port without understanding any of the details.
Here's an example of a Netgear hub.
On the front, we have 24 hour 45 ports, and on the back we've got 10 base two as well as 10 base five.
So, again, this would allow me to connect different cable types on the back, we could connect 10
base five as an example, and then on the front we could have UTP Oggi, 45 Capling.
As we know today, this has no intelligence.
There's no intelligence in the hub.
There's no intelligence in the repeater.
Remember, this is just repeating the signal from one port to another.
This is a multiple repeater.
If something is received on this port, it just amplifies it out of all the other ports or repeats it
out of all the other ports.
Otherwise, we get attenuation of signals and the signals degrade over a period of time, which restricts
the length of a cable.
This allows me to increase the length of the cable.
Now, the problem in those days is the more devices that you have on the network, the more collisions
that you're going to have, which causes problems and slows the network down.
I'll talk more about that later.
But the idea is this is a hub.
This is a repeater.
We don't worry too much about these days.
A lot of people say, David, don't even show me hubs because they're pointless, but they forget that
wireless.
This is an example of a wireless access point.
Very modern wireless access point supports Wi-Fi.
The latest version of Wi-Fi at the time of this recording, a Wi-Fi network or a wireless network is
essentially a hub in the air.
We are sharing the air, so whatever I'm saying can be heard by you if you're within range.
Both of us can't speak at the same time because it's a shared medium.
We are sharing the air now.
Wi-Fi six does try and implement some very clever stuff to allow multiple devices to talk at the same
time.
So it kind of approaches a switch, but it's still acting as a hub.
So what is a switch?
Here's an example of a switch.
This is an older switch, 37 50, very popular for doing labs.
Cisco Labs.
Notice lots of ports on the switch.
We've got 48 ports on the switch.
The number of ports on your switch varies.
You can have very small switches.
You could have larger switches.
Here's an example is a five port switch, DP linked switch, very small switch.
He has another four port switch from T.P link.
So you don't necessarily have lots of ports.
But in an enterprise environment, you typically will.
You'll have a lot of ports on the switch.
These are smaller switches.
The point is, is that the form factor or the way that these devices look varies.
But the big difference between a switch and a hub is a switch.
Has intelligence, a switch actually reads what are called the frames received on Ethernet.
When you send data onto Ethernet, we are sending what's called a frame.
So this device uses what's called a Mac address table.
It's the same as these devices of the topia.
They basically receive frames and they have the intelligence to only forward the frames out of the correct
ports.
So if there was a device with a certain Mac address on this port and traffic was received on this port,
going to that Mac address, it would only be sent out of that port rather than out of all ports.
A hub or multiple repeater is done.
When traffic is received on one point, it just simply amplifies it or floods.
It is the term out of all ports.
So everyone receives that frame here.
A switch has a Mac address table.
It has some intelligence and it learns where Mac addresses are in the network.
And then it'll only forward the traffic out of the relevant ports based on the destination Mac address
in a frame.
So if traffic comes in this port, it's going to you based on your Mac address.
It's learned that you're connected to this port.
When traffic arrives in this port, going to your Mac address, it's only going to be sent out of this
port, whereas if it arrived on a hub, it would send it out of all ports.
It's a big difference between a switch and a hub is a switch, has intelligence.
It works at what's called layer two.
We'll talk about that later in a moment.
So it has some intelligence and it'll only forward the frames out of the correct ports.
Now, some people would say, but hold on a minute, David.
What is a bridge?
A bridge you can think of as an intermediate device between a switch and a hub.
So we had repeaters first, then we got hubs, and then we had bridges, which basically did things
in software.
They learned where the Mac addresses were of devices in the network.
And then someone rebranded their devices as switches because they could learn Mac addresses and hardware.
So they use something called an application specific integrated circuit or async.
So the lines are a little bit blurred, but for the corner, you don't have to worry about that.
A switch learns where devices are.
It learns the Mac addresses are and then will only forward the traffic out of the relevant ports.
A bridge was an intermediate device between a switch and a hub.
So historically we had repeaters and we had hubs and we had bridges, software switches, if you like,
and then we have switches today.
Now notice the number of ports on the switch.
There are many, many ports on the switch.
So that's one of the features of switches.
They allow us to connect many devices in our local area network.
They essentially use for sending traffic within a local area network or LAN, we're not going to try
and send it from one network to another.
These operate on Mac addresses using what's called layer two in the same model or TCP IP model hubs
or layer one devices.
They are basically dumb devices.
They don't understand what they receive.
These are called layer two devices because they use Ethernet frames and then we have routers which use
IP addresses to route from one network to another.
They are called layer three devices.
We'll talk about those terms in a separate video.
Layer one layer to layer three, layer four and layer five to seven.
You need to know those layers.
You need to know the TCP, IP and Odissi models.
So don't worry too much about that for the moment.
Just get an understanding.
Dumb device repeats everything that focuses on one port out of all other ports.
More intelligent device uses Mac addresses, learns where devices are and then we have routers.
Now your home device might look something like this.
t.P like this is a little TPE link.
Rawda It allows us to route from one network to another.
Typically little routers like this allow us to go from our Ethernet LAN local area network onto the
Internet, so to what's called a wanne wide area network.
So Ethernet ports, this is how we connect our devices to the broader.
Wireless and then we've got a connection to the Internet, here's a Cisco router, what you'll notice
is this Rouda is as big as the switch, but it has far fewer ports on it.
We've only got a few Ethernet ports and then we've got other types of ports.
These are what are called serial ports.
Now, fortunately, in the scanner, you don't have to learn about these serial interfaces.
They were very slow, older interfaces, the most common when technology and LAN technology to today's
Ethernet.
So Ethernet is what you need to know.
So that's why I'm spending so much time discussing Ethernet.
These older interfaces aren't that important today.
But think of your home, Brada.
How do you connect to the Internet?
Maybe you've got an cell connection.
So your service provider mine here in the U.K., British Telecom, they've given me an Edsel connection.
Now, some of you may be fortunate enough to have fibre to your home.
So in actual fact, your one connection is Ethernet in that case.
But in the old days, it might have been something like the serial interface.
But notice this router here.
This is an interesting router, 1800 series Rawda.
This is an older router that would be used in small medium business or in a remote branch office of
a large corporate.
This device does a lot of things.
It has old telephone connections here where you could put old analog phones in.
So these Porscha, these ports would allow you to connect an old analog phone to the router, and then
this would allow you to make telephone calls to your service provider like AT&T or British Telecom,
etc..
It's also got a way, an interface.
So one of these interfaces could go here.
It also allows us to connect to the Internet.
It's also got like a switch part to it.
So the idea here is this is kind of like a hybrid device.
Raddest today mix a lot of switching with them.
Like I said, nothing is as simple as it seems.
In its purest form, a router will route from one network to another.
So as an example, we are routing from Ethernet to serial or we are routing from physical Ethernet to
wireless or we are writing from one connection type to another.
So as an example, this Rawda could support voice over IP.
We could have IP phones talking to analog phones, but this is where it gets a little bit less clear
cut.
This is what you need to remember.
A router has routing functionality in its most basic form.
A router rots from one IP network to another.
So here we are talking about IP addresses such as IP version for IP Version six addresses.
We are routing from one network to another, as in one IP network to another.
In a lot of cases we would be routing from one physical media to a different physical media.
This is typically used for connections to the Internet or to a wide area networks.
So we are connecting from a local area network to a wide area network.
Switches are typically used in the local area networks or local within the building.
As an example, local at your home, you're not going to use this to route to the Internet or route
to other sites.
A router does that function so it rots from one network to another layer to switch, as this is called.
User's Mac addresses, but switches today have routing functionality.
So switch like this is called a layer three switch because it has routing capabilities built into it.
And then it'll route from one VLAN or virtual local area network to another virtual local area network,
basically from one subnet to another subnet.
We'll talk about that later.
Thing to remember is basic definition routing, switching dume device.
So no intelligence here.
Intelligence based on MAC addresses, intelligence based on IP addresses.