Now you will learn a lot more by doing rather than just watching me talk about protocols and talk about
things.
So make sure that you download this packet tracer file and try this yourself.
I'm gonna walk you through a scenario and a few scenarios in this video and in subsequent videos
and labs.
But try this yourself you will learn far more by doing than by watching or listening.
You learn to ride a bicycle by riding.
You don't learn to ride a bicycle by watching someone else ride a bicycle or watching videos.
So try this yourself.
Okay.
So in this example I've got a topology consisting of multiple devices so zooming out I've got a whole
bunch of devices.
But for this initial video we're going to concentrate on this P.C. which is in our internal network.
In other words think of this as being at your home or company.
And then we've got a device that's connected to the Internet here.
So this would be our Internet router.
What we're gonna do however is connect to a server in our internal network.
Now at home you may have multiple Internet connected devices.
You could as an example simply open up a web browser on your P.C. and connect it to your Internet router.
As an example if I open up a web browser and connect to an IP address in my network and don't worry
too much about IP addresses at this point if you don't understand them.
Basically an IP address is a number that you allocate to a device that allows it to communicate using
a protocol which in this example is IP, IP version 4 in this specific example here.
I've got a BT home hub when you connect to a websites such as facebook.com that is going to be
using a protocol in this example HTTPS which is an encrypted version of HTTP.
A different protocol but that's kind of what it is.
We encrypting HTTP so you may have devices at home that you can connect to.
We gonna mimic that or represent that in Packet Tracer.
So on the left here I have some servers running internally.
I have a Internet router which is connecting me to the Internet as a further demonstration.
I've got an iPhone.
I could connect to that light.
That's a cue light using Bluetooth and then do something to that light now in your home you may have some
devices that are connected via IP as well that light isn't using IP as in normal IP it's using Bluetooth.
I'm connecting to that light via Bluetooth from my iPhone and turning it on and off but this light as
an example is connected via IP so I can go on to my phone and then I could say OK let's turn that light
off.
So it's gone off.
Turn it on now the way that works is I'm simply connecting to that light via TCPIP.
You can actually look at the traffic on your home network using an application called wireshark.
I'll talk about that in a separate video but in this example let's use Packet Tracer so that we can
talk about the same protocols together.
So on this P.C. I'm gonna open up a desktop and I'm going to open up a web browser now before I connect
to a server I'm gonna change the packet tracer mode to simulation mode so that we can see the actual
packets going across the network.
Now I need you to know some terms for the CCNA exam.
It's basically how we referred to stuff if you like at the different layers.
So when data is sent at the physical layer we're sending zeros and ones across the physical layer that's
known as Bits
So the bits of data are represented on a fibre cable as light.
So as a basic analogy if there's light it means a one.
If there's no light it means a zero.
So zero one would represent our Bits
or our Binary values, on copper
do we have electricity or not?
So most fundamental example would be if there is electricity on a wire it means one if there is no electricity.
It means a zero.
So think of this as a light going on and a light going off is it on.
Is it off.
And that represents our Bits.
So at layer one we have bits on top of that we have frames.
So at layer two we talk about a frame.
So when we're sending data through an Ethernet switch which is a so-called layer two device we are sending
frames.
So I'll use these terms.
Frame is getting switched from one port on a switch to another.
So when you hear the term frame remember layer two at layer three we have what are called packets so
a router which is a layer 3 device will route packets from one interface to another and at layer four
we have segments.
So layer 1 is bits, Layer 2 is frames, Layer 3 is packets, layer 4 segments and then at layer
5 to7 we have an application.
Now let me warn you as I demonstrate these protocols it's gonna take time because there's a lot of
information you may find that it gets a bit boring if you do then do this yourself have a look at the
protocols yourself and try and understand the messages but I'm going to spend quite a bit of time going
through layer 2, layer 3, layer 4 and the layer 7 applications to try and help you understand
what's going on.
This kind of stuff is really important to understand.
It's basic nitty grittys foundational stuff can be boring but it's important to understand you can't
understand networking if you don't understand this stuff.
So spend the time learning your protocols you will need to put in the effort and spend time learning
your protocols if you really want to understand networking if you want to become an ethical hacker you
need to understand the protocol so that you can hack them if you want to become a network engineer you
need to understand the protocols to be able to configure network devices properly and troubleshoot network
devices or troubleshoot network issues if you want to become an a good application developer you need
to have an understanding of the underlying applications many nightmares are caused today for network
engineers because of badly written applications application developers assume some of them who write
bad applications that there's unlimited bandwidth there is no unlimited bandwidth if you write a poor
application it's going to make a network engineer's life very difficult as a lot of old network engineers
will say it's always the networks fault and all the rubbish comes from the top and lands on our heads
because people will blame the network even when there's an application that's at fault make sure that
you spend your time learning your protocols so that you can prove it's not a network issue but it's
an application issue.