The CPI is a combination of two protocols.
These are the actual in my screen, just these are the transmission protocol, transmission control
protocol plus internet protocol.
So.
These two particles form part of the Internet protocol suite IPS.
So a conceptual model of how Nature Protocol sent network traffic over the internet that breaks down
network communication into four layers, as shown in this illustration.
So as you can see, Internet Protocol Application Layer transports their internet layer link layer,
and these are the what these layers use, what protocols, says Laotians.
And this is the link layer is the physical layer.
So, uh, these are the two four layers from a protocol stack.
So these links here's the all clear, uh, link layer.
This is the layer one, layer two, layer three and layer form.
This start with a link, clearly and one.
So this layer is the lowest level.
And this, uh, describes the physical mechanisms used, uh, to transfer information between nodes
on a local network.
Uh, Ben.
One examples include, uh, internet here.
Can I show you?
So this is the Ethernet port, for example.
Um, or point to point, uh, protocol.
Uh, so these are the physical layer and top of them.
This is the layer number two layer number two.
Uh, so this is the internet layer.
So this layer provides the mechanisms for addressing network notes.
Well, I can layer one.
The nodes don't have to be located on the local network.
This level contains the, uh, IP for IPv6 on a model networks.
The actual protocol used called either B I IP version four or IP version six.
And and then let's talk about our, uh, third layer transport layer.
Yeah.
Transport layer these layers is responsible for connection between clients and servers, so sometimes
ensuring the correct order of Pekar's and providing service multiplexing service multiplexing allows
a single node to support multiple different services by assigning a different number for each service.
So this number is called a part TCP.
The user data protocol operate on this layer.
TCP and UDP operate in this transport layer.
And lastly, we have application layer here, so this layer contains network protocols such as Hypertext,
the hypertext transfer protocol ATP, which transfers web page contents.
Uh, we have the simple mail transport protocol for which transferring which transferring email and
domain name system protocol, which converts a name to and not on the network.
Further, this course we will focus primarily on this layer, actually, but we will focus on all of
this there.
So this is the most important layer for us.
Each layer interacts only with the layer of two and below, but there is a must be external interaction
within the stack.
So like that.
One.
Yes.
There.
So.
Now, let's pretend that new figure.
Uh, for better understanding.
Um.
Yes.
This is the one box here.
And this is the mail.
This will be our mail application.
Mail application.
Vacation.
This is the mail application.
And, um, this is the human years, so it's.
Justin, users here, for example.
This will be our user, so.
It's it's some books here as well.
So this will be a user interface interface, which is harsh HTML hash, HTML rendering, and we have
we will conduct ourselves here.
Content partners like, uh, tech such will jpg content.
Serves.
Passers.
What this feeling is text, for example, hushed html jpg, the on the wheel, uh, top of below them
is very real.
Have network communication network home.
So what these will is and SMTP is SMTP, for example, pop three or three and IMAP.
So this is the email application.
Uh, so SMTP, POP3 and IMAP is the mail protocols, and this will be network network.
Here.
And servers here, server.
Sir.
This network report is directly the server and user interface.
Will direct that it'll go to our homeland.
So typically, applications contains these components.
First is network communication.
So this component communicates over the network and processes incoming and outgoing outgoing data.
What email application?
The network communication is most likely in the standard protocol, such as a SMTP pump three and IMAP,
and we have here content partners as well.
So data is transferred over.
A network usually contains content that must be extracted and processed.
Content might be include textual data such as the body of an e-mail or it might be contain pictures
or videos.
And we have user interface for user.
So the user interface allows the user to be received emails and to create new emails for transmission
in a mail application.
The user interface might display emails using hashed email or be in a web of a browser.
Not that the user interacting with the user interface doesn't have to be human.
Being caused by the application that automates the sending and receiving of emails triggered a command
line tool.
And we have here data encapsulation, which we will discuss this in the next lecture.