All language subtitles for 3. Protocol Stacks

And welcome back.

In this video, I'd like to chat with you about a methodology for better understanding the

individual components that are used as part of an IP network that allows clients and servers

to communicate with each other.

And I'd like you to think of this discussion we're about to have as a recipe for communications

for clients and servers to talk with each other.

Or another way we could say this is a suite of protocols or rules that's going to allow

clients and servers to talk to each other.

And behind the scenes, there's a lot of detail that has to happen for clients and servers

to talk to each other.

And so oftentimes, we'll develop frameworks or models to help represent each of those

individual components.

So back in the early days, decades ago, a standards group came up with a logical model

regarding all the stuff that needs to happen between a client and a server so they can

effectively communicate with each other over a network.

And it involves seven layers.

And if this was like, I don't know, a couple of decades ago, I would say, boy, this model

is called the OSI reference model, it'd be important to understand each and every single

detail in this model.

But I'm not going to say that because we don't use that model.

It's just like an idea that helps describe the details of what has to happen when two

devices on a network communicate with each other.

So let me clean up that a little bit.

And let me just go ahead and put a little X there to represent we don't need to worry

about the OSI reference model anymore.

And you might say at first glance, wait, wait, I see OSI reference model all the time and

documentation and literature.

And that's because it's a common reference model.

But it's not like a real suite of protocols or rules that computer networks that we actually

use today.

What we actually use today is something called the TCPIP protocol suite or a suite of protocols

all working together.

And this TCPIP protocol suite, these protocols that all work together to allow clients and

servers to talk to each other, it has these four separate logical functions.

However, when we actually work with TCPIP networks, we actually have borrowed a layer

or two and a name or two from the OSI reference model.

So the only thing we really need to worry about is this one right here.

As far as the actual set of rules and protocols that we use today in our corporate networks

and our home networks and on the internet.

So if you hear somebody talking about the TCPIP protocol stack, which is being used

today, and they talk about layer three or layer two or layer four, the transport layer,

it all goes back to this representation of the categories or the functions that need

to happen on the networking devices as they work with and process and forward data over

an IP network.

So let's imagine a computer like this one, computer two, that wants to talk to a server

out on the internet.

I'll put a big S there for server.

In this case, computer two would be the client and the server out on the internet would be

the server who's providing the services.

And then the question is, okay, what type of service does this client want?

Does the client want to go to a web page?

Or does the client want to ask a server about the IP address behind a name?

Or does this computer want to remotely connect to a system?

Or does the client want to go ahead and print?

Or does the client want to forward an email message towards the email server?

And so in the world of computer networks, these are all referred to as services.

They're also very commonly referred to as applications, not to be confused with a local

program like Microsoft Word or something like that that's running on a computer.

So if we're talking to another person saying, hey, what programs or apps are you running

on your computer?

We'd be talking about things like Word or on your mobile device, applications like Spotify

and things like that.

And we're talking about various services that a client might want to request from a server.

We're focusing right here at this portion of the protocol stack, and that is called

the application layer.

And here's what you and I get to do.

In the very next video, we're going to focus our attention, narrow our attention down to

just that section of the protocol stack, just the application layer, to take a look at what

are some of the common features and services and applications that we would want to use

as a client over a network today.

So we'll do that in the next video, and I'll see you there in just a moment.

Meanwhile, I hope this has been informative, and I'd like to thank you for viewing.

Thank you for watching.