Would you like to learn about the OSI model or the open systems interconnect model and
how it pertains to data transfer and networking?
If so, this video is for you.
Hi, my name is Michael Gibbs, and I'm the founder and CEO of Go Cloud architects and
go cloud careers.
And we're an organization that's really dedicated towards building the most high performance
cloud computing, and networking careers.
Personally, I've been working in technology now for over 25 years, I've been helping others
get their first tech job or get promoted in tech from within two decades.
And I want to help you get your first cloud architect job, your first cut engineer job,
or any tech job that you desire.
Today, we're going to talk about the open systems interconnect model, which is a seven
layer model of data communication.
And why is the OSI model or the open systems interconnect model so important, it forms
a common language for people to talk about how data is communicated.
I like to speak Greek in my house, but I also speak English but let's say I spoke to you
in Greek, and you didn't speak Greek, you only spoke English and we were to tie or try
and talk we would have a problem.
So when it comes to precision communications, we have to have what's called a common lexicon,
or a common word or a common language.
And that's what the OSI model stands for.
The open systems interconnect model is to help you understand and communicate with other
professionals.
Networking, we're really only working with four layers of this model.
But when it comes to end to end communication systems are actually seven layers, we're going
to make it simple what occurs at each layer.
So you understand this, you may find that on your AWS certifications exams, you'll definitely
find them like a Cisco Certified network Associate exam.
But to really work in technology, you need to understand this, especially when it comes
to troubleshooting, when things break.
So we're going to define seven layers, and we are going to start with the physical layer.
The physical layer is the wire, effectively, that connects to organizations.
So if you plug in your cable to the back of your computer, that physical cable is the
physical connection or your wire, that's the physical layer.
Now, realistically speaking at the physical layer, it could be a fiber optic connection
where we're sending light, or it can be a physical like a wire where we're sending electrons
on the wire.
But that's really what's going on at the physical layer.
Now at the physical layer, what we're sending is called bits.
And now you know, so Layer One is the physical layer.
Now let's talk about layer two, or the data link layer.
The data link layer is the actual hardware that we're dealing with, you may go to the
back of your computer and plug in that Ethernet cable into the Ethernet port.
That ethernet port is the hardware that's associated with it, that is your Ethernet
card or your network interface.
Now, this is a hardware layer.
And if you note on your computer, if you look at its MAC address, there's a hardware address
called the MAC address.
at layer two, as we're talking about here, we have a hardware address.
Now a MAC address is actually burned into the card.
So it has a physical address, and it's generally permanent.
Now we can tune it under certain software environments.
But at layer two, we're talking about a physical address.
Now at layer two, we're sending something called frame.
So let's go back to it layer one wire and we send bits, layer two data link layer, that
card layer and we are standing.
Next we get into where the fun is for the network Architects like me, then network layer,
this is where our logical addresses are.
So for example, you put an IP address on your computer, that is a layer three network protocol.
So we're dealing with a logical address, one that you can manually assign.
And when I started, we were dealing with AppleTalk, IPLS, all kinds of addresses.
But in these days, it's real simple.
network layer addresses are only IP addresses.
And what do we send at layer three packets.
That's why an access control this is often called a packet filter.
Now you know layer one wire layer two card layer three, the logical address that you
assign.
Now let's take it up a notch to the transport layer, how we send our data.
So we can send our data in multiple ways.
If we need reliable communication, we can use something called the Transmission Control
Protocol.
And here's how that works.
I send data to the recipient, the recipient acknowledges my data, and then I send the
recipient more data, they acknowledge the data, kind of like having a conversation.
Did you receive it?
Yes.
Did you receive it?
Yes.
Did you receive it?
So at the transport layer, we've got multiple protocols, but we're going to be so we've
got for the most part TCP or transmission control protocol like I just described that's
used for reliable transport.
We also have UDP which is used for non reliable transport like
a voice call or a video call, if you're watching a YouTube video, you're using UDP, if you're
on Netflix or using UDP.
Now traffic at layer four is considered segments.
So layer one, wire bits, layer two card frames, layer three packets, IP address, layer four,
TCP, UDP, or ICMP, Internet Control Message Protocol that's used for network testing,
for example, there are layer four protocols.
Now, you know, the first four layers, and realistically speaking, this is where networking
live and dies.
It's the end of it, all of it.
But let's talk about three other layers.
We at the fifth layer have something called the session layer.
And this kind of really controls the connection.
We're dealing with sockets, and for example, in this situation, and what we're sending
at this point is data.
But you know, it's part of the system.
So we're covering so layer one wire, we send bits, layer two data link, we send frames,
layer three IP address, for example.
And we send packets, layer four, transport layer, TCP, UDP, ICMP, and we send segments,
layer five is session.
And guess what we're sending data to soar above those critical networking things.
Now, let's get into layer six, or the presentation layer.
The presentation layer presents the data to the applications that you and I use, which
we'll talk about next.
Now, there is one thing in the networking world that does go on here, and this is encryption.
So for example, you might have some TLS based security at this layer, and realistically
speaking, that is at layer six, but we're still sending data.
So what do we have layer one, wire bits, layer two, card, Data Link, MAC address, and we're
sending frames, layer three logical address, like an IP address, and we're sending packets.
layer four, a session controls the connection.
And we're sending data layer six presentation layer, and what are we doing here?
We are doing some encryption, and we were presenting data to the application.
Okay, layer seven, the application layer.
What is it?
It's the application that you and I use.
So web browser application layer, things like HTTP, DNS, SSH applications that we use are
layer seven at the application layer, and we're sending data.
So we'll go through it one more time physical layer wire, we said bits on the wire, layer
two data link.
This is the hardware part of our situation.
at layer two, we're dealing with MAC addresses, and we are passing frames, layer three, the
network layer.
This is where we have our logical addresses or IP addresses and we're passing packets
layer four transport does our protocol TCP, UDP, ICMP and we are sending segments layer
five this session, which controls the connection, and we are sending data layer six at the presentation
layer.
We are doing our encryption and presenting our data to the application layer and we are
sending data.
And layer seven is the fun applications we use like our web browser.
It's our user interface and at this layer we are sending data.
I hope you've enjoyed this video on the open system interconnect model, the OSI model,
the seven layer ASR OSI model, because this will help you when you speak to networking
professionals, cloud computing professionals or you're troubleshooting any kind of communications
in the technology world.
This is Michael Gibbs, and I look forward to seeing you in another video.
Take care everyone