Now let's summarize the eyes. Always. I model in action and have some review questions for Section one and Section two off the scores.
The eyes was I Model is a conceptual model. It's a group of concepts that characterizes and standardizes. The communication functions off a telecommunication or computing system.
The eyes OS I model is just concepts. You can bend upon these concepts any hardware or software system that can communicate with each other.
This conceptual model is regardless off underlying internal structure and technology.
The goal of this model is to provide interoperability off Diver's communication systems with the standard protocols, which means
when the systems can communicate with Linux systems,
any vendor can manufacture or implement a hardware or software system that communicate with another hardware or software system implemented by another vendor.
Since they are using the same protocol, this is the only condition or criteria that they must use the same communication protocol.
The eyes always. I model partitions, a communication system into abstraction layers.
The functionality of each layer is contained into itself.
The functionality of each layer is done
through interoperability with the upper layer and the lower layer as well.
The original version off the model,
they find seven layers. It's very important to know these layers application presentation session, transport network, datalink and physical layers.
Each layer serves the layer above, and it is served by the layer below it,
or vice versa. Each layer can be served by the above. Answer the lower layer. It depends whether you are sending or receiving data when sending data. The data is going downwards when receiving data later is going upwards through the seven layers.
Remember always that layer one is at the bottom and later seven is at the top.
Earlier that provides other free communications across the network provides the path needed by applications above it.
this layer calls the next layer, which means the lower layer to it. After providing the puff to send and receive packets that compromise the contents off that path
from where did get didn't get that
off from the above layer.
So this lower layer got the path from the above layer, and then it does the functionality off. Sending
two instance at the same layer are visualized as connected by a horizontal connection in that layer. Remember
that the only physical connection is between the two physical layers only, and there is a logical layer that is between
the application layer here and the application layer there. The application. We're here at the sending side at the application layer there at the receiving side, there is a logical connection
the presentation and the presentation, the session and the session, the network, the network, the datalink and each of the seven layers is connected
virtually but one off them is connected physically, which is the physical year here, and the physical layer there.
Let's have a look at this diagram. This is an important Bagram. Let's look at sending at the left side
the layer 77 sons data.
added toe the heather at six at Layer six.
considered as L six data
where at the layer five h five is added
and now see the same thing happens one time again.
And six plus H five are both considered as l five data where at the transport layer, Etch four is added at 654 are old headers added by layer six, layer five and layer four. Consequently,
both L five and Etch four are considered as L four data, where at three is added
now the only layer that adds heather and trailer trailer, which means that it's something before the data. And heather. There's something after the reader. The only there that adds heather and trailer is the datalink clear, and the physical layer
considers all the data as zeros and ones. Then it is passed through the transmission medium. You can see at the right side that the reverse thing is happening. It's vice versa. It's the reverse action off things that happened at the left layer.
You can see that each layer added each heather or trailer added by a layer at the left side is red and removed by the same layer by the corresponding layer every at the right side, so
edge to Tito are red and removed by the datalink layer. At the receiving side. That three is red and removed by that
network, clear at the receiving side, so
at the receiving side at later seven off the receiving side, you can only see L seven data that was originally sent by the application layer at descending side.
That's why we we say that there is a logical communication between the application at the Sunday inside at the application at the receiving side, because they are sending
the same data and receiving the same data that has Bean sent.
Let's summarize and say that the open system interconnection the Always I modern defines a network
a networking framework to implement protocols in the seven layers. Now let's have some review questions about Section one and Section two.
The first question says the computer network is composed off computers dots, and that's connected through transmission media.
What are the other components off computer network
peripherals? Remember preference. Any hardware piece that can be connected to a computer
connecting devices? This is
the other component of a computer network. So the complete sentence would be the computer network is composed off computers reference and connecting devices connected through transmission media.
The second question Transmission media can either be
made off or or it can be using that as a transmission. Media
transmission media can either be wired, made off copper
or fiber optic as materials, or it can be wireless using the air as a transmission
medium or as a media off transmission.
This would be the complete sentence.
The most commonly used networked apology nowadays is there
start apology where the computers are connected to a central device, which is there.
Switch off course. It can be a hub, but we are talking here about the most commonly used, and here I've chosen it to be the switch toe let you give familiar with the most commonly used device.
Based on the cover of geographical area, the network can either be a or A.
It can either be a Len or a went off course,
while according to the transmission type, it can either be
client server network.
Now let's move to section tow the most commonly used types of copper cables. Is there
twisted pair, which is divided into
STP, which means she'll that Mr Pear and You tippy, which means unshielded with the pair cables according to the type of shielding.
The advantages of fiber optic cables over copper cables are that it is
festive and can afford higher capacity and
more immune to E. M. I. Electromagnetic interferes
more secure than the copper cables off course.
Since it is not susceptible to sniffing
the term OS. I stands for
open system interconnection.
The most commonly used protocol over the Internet. Is there
TCP I people too cold?
Among the protocols that work in the application layer are there
and others. Of course,
the transport layer can work in either or modes off delivery in either reliable or
best effort Moods off delivery
the main functionalities off the network layer out of there
and routing functionalities.
And ofcourse, the routing is based on the addressing
off course. The type of addressing at the network clear is their logical Addressing
the network layer is responsible off.
What about addressing that? He is a question, of course.
Logical addressing while the datalink clear is responsible off. What type of addressing