OSI MODEL EXPLANATION

The OSI Model layers are typically described from the top layer down. The layers are described as Application, Presentation, Session, Transport, Network, Data link and Physical layer. In this section we are going to explain how the data travels from the student computer to access the OnlineLearning system server in Cobham College IT Center.

 

Student’s/Lecturer’s computer >

Ø  7 - Application layer

The application layer interacts directly with the user's data and recognize it, such as the student. The data of the student will travel from their computer to the server of the OnlineLearning system. Software applications like the internet browser are used to initiate communication with the user in order to access the system. The software used clearly does not fall into this layer. Application layer only responsible for protocols and data handling for the software being used.

Ø  6 - Presentation Layer

Presentation layer mainly responsible for preparing the data for use by the application layer. This means that this layer is in charge of the translation, encryption and compression of the data. All data entered by the student, such as username and password, will be changed into a bit stream before being transmitted. Encryption will be added to student data so they can protect the confidentiality of their data. So finally, the Presentation layer will compress the data to reduce the number of bits in the data to improve the speed and effectiveness of communication.

 

Ø  5 - Session layer

In the Session layer, the construction, direction and conclusion of connection between devices occur. Which in this case are the Student computer and OnlineLearning system server. After the connection is established, the data then passes to or from the transport layer.

 

Ø  4 - Transport layer

It is responsible for the transmission of data across network connections. This layer will coordinate how much data is the student sending and how fast and where it could goes. Transport layer will do flow control for inter network communication, so the flow can determine the most optimal speed for data transmission to make sure that the sender (student) has fast connection, so the OnlineLearning system server then will not be overwhelmed with slow connection. Once transport layer has completed its function, the data is then passed to or from the network layer.

 

Ø  3 - Network layer

It handles the routing of the data, routing is finding the best physical path for student data to reach OnlineLearning System server in the Cobham College IT Center.

 

Ø  2 - Data link layer

This layer is often divided into sublayers called media access control (MAC) and logical link control (LLC). The layer sets up links across the physical network. When data link layer receives data from the physical layer, it checks for transmission errors and then packages the bits into data frames. At the data link layer, the data passes to or from the final layer which is the physical layer.

 

Ø  1 - Physical layer

This layer encompasses the network cables, power plugs, etc. Student data that has been passed down from previous layer will be convert into signals and transmit over local media.

 

OnlineLearning System server >

Ø  7 - Application Layer

The OnlineLearning system server will perform as a website that stores all resources related to the educational purpose such as images, videos and files. The server will respond with the required content.

Ø  6 - Presentation Layer

The data transmitted to the server is encrypted. Thus, the presentation layer will be responsible for decoding these data in order for them to be readable and for the receiving device that is the server to understand them. However, this layer will also translate the data into the language that the application layer of OnlineLearning system server in the Cobham College IT Center can understand.

Ø  5 - Session Layer

After all the data from the students computer has fully exchanged to OnlineLearning system server, The communication session between both devices will be close to prevent wasting resources.

Ø  4 - Transport Layer

In the transport layer for the user's computer, the data decomposed into bits called segments. So then the segment will be aggregated to data that the session layer can consume.

Ø  3 - Network Layer

For the network layer of the server, the small data units known as packets will be reassembled into segments which will be used on the transport layer.

Ø  2 - Data Link Layer

The received frame of the physical layer will be reassembled in two packages and then transferred to the network layer.

Ø  1 - Physical Layer

The physical layer will receive the signal and convert it into bits and switch it to the Data Link layer as a frame.