This time we will discuss about the OSI (Open System Interconnection) layer, if you want to explore network computers, of course you must definitely understand the OSI (Open System Interconnection) layer and for example.

In the past before the creation of OSI, to conduct a communication on a computer network had a difficulty, because each vendor and developer at that time used their respective network protocols, making it difficult for users when exchanging data from one computer with another computer. because the network protocols owned by each computer are different.

Seeing this, in the 1980s the international standardization organization namely the International Organization for Standardization (ISO) created a reference model called OSI. The OSI model created by the International Organization for Standardization (ISO) provides a structured logic framework for how data communication processes interact through networks, this standard was developed for the computer industry so that computers can communicate on different networks efficiently. The OSI model created by the International Organization for Standardization (ISO) consists of 7 layers. Each layer is specifically responsible for the data communication process. For example, one layer is responsible for establishing connections between devices, while another layer is responsible for correcting “errors” during the data transfer process.

The OSI (Open System Interconnection) layer is a system that allows all types of data packets or bits to reach the server to the client computer and the OSI (Open System Interconnection) layer is the communication standard applied in computer networks. That standard is why all communication tools can communicate with each other through the network. The OSI reference model illustrates how information from an application software on a computer moves across a network media to an application software on another computer. The OSI reference model is conceptually divided into layers & layers, where each layer has a specific network function.

The main purpose of using the OSI (Open System Interconnection) layer model is to help network designers understand the function of each layer that is associated with data communication flow. Includes the types of network protocols and transmission methods.

Different then TCP / IP which only has 4 layers, OSI (Open System Interconnection) has 7 different layers with different ways of working. OSI (Open System Interconnection) has more layers with the aim that each process runs more smoothly and clearly, without too much burden.

The following are the 7 layers in the OSI (Open System Interconnection) model and their functions, the 7 layers are:

1. Layer 7 – Application Layer and Its Functions

This layer is the interface and is the first layer that comes in contact with the data.

Application Layer is also the last layer that is missed when the client has received incoming data.

The protocols at this layer are:

• HTTP

• FTP

• SMTP

• NFS

As a layer that releases data in a network as well as a data viewer, the Application Layer has main functions, including:

1. Work together between the application and the network to present the interface.

2. Set the process for an application capable of accessing the network.

3. Displaying error messages on the connected network.

4. Display the process of an existing network.

2. Layer 6 – Presentation Layer

The main function of this layer is to translate data transmitted from and to the application.

Of course, any data that is translated will fit the format of the application.

3. Layer 5 – Session Layer

The main purpose of the Session Layer at the OSI layer is to do a definition of a connection can be established and see the process.

There are several protocols at this layer, including:

• Software redirector

• Virtual Network Computing

• Remote Desktop Protocol

This layer can also manage an incoming connection, such as making, maintaining, or destroying that connection.

4. Layer 4 – Transport Layer

This layer acts as an “introduction”. Its main functions at the OSI layer are:

1. Break the data set in data packages.

2. Sending data transitions obtained from the Session Layer to the Network Layer, and vice versa.

3. Label the number of each data packet.

4. Processing retransmission of data packets not found.

The Transport Layer at the OSI layer exists to make any data that passes through it run smoothly from the server to the client and minimize disruption.

The role of the Transport Layer is vital because it is in the middle of a massive process that is running on the network.

5. Layer 3 – Network Layer

This layer helps to identify an Internet Protocol (IP) address. The aim is to make each user connected to one another.

Not only that, the Network Layer can also function to create headers on each data packet and do routing.

However, to do this requires a layer-3 router and switch.

6. Layer 2 – Data-link Layer

This layer is very important because it has several vital functions, such as:

1. Correcting errors.

2. Determine the bits that fall into groups of a frame.

3. Hardware experience.

4. Determine the operation of a hardware (hardware).

In the Data-Link Layer there are also two levels of the data layer, namely:

• Logical Link Control (LLC).

• Media Access Control (MAC).

7. Layer 1 – Physical Layer

As the name implies, this layer is always associated with physical contact. In this layer, the relationship is very close to the signaling function.

This layer is also known as the one closest to the physical hardware of the network.

Physical Layer also has functions to define the transmission of various networks, synchronization between bits, network architecture & topology, and cabling.

At this level it can also define a NIC (Network Interface Card) interacting with one another (cable or radio media).

How is OSI (Open System Interconnection) layer works ?

The process of running data from one host to another on a network is quite long, all the data must go through each layer of OSI to get to the destination host. For example, when you will send an email to another computer on a computer network.

The process that occurs first is the application layer, which provides an email application program that will be used to send data to other computers through the network. At the presentation layer the email is then converted to a network format. Then in the session layer a data journey session will be formed from the start to be formed until the completion of the sending process.

At the transport layer the data is broken up into small pieces and then it will be collected again at the transport layer of the recipient. At the network layer an address will be created and a path will be determined by the data to get to its destination. At the data link the data layer is formed into a frame and the physical address of the sending and receiving devices will be set.

Then at the last layer the physical layer sends the data through a network medium, to the transport layer of the recipient. Then the same path occurs on the destination computer but starts from the lowest layer (physical layer) to the top layer (application layer).

That’s a little explanation about the understanding of the OSI (Open System Interconnection) layer, a little history of the OSI (Open System Interconnection) layer, the functions of the seven layers and how it works. Understanding how the OSI (Open System Interconnection) layer can improve your understanding of how a computer network works and the protocols that work therein, Thankyou

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