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OSI Model Explained CCNA Part 2 in English | Open System Interconnection Model ,OSI Seven Layers Explained

What Is OSI Model ?
One computer is the main purpose of communicating with another computer. It seems that both computers are located in different locations and these two computers want to communicate. Then, when a computer sends the data, the data will be sent to the destinition media through many media. Some changes have to be made so that the data can not be found to be error free without going through the source from the source to the destination. These rules are called Protocols. And the model that is made up of these protocols is called the model OSI model. This model determines the ISO

OSI Model Explained CCNA Part 2 in English

The OSI model is divided into seven layers or layers. Layers of:


7. Application Layer:
This is the seventh layer of OSI model. The application layer provides the user interface and process the network data. The applications that work on the resource layer, sharing resources, remote file access, directory services, etc. Some protocols for the application layer's port addresses are given

Protocol  :       FTP, TFTT, Telnet, DHCP ,DNS ,POP,  IMAP, SMTP, HTTP,
Port Address: 20/21 ,  69,    23    , 67/68   , 53   , 110,    143,     25 ,      80
Try to remember port numbers. Because in the CCNA exam, there are usually such questions, such as the port number of the HTTP?

6.Presentation Layer:
This layer works as a data translator for network services. These layers work on data conversion, data compression, decryption etc. The data formats used in this layer are: JPG, .mpeg etc.

5. Session Layer:
The work of the session layer is to create connections between sources and destination devices, control that connection and disconnect at the end of the need. 3 types of control are used to send data.

Simplex: The data in Simplex flows on one side.
Half Duplex: When the data flow of one-way data flow in the half-duplex system, the data on the other side of the data is flowing.
Flowers Duplex: Due to the full duplex system, the data may flow both at the same time.

4. Transport Layer:
Fourth layer transport layer of OSI model. The work of this layer is to ensure the data obtained from the session layer reliably reach the other device. This layer uses two types of transmissions to reach data:

Connection Oriented
Before sending data to the connection oriented, the sender creates a single connection signal with the customer. It happens in case of TCT.

Before sending data to the Connectionless Oriented, the sender does not have any connection with the subscriber to the connection of any single signaled signal. It happens in the case of UDP.

3. Network Layer:
The job of the network layer is addressing and packet delivery. This layer includes encapsulation by adding network address to the data packet. The router is used in this layer and the routing table is created.

2. Datalink Layer:
This is the second layer of OSI model. The task of the Datalink Layer is to send datagrams from one device to other devices through the physical layer. This layer creates logical links between the two devices. This layer transforms the data into frames.

1. Physical Layer:
The bottom layers of the OSI model are the physical layers. This layer will be transmitted to a device with any device in any way, whether it is an electronic signal or a data bit format etc. This layer contains data bit-to-bit transfer. The devices used in this layer are hubs, switches etc.

There will be more such tips and tricks in our next lecture.
The OSI model is like this today. Our next lecture is TCP / IP. Thanks For Reading Post 


  1. This concept is a good way to enhance the knowledge.thanks for sharing. please keep it up machine learning certification

  2. Thanks for taking the time to share this article here about the CCNA. Your article is very informative and I will share it with my other friends as the information is really very useful. Keep sharing your excellent work. Simply2cloud offers the Best CCNA Training in Delhi at most affordable prices.


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