Computer Networks (OSI Model)

Hello Guys, This is my second blog writing about Computer networks. Computer networking knowledge is very curial for understanding how the internet works. So let's start.

OSI Model:-

OSI model stands for open systems interconnection model. It was developed for how two or more computers communicate together. It's a standard of how peoples and servers communicate with each other. There are a few layers in the OSI model internet is very complex there a lot of this happens on the internet. There basically seven layers in the OSI model.

1) Application Layer.

2) Presentation Layer.

3) Session Layer.

4) Transport Layer.

5) Network Layer.

6) Data Link

7) Physical

Application Layer:- Application layer is what as the name suggests an application. the user who is interacting with the application like sending messages, surfing the web and etc is done at the Application Layer. In simple words, the application layer contains applications like browsers, messaging applications and so on.

So you send data from the application layer to the presentation layer.

Presentation Layer:- after getting data from the application layer. The presentation Layer converts the data eg: if the data contains strings, or a number so it will get converted into machine code like from ASCII to EBCDIC. EBCDIC stands for extended binary coded decimal interchange code. Encryption, compression and translation of data are done in this layer.

Then after the data is sent to the session layer

Session Layer:- Session Layer is the layer of the ISO Open Systems Interconnection (OSI) model that controls the dialogues (connections) between computers. It establishes, manages, and terminates the connections between local and remote applications.

So next the data is transferred to Transport Layer.

Transport Layer:- So now the user has sent the data using the application layer to the presentation layer and the presentation layer has sent the encrypted and compressed data to the session layer session is established in the session layer and now transportation of data takes place how data will transport to another user. basically, transportation is done using TCP and UDP protocols. protocols are nothing but how data is transferred

Now we come toward Network Layer

Network Layer:- Network layer works very simply like the transmission of received data segments from one computer to another located in a different network. basically above the layer where communicating with its own network but the network layer is not communicating with a different computer network. This is where the router lives. logically addressing is done in the network layer. because we know that every computer has its own IP address. Load balancing is also done in this layer.

Data link Layer:- so the data link layer will be the data packet from the network layer. This data packet contains the IP address of both computers. What does the data link layer do? data link layer does the physical addressing of data packets. physical addresses are MAC addresses. now mac addresses of the sender and receiver are assigned to data packets.

Physical Layer:- Physical basically consists of the hardware section. the data you get here is like 0's and 1s and this is transported using wires or local media like electrical signals or light signals in the optical fibre cable or whatever or a radio signal in case of wifi

OSI Model Diagram

There's another model called TCP/IP model

It's mostly similar but little bit of difference between layers like TCP/IP model has 5 layers

1) Application Layer

2) Transport Layer

3) Network Layer

4) Data Link

5) Physical

TCP/IP is used commonly nowadays and OSI models are concept based.