Hello mates and welcome back.
Today I am here with an interesting topic which is OSI Model, the network theater (something I came up with😅). Let us learn it in a fun way so you can understand and remember it better. Let the fun begin!!!
What is OSI
OSI model stands for Open Systems Interconnection Model which is kind of a way your data is processed through the network. I guess you are a bit struck. Don’t worry, let me put it straight with an example. Imagine you have a friend and living way back in the 1900s(just imagine). How would it be, without the internet and mobiles, feels bizarre right? Anyway, now you are in the 1900s and you need to communicate with your friend. What would you do? Yes, you are right. You simply write a letter to your friend and send it to him. Wait a minute. That sounds simple, but there is a lot that happens between you sending a letter and your friend receiving it. How about we break down the steps in between and understand, shall we?
If you are a cyber geek too in that era, then you would definitely be concerned about your privacy of the letter. This is why you wrote the letter in Morse code so that only you and your friend can understand. After you have finished writing, you put it in an envelope and then dropped it in a post box. The next day postman collected it and took it to the post office. There the letter is sorted as where to go(the location of your friend). Now they stamp the post with their postal address and send it to shipping. It now travels to reach the destination.
Now let us see how it gets received at the other end. It traveled by bus and reached your friend’s town. They check if it is legit by verifying the postal stamp. It again gets sorted to which street the letter has to go. Placed at the postman’s desk. He gets the letter to your home mailbox. You receive it Translated the Morse code to the original language and you read it.
Interesting, isn’t it? Now you may be wondering why this is all so related to the OSI model which we should be discussing. I told ya. We are going to learn it in an easy way. The easy way to learn anything is by picturing how it works. That is why I made you picture the whole thing. You still can’t connect the dots!! Don’t worry. I’ll connect them and by the end, you will be a pro at this🤝. Just remember and picture it whenever necessary.
Layers in OSI Model
There are a total of 7 layers in the OSI Model. They are
Let us learn about each of them and connect it with our story. The OSI model starts from the Physical layer, but for better understanding, I’m going to start with the Application layer.
Application Layer : This layer is the most familiar layer for us as we can directly access it. This is the GUI of the application. Like the letter, we are the owners of it and can do what we can as long as it supports(Like you can’t cook it and send it, you can only write on the letter. As long as your features support you can do whatever you want).
Presentation Layer : This is where standardization starts to take place. Like whatever the function we provide in the GUI it has to be handled in the same way. For example, we have email software and the information we provide in it has to be handled and sent to the receiver without any loss, even if the receiver has a different email client. Here come Security features such as data encryption, which in our story is the Morse code we used to provide security to our letter.
Session Layer : By the name itself we can conclude that it manages sessions. Once the data is translated successfully from the presentation layer, this layer creates a session between the two computers and once the connection is established session is created. This layer includes authentication and re-connections. Here the data is divided into small chunks of data called “Packets” and sent. In our story, as we put the letter in the post box, a session is created between our and your friend’s mailbox, and then the transportation starts. This brings us to our next layer.
Transport Layer : This is the vital part of transmitting data across networks. It manages the delivery, error checking of the data and provides reliability in delivery. It regulates the size and transfers the data between systems. It uses either TCP or UDP protocol. Like our letter being sent to the post office, where it is checked and divided into which category it belongs to.
Network Layer : This is where the interesting part begins. Sorting and assembling of the divided small chunks of data happen to make a larger chunk of data(complete data). And then it chooses the best path to send the data which is effective in all ways(time and distance-wise). IP addresses of the computers are dealt with in this layer. As in our story, our letter gets sorted as to where to go along with other letters(The postal office just don’t deliver our messages, but other messages too)
Data Link Layer : After receiving packets from the Network Layer(along with IP address) MAC address(Media Access Control) of the other computer is assigned to it. In every network-enabled computer, there is a NIC(Network Interface Card) which has a MAC address burnt into it. It also corrects the errors that may have occurred in the Physical layer. Like in our story stamping the postal address and shipping it.
Physical Layer : This is the topmost layer in the OSI Model and easiest to understand. This works with the physical components which communicate with signals and bits(0’s and 1’s) by sending the data from one physical layer to another physical layer. Here we come across switches, hubs, etc. In our story going through one transport to another(maybe by bus😅)
This OSI Model is a two-direction model as it goes from Application Layer to Physical Layer in one computer while in the other end it starts from Physical Layer to Application Layer. Data is transferred in this way across the network and shared between two systems/computers.
So I hope all your dots have been connected and next time someone asks you about the OSI model, you are going to rock it. That’s all from my side today and catch you up again in the next post. Check out my Instagram to get more updates and tricks.
Till then take care and Happy Learning!!!👋👋👋
