Osi Model | Computer Networking (easy And Quick Guide)

What is computer networking?

Lets Say OSI is a package of rules. And in Networking always remember, rules = protocols. So any protocol you will hear in future, get to know that it's basically means "rules".

Some questions you might have like what is OSI model?, why we need OSI model?, what if we don't use it?, what are the advantages/disadvantages, let's cover them all!

so firstly let's clear,

WHAT IS OSI MODEL?

consider a scenario, there are two users A and B. User A has windows in his pc and user B has mac-os in his pc. Suppose windows supports ASCII code system and mac-os on the other hand understands only EBCDIC system. So is their any possibility of communication between this computers?

Answer is No. So there must be a rule to perform a successful communication between those devices and hence we have OSI model in our hand.

so OSI model is set of rules that every manufacturer will accept so the communication will be successful, which is the most priority and basic use of the Internet! This also clears why we need OSI model as well.

there are several different types of rules in OSI model, let's have a look into those:

7-LAYER OSI MODEL PROTOCOLS(RULES) :

APPLICATION LAYER - As name suggest, this layer consist of Application layer rules that every application such as chrome, firefox etc. application shall obey it doesn't content application but the rules that application should follow. which are the protocols? : http/https etc.

PRESENTATION LAYER - Imaging user A sending message of 'Hi' to user B, and when we talk about internet, we need protection for our data, as a user want his privacy at being online so in presentation layer Encryption occur which convert our alphanumeric values(which content alphabets and number) into hexadecimal encrypted value along with abstraction(which reduces the size of data). And that's not only this layer do, but also Translation (conversion of simple language data into machine understandable code) is done here too.

SESSION LAYER - You currently on your browser, connected with some server to read this blog, suppose you wanted to write your own blog, so in that case you want your own account, right? and the moment you write a blog and publishes it, it will be reflect to your account and not in my account, also when you log out, its only you who is logged out. it's so accurate, isn't it? its all of because session layer. it set up and manage connection that enables sending and receiving of the data, it also help in termination of the connection that was done by this layer itself. and lastly it also tracks the client site activity by authentication and authorization.

TRANSPORT LAYER - Let's get back into our example when User A sends message to user B of 'Hi', so that data is now encrypted and abstracted also. Now TRANSPORT LAYER will segment the data(it will divide the data into parts) along with checksum (just a set of bits in arrangement that will help us to detect any data loss if that happens). that's not the only this it do, but it allows flow control - if client supports 10mbps and server supports 100gbps(say) so there must be flow control of data to avoid load on either of devices.

NETWORK LAYER - Now user A's message 'Hi' is reached on a server, how the server will find User B? so by Logical addressing by using routing that choses network destination with correct device by using unique IP address. that's not the only thing it does, but it do all this thing very fast by the term path determination which means it finds the faster route than other. also all this data is transferred as Data packet. remembered we talk about segmentation in transport layer? so data packet is nothing but IP address + segmented data

DATA LINK LAYER- say data arrived at your device but to which application we have to send the data? so here comes Physical addressing which content mac address of both sender and receiver with data which is called as FRAME. It helps the data to send on correct application. say User A send the data to whatsapp so User B will receive the data in whatsapp only not on any other application.

So it is what all about the OSI model if you gained any knowledge out of it, I appreciate! thank you for reading !