Rise of Internet

In today’s era internet is a way that we communicate, book ticket, transfer file and data to other, watch live stream etc.. activities done by the help of the internet. But this blog is not about the capability of the internet. the motive of this blog is to tell how internet work under the hood and how the actual data is transfer between device to device

Overview

In this article, we are going to study how the file, data, video is transfered over the internet. how does the online zoom, google meet take place etc..

Problem Statement

Imagine you are in the era of the where internet just discovered. At that time the only we can share the file, image and video etc … only possible by storing the data in the cd, dvd etc… and streaming is not even exist and possible.

Also, this is one more problem is the two devices like computer and laptop how they are going to communicate each other. Even they can share data if both are at the end of the world.

Introduction to the OSI model

To resolve this problem this International Organization for the standardization give a theoretical framework called OSI model. OSI model is divided into 7 layer and these 7 layer are responsible for the communication of the two and more devices. The idea is if devices need to communicate with each other they need to follow some sort of protocol. these protocol decide which kind of data we share over the internet.
Some protocol are HTTP, TCP, IP, UDP etc.. these are the popular protocol which is used to share the data. In which TCP/IP.

These 7 layer plays all the role of the communication. the name of these are give below along what they do individual

Application Layer

This layer is the top most layer and is exposed to the end user for eg whatsapp, gmail, etc…
This layer follow some protocol like HTTP, FTP, SMTP and DNS.

HTTP: stand for Hyper Text Transfer Protocol**.** This protocol is depend on the TCP. which ensure the delivery of data from one device to another device. In the upcoming article I’m going to explain more about the 3-way handshake.

Presentation Layer

This layer is responsible in converting the plain text into the cipher text so that hacker and anyone can’t read the message or data during transport.

The data moves from the Application layer to presentation layer and it also compress the data.

Session Layer

This layer is reponsible for create a channel, communication medium by which data (packet) move from sender side to receiver side

Transport Layer

All the magic of data sharing and communication happened at this point where data (packet) is going to follows some set of rule for the communication.
Most commonly used protocol are TCP and UDP

TCP stand for transmission control protocol, this protocol make sure the reliability and ensure the data is delivered successfully and completely
where as, UDP stands for User Datagram Protocol, this protocol is mainly when data is delivered where reliability does not play much role and communication is done in a very fast manner.
Now, At this point the question is arise when to use which protocol and why?

TCP:- this protocol ensure data will be delivered to you in a complete form with any data loss. But does it mean.
It means suppose I’m share a code file which contain the major feature of the company and I want to share this file to my develop friend. So, if the network is unreliable the file may result in the loss of the code and also file get corrupt at that point i want my data should be delievered to the develop proper and complete (Integrity). At that point of time TCP play a significate role.
use case of the TCP are email, file transfer, remote terminal access etc…

UDP:- this protocol ensure data is delivered but it does not ensure data will send to you is complete. Now at this point again a question is arise then what is the usecase of sure protocol, why sure protocol exist
The reason such protocol exist because of one reason low latency. when i want the data must delivered in the real time At that point of time UDP exist.
Most common example is vedio streaming, chat system, live score, even gaming as well etc… use UDP for the real time data.

Network Layer

This layer is like the postman which require usually know the sender and receiver logical address.

As well as there are 2 more layer which help in the flow of the packet from one network to another network which is also know as Data link layer and physical layer.

TCP v/s UDP

Protocol	TCP	UDP
Reliability	More reliable	Less reliable
Connection	3-way handshake	No handshake
protocol	HTTP, HTTPS, SMTP etc	DNS, VoIP etc..
use case	Email, file transfer, remote access etc…	live stream, stock, market etc..

Summary

key rule to remember is when we need data must delivery complete use TCP. and reliability does not much and where data loss is bearable at that point of time use UDP