Learn Computer Basics
Chapter one: OSI model
Mr Shark
Hello people this is Shark the author today we will learn about computer networks and there's my assistant Nemo who's gonna assist us
Mr Shark
So first thing we will learn about computers is how they communicate
Nemo
Liked wired and wireless?
Mr Shark
Yes nemo but there's a protocol that every computer follows while communication. Wired and wireless are subjects where we will discuss later-
Nemo
Oh i know the protocol you're talking about its osi model right ?
Mr Shark
Yes Nemo its the very same osi model but for those who don't know osi model is a 7 layer protocol which is the main backbone of communication between different computers
Mr Shark
tell me the name of the 7 layers nemo
Nemo
The osi model has 7 layers namely
Application layer
Presentation layer
Session layer
Transport layer
Network layer
Data link layer
Physical layer
Mr Shark
Very good that's absolutely correct and while communicating the computers follow from the app layer down to the physical layer from where the data travels in raw bits to the physical layer of other computer and from that physical layer it goes upto application layer for us to look at
Nemo
But Uncle Shark does this happen all the time ? Like every second ?
Mr Shark
Yes Nemo it happens with every single packet sent on the network this is how networks work as we know the data is sent into the forms of small packets each packet follows this protocol until it reaches the destination.
Mr Shark
Okay guys now we have to end this chapter we'll meet again in the next one
chapter 2
Mr Shark
Ayo guys its the night before exam and i am writing this new chapter
Nemo
yea because Mr Shark knows he is gonna fail
Mr Shark
Lol but anyways today we'll take a hop on to the tcp ip model
Nemo
But whyyyy??? what about osi model ?
Mr Shark
Why? Because osi model is useless anyway
Mr Shark
you see in 1960s the networks weren't designed to allow resource sharing among users in different networks and because of this internet was started as a project to interconnect various LANs in US universities nd govt installations to what was called Arpanet using leased telephone lines
Nemo
Yeah but what's that got to do with the osi model ?
Mr Shark
Yeah we are gonna talk about that now- so you see this new project was using satellites radio networks etc right ? because of that the osi model failed
Nemo
I seee but how did they fix that?
Mr Shark
They introduced a new architecture called the tcp ip model it was more flexible and could easily take in heterogeneous networks they are versatile and just 5 layered unlike the osi model
Nemo
Oh what are those layers?
Mr Shark
They are
Application transport network data link and physical
Mr Shark
The first three layers of the osi model were merged into one application layer
Mr Shark
For today this is enough let's dive deeper into it later
chapter 3 the tcp ip model
Okay sorry for the long delay
Nemo
Mr shark ? Where are you?
Mr Shark
Here i am sorry i took too long to create the script ( i was busy watching movies and sleeping)
Mr Shark
Well yeah the tcp ip model
Nemo
yea we were talking about that you said you'll explain more in the next chapter
Mr Shark
Yeah right thanks nemo
Mr Shark
So yeah i was saying that the tcp ip model was a shrinked down and more compatible version for various devices across the internet which didn't work well with the osi model when the computer scientists tried to implement it on a vast scale
Mr Shark
and the layers became something like
Application
Transport
Internet
Network access
Now all these names are just a more polished version of names in previous osi model hut they are the same thing
Nemo
You're gonna explain them too in this chapter right ?
Mr Shark
Yes nemo don't be hasty tho
Mr Shark
Haha so first is the Network access layer which is again the basic physical layer consisting of cables wifi radio networks mac addresses et cetera and is most of the time out of our control
Nemo
Wait- why is it out of our control-
Mr Shark
When I say its out of your control i mean you can perform operations like playing with wires networks packets and physical address ( mac addresses) but you can't make them or develop them- physically you'd have to be a researcher or a scientist for that-
Nemo
I see i see so its something related to having partial control but not complete is that right?
Mr Shark
Exactly its more easier to understand when you play with them
Mr Shark
Next is internet layer which is responsible for routing and logical addressing
Nemo
Wait wait wait Mr Shark- what are these i don't understand-
Mr Shark
Its okay let me tell you in short
Routing is like playing a guide when you visit another country our computers are dumb cute machines that need a brain( well they have a brain but they can't think { yeah i know about artificial intelligence i'll tell you later in detail})
Nemo
So you're saying routing is providing the way for the traffic ?
Mr Shark
Yes nemo- that's what routing means in simple words
Nemo
What about logical addressing? It sounds too complex-
Mr Shark
Its not that complex young man- logical addressing refers to assignment of destination address and source address to your envelope of your information you can't just throw your letter in the air and expect your crush to catch it and read it do you?
Mr Shark
Exactly, lets move on to the next layer
Nemo
Yay transport, i wanna grow up and build a transport business i'll have so much money
Mr Shark
Yeah ? Study first kiddo- so transport layer refers to the same transport layer from osi model it is responsible for selecting protocols or certain sequence of instructions or primitives (or format) in which data is being transferred now these protocols can be of two types tcp and udp which you'll mostly encounter while working in a company or something unless its space agency
Mr Shark
Tcp stands for transmission control protocol and is a reliable and much secure method of transferring data now this data transfer is slow- very slow but reliable
Mr Shark
this episode is too long right?
Nemo
yes Mr Shark i am tireddd-
Mr Shark
Alright we'll continue in next chapter
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