PHYSICAL LAYER- Layer 1

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Please watch this video on Physical layer by clicking on the tag.



In this video i have discussed about Physical layer of the OSI model i.e. the 1st Layer of the OSI model, Basic function of the layer, data flow chart, how data is transferred from sender to receiver, data encapsulation and decapsulation and short difference between between OSI and TCP/IP Model.



In the table i have mentioned about which form of energy will require what type medium or wire to transmit.

Now in this diagram you can see format of data transfer from Application to Physical layer, to make it understand we need to see all the tasks performed by each layer from 7th to 1st.

Let us take an example, Support a user X wants to open https://www.google.co.in so what exactly he wants is to access secured version of http so firstly system of user X will transfer an https request to Application layer. Application layer will put an port header 443 on the request data and pass it further to Presentation layer, Physical layer will encode the data and compress it and transfer it forward to Session layer, Session layer will define time limit to the data means lease time and lease expiry, Session will transfer to Transport layer, transport layer will identify whether the data will be transferred by TCP OR UDP and will put a transport header on the data and will form a segment, segment will be transferred to Network layer, Network layer will put a network header (containing ip address of source and destination) on the segment and create a packet of that segment that packet will be further transferred to Data Link layer, Data link layer will add data link header (MAC Address ) and data link tail (CRC) and packet will be converted into Frame and frame when transferred to Physical layer it will be converted into electrical form. 

You can see in this diagram how data is been transferred from Application layer of sender to Physical layer of receiver and the whole process shows Data Encapsulation and Decapsulation.

Next we have comparison between OSI Model and TCP/IP Model, both the model are vital for CCNA or networking students.

So, Difference in OSI and TCP/IP are as follows :-

• OSI model have 7 layers while TCP/IP model have 4 layer.
• Top 3 Layers of OSI model i.e. 7, 6 & 5 is merged into 1 layer in TCP/IP as Application layer all the tasks that were performed by Application, Presentation and Session layer in OSI is done by single layer in TCP/IP.
• Transport layer remains same like OSI.
• Network layer is changed to Internet layer in TCP/IP.
• Data link and Physical layer is merged into Network Access layer which performs a combined task of both layers in one.

So that's from OSI model and physical layer. Please do subscribe to my blog as i always post blogs related to Networking, CCNA, Electronics and new technologies.

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SESSION LAYER NO- 5

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This video is about the session layer of OSI model.
What is the basic of the session layer to view the video click on the tag.

It is the 5th layer of the OSI model and is useful defining time bracket for task, lease time for IP etc.

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APPLICATION LAYER NO- 7

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Please check my new video on Application Layer of OSI model. In this video i had discussed on Application layer basic and how does it works. Find it by pressing on link or on video



your feedback is required most and please feel free if you have any suggestions.

Now we will discuss about 7th layer of OSI model i.e. Application layer.


In this diagram we can see that from Application layer a port no of the function that has to be performed for e.g. 443 for https or 80 for http is placed like a header on data i.e. called as Application header and forward to Presentation layer.

The list of port numbers is very long some are given below i.e. used mostly :-

If you have to ask something please feel free. so, That's it from this post, See you in my next post. Please do subscribe. 

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OSI MODEL

Hey there guys,

This video is about OSI MODEL. In this video we have just explained the basic diagram of OSI MODEL. We will make separate video on each layer. you will get an introduction idea about OSI MODEL means what is OSI MODEL, who and when it was developed, data transfer in OSI MODEL and Basic layout of the layers.
Please find my new video by clicking on the tag on OSI MODEL.

You can also copy this link to your url - https://www.youtube.com/watch?v=nFNMiq9yxck&t=25s
if tag doesn't work.

So, what exactly is OSI Model?.

OSI means Open System Interconnect

In 1974, ISO (International Organization for Standardization) developed a model that was useful in the field of Communication. It is a 7 layer Architecture, A standard set for data transfer with all 7 layers have there own specific task to perform.

7 layers are as follow :-
1. Physical Layer
2. Data Link Layer
3. Network Layer
4. Transport Layer
5. Session Layer
6. Presentation Layer
7. Application Layer

But representation in OSI model is vice versa of this order.

These layers are categorized in 3 classifications depending on there functions. They are as follows :-
1. Upper Layer or Software control Layer
2. Heart of the OSI
3. Lower Layer or Hardware control Layer

1. Upper Layers or Software control Layers :- In this category 3 layers placed Application layer, Presentation layer and Session layer. These layer is responsible for functions to be controlled by software. E.g. - A user is entering https on url of it's computer browser then application layer will place port no 443 header on the data and by the help of encoding the data format will be changed and compressed and all this function is been performed by presentation layer and then session provides time specific for task means to say lease expiry is a good example for this i.e. the function of session layer. So it's clear now that all the function performed by these three layers are been done by the help of software i.e. why it is know as Software control layers.

2. Heart of the OSI :- It is the central layer of the OSI model i.e. Transport layer. It's main function is to identify whether the data will be sent from TCP or UDP.

3. Lower Layers or Hardware control Layers :- These layer is responsible for functions to be  controlled by hardware. In this category 3 layers are placed Network layer, Data Link layer and Physical layer. Router works on layer 3 i.e. Network Layer, Switches works on layer 2 i.e. Data Link Layer and the Last is Physical i.e. basically a layer which deals with wires and cables so all the three layers are controlling hardware i.e. why they are known as Hardware control layers.

Now the question comes in mind is why OSI was developed? what was the need???

In late 80's every vendor was using it's own proprietary method for communication so as a result only same vendor devices were able to interact with each other but they were not able to communicate with other vendor devices. To finish that barrier OSI was developed and was accepted by every vendor.

In the above pic the method of data transfer is shown in OSI model, what happens when data is transfer by the sender to receiver.

That's it from this post. If you have any questions please fell free to ask and it you like my video or post then please share it and don't forget to subscribe.

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