PHYSICAL LAYER- Layer 1

Hey there guys,

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.

Regards

Thank you

Enjoy

Good Luck 👍