How each of the Network Protocol layers work behind the scene

January 16, 2020

When we type google.com in our browser, we see the google home page. We are unaware of the back scene about how the each layer of the protocol works. In this post i will describe, how each of the protocol layer works.

First of all let’s see what are the layers involved in OSI and TCP/IP protocols.

TCP/IP and OSI Layers

Layers and their functions of OSI model

Layer	Task At Layer
Application Layer	Web browser that the user interacts with. (Google Chrome)
Presentation Layer	It takes care of syntax and semantics of the information that is exchanged between two systems. (Encryption and Decryption, Data Compression)
Session Layer	It establishes, manages and terminates the communication session. (Response Time)
Transport Layer	Segments and Reassemble the message, Adds port address, Connection control (TCP or UPD), Flow Control, Error control
Network Layer	Moving the packets from source to destination through routing. (Add IP Address to header)
Data Link Layer	- Defines the format of the data in the network, - Responsible for uniquely identify devices on the network, - (Adds MAC address and Logic link control LLC)
Physical Layer	- Transmit the bits from one node to another., - It establishes, maintains and terminates the physical connection., - It specifies what sort of media is used for transmission, this may includes cable type, radio frequency

Layers and their functions of TCP/IP model

Layer	Task At Layer
Application Layer	- User interact with the application, - Uses HTTP, FTP, Telnet
Transport Layer	- Responsible for reliable, flow control and error correction, - Uses either TCP or UDP
Network Layer or Internet Layer	- Transmission of packets, - IP, ARP and ICMP
Network Interface Layer	- How the data is to be send from the physical layer