This a brief description of the seven layers of the OSI Model.

2. INTRODUCTION
 The Open Systems Interconnection (OSI) model describes
seven layers that computer systems use to communicate over
a network.
 It was the first standard model for network communications,
adopted by all major computer and telecommunication
companies in the early 1980s
 The OSI 7-layer model is still widely used, as it helps visualize
and communicate how networks operate, and helps isolate
and troubleshoot networking problems.
 OSI was introduced in 1983 by representatives of the major
computer and telecom companies, and was adopted by ISO as
an international standard in 1984.

3. In order to accomplish successful network between computers, seven layer OSI
Model is build.
Each layer in the OSI Model is a package of protocols.
APPLICATION LAYER PROTOCOLS

4. THE
SEVEN
LAYERS
OF THE
OSI
MODEL

5. LAYER 7: APPLICATION LAYER
Application layer is used by applications that use network.
Eg;
HTTP
HTTPs

6.  There are various protocols which make various applications that use network to work.
All these network protocols form the Application Layer.
These protocols help in :
File Transfer Web Surfing E-mail
FTP HTTP/S SMTP
File transfer protocol (FTP) is a set of rules that computers follow for the transferring
of files from one system to another over the internet.
HTTP stands for HyperText Transfer Protocol.
It is a protocol used to access the data on the World Wide Web (www).
The HTTP protocol can be used to transfer the data in the form of plain text,
hypertext, audio, video, and so on.
The Simple Mail Transfer Protocol
is an internet standard
communication protocol for
electronic mail transmission. Mail
servers and other message
transfer agents use SMTP to send
and receive mail messages.

7. LAYER 6: PRESENTATION LAYER
Presentation Layer receives data from the application layer.
This data is in the form of characters and numbers.
These characters and numbers are converted into machine understandable language or
binary language by the Presentation Layer.
Now, this conversation of the characters/numbers into binary form is called as Translation.
Before data is transmitted, presentation layers reduces the bits that are used to represent
the original data . This bit reduction process is called as Data Reduction and it can be Lossy
or Lossless.

8. To maintain the integrity of the data, Encryption is done. This enhances the security of
the data.
At the sender side, the data is encrypted and at the receiver side the data is decrypted.
SSL(Secure Sockets Layer) Protocol is used in the encryption and decryption process.
Encrypted Decrypted

9. LAYER 5: SESSION LAYER
 Session layer helps in setting up and managing connections
enabling sending and receiving of data followed by termination of
connections and sessions.
 Session layer uses APIs which allows applications on different
computers to communicate with each other.
 Functions : Authentication and Authorization

10. LAYER 4: TRANSPORT LAYER
The layer below the Session Layer is the Transport Layer.
The Transport layer controls the reliability of the the communication through
Segmentation, Flow Control and Error Control.

13. LAYER 3: NETWORK LAYER
Network layer works with data segments received from the transmission layer from
one computer to another in different networks.
Data units in the network layer are called Data packets.
It is the layer where routers reside.
Functions of network layer:
Logical Addressing : A logical address or virtual address is an address that is generated
by the CPU during program execution. A logical address doesn't exist physically.
The logical address is used as a reference to access the physical address.
Routing : Routing is the process of selecting a path for traffic in a network or
between or across multiple networks. ... Packet forwarding is the transit of network
packets from one network interface to another
Path Determination: The path determination function enables a router to evaluate the
available paths to a destination and to establish the preferred handling of a packet.
Data can take different paths to get from a source to a destination. At layer 3, routers
really help determine which path

14. LAYER 2: DATA LINK LAYER
 The data link layer receives data packets from Network later to the Data Link layer.
Data packets contains IP addresses of the sender and the receiver.
There are two kinds of addressing:
1. Logical Addressing : Network layer
2. Physical Addressing : Data link layer

15. LAYER 1: PHYSICAL LAYER
One of the major function of the Physical layer is to move data in the form of
electromagnetic signals across a transmission medium.

16. OVERALL VIEW

17. THANK YOU!!!