This document describes the seven layers of the OSI model and provides brief definitions of their functions. It explains that the physical layer coordinates signal encoding and transmission over a physical medium, the data link layer transmits bits between adjacent nodes using reliable links, and the network layer delivers packets from source to destination across multiple networks through routing and addressing. It also summarizes that the transport layer provides process-to-process delivery of entire messages, the session layer establishes and synchronizes communication between hosts, and the presentation layer handles syntax and semantics of exchanged information. Finally, it states that the application layer enables users to access the network through services like file transfer, email, and the world wide web.

1. OSI LAYER FUNCTIONS
S.SUDHA

2. LAYERS IN OSI MODEL
• APPLICATION LAYER
• PRESENTATION LAYER
• SESSION LAYER
• TRANSPORT LAYER
• NETWORK LAYER
• DATA LINK LAYER
• PHYSICAL LAYER

3. PHYSICAL LAYER
Coordinates the functions required to
carry a bit stream over a physical medium.
• Signal Encoding
• Transmission Medium
• Bit synchronization
• Transmission type
• Transmission mode
• Topology
• Multiplexing
• Interface
• Bandwidth
• Signal type

4. DATA LINK LAYER
Transmitting a group of bits between adjacent
nodes using reliable link.
• Physical Addressing
• Flow control
• Error control
• Medium Access Control
• Synchronization
• Node to node delivery

5. NETWORK LAYER
Source to destination delivery of a packet across
multiple networks.
• Routing
• Congestion control
• Logical addressing
• Address transformations

6. TRANSPORT LAYER
Process to process delivery of the entire
message.
• Host to host message delivery
• Application to application communication
• Segment and reassembly
• Connection

7. SESSION LAYER
Establish , maintains and synchronizes the
interaction among communicating hosts.
• Session and sub sessions
• Synchronization
• Dialog control
• Session closure

8. PRESENTATION LAYER
Concerned with the syntax and semantics
of the information exchanged between two
systems.
• Translation
• Encryption
• Compression

9. APPLICATION LAYER
Enables the user to access the network.
• Network abstraction
• File access and control
• Mail services
• Remote login
• World wide web

10. REFERENCE
• Data communication and networking
Behrouz Forouzan
Tata McGraw Hill
• Computer Networks
Andrew S.Tanenbaum
Prentice Hall of India

11. THANK YOU