The document discusses the OSI model, developed by the International Organization for Standardization in 1974, detailing its seven-layer architecture that facilitates data transmission across networks. Each layer, including the physical, data link, network, transport, session, presentation, and application layers, has distinct roles such as error correction, addressing, and session management. The summary highlights the interdependence of these layers in ensuring reliable and efficient data communication.

1. BS Telecommunication System
Session : 23-27(Morning)
Topic : OSI MODEL
Group A
• Mubeen Zahid
• Zain Haider
• M . Faizan
• Hamza Khan
• Abdullah Mehboob
• M. Taha
• Habib Khan
Submitted To : Ma’am Sadia
Subject : Introduction to telecommunication
Roll No
1. BSTS-23-09
2. BSTS-23-30
3. BSTS-23-22
4. BSTS-23-11
5. BSTS-23-31
6. BSTS-23-04
7. BSTS-23-24

2. The OSI Model
OSI stands for Open Systems Interconnection.
It has been developed by ISO – ‘International Organization of
Standardization‘, in the year 1974.
It is a 7 layer architecture with each layer having specific
functionality to performed.
All these 7 layers work collaboratively to transmit the data
from one device to another across the globe.

3. Physical Layer
1 Physical Specs
Defines physical and electrical
specifications
2 Transmission Media
Cables, wireless, fiber optics, etc.
3 Encoding/Signaling
Converts data into electrical signals
Uses
Responsible for the
physical and electrical
specifications of the
network, including cables,
connectors, and signal
transmission
Purpose
Ensures the reliable
transfer of data bits
between devices.
Examples
Ethernet cables, coaxial
cables, optical fibers, and
radio waves

4. Data Link Layer
Error Detection
Identifies and corrects errors
Access Control
Regulates access to shared
media
Framing
Packages data into frames
Uses
Responsible for the reliable and
error-free transfer of data frames
between directly connected
devices.
Purpose
Ensures the accurate delivery of
data by detecting and correcting
errors that may occur in the
Physical layer.
Examples
Media Access Control (MAC)
addresses, Ethernet, and Wi-Fi.

5. Network Layer
IP Addressing
Assigns logical addresses
Routing
Determines best path for data
Packet Switching
Breaks data into packets
Logic Circuits
Manages network traffic

6. Transport Layer
1 Flow Control
Manages data rate between devices
2 Error Correction
Ensures reliable data delivery
3 Segmentation
Breaks data into smaller packets
Uses
Responsible for end-to-end
communication and the reliable
transfer of data
between applications.
Purpose
Ensures that data is delivered in the
correct order, without errors, and
without
loss.
Examples
Transmission Control Protocol (TCP)
and User Datagram Protocol (UDP).

7. Session Layer
Checkpoint
Establishes & maintains sessions
Synchronization
Coordinates communication
Recovery
Restarts interrupted sessions
Purpose
Ensures the smooth and
continuous flow of data between
applications, even in the event of
system failures or interruptions.
Uses
Responsible for establishing,
maintaining, and synchronizing
communication sessions
between applications
Examples
Session management protocols
like RPC and SQL

8. Presentation Layer
Data Formatting
Converts data to common
format
Encryption/Decryption
Secures data transfer
Compression
Reduces data size for
efficiency

9. Application Layer
HTTP Web browsing
SMTP Email
FTP File transfer
DNS Domain name resolution