Download Why to learn OSI reference Model?

Why to learn OSI reference Model?
The answer is too simple that It tells us that
how communication takes place between
computers on internet but how??
Nowadays, When we talk about communication of
computer we got to know a term communication
protocols. What are they??
Set of rules which defines the rules followed by all
involved in the process of communication but
what are they actually??
What if someone
rules/Protocols?
is
using
some
other
If it is necessary to communicate with computers
following totally different protocols then we have to
connect a device called Gateway between such
systems. Gateways are computers loaded with special
software, which do the job of translation work from
one protocol to other so that communication between
heterogeneous systems may take place.
The Seven-layer Architecture of the OSI model
PHYSICAL LAYER
To Data link Layer
From Data link Layer
TRANSMISSION MEDIUM
• Physical layer is the bottom layer of OSI model
• It is responsible for the actual physical connection
between the devices. Such physical connection
may be made by using twisted pair cable, fiberoptic, coaxial cable or wireless communication.
• Physical layer is concerned with transmitting raw
bits over a communication channel.
• It deals with mechanical and electrical
specifications of the interface and transmission
medium and also defines the procedures and
functions that physical device and interface have
to perform for data transmission.
• Physical layer is the bottom layer of OSI model
• It is responsible for the actual physical connection
between the devices. Such physical connection
may be made by using twisted pair cable, fiberoptic, coaxial cable or wireless communication.
• Physical layer is concerned with transmitting raw
bits over a communication channel.
• It deals with mechanical and electrical
specifications of the interface and transmission
medium and also defines the procedures and
functions that physical device and interface have
to perform for data transmission.
Function of Physical layer
• Transforming bits into signals
• Bit Synchronization
• Provides physical characteristics of interfaces and
medium
• Bit rate control
• Line configuration
• Transmission mode
• Physical topologies
• Multiplexing
• Circuit switching
DATA LINK LAYER
Functions of Data link layer
•
•
•
•
•
•
Framing
Physical Addressing
Flow control
Error control
Access Control
Feedback
Network Layer
Functions of Network layer
• Logical Addressing
• Routing
Transport Layer
• Transport layer provides two types of services
– Connection oriented
– Connectionless
Session Layer
Function of Transport layer
• Segmentation of message into packet and
reassembly of packets into message
• Connection management
• Service point addressing
• Flow control
• Error control
Function of Session layer
• Establishment, maintaining and ending a
session
• Dialog control
• Dialog separation or Synchronization
Presentation Layer
• Different computers may use different coding
schemes for data transmission. For example
some computers may send the most
significant bit of a byte first and least
significant bit last and in some other
computers it may be other way round, the
sequence may be different at byte level also.
The job of the presentation layer is to do the
job of code translation and present the data in
the format used at the destination computer.
Functions of presentation layer
• Data Presentation or Translation
• Data Encryption
• Data compression
Application Layer
• This is the layer with which users have direct
interface. At the transmitting computer the
message originates at this layer and at the
destination computer the message is finally
received by this layer and presented to the
user in desired format. The data packets at the
application layer are known as messages
Functions of Application Layer
•
•
•
•
Network Virtual Terminal
File transfer, access and management (FTAM)
Mail services
Directory services
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