4. The open systems interconnection (OSI) model is a conceptual model
created by the International Organization for Standardization which enables
diverse communication systems to communicate using standard protocols.
In plain English, the OSI provides a standard for different computer systems
to be able to communicate with each other.
The OSI Model can be seen as a universal language for computer
networking. It is based on the concept of splitting up a communication
system into seven abstract layers, each one stacked upon the last.
OSI MODEL
7. LAYERS OF OSI MODEL
Application Layer
The application layer is
not an application.
Instead, it is a
component within an
application that
controls the
communication
method to other
devices. It is an
abstraction layer
service that masks the
rest of the application
from the transmission
process.
Presentation Layer
The Application Layer is
topmost layer in the
Open System
Interconnection (OSI)
model. This layer
provides several ways
for manipulating the
data (information)
which actually enables
any type of user to
access network with
ease. This layer also
makes a request to its
bottom layer, which is
presentation layer for
receiving various types
of information from it
Session Layer
The layer 5 (control of logical
connections; also session layer)
provides inter-process
communication between two
systems. Here you can find
among others the protocol RPC
(Remote Procedure Call). To
resolve failures of meeting and
similar problems, the session
layer services for an organized
and synchronized data
exchange. To this end, recovery
points, so-called fixed points
(check points) introduced,
where the session can be
synchronized after a failure of a
transport connection again
without the transfer must start
from the beginning again
8. Transport Layer Network Layer
LAYERS OF OSI MODEL
The transport Layer is
thesecond layer in the
TCP/IPmodel and the fourth
layerinthe OSI model. It is an
endtoend layer used to
delivermessages to a host. It
istermed an end-to-end
layerbecause it provides a
pointto-point connection
ratherthan hop-to-hop,
betweenthesource host and
destinationhost to deliver the
servicesreliably. The unit of
dataencapsulation in the
Transport Layer is a segment.
The network Layer is the
third layer in the OSI
model of computer
networks. Its main
function is to transfer
network packets from
the source to the
destination. It is
involved both the
source host and the
destination host.
Data Link Layer
The Data-link layer is
the second layer from
the bottom in the OSI
(Open System
Interconnection)
network architecture
model. It is responsible
for the node-to-node
delivery of data. Its
major role is to ensure
error-free transmission
of information.
Physical Layer
The physical Layer is the
bottom-most layer in the
Open System Interconnection
(OSI) Model which is a
physical and electrical
representation of the system.
It consists of various network
components such as power
plugs, connectors, receivers,
cable types, etc. The physical
layer sends data bits from
one device(s) (like a
computer) to another
device(s).
9. TCP/IP Model
The OSI Model we just looked at
is just a reference/logical
model. It was designed to
describe the functions of the
communication system by
dividing the communication
procedure into smaller and
simpler components.
TCP/IP was designed and
developed by the Department of
Defense (DoD) in the 1960s and
is based on standard protocols.
It stands for Transmission
Control Protocol/Internet
Protocol. The TCP/IP model is a
concise version of the OSI
model. It contains four layers,
unlike the seven layers in the
OSI model.
