OSI (Open System Interconnection ) Model in Computer Networks

Open Systems Interconnection
(OSI) model is a reference tool for understanding
data communications between any two networked systems. It divides the

communications processes into seven layers. Each layer performs specific
functions to support the layers above it and offers services to the layers
below it. 
The three lowest layers focus on passing traffic
through the network to an end system. The top four layers come into play in the
end system to complete the process.

A networking model offers a generic means to
separate computer networking functions into multiple layers. Each of these
layers relies on the layers below it to provide supporting capabilities and
performs support to the layers above it. Such a model of layered functionality
is also called a “protocol stack” or “protocol suite”. 
Protocols, or rules, can do their work in either
hardware or software or, as with most protocol stacks, in a combination of the
two. The nature of these stacks is that the lower layers do their work in
hardware or firmware (software that runs on specific hardware chips) while the
higher layers work in software.

The main characteristics of the OSI model include the

• Helps users understand the big picture of
• Helps users understand how hardware and software
elements function together
• Makes troubleshooting easier by separating
networks into manageable pieces
• Defines terms that networking professionals can
use to compare basic functional  
   relationships on different networks
• Helps users understand new technologies as they
are developed
• Aids in
interpreting vendor explanations of product functionality

Name of seven OSI model layers are following: –
1.     Application
 2.     Presentation  Layer

                                               3.     Session

                                               4.     Transport
                                               5.     Network
                                               6.    Data
Link Layer
                                               7. Physical
 These all Layers are explain in next post….


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