Friday, 30 January 2015

Computer Studies Made Simple : Open System Interconnection Model / OSI

Open System Interconnection Model / OSI :

This model allows communications between two systems with different architecture.

Composition of OSI

It consists of seven layers.

These are as follows:

1.       Physical Layer

2.       Data Link Layer

3.       Network Layer

4.       Transport Layer

5.       Session Layer

6.       Presentation Layer

7.       Application Layer

Physical Layer

This is the bottom layer of OSI Model.

It is responsible for transmission of bits and data and determines the control signals.

It also defines the characteristics and type of transmission medium.

It also defines the type of encoding

It determines the data rate or number of bits that should be sent per second.

Data Link Layer

This layer divides stream of bits into small easily handled units called frames.

It ensures system to control rate of transmission of data such that there remains a balance between rate of receiving and transmission of data.

It also detects damaged frames  and prevents duplication of frames.


Network Layer:

This layer manages the establishment,maintenance and termination of network layers.

It determines a path between sender and the receiver and manages the delivery of data from source to destination.


Transport Layer:

This layer is responsible for ensuring efficient data transmission takes place between the sender and the recipient.

It eliminates errors in the messages and divides larger data packets into smaller ones for efficiency in data transmission.


Session layer:

This layer pertains with users management.

It helps in establishing,managing and terminating connections between users.


Presentation Layer

This layer plays a role in changing data and formatting it such that it canbe transmitted between the sender and recipient effectively.

It can also compress a large sized data into smaller size a process called compression.

Application Layer:

This layer provide services to the users such as emails,network sharing etc.

     



   

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