What is an OSI?

•OSI stands for Open System Interconnection

•This was developed by the ISO (International Organization for Standardization) in the year 1977.

What is the Main Objective of the OSI

Model?

–To standardize Networking to make sure that everyone was connected through a common network standard.

7 Layers

Layer Function7 Application

6 Presentation

5 Session

4 Transport

3 Network

2 Data link

1 Physical

To Remember the 7 Layer

Layer Function

Note

7 Application All

6 Presentation People

5 Session Seem

4 Transport To

3 Network Need

2 Data link Data

1 Physical Processing

PHYSICAL

•This is the Layer that physically connect the networks together.

•Hardware•Medium of Signals

–Such as Cables, satellite, etc.

Some Physical Layer Devices

Split the data into packets This layer makes possible divide a way to exchange data

or a common local media

DATA LINK

Send packets to address Supplies the means to

exchange pieces of data over the network between identified and devices.

NETWORK

Ensures that packets arrive, and error free and are in correct order

TRANSPORT

Established and coordinates connection between computers

This layer establishes, manages, and terminates connection also known as session between 2 network address

SESSION

Allows transfer of files between different formats. Encryption is one of the services in this layer.

Encryption is the translation of data into a secret code. Encryption is the most effective way for data security. To read an encrypted file you must have a password or a secret key.

PRESENTATION

This is the layer where people do their work , such as sending e-mail or requesting to transfer a file across the network

E-mail, files requests, file transfers, etc.

APPLICATION