Introduction To The
Open Systems Interconnect Model (OSI)
Introduction
OSIis a standard
description or "reference model" for how messages should
be transmitted between any two points in a
telecommunication network. Its purpose is to guide
product implementors so that their products will
consistently work with other products.
The Model
The
OSI model was created by
the IEEE committee so different vendors products would
work with each other. You see the problem was that when
HP decided to create a network product, it would be
incompatible with similar products of a different vendor
e.g IBM. So when you bought 40 network cards for your
company, you would make sure that the rest of the
equipment would be from the same vendor, to ensure
compatibility. As you would understand things were quite
messy, until the OSI model came into the picture.
As most would
know, the OSI model
consists of 7 layers.
Each layer
has been designed to do a specific task. Starting from
the top layer (7) we will see how the data which you
type gets converted into segments, the segments into
datagrams and the datagrams into packets, the packets
into frames and then the frames are sent down the wire,
usually twisted pair, to the receiving computer.
Please
select one of the 7 layers by clicking on it, or simply
use the menu :)
The
OSI flash below is provided
to help you futher understand the functionality of the
OSI model:
The picture
below is another quick summary of the OSI model:
When you're
finished reading through the OSI model, to understand
how data travels through the layers and clearly see the
header which each layer add\removes, visit the
Data Encapsulation - Decapsulation
page.
