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.
