Why bother?

Application Layer

Presentation Layer

Session Layer

Transport Layer

Network Layer

Data Link Layer

Physical Layer

Layer Overlap!

Exam Summary

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The Open Systems Interconnection (OSI) Model Explained

Target Audience

This e-book is aimed at:

·         Anyone totally new to networking and needing to get up to speed with the OSI portion of the CCNA

·         Anyone who finds networking books or manuals difficult to understand

·         Anyone who gets the feeling that networking books and manuals seem to be aimed at people who already understand networking

·         Anyone who’s been to a networking course already but wishes the trainer would have made just that little bit more effort to explain things better

·         Anyone who’s been to a course, or read a book about the OSI model but would like it explained again, in a slightly different way.

If you’ve ever been reduced to an "I’ll never understand this in time for my exam!" panic by intimidating techno-speak, this e-book is for you.

My objective in writing this e-book is to explain the different layers of the OSI model once and for all.   My strategy, which during my training career, I have found works every time, with hundreds of exam candidates is keeping it simple.

In the following chapters we shall discuss:

·        Why have a networking model at all?

·        The advantages of having the OSI model

·        Understanding the layers

·        What you need to pass the OSI portion of your exam

·        Watch out! Layer Overlap!

Before we go on, I think the chaps behind the OSI deserve a mention.

The International Organization for Standardisation (ISO) developed the OSI Model in the early 80s, although the OSI is not all they are known for. These guys do standards for everything, and I mean, absolutely everything. Take a look at some of the technical committees they have:

TC 8          Ships and marine technology

TC 10        Technical product documentation

TC 20        Aircraft and space vehicles

TC 22        Road vehicles

TC 23        Tractors and machinery for agriculture and forestry

TC 68        Banking, securities and other financial services

The next page discusses why they bothered inventing the OSI model at all.

Click here to continue…..