What’s The OSI Model

OSI Model: The 7 Layers Of Networking

What’s The OSI Model? Since we can’t actually see what happens when we send an email, the Open Systems Interconnect (OSI) model was created to represent data traveling through the network.  The OSI model takes a layered approach starting at the physical equipment and goes up to the application layer then back to the physical layer.  This model allows users the ability to understand the 1 and 0’s (binary) of networking.  Let’s look at every layer a little more in-depth.

OSI MODEL LAYERS

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Layer 7 – Application Layer

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The Application Layer is what you’re using to read this blog.  This layer houses all the applications a user will interact with.  Examples are Chrome, Safari, Facetime, Internet Explorer, Etc

Layer 6 – Presentation Layer

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The Presentation Layer decides how things are presented to the user.  It’s responsible for encryption and decryption as well.  For example, when you log into your online bank the presentation layer ensures that the information is encrypted via SSL.

Layer 5 – Session Layer

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The Session Layer is responsible  for initiating and terminating sessions.  So whenever you need to communicate with another person or device, the session layer makes it possible.

Layer 4 – Transport Layer

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The Transport Layer is responsible for transporting data.  It accomplishes this via two methods.  UDP and TCP.  UDP transmission is very fast but maybe unreliable, while TCP is slower but very reliable.

Layer 3 – Network Layer

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The Network Layer is where IP addressing and routing reside.  An IP address is simply your device’s address on the network.  This address is routed to its proper destination via a router.

Layer 2 – Data Link Layer

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The Data Link layer is where mac addresses and switching reside.  MAC addresses are simply the physical address of every device on your network.  A switch ensures that the data gets to the correct destination on your network.

Layer 1 – Physical Layer

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The Physical Layer is comprised of the physical components.  From cabling to motherboards and CPU pin layouts.

Remembering The 7 Layer OSI Model

TOP DOWN

ALL PEOPLE SEEM TO NEED DATA PROCESSING

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BOTTOM UP

PLEASE DO NOT THROW SAUSAGE PIZZA AWAY

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