Hi! Networking is all about data transfer. But how does it get to where it needs to go? The OSI Model helps describe what’s happening in a networking system.
What is the OSI Model?
It's a conceptual framework that describes the functions of a networking or telecommunication system. It gives network admins a visual representation of where a networking issue might lie. It also helps application programmers decide what part of the system their application might need to communicate with or interact with.
What are the Seven layers?
7. Application Layer - This is the layer that consumers/end users interact with. Examples of this layer in a system would be ...the application! A web browser is an example of this layer
6. Presentation Layer - This is the layer that presents the data for the application. Before data is ready to be used or presented to an application, it has to be formatted. An example of something that happens at this layer is data encryption and decryption for secure data transmission.
5. Session Layer - In a 7 layer dip...this is where the cheese goes :) but in our case, this is referring to the layer in which two computers or servers are communicating with each other...is something called a "session". Things that happen this layer are call "functions" an include things like setup, coordination and termination of those session. It's basically the layer of the system that is responding to service requests from the presentation layer and sending service requests down to the next layer.
4. Transport Layer - This is where the coordination of data transfer between two computers happens. How much data is going to be sent? How fast does it need to go? Where is it going? This is where TCP/IP (Transmission Control Protocol / Internet Protocol) is working its magic.
3. Network Layer - This is where the internet router functionality is happening (aka packet forwarding, data routing through different routers). In order for data to get from your home router to someone else's, it needs to take a bunch of different paths. Routers are the ones making that happen at this layer. Also, IP Addresses work at this layer!
2. Data Link Layer - This is where Node-to-node data transfer is happening and where network switches are working! What are network switches, you might ask? They're simply devices that connect other devices to a network by using pack switching to receive and forward data to the destination device. What's packet switching? That's just a fun technical way of describing the method of sending tiny bits of data from one place to another.
1. Data Link Layer - This is the physical part of the system where all the electrical and physical stuff happens. Think network cable types, radio frequencies...etc. When your computer isn't working and someone asks "is your computer plugged in?" and you realize that it was NOT in fact plugged in...you had an issue at the physical layer.
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