Welcome to our crash-course in Networking, hopefully these guides help you gain a better understanding over how our computers communicate with each other.
The Concept of Abstraction
To understand networking, you need to understand on the foundation by which networking is built off of. Abstraction is the concept borrowed from math and logic, and is used heavily within programming and computing, where a certain “system” only cares about what it’s inputting and outputting. We call this “black-box” abstraction, and it helps in understanding the big picture of networking. You don’t need to know how your text message gets turned into electrical bits and radio waves, but just need to know that there is a system, or multiple systems, present on the journey from your phone to someone else’s phone.
In Networking, we depend on abstractions in the form of “Layers” (see below), where each layer serves a particular purpose and only that purpose. We organize these layers with Communication Protocols made by very smart people decades ago. You don’t need to know all the protocols, you just need to know how they interact with each other to create our Networks by which our computers communicate with each other.
The Layers of Networking
For our purposes, we will be going over the OSI Model, which was standardized in the 1980’s, replacing the older confusingly-named TCP/IP Model created by the US military in the 70’s for ARPANET. Keep in mind, there is no “OSI Model” on your computer, this is just a helpful model to organize our protocols around.
Don’t be scared if you don’t know all of these yet. What you need to know right now is that there are 7 Layers and each layer “stacks” on top of each other from the lower-levels to the higher levels to allow computers to communicate with each other.
We go over each of the layers in their own section, as you might have seen in the page list. Start at “The Physical Layer” if you don’t know any of these, and work your way up the stack.
21 The Physical Layer
22 The Data-Link Layer
23 The Network Layer
24 The Transport Layer
25 The Session and Presentation Layers
26 The Application Layer