/ The Building Blocks of IT

The Foundation

We will attempt to explain Layers 1-4 of the OSI model through the construction of two hotels, each on opposite sides of a city. Networking is all about two computers communicating, but as humans have be communicating for a rather long time, it makes sense to try and juxtapose these two forms of communication in an attempt to provide a great lattice for which the networking knowledge to cling onto. This isn't a replacement for the technical learning, but should act as a layperson's explainer to help understand what can otherwise be challenging concepts.

When learning about IT, there are many tempting shortcuts available. These include rushed bootcamps, certification dumps that hand you the answers, and other methods that allow you to claim competency in areas where you lack actual understanding. These shortcuts often result in a weak foundation, which can negatively impact you in the long run. The bottom line is that you need to genuinely learn and understand this material, as it will inevitably catch up to you if you don’t. There is very much a "crawl, walk, run" progression here, and it often takes years just to realize how much more there is to learn.

The foundational analogy we’ll use is simple. Imagine two people in Las Vegas for yet another Cybersecurity conference. They are staying in different hotels and need to coordinate dinner plans. This is a straightforward scenario, much like a computer needing to load Google to find an answer for the latest ticket in the queue.

Layer 1 - Physical

In this example, we are explaining Layer 1 of the OSI model: the physical layer. Do not let the word "physical" confuse you. Wireless communication is physical, just like copper (both UTP and coaxial) and fiber optic cables. This is where analogies come in handy.

Let’s revisit the problem statement: two people in two different hotels need to coordinate dinner plans. Since this is a Cybersecurity conference, they do not trust modern communication methods or even the hotel staff. This leaves only one option: one person has to physically walk to the other to sync up on dinner plans.

Here is how it plays out. One person leaves their hotel room, walks through the halls, exits the building, crosses the streets of Las Vegas, enters the other hotel, takes the elevator up, and knocks on their friend’s door. That is the physical layer. For communication to happen, there must be a way to physically get from one place to another. Whether it is a person walking across town or a bit traveling through cyberspace, the principle is the same.

Now, consider wireless communication. If they had radios, they could talk to each other that way, provided they were within range. Radios are not the most secure option in Vegas, but they would still work. The key point here is that communication requires a medium to transmit information. However, just like road closures or heavy traffic, physical barriers such as brick walls or interference can disrupt the path of wireless signals. This introduces us to how wireless signals work, but we will save that for later.

In the end, the physical layer is simply the means by which two entities can connect and communicate. There is a lot of detail here, but at its core, it is about how two computers (or people) can send a bit from one to the other.

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