The Seven Layers of the OSI Networking Stack... for Marketers
Matt Trifiro
Open wins. Helping founders and investors build commercial open source companies.
I am not a network engineer, but I have to earn their respect to do my job. One of the hardest things has been for me to make sense of the seven layers of the OSI networking stack.
My networking friends throw out phrases like, "we operate a layer 3 network" and "let's use VLAN tags at layer 2," as if they were talking a common language mere mortals could understand. More often than not, I am slightly bewildered.
Even network practitioners have trouble remembering the layers, having invented tortuous mnemonics like "Please Do Not Throw Sausage Pizza Away!" to help them. While the mnemonics might be clever, even useful, they provide no explanatory power.
A better way to think about the OSI stack is as a set of additive processes. It's not a static thing; it's an active mechanism. Each layer of the stack performs a process on data. Each layer also completely embeds all the layers below it. Higher layers don't need to understand how the lower layers work.
Building and Delivering a Birthday Cake
Imagine you're sending a birthday cake across town to your friend. If you play along and treat this as a way to learn about the seven OSI layers, I promise your understanding will improve.
The layers:
7. Application Layer (The Party Planner): This layer figures out what kind of cake you want (email/video call), wraps it nicely (encodes data), and labels it for delivery (adds addresses).
领英推荐
6. Presentation Layer (The Baker): This layer takes your recipe (data format) and makes sure it's understood by the recipient's oven (application software). Imagine converting a gluten-free recipe for a regular oven.
5. Session Layer (The Delivery Person): This layer establishes a connection with the recipient (like knocking on the door) and makes sure the cake arrives complete (manages data flow).
4. Transport Layer (The Reliable Car): This layer breaks down the cake into manageable slices (packets) and ensures they arrive in the right order, even if traffic jams (network congestion) occur.
3. Network Layer (The Map App): This layer figures out the best route for the car (chooses network paths) and tells it where to turn (routing protocols). Think of using Waze to avoid traffic.
2. Data Link Layer (The Bridge): This layer gets the cake slices across the physical connection (like a cable or Wi-Fi) without dropping any crumbs (error checking). Imagine checking each slice as it crosses a bridge.
1. Physical Layer (The Road): This layer is the actual path the cake travels on (wires, cables, radio waves). It's the foundation for everything else.
Each layer adds in the stack plays a critical role in making and delivering a cake, like putting it in a box, labeling it, and loading it onto a car. These layers work together seamlessly to get the cake delivered, just like network protocols work together to get data where it needs to go.