What is the OSI model used for in Computer Science

Question

I’ve read and seen videos on the OSI model and from what I remember it’s just a reference model for how you should develop a network in a computer but it’s not strict in that you should follow it exactly how it looks?

I could be misremembering but if I’m not then my question is why do we use it in the first place? Is it just a checklist of sorts to make sure we’re including the main parts?

Also as a follow up question, in networking I always see ports as in port (long number) I am always confused are these actual physical ports?

In: Technology

Answer 1

The OSI model is used to try and segment the complexity of a network transaction into distinct blocs of focus. You write software that uses the network, but you don’t need to develop a full networking stack for every piece of software you write because your main focus is handing things off to the next layer in the model where someone else has written something you can interface with. Their layers can then interface with other layers, which allows for a higher degree of interoperability. Your application doesn’t care if the network it goes across is copper or fiber or microwave or wifi, just like the network doesn’t care if your data is for a web application or a database transaction or a streaming video. Being able to visualize semi-distinct boundaries between the various functions necessary for transactions allows us to focus on what we’re good at and let someone else worry about the rest of it.

The model is there so that people build networks and applications in a comparable manner. There are other models – for people who are only focused on the network level and not on the application development, for instance, might be more inclined to apply the TCP/IP model.

TCP/IP ports are not physical ports. Physical ports would be defined in layer 0/layer 1, while TCP ports are in layer 4. The ports you’re talking about are logical segments of that further help the network understand what kind of data it’s passing – “Ah, this is web traffic so I’ll point it at the web server, and this is a DNS request so it goes to the DNS server, and this is an e-mail so it goes to the e-mail server.”