r/computerscience • u/mindxxx • 7d ago
Help where can i learn how the internet physically works?
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u/mc_pm 7d ago
Read about the OSI model of networks. There are 7 layers (well, we don't use all of them) that build on each other. The lowest is the physical layer, but it will help to get an understanding of the whole OSI model before trying to dig in too deep on the physical.
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u/binarycow 7d ago
And eventually, you realize the OSI model is a lie 😜
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u/Plane-Election4466 7d ago
Interesante are you saying this as a joke or as someone who understands so much that the OSI model is basically just newbi stuff
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u/binarycow 7d ago
I'm a network engineer.
The OSI model is the model for the defunct OSI protocol. The TCP/IP model is the model that is appropriate for the modern age.
But the "lie" comment is because both models are guidelines, not rules.
As an example, which layer ARP is in is hotly debated. The "best" answer is layer 2.5 - which isn't a thing.
Another example - what layers would this packet be?
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u/g1bber 7d ago
I’d argue the packet you showed is an L2 packet since its first header is an Ethernet header. What it carries is irrelevant.
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u/binarycow 7d ago
Ah, I see. So, basically, what you're saying is that everything is layer 2, since basically everything has an ethernet header first.
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u/g1bber 6d ago
No. I’m saying that this is an L2 packet because it includes the L2 header. If it had been decapsulated, it would be at a higher layer.
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u/binarycow 6d ago
If you wanna be that technical, then it's a frame, not a packet.
Or, use context clues to understand what people are talking about. It's a sad day when someone is more pedantic than me.
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u/g1bber 6d ago
If you assume a packet is only L3, the question itself doesn’t make sense. Packet is broadly used to to refer to a PDU at any layer these days.
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u/binarycow 6d ago
Yes, which is why I used the term.
I was also asking what layers all of the PDUs were in, not just the first.
Context!
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u/Plane-Election4466 7d ago
Wouldn’t arp be in the data link Layer because technically it’s for the physical aspect the first layer but not totally physical as it’s a data aspect which makes it a data link layer. And because of the image you sent me talked about VLANS that’s obviously a Data link packet so a layer two packet to be exact.
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u/binarycow 7d ago
Some people say ARP is layer 2 because it's addresses are MACs.
Some people say ARP is layer 3 because it deals with IPs.
The image?
- Layer 1
- Layer 2
- Layer 3
- Layer 3
- Layer 2
- Layer 3
- Layer 4
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u/davesaunders 6d ago
I started my internet career in 1989 and participated in the standards development of the OSI models. I did multiple keynote speeches at internet trade shows about the OSI layers when it was still believed that OSI was going to replace TCP/IP. The OSI layers are academic but weakly map to reality.
Saying the OSI model is a lie is funny and largely true.
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u/Antidote12- 7d ago
If you want a detailed book you could check out Computer Networking: A Top-down Approach by Jim Kurose
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u/Arcanite_Cartel 7d ago
The first thing to learn is that you don't mean physically (i.e. the electronics, physics, etcv), at least I don't so. You mean: How does each layer work? The internet is a tiered set of protocols and standards, implemented by hardware and software.
But any, here is an intro:
https://web.stanford.edu/class/msande91si/www-spr04/readings/week1/InternetWhitepaper.htm
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u/ItsAMrE4U 7d ago
I took a CCNA Level 1 course and that taught me everything I would want to know about how the internet works.
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u/Majestic_Rhubarb_ 7d ago
When you say physically, what do you visualise as the physical things you want to learn about ?
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u/Rich-Engineer2670 7d ago
Depends a little on what you mean by Internet.
If you just mean the TCP/IP protocol, routing, DNS and other layer-3 parts, anything from Douglas Comer is a good start. But, if we're getting into the lower layer-2 and layer-1 stuff, switching, optics, etc. that's a whole different item. Start at layer-3.
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u/watercouch 7d ago
Tubes by Andrew Blum is a good introduction to the physical internal, its history and economics. Try your local library or Libby app.
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u/guacamolejones 6d ago edited 6d ago
I see a lot of comments in here telling you to study TCP/IP etc. This is NOT how the internet "physically works". Study electrical engineering if you want to know about that. The funny thing is, the first layer in the OSI model is the "physical" layer and many of the people telling you to study upper layers should know this. Everything above the physical layer is really just a layer of abstraction.
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u/Forward-Facer 4d ago
"It all started with the big bang..."
Okay but on a serious note, learning about electromagnetism would be important. I thought Star Talk's video from a few weeks ago on light was a lot of fun, and does certainly relate to how the internet is physically running:
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u/Humbleham1 3d ago
Physically, it's a series of low-voltage electrical signals and light pulses relayed by routers and amplifiers through copper and fiber optic cabling.
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u/rtharston 1d ago
I’ve read a lot, but in the end a good YouTube video has helped me understand in a way just reading hasn’t. I can’t find all of my favorites right now, but here is a great one to get you started:
https://www.youtube.com/watch?v=L6bDA5FK6gs&pp
Then check out the rest of their channel for more. Great wealth of computer knowledge from lots of great people.
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u/JmacTheGreat 7d ago
First, learn about internet protocol:
https://en.wikipedia.org/wiki/Internet_Protocol
Then, make sure you understand TCP and UDP.
From there, the internet is effectively a bunch of computers specifying senders/receivers and shooting data at each other…