Eli5: How do large properties/campuses have such large bandwidths for internet

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How are they able to support thousands of users at one time? I do a speed test and they aren’t like fiber optics level of speeds so how can they have so many users at one time? Is it because there are so many routers placed around the area? But even when I’m on campus I don’t see any wireless routers outside.

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Anonymous 0 Comments

I’m seeing a lot of answers here claiming they just have massive connections, which is not necessarily true. I’ll chime in here as a network engineer (I can add my certifications if someone is curious).

Let’s start with your home network as an example. Your little ISP provided box is what we would call an edge device. This device takes everything going out or coming in and shoves it through as fast as possible. GO GO GO GO GO is what it does. Remember though, this is an “edge” device. So there is an inside (your house) and an outside (the big scary internet).

Now let’s look at a campus. A campus can be multiple buildings or one big building. But they’re all “the inside”, meaning that traffic from one building to another, or inside the building stays “inside” and doesn’t go “outside”. The campus can even have a data center in another location, but have a tunnel to it. So that data center would still be “the inside”, despite using a “outside” line. So only the traffic for the data center would hit the “edge” device we see above. All this “inside” traffic gets a lot of priority. Which brings us to something called QoS (Quality of Service). What this does is allow us to limit or unlimit different kinds of traffic that goes through the “edge” device. So, you could allow all the traffic to the data center without any limitations, because that’s all “inside” traffic, but you could limit how much Spotify traffic there is, which would be “outside” traffic. You could also have a few lines going to “outside” traffic that have a load balancer, so if one line is getting full, the load balancer switches traffic to the other line. There’s a little more to it than that, but this ELI5 after all 😉

All in all, if you use all these tricks and a few more, it’s pretty rare to need more than a few 1 Gbit/s lines to connect up a big campus. There are always exceptions and design choices to be made based on physical, financial and technological constraints, so every system is different, but in a nutshell this is what happens.

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