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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> 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
So, first thing is, most people aren’t using much – or any – bandwidth most of the time. A 10Gb/s connection will comfortably support 10,000 normal users, and the university will likely have various caching servers running as well, so if you think you’re downloading updates from Microsoft or Steam, there’s a fair chance it’s being served from a local cache on campus.
The exception here is if the university has some serious science equipment – like radio astronomy or particle accelerators which generate epic quantities of data. These will have their own private links to whatever computational cluster or data store supports those instruments, but the university may then have invested money in beefier internet connections for partners at other institutions to access that data – in which case you start moving from 10G into 40-100G connections. Many countries also have academic networks such as [JANET](https://en.wikipedia.org/wiki/JANET) or [GÉANT](https://en.wikipedia.org/wiki/G%C3%89ANT) linking universities for this purpose. The links are usually dedicated fibre – not the public internet. So the university may have a “general” 1Gb or 10Gb connection to a transit provider onto the general internet, and then a >10Gb connection to JANET/GÉANT/etc. 100G interfaces are now becoming pretty common as hardware is upgraded. Depending on the nature of the institution and how much inter-university traffic they’re doing, it could be that the “many tens of gigabits of outbound connectivity” is almost entirely connections to the academic networks with only a very small transit connection to the wider internet.
Now, as to why *you* can’t see those sorts of speeds when you run a speed test, there are a bunch of possibilities:
* Your device is incapable of supporting those speeds (especially if it’s over wireless – you will be capped by the wireless throughput of the link).
* Your local node is congested – even if you have a laptop plugged into a Gb ethernet port, that only means you’ve got Gb to the switch. There’s nothing to say that the switch on your floor of your building is able to pass that much data through to the campus core router (or even the main aggregation switch in your building) and onto the internet. You are competing for bandwidth with everyone on your floor, in your building and then on campus.
* You are throttled as a user. If you’re accessing the network as a guest, you’ll probably get lower speeds than if you are authenticated on the network – and even as an authenticated user you may be limited to prevent any one person hogging resource. I’ve seen exactly this in a government building where I as a guest could get 300Mb/s on a speed test, but my host – on a computer sat next to us (signed in with her staff account) could get 700Mb/s. Sysadmins will always give themselves lots of capacity. Staff with requirements (like astronomers shunting big data around) will have enhanced privileges. The accounts department working in Sage and Excel will have a much lower limit, same for undergrads.
* Your connection is being managed by Quality of Service tools. There’s a tonne of ways to rate-limit types of traffic. For instance if someone is trying to download a multi-GB file, that’s not particularly time (latency) sensitive. It’ll get throttled so that it doesn’t interfere with the phones (VoIP) or audio/video streaming which *are* latency sensitive (you’ll notice if they start skipping). Your download might take 7 minutes instead of 5, but that’s not really a problem. Email can also wait – it doesn’t really matter if an email goes in a second or gets queued and goes 5 minutes later. Speed-testing – when detected – gets hammered, and even if it successfully disguises itself as something else, will get managed and throttled in accordance with set policy.
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