Let’s say I have a 100mbps internet connection. I call the ISP and pay extra for a 200 mbps connection, and it gets faster with no new hardware. Does someone turn a knob somewhere?
Thanks.
In: Technology
It’s literally just a setting.
Back in dsl times, your max speed could depend on a lot of things. I would *always* turn up the speed to max stable speed for our customers, no matter their plan.
With fiber, it’s just a setting. Either “check this box for this speed”, or just configure it on your own.
Former Tier II internet tech support for a small ISP that didn’t have it’s shit together checking it!
Regardless of if you’re connected via fiber, ethernet, or cable modem generally speaking the larger network you’re connected to is set up kind of like a tree. Each end user household (individual apartments, houses in a neighborhood) are the leaves. Several leaves are connected to a twig, which then connects to a branch, which may meet up with other branches and ultimately leads to the truck (the whole rest of the internet).
The “twigs” that connect several “leaves” are usually smaller pieces of equipment that aren’t terrible expensive and literally just bring many connections into a single line. They pass this on to “branches” that have larger, more expensive equipment that is programmable. An entire apartment high rise wired for cable modems may have one “twig” per floor feeding into a single “brach” that controls all of the cable modems in the building.
Now on to the nitty-gritty on how someone actually sets bandwidth for end users!
For ethernet networks the process is relatively straightforward. The “twig” pieces of equipment are usually ethernet switches, relatively cheap pieces of equipment that have one or two ethernet ports “in” and a few dozen ports “out”. [Here’s a good example if you want to know what they look like](https://www.allhdd.com/networking/switch/48-port/hp-j9728a-nbp/?src=ggl&gclid=CjwKCAjwq_D7BRADEiwAVMDdHslRgLc_xYF_uQNtCjj0Wpn7bejCrEwU6lHPo_H_ewaXgzO_20a-VhoCUpAQAvD_BwE).
When the network is initially being built in the engineers program these switches and carefully record which unit or home is connected to wich port (and usually label the actual cables). Usually the programming on these switches includes several files specifying how much bandwidth a port should be allowed.
When a customer moves in or changes their bandwidth package it’s just a matter of telling the switch that they’re connected to to operate with the desired bandwidth specification file already running on the switch. Most big ISPs have this automatically linked to their customer service software so when a person in the call center hits a button confirming the customer bought a particular bandwidth package the switch updates to reflect that. The ISP I worked for did not have it’s shit together, so my coworkers and I would manually log into the switch via a command line interface and reprogram the customer’s port to use the specified package.
Cable modem networks are somewhat similar, with a few key differences. In a cable modem network (also referred to as DOCSIS) all of the “twig” equipment isn’t necessarily remotely programmable. Instead, the “brach” hardware is where the action happens.
This piece lf equipment is called a CMTS, or Cable Modem Termination System. These bad boys talk to all of the modems on the network and can do things like monitor signal levels and even reset them remotely. A CMTS tracks all of this by the cable modem MAC address, which is why the Comcast rep with often have you read the information off of the label on the modem.
Setting bandwidth on a CMTS is accomplished in a similar fashion to on an ethernet switch. Several bandwidth package files are programmed in ahead of time, but instead of setting a customer’s port to one of these files their modem is set based on their MAC address. Each CMTS has a huge chunk of code on it that lists the bandwidth settings and then a huge wall of “give this MAC address this package, give that MAC address this package”.
Just like with ethernet, ISPs that have their shit together have their CMTSs linked to their customer service software so the file is updated automatically when the sales rep completes an order. If not, a person needs to connect with the CMTS and manually edit the programming to specify that a certain modem should operate on the desired bandwidth package.
Your speed is artificially limited by the ISP’s piece of equipment on the other side of the wire from your modem (be it DSL, cable, fiber transceiver, wireless transceiver, whatever). Software tracks the amount of data sent to you over time, and when the amount exceeds your limit, the device will briefly take your data hostage and hold on to it for a short amount of time, rather than immediately sending it on to you.
The server you’re downloading from is looking for acknowledgements from you — your device will periodically tell the server how many packets of data it has received. When your ISP throttles your data rate, the server notices that it sent 100 packets but you only got 80 of them so far. Based on this, the server now knows that you can’t handle data at that speed. So, the server starts sending data to you more slowly. At some point, the server and your ISP balance out — the server sends data just below your limit, and your ISP stops delaying your data.
Turning on more bandwidth is just your ISP instructing their hardware to allow more data through.
They just lift a data rate cap that their system puts on your service. It’s all in a database, and the customer service rep selects a button for the new cap. That information goes to another part of the ISP’s system that controls your connection, which then allows 200 maximum instead of just 100. They really can set it at whatever they want.
One time they had to come out and replace my modem when I wanted higher service because the old one couldn’t handle it. But they still had to make their change at their end to allow the extra speed.
You get the same cable for various speeds. The modem using the cable has to do some handshaking with the remote side. It negotiates the speeds. The remote side can simply says “you get 100 Mbps from me”. Your modem says “ok, I take it”.
A modem can dynamically adjust the speed according to quality of the transmission, but the remote side wouldn’t allow that your modem can negotiate a higher speed than your maximal speed you paid for.
The ISP puts it in their computer, which sends a file to the modem, saying to only go this fast. Your modem can potentially be hacked for faster speeds, but the ISP will see on their computer and not like it.
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