When the consumer Internet came of age back in 1990, there was never any grand plan to insure a consistent speed from one point to another. Somewhere along the line, as the Internet went from an academic tool to an essential consumer device, providers in their effort to “out market” one another began to focus on speed as their primary differentiator. By definition, the Internet is a “best effort” corroboration between providers to move your data. No one provider can guarantee a consistent Internet speed for everything you do. They only have control over their own physical lines, and even then, there are variables beyond their control (which I will address shortly).
Let’s take a look at the speed of wired networks common to most consumers, Cable and DSL.
The physical line into your house is generally what your cable or DSL provider is talking about when they advertise your Internet speed. Essentially, how fast is the link between the providers NOC and your house. Generally you will have a dedicated line for this, and so your speed on this last mile link does not vary.
The good news is that most consumers are more concerned with watching movies, video, listening to music, etc. than they are about pulling research data of some obscure server in Serbia. Given this reality, the Industry has gotten very smart, and popular content is not hosted at some distant server, but is usually distributed locally to each provider. The best example of this is Netflix. Your Netflix content is most likely coming from a server hosted a few miles from your house in your providers NOC, and not from some grand Netflix central location.
Why is Netflix data hosted locally ?
The dirty industry secret is that your provider pays a fee when you go off their network for data. There are also potential capacity problems when you go off their network. Is this a bad thing? No not really, it is just a matter of efficiency. We see similar practices in other product distribution models. You don’t drive to New York to pick up a toaster, there is usually one waiting for you at your nearest discount store. For the some of the same reasons, that you don’t go to New York to pick up a toaster, your provider tries to host your digital data locally when possible.
What does this mean for your Internet Speed?
It means that when you retrieve content that your provider hosts locally you are likely going to get your advertised speed. This also holds true for some speed test sites, if they are hosted within your providers network they are going to register a constantly higher speed.
What happens to your Internet speed when you go off your providers network?
There are several factors that will effect your speed.
The main governing factor affecting speed is the capacity the of your providers exchange point. This is a switching point where your provider exchanges data with other networks. Depending on how much investment your provider put into this infrastructure this switching point can back up when there is more data being moved than it has capacity to handle. When this happens you get gridlock at the exchange point, and your Internet speed can plummet. Gridlock is always a real possibility because your provider just cannot anticipate all the content you are retrieving and sometimes it is not hosted locally.
What does my provider to to alleviate gridlock not their exchange point?
Some providers will actually lower your Internet speed when you are crossing an exchange point. Or if their circuits are overloaded in general. I experienced this effect which I described in detail a few months ago when I was updating my IPAD.
After the exchange point the speed at which you get your data external to your providers network depends on the whims of every provider and back bone along the route. That obscure research paper from that server in Serbia , may have to make multiple hops to get out of Serbia and then onto some international back bone, and finally to your providers exchange point. There is no way anyone can anticipate at what rate this data will arrive.
How can I run a speed test that better reflects my speed out to the real Internet, by passing locally hosted speed test servers?
A few years ago we ran into this tool set that deliberately tries to retrieve all kinds of remote data to measure your true internet speed. You can also search out files hosted on obscure servers and try to download them. Perhaps I’ll run a follow up article documenting some of my experiences.