Where do ISP’s get internet connection?

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Have you ever wondered where do ISPs get internet connection? Well If so , This Article should explain , and it isn’t as simple as it sounds.

This might seem obvious , but a lot of people don’t know this. When i didn’t really understand networking , i thought that basically all the ISPs connect to someone like ICANN or INAN, but now i realize that that was a ridiculous Idea.

Why is that not the case? Well:

1) Even the worlds most powerful routers and switches like the Cisco CRS3 router could not possibly route all of the worlds traffic.

2) This would be very bad for internet freedom , since ICANN could block anything and would have total control of the internet. This is not the case because the internet is for the most part uncentralised.

The internet is just a large network. Regular consumers connect to ISPs which are actually large networks. ISPs just connect to each other in order to be able to route traffic between each other.

However , there is a major problem with that. Every ISP could connected to every other ISP, but as you can imagine , that is obviously impossible. Therefore ISPs connect to Internet exchanges , also known as Tier 3 providers or IXPs (stands for Internet Exchange Points). A few examples of internet exchanges are: PLIX , INEX , FICIX, FVG-IX, etc.,

There is usually at least one Internet exchange per country , for large countries like the US there might be one or more internet exchanges per state or whatever. ISPs and Datacenters connect to the internet exchanges, some / most ISPs and Datacenters connect to multiple internet exchanges.

This does not mean that ISPs do not connect together, in fact they do. Some ISPs do connect together , however most traffic is router through internet exchanges.

To look closer at internet exchanges, lets focus on the INEX (Internet Neutral Exchange) which is the main internet exchange in Ireland. Most Irish ISPs connect to the INEX exchange. A full list can be found here:


Here you can find , My ISP (CableComm), And all my other previous ISPs (Vodafone, Eircom). Some datacenters are also connected here, including Netflix, and a lot more.

But there is a problem, is all Internet exchanges, connected to all other internet exchanges. Well , ok, it might be possible , but there would be a lot of unnecessary Fibre connections , and it would overcomplicate routing.

Therefore , IXPs or internet exchanges connect to larger internet exchanges like the EURO-IX. There is probably a main internet exchange in the US , Canada , China, etc.. But i was too lazy to do the research so you will have to find them out yourself 😀

So, these internet exchanges connect to a worldwide internet exchange, right? Err, not really. Why?

Well, as i said before, Even the worlds most powerful routers / switches like the CRS3 could not route all that data. Therefore , these internet exchanges just connect to each other.


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1 Comment

  1. Justin February 13, 2014 at 7:34 pm

    Very nice article thanks!

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