by Charles Miller

Over the course of the last month I received three different questions from three different people, all three touching somewhat on the same topic. The questions all revealed the need for at least a little understanding of the tiered infrastructure that makes up the internet we all use. I chose that word "tiered" very carefully because the internet is actually divided into three distinct divisions that are called "Tiers."

The internet connection you have in your home is provided by a Tier 3 Internet Service Provider (ISP). Tier 3 ISPs are the smallest companies providing what is typically called "last-mile" connections to end-users such as you and me. Tier 3 ISPs serve retail customers in the local market and do not have extensive international networks. Tier 3 ISPs are smaller telecom companies, and yes; in the overall scheme of things companies such as Megacable, Telmex, and TotalPlay are considered small companies. They have to rely on purchasing transit from Tier 2 ISPs to access the internet outside of their local area.

Tier 2 ISPs could be considered to be wholesalers who rarely if ever have any contact with retail customers like you or me. For the most part they deal only with the Tier 3 internet providers and very large companies. Here in Mexico some of the Tier 2 ISPs are Uninet, Axtel, Alestra, Marcatel, Transtelco, and Bestel. If you have occasion to troubleshoot your internet connection using the "trace route" test you might see one of those names listed as one of the servers through which your connection passes. The Tier 2 ISPs provide internet connectivity to the lower Tier 3 providers in regional markets that may cover all or parts of several countries.

Then there are the Tier 1 ISPs that are the backbone of the internet. They are broadly defined as international networks that can reach every other network on the internet. There are only about a half dozen global Tier 1 ISPs, these include AT&T (United States), Deutsche Telekom (Germany), Liberty Global (Netherlands), Nippon Telegraph and Telephone (Japan) and Tata Communications (India). There are also some Tier 1 ISPs that are referred to as "Regional" because they do not quite have an all-inclusive worldwide presence. These include China Telecom, Vodafone (United Kingdom), Telstra (Australia), and others. The key characteristics of Tier 1 ISPs are that they all own their own network infrastructure of servers.

The way all this works in practice is that when you or I connect to the internet we are doing so by using our local Tier 3 ISP and paying them for the connection. Our local Tier 3 ISP then buys its connection to the internet through a wholesaler called the Tier 2 ISP, and that is the internet connection we share with everyone else in town. Then when the Tier 2 needs to reach a destination out of its area, such as outside Mexico or outside North America, the Tier 2 purchases a connection from one of the big worldwide Tier 1 ISPs.

Where do the Tier 1 ISPs purchase their connection to the internet? The short answer is they do not have to because most of the T1s have a global reach. When they do need to connect through another Tier 1 it is usually handled through cost-free peering arrangements that work so long as each Tier 1 is exchanging an equal volume of incoming and outgoing data with the other Tier 1s.

So, try to keep all this in mind the next time you are tempted to complain to your local Tier 3 Internet Service Provider that you cannot connect to a web site half way around the world. Your connection issue could very well be the fault of the Tier 2 or Tier 1 ISP and not the fault of your local Tier 3 providing the internet connection to your house.

**************

Charles Miller is a freelance computer consultant with decades of IT experience and a Texan with a lifetime love for Mexico. The opinions expressed are his own. He may be contacted at 415-101-8528 or email FAQ8 (at) SMAguru.com.

Discover Lokkal:
Watch the two-minute video below.
Then, just below that, scroll down SMA's Community Wall.
Mission

Visit SMA's Social Network

Contact / Contactar