In this video, Mike discusses the structure of the Internet. Starting with the Tier 1 carriers, he shows how carriers at each layer interrelate with their peers and also how they interact with tiers above and customers below. This video provides a good structure for layering your wide area networking knowledge.
- [Mike] It's easy to say that the Internet is simply a big wide area network, and that's technically correct, but the Internet is actually broken up into what we call tiers. And, what I want to do is take a moment and kind of give you an idea of how the Internet really works because, well, it's funny and it's interesting. Let's start with the good ole USA. So, here's a map of the United States. And, around the United States are about but they provide internet to very large customers. What's interesting about these companies However, between these 10, they do cover the entire United States, which makes for an interesting situation. The problem is, is because none of these big carriers cover the entire United States, they have to work together. Now, keep in mind, what makes this funny is that these people are competitors. They hate each other's guts. They want to crush each other, but they have to work together because nobody can cover the United States completely. And, as a result of that, these different companies that are competitors, create what are called peering agreements. So, these peering agreements basically go, "Look, I hate you and you hate me. "However, let's go ahead and allow each other to "let each others traffic go through and that way, "together, we can cover more of the United States." By the way, this is not unique to the United States, it's just that I know the U.S. peering better than anyplace else. You have the same problem in Europe and every place else as well. So, you have all of these guys that are peering. Now, the problem is, is that they have to have a place where they interconnect. Think about this for a minute, in order for them to share stuff, they have to interconnect. And, there are these places that are dotted around the United States, called Network Operation Centers, or NOCs. And, the idea behind these places is that they're owned by third parties. So, these folks will get together, they'll build a big building and it's going to have lots of generations, because you never want this thing to go down, and big semitrailer trucks full of diesel to power and lots of security guards with automatic weapons I mean, these are scary places but we need them desperately because, what they will do is they'll go, "Ah, we are a NOC." and then they will build routers inside these NOCs and you then run a connection between and that's how we interconnect. I've been to these places. They're absolutely amazing. I've been to one, when you walk up into a floor half million dollar routers and here's one company, and here's another company, and there's one little piece of singlemode fiber that's interconnecting between them, just kind of hanging between the routers, going through the concertina wire. And, I'm looking at my very armed guard, who's acting as my guide, and I'm like, "Wait a minute. Are you telling me "all I would have to do-" and I started to reach towards it, So, these are pretty serious situations. So, what we have is all of these Tier 1 people who work together. Now, the next step we're going to have is Tier 2. as a Tier 1 provider, but they do have a fairly good coverage area. And, they don't completely cover the United States, but they have big places, and they tend to be in multiple spots at once. Tier 2s have not come up with a peering agreement with the Tier 1 providers. just like you and I do. However, they do have some peering agreements with some folks. So, if you don't pay for anything, you're Tier 1. If you pay for a few people and a few places, but otherwise, you're peering with others, you're Tier 2. There's lots and lots of Tier 2s out there. They show up at these Network Operation Centers just like anybody else does, but they're not quite as big. probably more familiar with, is Tier 3. Tier 3 are the big internet service providers. So, they have names like Comcast or AT&T, and they tend to have lots of presence all over the place, but they're not totally interconnected. Tier 3s make their money by selling internet services to individuals and corporations. So, they almost have no peering agreements and they're paying for their internet. So, we have Tier 1, we have Tier 2, and we have Tier 3, and then, at the bottom of the food chain of the internet are people like you and me who pay our monthly bills so that we can get on the internet. Now, keep in mind, what I'm giving you is a quick overview. It is very fuzzy here. Somebody who's a Tier 2 today could be a Tier 3 tomorrow or vice versa. These guys are constantly in litigation. They are constantly arguing with each other and this is a very fluid thing, but in general, if you're not paying for anything you're Tier 1, if you have some peering but you're paying for a little bit, you're Tier 2, and if you're pretty much paying for everything you've got, you're Tier 3. (upbeat music)
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