## how ISPs work

I'm trying to understand how ISPs agree to connect to each other by considering a hypothetical situation:

Suppose I wanted to start my own ISP in a small town. Would I have to pay to connect to another network that is already connected to the internet (hence that would make me connected to the internet too, so I could provide the internet to my customers through the other network)?

Since my ISP is really small, the network I connect to wouldn't get a lot of traffic coming from my ISP (in fact, I would take care of any abusers who download too much, to keep my traffic to a minimum agreed with the other network). So would the other network charge me a fee to connect to their network?

What if I had one really good website hosted on my network? Say in that small town, is a company that's famous for its cookies, and they are willing to put up a website only on my ISP or no ISP at all. Would the network allow me to connect to them in order to get that one website? Would other far away networks (that have peering agreements with the network I want to connect to) pressure that network to let me on, so that everyone in the world can visit and order cookies online? (the idea I'm trying to get at is can a good website like Google, which all ISPs want to connect to, start its own ISP and get free connections to other networks, since all the other networks would want to connect to google quickly?)

I would pay for all the physical cables required to connect me to the other network. But would I have to pay something in addition?

Also, at internet exchange points, I've heard that 100s of ISPs can interconnect. Can anybody connect at an internet exchange point? Is it free?

Can the phone or cable company pressure other networks to let me connect to them, because that way they get more business from my ISP because I still have to pay the phone and cable companies for my customers to reach my ISP (actually which way does it work: do customers have to pay the phone company and the ISP, or does the ISP have to pay the phone company and the customers just pay the ISP)?
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 Quote by RedX I'm trying to understand how ISPs agree to connect to each other by considering a hypothetical situation: Suppose I wanted to start my own ISP in a small town. Would I have to pay to connect to another network that is already connected to the internet (hence that would make me connected to the internet too, so I could provide the internet to my customers through the other network)?
First you would need to lease a connection to the internet and have the necessary hardware and software to act as an ISP. How are your customers going to connect to you?

Even at public peering points (and yes you do have to pay) most comapnies that will peer (allow you to connect to their internet backbone) will only accept T3 as a minimum.

 Since my ISP is really small, the network I connect to wouldn't get a lot of traffic coming from my ISP (in fact, I would take care of any abusers who download too much, to keep my traffic to a minimum agreed with the other network). So would the other network charge me a fee to connect to their network?
See above.

 What if I had one really good website hosted on my network? Say in that small town, is a company that's famous for its cookies, and they are willing to put up a website only on my ISP or no ISP at all. Would the network allow me to connect to them in order to get that one website?
See above.

 Would other far away networks (that have peering agreements with the network I want to connect to) pressure that network to let me on, so that everyone in the world can visit and order cookies online?
No.

 (the idea I'm trying to get at is can a good website like Google, which all ISPs want to connect to, start its own ISP and get free connections to other networks, since all the other networks would want to connect to google quickly?)
No.

 I would pay for all the physical cables required to connect me to the other network. But would I have to pay something in addition?
See my first response.

 Also, at internet exchange points, I've heard that 100s of ISPs can interconnect. Can anybody connect at an internet exchange point?
No.
 Is it free?
No.

 Can the phone or cable company pressure other networks to let me connect to them, because that way they get more business from my ISP because I still have to pay the phone and cable companies for my customers to reach my ISP (actually which way does it work: do customers have to pay the phone company and the ISP, or does the ISP have to pay the phone company and the customers just pay the ISP)?
See my first response.

Do some research and tell me how you expect people to reach you. By dial up? Are you going to try to resell facilities and install a DSLAM and resell DSL? The first thing you need to figure out is where these customers are, what type of interent connection and the associated hardware and software necessary can you afford. That will determine pretty quickly what you can offer.

Then of course WHY would people pay to connect to you?

I'll be glad to get more specific if you will be more specfic. I design and sell backbone access to large ISP's and telephone and cable companies.
 Thanks for the reply. Unfortunately, the technical details are a bit over my head. I'm in no way wanting to start a small ISP in real life (I clearly don't understand the technical side of networking at all). I just wanted to know how the networks agree to hook up with each other. I read on Wikipedia that large ISPs will peer with each other without charging each other because it's mutually beneficial, rather than paying a third party (like a telephone companies' telephone line I suppose) to connect the two networks. I was under the impression that the large ISPs owned and built the backbone, and peered with each other so that all the data would go through the backbone that they owned, so they wouldn't have to pay for data through a 3rd party's line. But you say you sell backbone access to the large ISPs, so I guess this is not entirely true, and some of the backbone is owned by people not even in the ISP business? As for the T3 requirement, is this because if your line is slower than T3, then when other networks send your network data at the exchange point, physically the electrical signals that comprise the data will get reflected back to the other networks? If this is not the case, and your line is slow, say a T2, then data will be transferred to your router faster than it is coming out (since other networks will be transferring your data to your router on a T3, and you will be transferring this data out of your router to your customers on a T2), and you'll get a buffer overflow and dropped packets, but that doesn't affect the other network, just yours. So I assume the reason you need a T3 is so that data doesn't get reflected physically?

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## how ISPs work

 Quote by RedX I read on Wikipedia that large ISPs will peer with each other without charging each other because it's mutually beneficial, rather than paying a third party (like a telephone companies' telephone line I suppose) to connect the two networks.
AT&T has a very large internet backbone in the US. They also act as an ISP. But most ISP's (there are many) do not own backbones, they lease access from a backbone provider. I work for one of the largest backbone providers.

 I was under the impression that the large ISPs owned and built the backbone, and peered with each other so that all the data would go through the backbone that they owned, so they wouldn't have to pay for data through a 3rd party's line. But you say you sell backbone access to the large ISPs, so I guess this is not entirely true, and some of the backbone is owned by people not even in the ISP business?
Yes and no. AT&T, Verizon, & Sprint (all of which are or were local phone companies) are the biggest backbone providers, but they are not the only big players. So it might help if when referring to Tier 1 peering that we call them backbone providers instead of ISP's because it's easier for me, I'm in pain and on painkillers, so I apologize for the lack of quality in my response. I am also only referring to the internet in the US, outside of the US you get into government owned networks and weird stuff outside of my realm of expertise. The Tier 1 providers almost exclusively peer at privately owned facilities.

The peering arrangements are proprietary, but yes, there are agreements to fairly trade data between providers. This is were problems arise when one company decides that another is handing off too much traffic. But that's a whole other discussion.

The costs are for the space, the equipment, maintenance, etc...

Everything I have is proprietary and I cannot share. You've got a lot of good questions, let me see if I can find some accurate information on different types of peering for you.

Also, there is a member that works for an internet provider in Europe and they can tell you how things operate there.
 Mentor Blog Entries: 4 Here is an example of the basic requirements AT&T sets for private peering. The bandwidth requirements are large, as you can see. http://www.corp.att.com/peering/
 Thanks, that was helpful. I have the luxury of not having to need to know about computers and technology at the level you understand it (professional) to operate in life, but just to satisfy my curiosity, so your answer sounds good by my ears!

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