How does a local ISP deliver service when, say, Comcast has a monopoly?

Ok, as a small ISP I think I can answer this. Basically you buy transit from a larger ISP, it's pretty simple. Gone are the days of buying a T1/T3 or SONET or MPLS drop from a local (I/C)LEC. Nowadays it's usually a MetroE circuit, or something similar, which is petty much just an Ethernet drop to your router from a larger "Metro" network. It can run from a few hundred dollars to a couple thousand in typically 3 or 5 years terms. Bandwidth itself is cheap as hell and you're usually paying for the install. For example a 10Mbps drop might cost $600/mo while a 50Mbps might cost $700/mo and a 1Gbps drop will cost $1500/mo. Price is completely related to the distance from their outside plant to your location and the difficulty in getting it to you.

Your transit providers do all the peering and what not with the other networks. You are routed a subnet of their IPs or they just swip/rwhois it over to you. Basically, you're just buying a big, fat, expensive and, ostensibly, highly reliable internet connection. The difference between than and any other consumer internet, like the service you provide, is you have a maximum guaranteed bandwidth from your transit while consumer internet is "best effort" (no guarantee). You just pull fiber, cable, or wireless to your customers and push them onto your transit provider. So you're essentially reselling your internet connection to people on your network. You compete on trying to provide a better network; less congestion, better support, and so on.

Networks ontop of networks ontop of networks. Fundamentally you're no different than "Comcast" except they are so large they have their own peers at the various meetups and their own Metro and national network. Your local Comcast gets transit/last-mile from their bigger network. That said, I'm pretty sure even they buy transit because when we had a fiber cut TWC was partially down as well, which means they either lease or buy from that same company (layer 1 or 3 I do not know). It really comes down to the fact you and Comcast are designed to deliver service to consumers and all that entails; rolling trucks, training support and techs, billing, and monitoring hundreds or thousands of connections. Last Mile/Transit providers are designed around delivering service to much fewer customers, who have their own IT/network admins, and whose network technology while similar in physical hardware is very different in management and overview.

In the end, the transit provider could care less if you're an ISP, a data-center, the next Youtube, or a Pizza Parlor.

/r/networking Thread