That's what started the whole net neutrality thing.
trying to condense lots of information.
there are pretty much 3 types of providers to the internet.
Tier 1, these reach "most" places, they are people like GTT, NTT, cogent, Layer 3 etc, they have networks across the world.
these are the kind of players that will own the under sea cables. that connect continents.
Tier 2, these providers are like super regional providers, they may supply to a country, but not to the world, they will need to peer with tier 1 providers in order to "reach" everywhere in the world. these are guys like BT, Telus, Verizon, Comcast, and they will usually peer with multiple tier 1 providers.
Tier 3, these are regional providers, people like Kcom in the UK, or Cleveland one in the US. these guys serve only small areas, (i.e they don't personally have global reach.) they must peer to reach places outside their service area. they usually peer with a single higher tier ISP, basically just having the last mile, operating customer services etc.
Everybody has an expense in setting up and sorting out those connections, and obviously the more traffic you carry, the more (newer and faster) equipment you need.
Hence why at a residential model we have a situation where if you want a faster connection you pay more.
the same is true for Tier 3 providers, when they want to offer a better service to their customers, they pay more to their upstream providers.
the people in the middle, (large tier 1 Say GTT and Level3) they both sell services in datacenters, and both sell to tier 2 providers.
so A BT (T2) customer in the UK, may request data from a website hosted in the states on GTT, then connection path may go like this:
BT (t2) -> layer3 (T1) -> GTT (T1) -> servrer
but at the same time there is pobably a person in the US requesting something from a Layer 3 hosted server in the UK.
Comcast -> GTT -> Layer3
Rather than working out the exact billing between then ISPs of the same tier, usually have a gentlemans agreement to carry each others traffic fairly, in the incoming/outgoing byte counts are roughly the same, so this make sense.
GTT don't bill Layer 3 for 100Tb of traffic for November, and then also pay a bill for 100Tb of traffic in December.
And yes, that is actually a little dodgy, for the rest of use exchange of services and bartering is legally the same as being paid to trade, and therefore is mostly used as a for of tax evasion.
This became a problem in 2014/15 for Comcast and the other provider where netflix hosted their services.
the trouble is that because so many want to watch netflix the "balance of traffic" became very unbalanced.
now rather that ISP saying to comcast I guess we both owe each other the same. now if they were exchanging invoices at the end of the month it'd look more like 100Tb invoice one way, 10,000tb invoice the other way.
the service providers didn't want to break their agreements to not actually bill each other and exchange money, so instead one ISP too steps to redress the balance by slowing down traffic to the other provider.
in many cases actually making the netflix service unusable to the customer.
and that was crappy, because netflix were providing the service, their servers and networks were good enough, it wasn't their fault that the service was bad, so they wouldn't release people from contracts or give refunds or compensation.
AND the ISP could happily say that the traffic shaping was inside their network policy, they were still providing connectivity of "upto" whatever speed they sold. (and you could see that with online speed checks,
it was ONLY netflix that was affected.
the net neutrality law had meant that the service provider could not favour one provider over another, -stopping specific throttling of netflix.
Of course the "REAL" solution to the problem wasn't to throttle the traffic, it should be to introduce billing metrics, rather than assume symmetric peering. the real problem is that these peering agreements were setup way before video streaming, when residential ISPs setup a good enough network to serve proper fast broadband, but ignored that upstream they would need to request more traffic, the assumptions of the past no longer hold true today, and they should have been changed.
the other trouble (in the US) is that you have defacto regional monopolies,
if you have a provider that won't pay their upstream provider for a decent amount of bandwidth, and want to keep assuming symetrical peering, and they get throttled because of that, you cannot move to a different provider, because there likely is not one in your region.
this net neutrality basically isn't an issue in places with real competition.
If I don't like my BT service, I can change is to sky, or talk talk, Bee, or any other provider I like,
I believe that AOL still exist, charging old people with broadband for dialup, even though they have broadband as they don't known that they can cancel dialup and still get the internet.
