[paranoidrobot]

> Netflix might have data centers that gets closer, but nothing will ever get as far reaching and close as P2P would. A residential building who are all watching the same movie would only have to download the movie from building <> internet once.

This assumes that residential internet connections act like a larger version of your home LAN.

For all the ISPs that I know about in Australia, all of those connections are terminated within the ISPs network in a central location. This is done using PPPoE/IPoA which is handled generally at the state level.

Even for HFC networks where the local node is a shared medium, you can't get client-client communications.

Perhaps the situation is different for small WISPs, but I can't see it being too different for most people. Happy to learn more if you have examples.

[stephen_g]

With the NBN, most providers don’t use PPPoE anymore but instead just plain IP.

Every NBN connection goes back to one of 121 Points of Interconnect (PoIs) (which is way too many by the way but was a dumb and misguided decision imposed by the ACCC). At the PoI it gets to the provider through a Network to Network interface (NNI). The provider’s switch that plugs in here is the earliest that a P2P connection could loop back (but only to somebody in the same region, that is, connected to the same PoI), and is also the closest that a Netflix OpenConnect device could be (although it might not be cost effective to rent the rack space there vs. putting it in a data centre in a capital city).

A lot depends on the provider, however, on how they have structured their network. Apparently some do tunnel all their connections back from the PoI to a central location even though they don’t have to.

But for most, I expect the provider’s backhaul to the PoIs in a state would all go back to the capital city of that state, which would then be interconnected to the neighbouring states capital cities (this is what the ISP I use, Aussie Broadband does at least).