[ta1243]

Even if you had a dedicated fibre back to a 1G port on a switch in a data centre, there's going to be bottle necks at some point. Sure they could ensure that 48 port switch you're connected to has no contention, but non-blocking networks aren't cheap, and are needed in the vast majority of cases.

[namibj]

That said, the classic case of game release can be handled with a bit of P2P if the oversubscription happens late enough to have sufficiently many downloads that can share among themselves without causing congestion for others.

Just traffic shape that protocol/connection to only use a connection free share of upstream if upstream is currently close to dropping packets, and work a bit with others to get swarms to prioritize downloading from nodes close in IPv6 address space.

[ta1243]

Depends on your peer

You and your nearest 400 neighbours plug into a non-blocking 1g port network. Find you can do 1g to your neighbours

But you need a 400g uplink (and remember to account for resilience), so you go into a switch with 40 400g ports, ok, that's 1.6tbit

Scale this up to a small town with 20,000 people and you need 20tbit of backbone to serve your residents with 1G non-blocking, very few will ever use the full 1G

Sharing bandwidth makes perfect sense. If you want uncontended (to where? Local IXP, a major IXP? One on the other side of the world?) then get a business line which gives you uncontended connectivity.

[namibj]

Uncontended to a dense 1U switch, say 24 downstream ports of 100/200 G QSFP. That's uncontended for 2400/4800 customers with their own 1G links. So about 4~30k people worth, so no, not even up to full city for all but the smallest cities.