Depends, ISP can have connection of10Gbps wich is fastest speed over optical cable. Alot of ISP-s have more of fiber optics so formula is N x10Gbps . ( N is number of fiber optic cables ).
But if you think of fastest speed on1 PC it still can be10Gbps. But the problem then is HDD wich most of time speed of HDD is lower then speed of internet.
Fastest internet speed in lab :2009 Alcatel-Lucent[7] speed:15 Tbit/s distance:90 km
