Let's say I have 4 computers on a gigabit switch. Is the switch's gigabit rating the speed for all connections added up or the speed between any two computers? For example if computer 1 was transferring a file to computer 2 at max speed and computer 3 was sending a file to computer 4 would the 1 to 2 and 3 to 4 connection each go at 1000mbit (after accounting for overhead, of course) or would the combination of the two transfers be limited to 1000mbits?
I'm assuming the answer is the latter and as such I have a follow up. If computer 1 and 2 were each connected to switch A and switch A was connected to switch B and then computers 3 and 4 were connected to switch B would we then see simultaneous gigabit speeds between (1 and 2) and (3 and 4). In this scenario though I assume you'd lose that benefit if there was a simultaneous transfer between (1 and 3) and (2 and 4) since the connection between A and B would be the binding constraint.
If my assumptions above are correct would it make sense to use 10gbe switches even though all clients are only 1000mbps for the added simultaneous throughput?