roscore reduce network bandwidth

edit

I just got warned about overloading my local network if I placed a bandwidth heavy sensor on one machine and the roscore on a different computer. What I don't understand is exactly how roscore coordinates data transfer.

For example, the roscore node is on machine A, and the sensor is on machine B. If all of the processes that need access to the data rich sensor remain on machine B, will that still require heavy network bandwidth? In other words, does all data get passed through the roscore on machine A, thereby overloading the network? or does it actually coordinate direct tcp sockets between processes so that I could intelligently separate my processes to prevent network overload?

Thank You!