On a Windows machine, the standard TCP Window Size is 64KB. 64KB converted to bits = 524288
64KB = 65536 Bytes
65536 Bytes * 8 = 524288 bits
Calculate TCP throughput:
Window Size / RTT = Throughput
Windows Size in bps (bits per second)
RTT in seconds
Throughput in bps (bits per second)
Lets say you have a 1Gig link between Miami and NY and your latency is 33 milliseconds.
524288 bits / 0.033 = 15,887,515 = 15.8 Mbps MAX Possible Throughput
What this is saying is that if you have two servers, one in Miami and one in NY, and you start a file transfer between the two of them, the most throughput you will get is 15.8Mbps. It doesn’t matter that you have a 1Gig link.