Consider an Access Point with a packet queue that can hold up to 50 packets and a network whose bottleneck is a link with a datarate of 50 Mbit/s.
There are quite a few nodes connecting wirelessly to the Access Point, one of them uploads a file (1.5 GB) via FTP to a remote server. When observing the average throughput of the FTP upload, I have noticed it is around 13.7 Mbit/s. And now I wonder how this is possible? The bottleneck is 50 Mbit/s, right?
The only reason that I can think of is this: The bottleneck must be somewhere else. And since all physical connections of the network support a higher datarate, it must be with the Access Point.
The TCP MSS = 1460 bytes, its advertised receive window is scaled to 1,460,000 bytes. Is it possible to determine the network's bottleneck with this data? If so, how?