The window size is the maximum number of bytes of data that can be transmitted in one segment. Increasing the window size for a TCP-based file transfer would increase throughput until the slowest link in the path saturates. It would be preferable to have a window size appropriate to the size of the link. There would be less buffering, the ACKs would return more quickly and more of the bandwidth would be used. Ideally you are looking for a Window Size >= Bandwidth * RTT.
Re: What is TCP window sizing?
The window size is the maximum number of bytes of data that can be transmitted in one segment. Increasing the window size for a TCP-based file transfer would increase throughput until the slowest link in the path saturates. It would be preferable to have a window size appropriate to the size of the link. There would be less buffering, the ACKs would return more quickly and more of the bandwidth would be used. Ideally you are looking for a Window Size >= Bandwidth * RTT.