Robust FTPRWIN(Receive Window)
The TCP Receive window size is the amount of receive data (in bytes) that can be buffered at one time on a connection. That is the amount of data the sending host can send before waiting for an acknowledgement and a window update from the receiving host. Matching the receive window to even increments of the MSS increases the percentage of full-sized TCP segments utilized during bulk data transmissions is the MaxMTU ( 40 bytes for TCP and IP headers).
The RWIN default is 8192 bytes rounded up to the nearest MSS increment
for the connection. If that isnÆt at least 4 times the MSS, then itÆs
adjusted to 4*MSS, with a max size of 64k.bytes. With widows 95 default
MaxMTU of 1500, the default RWIN is rounded to 8760 (1460*4).Performance
can be greatly improved by setting RWIN to a lower value such as 4 times
your MSS (MTU-40).The trick is to bring it to a value below 8192.Many
users have better success with 6,8 or even 10* MSS.
However; manually setting RWIN may decrease performance because it takes
the control away from windows, and if the MTU is negotiated to a different
value, then the size of the RWIN is no longer a whole integer multiple.
Therefore; for adjusting RWIN to be effective you must make sure your
MTU is set where it will not renegotiate to a lower value.
Note: If you are experiencing problems such as your browser stopping
in the middle of a page, an MTU value of 576 might fix the problem.