TCP Window size strange behaviour

[Philip <philip.lawrence3@xxxxxxxxxxxxxx>]

I have searched the archives and found nothing other than I have tried 
already. I want to increase the TCP window size on an ftp server. I have
on  sender and receiver, both Tru64:

inet:
tcp_recvspace=122880
tcp_sendspace=122880

Using tcpdump to monitor the connection the receivers window size is 
65536 as is the senders. However if I connect from a Linux system the 
Tru64 server advertises a window size of 122880 and the Linux system 
window size is very small indeed.  On Linux I am using lftp and ftp on 
Tru64. The ftp data transfer rate over a WAN is a lot higher using a 
Linux client than the Tru64 client, I have backed off Tru64 transfer 
rate using 'netstat -limit' to reduce resends now I am looking at window
size.

I cannot understand why the difference in TCP window size when 
connectiong for Linux and Tru64, could anyone shed any light?

Thanks and regards

Phil Lawrence

philip.lawrence3@xxxxxxxxxxxxxx