Firstly this happens on all machines in my environment (servers, desktops, multiple hardware types and configs)
When I copy a file across a WAN link (Cisco PIX VPN over DS3's) from a NT4,0 machine to a WIn2k or a NT4.0 the data transfer rate is very slow. Doing the same test with the same files from W2k to W2k is dramatically faster (about 10 times faster)
From looking at sniffer tracers the file copy to or from NT4.0 machines show the protocol as NetBIOS over TCPIP, Win2k to Win2k just shows TCPIP.
We have tried changing the default MTU/RWIN settings in the registry but this only has a minor impact on performance.
So my question is
What do Win2k machine talk to one another so much master that NT4.0?