There is a new feature available in Windows Vista and Windows Server 2008 that allows to increase the value of the TCP Receive Window size over its default maximum value, 65,536 bytes.
This feaute that is configured by default, in some circumstances, for example Firewall products that doesn´t implement correctly TCP Window Scaling, could impact the performace of some network operations launched from a Vista/Win2008 machine, some programs may respond slowly or may stop responding.
The command to check the configuration of this feature is:
netsh interface tcp show global
The command to change the configuration of this feature is:
netsh interface tcp set global autotuninglevel=disabled|highlyrestricted|restricted|normal|experimental
Where:
disabled: Fix the receive window at its default
value.
highlyrestricted: Allow the receive window to
grow beyond its default value, but do so
very conservatively.
restricted: Allow the receive window to grow
beyond its default value, but limit such
growth in some scenarios.
normal: Allow the receive window to grow to
accomodate almost all scenarios.
experimental: Allow the receive window to grow
to accomodate extreme scenarios.
WARNING: This can dramatically degrade
performance in common scenarios and should
only be used for research purposes.
![share save 171 16 TCP Window Scaling : [AutoTuningLevel]](http://www.hkeyusers.com/wp-content/plugins/add-to-any/share_save_171_16.png "TCP Window Scaling : [AutoTuningLevel]"){kind=small}
Using HP thin clients with rdesktop and connection keeps dropping. This could be the answer. I’ve just disabled Autotuning. Fingers crossed.
Looking good. 2 hours and no dropped connections. Thank you for this post.