Ok, so this isn’t a new topic. It’s been around for quite a while but I have never
encountered it, so now that I have- it’s time for a post about it.
I have installed a new PC (Windows Vista 64bit) and connected it to my home
network using a wireless NIC (Realtek RTL8168B/8111b). The wireless router I
use is an Edimax BR-6215SRg. The same network has several other PCs connected
to it wirelessly and one PC that is wired.
When copying files to/from the new PC (HTPC) it seemed to simply freeze up. Even
though I could move the mouse pointer I couldn’t really do anything else…Now keep in
mind that this is a new PC (and it’s fully patched:SP1 and everything). Since this
is a new PC I started worrying that I have a hardware issue, yet after some research
on the Internet I found others that had similar problems due to the TCP receive window
auto-tuning issue in the new TCP/IP stack.
The advice was to simply turn off the auto-tuning feature by running the following
netsh interface tcp set global autotuninglevel=disabled
I decided to give it a try, and not surprisingly it worked. Personally, I find it very odd that
due to a networking your whole OS freezes up. When dwelling deeper into the issue
it seems that the new TCP/IP stack tries to manage data flow in a more efficient way by constantly
tuning the receive window set by TCP. This window allows the receiver to define the amount
of data it will receive before the sender has to stop data if it hasn’t received acknowledgments.
In older versions of Windows, the window size was set once (not tuning) which causes data flow
to be less efficient. Once I disabled the feature, I could see that my copying speed has dropped from
4.5 to 3.7. On the other hand it no longer froze my system…
I am not sure who is at blame here, my gateway, the NICs driver or the favorite target of the last few