Wireshark-users: [Wireshark-users] TCP Window Sizes
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From: Aaron Allen <Aaron.Allen@xxxxxxxxxxxxxx>
Date: Thu, 4 Sep 2008 10:12:31 -0400

This is primarily a TCP related question, so if there is a more appropriate forum for this question, please point me in the right direction.

 

I am trying to identify the source of a slowdown for an upload to Amazon S3 from a Windows 2008 server.  Packet captures seem to indicate the problem is with the TCP window size.  When I manually increase the TCP window size on another machine, I am easily able to get maximum bandwidth utilization.  But, for some reason, this 2008 machine won’t increase the window size beyond 64K.

 

I can’t increase the TCP Window size on the 2008 machine because of the new and “improved” auto tcp tuning.  Is there something else I should be looking for that could be causing the window size to not be scaled any higher?