Wireshark · Wireshark-users: Re: [Wireshark-users] TCP Window Sizes

[Hansang Bae <hbae@xxxxxxxxxx>]

Aaron Allen wrote:
> 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?

Are you sure it's not using RFC1323?  Do you have a sample trace that 
you can upload (in pcap format).  TCP setup and a few sampling during 
the upload will be fine.  Maybe it's scaling and you're not looking at 
the scaling factor?


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Thanks,
Hansang