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

From: Aaron Allen <Aaron.Allen@xxxxxxxxxxxxxx>
Date: Tue, 9 Sep 2008 12:48:59 -0400

It's possible I could be missing something.  I've attached a sample from the start of an upload to S3.  You can see that the packets from Amazon are being scaled, but the packets from my server aren't.

Thanks!
-Aaron

-----Original Message-----
From: wireshark-users-bounces@xxxxxxxxxxxxx [mailto:wireshark-users-bounces@xxxxxxxxxxxxx] On Behalf Of Hansang Bae
Sent: Monday, September 08, 2008 9:42 PM
To: Community support list for Wireshark
Subject: Re: [Wireshark-users] TCP Window Sizes

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?


--

Thanks,
Hansang
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Attachment: AmazonS3.pcap
Description: AmazonS3.pcap