Re: slow tcp on 100mbps wan, strange tcp window behaviour on ubuntu 9.10

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any idea what the rtt on the link ?

On Wed, Mar 10, 2010 at 4:14 PM, Andres Meyer <andres.meyer@xxxxxxxxxxxx> wrote:
> On Thu, 2010-03-11 at 00:59 +0100, Andres Meyer wrote:
>> On Wed, 2010-03-10 at 15:49 -0800, Stephen Hemminger wrote:
>> > If you use tcptrace to produce xplot graphs of sequence number,
>> > you get the attached result.  The upper line is the sequence number
>> > of the upper bound of the window.
>> >
>> > It shows the window for the sender is open but is not being used.
>> > This means the send window is not configured large enough on the sender.
>> > With current Linux kernels, you should not have to configure socket
>> > send buffers in the application.  It maybe that the application is
>> > using setsockopt to set send buffer space but not allowing for enough window.
>>
>> Thank you for the tip. I also studied this graph (and others) before
>> posting. I thought the same thing in the beginning, so I tried setting
>> the settings in the /proc/sys/net/ipv4 region in the kernel. I tried
>> with iperf and netcat. I even set the window with the -w option to
>> 1Mbyte in iperf (client and server), just to see if something would
>> change, but nothing did. Do you know another program that for sure does
>> not use this setsockopt for testing?
>
> I also tried with wget (client) and apache2.2 (server), same effect.
>
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