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Date:      Fri, 23 Nov 2012 07:52:51 -0800 (PST)
From:      Barney Cordoba <barney_cordoba@yahoo.com>
To:        Ingo Flaschberger <if@xip.at>, Andre Oppermann <andre@freebsd.org>
Cc:        freebsd-net@freebsd.org
Subject:   Re: Low Bandwidth on intercontinental connections
Message-ID:  <1353685971.91981.YahooMailClassic@web121601.mail.ne1.yahoo.com>
In-Reply-To: <50AF90D1.4020404@freebsd.org>

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--- On Fri, 11/23/12, Andre Oppermann <andre@freebsd.org> wrote:

> From: Andre Oppermann <andre@freebsd.org>
> Subject: Re: Low Bandwidth on intercontinental connections
> To: "Ingo Flaschberger" <if@xip.at>
> Cc: freebsd-net@freebsd.org
> Date: Friday, November 23, 2012, 10:05 AM
> On 23.11.2012 15:46, Ingo
> Flaschberger wrote:
> > Am 23.11.2012 13:47, schrieb Marc Peters:
> >> PR filed: http://www.freebsd.org/cgi/query-pr.cgi?pr=173859
> >
> > Downloads from ftp1.us.freebsd.org to Europe (ping time
> ~170ms), I see up & down ramping of transfer
> > speed (600kb/sec - 50kb/sec)
> > over serverall releases:
> > FreeBSD 6.3-PRERELEASE
> > FreeBSD 7.2-STABLE
> > FreeBSD 8.2-STABLE
> > FreeBSD 9.1-PRERELEASE
> >
> > Linux performs much better, max speed was 1.2Mb/sec,
> and is not as much up & down ramping as freebsd.
> 
> It's about 168ms for me and I don't see the problem here.
> Speed is about 18.4Mbps.
> 
> -- 
> Andre

It's probably something with the window timeout. On a local connection,
the acks come in before the window is fully sent (or very nearly)
while on a distant connection the window is sent and then there is a
longish delay/wait. This used to be a big issue on ftp servers back in 
the day. The algorithms for how to send stuff when the window left
was less than a full packet were poorly done.

BC



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