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Date:      Mon, 08 Mar 2004 10:24:31 -0800
From:      "Kevin Oberman" <oberman@es.net>
To:        Andre Oppermann <andre@freebsd.org>
Cc:        freebsd-current@freebsd.org
Subject:   Re: My planned work on networking stack 
Message-ID:  <20040308182431.4FA6D5D08@ptavv.es.net>
In-Reply-To: Your message of "Sun, 07 Mar 2004 23:50:11 %2B0100." <404BA723.C8141806@freebsd.org> 

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> Date: Sun, 07 Mar 2004 23:50:11 +0100
> From: Andre Oppermann <andre@freebsd.org>
> Sender: owner-freebsd-current@freebsd.org
> 
> David Malone wrote:
> > 
> > On Mon, Mar 01, 2004 at 11:18:34PM +0100, Andre Oppermann wrote:
> > >  [] automatically sizing TCP send buffers to achieve optimal performance
> > >     over a wide range of bw*delay situations.  (in progress)
> > 
> > Hi Andre,
> > 
> > This reminded me - do you know what happened to the plan to implement
> > SACK for FreeBSD? I'm working with a research group that's interested
> > in new high speed TCP techniques and they'd prefer to work with
> > FreeBSD, but they've been using Linux 'cos they need SACK. They
> > might actually be interested in spending some time implementing it,
> > if we weren't going to be clashing with anytone else.
> 
> I don't know of any current project or effort to implement SACK on
> FreeBSD.  It is not on my todo list and it doesn't fit there.  But
> I'm available if someone wants to discuss specifics and implementation
> details.

I know that our organization would love to see SACK. Much of the
high-performance network development that used to be on FreeBSD has
moved to Linux simply because SACK is essential. You can't run
trans-oceanic TCP streams of gigabit or more throughput without it.

Unfortunately, SACK is often looked upon as a waste of effort to those
who use nets in more commercial forms where aggregation of lots of small
streams is how fat pipes are used. Research big science are about the
only ones who have a real need for this kind of performance and it's
growing fast. Without SACK, FreeBSD will be a non-starter for these
purposes. 
-- 
R. Kevin Oberman, Network Engineer
Energy Sciences Network (ESnet)
Ernest O. Lawrence Berkeley National Laboratory (Berkeley Lab)
E-mail: oberman@es.net			Phone: +1 510 486-8634



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