[183479] in North American Network Operators' Group
Re: buffer bloat and packet pacing
daemon@ATHENA.MIT.EDU (Brett Frankenberger)
Thu Sep 3 14:13:18 2015
X-Original-To: nanog@nanog.org
Date: Thu, 3 Sep 2015 13:13:14 -0500
From: Brett Frankenberger <rbf+nanog@panix.com>
To: Saku Ytti <saku@ytti.fi>
In-Reply-To: <CAAeewD97v8kEtdewJj7SefOmtz4nJ-tz+-8qTx4_ZeqiNx6HtA@mail.gmail.com>
Cc: nanog list <nanog@nanog.org>
Errors-To: nanog-bounces@nanog.org
On Thu, Sep 03, 2015 at 05:48:00PM +0300, Saku Ytti wrote:
> Hey Brett,
>
> > Here's a paper that shows you don't need buffers equal to
> > bandwidth*delay to get near capacity:
> > http://www.cs.bu.edu/~matta/Papers/hstcp-globecom04.pdf
> > (I'm not endorsing it. Just pointing out it out as a datapoint.)
>
> Quick glance makes me believe the S and D nodes are equal bandwidth,
> but only R1-R2 bandwidth is explicitly stated.S1, D1, Sn, Dn are only
> ever mentioned in the topology. If Sender is same or lower rate than
> Destination, then we really shouldn't need almost any buffering.
Unless Sender is higher than R1-R2.
> Issue should only come when Sender is significantly higher rate than
> Destination and network is not limiting them.
I didn't read it in detail either, but at first glance, it appears to
me that the model is infinite bandwidth and zero latency between S and
R1, and D and R2, with queueing happening in R1.
That's not going to give materially different results than, having S-R1
be 4 times R1-R2, and R2-D being the same as R1-R2. So it fits well
with the original discussion here of 40G into 10G.
-- Brett
