[Cerowrt-devel] Comcast's NANOG slides re Bufferbloat posted (Oct 2016)

Neal Cardwell ncardwell at google.com
Thu Oct 20 10:44:06 EDT 2016

On Thu, Oct 20, 2016 at 8:15 AM, Rich Brown <richb.hanover at gmail.com> wrote:
> https://www.nanog.org/sites/default/files/20160922_Klatsky_First_Steps_In_v1.pdf

Regarding these passages from the slide deck:

   What do the results suggest?
   There may be a tradeoff between upload latency
   and upload throughput, and that tradeoff is
   not necessarily linear: there may be a “sweet spot”
   where latency is noticeably reduced, while the
   impact on throughput is negligible

   What happens next?
   Fixed buffer size setting impractical for scaled usage

I would agree that there is a delay/throughput "sweet spot", one that
varies across network scenarios. BBR congestion control is
specifically designed to dynamically estimate the bandwidth and delay
characteristics of the path, to estimate where that "sweet spot" is,
and operate near it.

The BBR paper ( currently on the ACM Queue site -
http://queue.acm.org/app/ ) has a diagram and discussion related to
this non-linear delay/throughput trade-off that the presentation


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