[Cake] COBALT implementation in ns-3 with results under different traffic scenarios

[Shefali Gupta]

Hello Jonathan,

Thanks for your feedback.

As suggested, we have produced CoDel and PIE graphs with small NIC buffer
and uploaded the corresponding graphs.

Link:
https://github.com/Daipu/COBALT/wiki/Link-Utilization-Graphs-with-Different-NetDeviceQueue-size

We have also uploaded one way end-to-end dela*y* graphs in Light traffic
scenario for CoDel, COBALT and PIE.
Link: https://github.com/Daipu/COBALT/wiki/End-To-End-Delay-Graphs

Thanks a lot for your help. We really appreciate it.

Regards,
Shefali Gupta
Jendaipou Palme

On Mon, Dec 10, 2018 at 8:45 PM Jonathan Morton <chromatix99 at gmail.com>
wrote:

> > On 10 Dec, 2018, at 2:30 pm, Jendaipou Palmei <jendaipoupalmei at gmail.com>
> wrote:
> >
> > As suggested, we changed the NIC buffer size to 1 packet for the
> simulation and also tried these different buffer sizes: 10, 50 and 75.
> >
> > The default NIC buffer size in ns-3 is 100 packets.
> >
> > Additionally, we also enabled BQL and tried.
> >
> > We see that the link utilization gets significantly affected when we
> keep the NIC buffer size small.
>
> Yes, that's what I'd expect to see from Reno-type congestion control, and
> is one good reason why alternatives to Reno were developed (eg. Compound,
> CUBIC, BBR).  You may wish to explore what happens with Compound and CUBIC,
> once your basic measurement methodology has matured.
>
> I would suggest using BQL, since it's available and represents a realistic
> deployment.
>
> If you were to add TCP (or parallel UDP/ICMP) RTT measurements, you'd see
> that the peak latency was correspondingly improved by removing the dumb
> FIFO hidden within the NIC.  I estimate that a 100-packet buffer accounts
> for about 120ms of latency at 10Mbps, which should definitely be visible on
> such a graph (being almost 250% of your baseline 50ms latency).
>
> Since latency is the main point of adding AQM, I'm a little surprised that
> you haven't already produced graphs of that sort.  They would have
> identified this problem much earlier.
>
> At present you only have COBALT graphs with the small NIC buffer.  For a
> fair comparison, Codel and PIE graphs should be (re-)produced with the same
> conditions.  The older graphs made with the large NIC buffer are
> potentially misleading, especially with respect to throughput.
>
>  - Jonathan Morton
>
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