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

Dave Taht dave at taht.net
Fri Nov 23 11:05:19 EST 2018

Jendaipou Palmei <jendaipoupalmei at gmail.com> writes:

> Hi Dave,
> We have added the results for CoDel and PIE in the same setup.
> Link:
> https://github.com/Daipu/COBALT/wiki/Light-Traffic

Wonderful, thank you. One new thing in cobalt is it responds much
earlier to stuff in slow start, and thus that first spike is much
smaller than it is with codel or pie. Network researchers spend way too
much time looking at stuff in congestion avoidance mode, where what we
see in the real world is most flows never get out of slow start.

As an example, slashdot.org, last I checked, started 78 flows over 2.2
seconds for a page load.

I'm still puzzled as to why queue utilization spikes and drops so
much on all three qdiscs in your simulation. In general we use a much
larger number of packets in our packet limit (1000 or more) and I am
thinking tail drop is controlling your queue more than any of the qdiscs
are at 10mbit with a 50ms delay. I haven't had enough coffee yet this
morning to do the bdp here, but that's another easy param to tweak.

Ns3, btw, also has fq_codel. I happen to be fond of what fq can do. if
you feel like another run, with the packet limit increased and that
added too? 

Care to try 100mbit? 20ms RTT? 80ms? :)

Can you put your test code up somewhere?

> Thanks for your help. 
> On Thu, Nov 22, 2018 at 9:02 PM Dave Taht <dave.taht at gmail.com> wrote:
>     Your light traffic graph is puzzling, with the synchronized drops.
>     Is
>     it possible for you to do another test run, same setup, with codel
>     or
>     pie?
>     On Thu, Nov 22, 2018 at 5:57 AM Jendaipou Palmei
>     <jendaipoupalmei at gmail.com> wrote:
>     >
>     > Hello Jonathan and Dave,
>     >
>     > Thanks for your timely inputs.
>     >
>     > We have implemented COBALT in ns-3. The main C++ file is here:
>     >
>     >
>     https://github.com/Daipu/COBALT/blob/master/src/traffic-control/model/cobalt-queue-disc.cc
>     >
>     > We have also added Queue length and Throughput graphs for COBALT
>     in our wiki:
>     >
>     > https://github.com/Daipu/COBALT/wiki
>     >
>     > Thanks and Regards,
>     > Jendaipou Palmei
>     > Shefali Gupta
>     > _______________________________________________
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>     -- 
>     Dave Täht
>     CTO, TekLibre, LLC
>     http://www.teklibre.com
>     Tel: 1-831-205-9740

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