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

[Jonathan Morton <chromatix99@gmail.com>]

>> We're currently working on the following:
>> 
>> 1. plots for the actual number of marks/drops per time interval for COBALT, CoDel, and PIE.
>> 2. zoomed in plots on small time intervals to show the dynamic behavior of the algorithm.
>> 3. a file showing the timestamp of each drop.
> 
> I await these with interest.

I noticed that some progress has been made here already, in particular I can now see cwnd graphs which make a very interesting datapoint when directly compared with the throughput and queue-occupancy graphs.  It's now definitely clear that the senders are using TCP Reno or some close variant thereof.

In fact, the three graphs are mutually inconsistent.  Aside from the sharp cwnd reduction events, the cwnd of all the flows increases roughly linearly over time, but the throughput remains flat while the queue is almost always empty (for Codel and COBALT).  This can only be explained if there's a hidden queue at the bottleneck, perhaps associated with the simulated NIC immediately downstream of the AQM.

I would suggest checking the simulation setup carefully for hidden queues of this sort.

 - Jonathan Morton