[Codel] [Cake] Proposing COBALT

[Eric Dumazet]

On Sat, 2016-06-04 at 13:10 -0400, Noah Causin wrote:
> I notice that issue with Steam.  Steam uses lots of ECN, which can be 
> nice for saving bandwidth with large games.  The issue I notice is that 
> Steam is the one application that can cause me to have ping spikes of 
> over 100ms, even though I have thoroughly tested my network using both 
> flent and dslreports.
> 
> I also notice that I get large sparse delays in the cake stats during 
> steam downloads.  The highest I can remember right now is like 22ms.

ECN (as in RFC 3168) is well known to be trivially exploited by peers
pretending to be ECN ready, but not reacting to feedbacks, only to let
their packets traverse congested hops with a lower drop probability.

https://www.ietf.org/rfc/rfc3540.txt