[Make-wifi-fast] [Babel-users] reducing delays in wifi mcast queues

[Jonathan Morton]

> On 19 Sep, 2018, at 3:04 am, Juliusz Chroboczek <jch at irif.fr> wrote:
> 
>> Recently I tried to deploy a few babel 1.8.2 nodes with the latest
>> openwrt, which I had to back out rapidly because I was dropping so many
>> babel packets under contention.
> 
> That's interesting.  Could I please see a log?
> 
>> A patch to universally enable babel ecn in net.c "solves" this problem,
> 
> Interesting.  AFAIK, ECN is only considered by AQM queues, so this implies
> there's a queue in the way that's dropping Babel packets.  Perhaps this
> queue could be convinced to treat Babel packets specially without having
> to hack around it using ECN?  Or perhaps, if we know which queue that is,
> we could modify Babel's packet scheduling to be more AQM friendly?

I assume it's the make-wifi-fast logic, which has fq_codel baked into the Linux wifi stack.  That would react to congestion and ECN as described.

 - Jonathan Morton