[Bloat] Congestion control with FQ-Codel/Cake with Multicast?

[Jonathan Morton]

> On 24 May, 2024, at 12:43 am, Holland, Jake via Bloat <bloat at lists.bufferbloat.net> wrote:
> 
> I agree with your conclusion that FQ systems would see different
> streams as separate queues and each one could be independently
> overloaded, which is among the reasons I don't think FQ can be
> viewed as a solution here (though as a mitigation for the damage
> I'd expect it's a good thing to have in place).

Cake has the facility to override the built-in flow and tin classification using custom filter rules.  Look in the tc-cake manpage under "OVERRIDING CLASSIFICATION".  This could be applicable to multicast traffic in two ways:

1: Assign all traffic with a multicast-range IP address to the Video tin.  Since Cake schedules by tin first, and only then by host and/or flow, this should successfully keep multicast traffic from obliterating best-effort and Voice tin traffic.

2: Assign all multicast traffic to a single flow ID (eg. zero), without reassigning the tin.  This will cause it all to be treated like a single flow, giving the FQ mechanisms something to bite on.

 - Jonathan Morton