[Ecn-sane] [tsvwg] Comments on L4S drafts

[Jonathan Morton]

> On 19 Jul, 2019, at 4:06 pm, Black, David <David.Black at dell.com> wrote:
> 
> To be clear on what I have in mind:
> 	o Unacceptable: All traffic marked with ECT(1) goes into the L4S queue, independent of what DSCP it is marked with.
> 	o Acceptable:  There's an operator-configurable list of DSCPs that support an L4S service - traffic marked with ECT(1) goes into the L4S queue if and only if that traffic is also marked with a DSCP that is on the operator's DSCPs-for-L4S list.

I take it, in the latter case, that this increases the cases in which L4S endpoints would need to detect that they are not receiving L4S signals, but RFC-3168 signals.  The current lack of such a mechanism therefore remains concerning.  For comparison, SCE inherently retains such a mechanism by putting the RFC-3168 and high-fidelity signals on different ECN codepoints.

So I'm pleased to hear that the L4S team will be at the hackathon with a demo setup.  Hopefully we will be able to obtain comparative test results, using the same test scripts as we use on SCE, and also insert an RFC-3168 single queue AQM into their network to demonstrate what actually happens in that case.  I think that the results will be illuminating for all concerned.

 - Jonathan Morton