Re: [tsvwg] L4S DSCP (was: L4S drafts: Next Steps)

[Steven Blake <[e-mail]>]

On Tue, 2021-03-30 at 19:12 -0400, Wesley Eddy wrote:
> On 3/30/2021 6:41 PM, Jonathan Morton wrote:
> > Okay, so what mechanism do you propose to contain the L4S
> > experiment to the participating networks?
> 
> I think the notion of a strong containment guarantee to
> participating 
> networks that you mention is a bit extreme in contrast to just
> reducing 
> the likelihood or severity of issues. There has been a lot of
> congestion 
> control experimentation on Internet paths that strong containment
> has 
> not been expected of.

How many of those experimental congestion control protocols set a RFC
3168-defined ECT marking on their packets and then failed to respond to
a RFC 3168-defined CE congestion signal by triggering multiplicative
decrease?
 

> I think the sense of the working group has been to take an approach
> of 
> collecting and recommending reasonable measures to identify and
> avoid 
> issues when experimenting with L4S.  This is mainly in Section 4 of
> the 
> ops draft right now.  I have not understood the general working
> group 
> direction to be asking for strong containment guarantees though, and
> I 
> don't think that needs to be a goal.

The recommended measures in Sec. 5 (not 4) of l4sops-02 are directed at
the operators deploying RFC 3168 and *not participating in the L4S
experiment* and consist of either disabling RFC-3168 ECN or of
instantiating configurations that depend on the capability to classify
on ECT(1) markings specifically, a configuration feature that doesn't
appear to be universally available in deployed software. Opinions
differ on whether these measures are "reasonable" or are directed at
the appropriate parties.


Regards,

// Steve