Re: [tsvwg] Scope of the L4S Experiment (was: Guard DSCP)

[Steven Blake <[e-mail]>]

On Tue, 2021-05-04 at 16:35 +0000, Black, David wrote:
> Mike,
>  
> > I had certainly understood the intended scope to be sets of
> cooperating/participating networks rather than the Internet as a
> whole.
> > How could it possibly be otherwise, with a change in the
> semantics of CE that is incompatible with existing standards, without
> at the same time obsoleting those standards?
>  
> Short answer (as I understand it) – L4S was originally intended to be
> compatible.  For details of what compatible means in this context,
> see Section 4.3 of RFC 4774 (Option 3:  Friendly Coexistence with
> Competing
>  Traffic, https://datatracker.ietf.org/doc/html/rfc4774#section-4.3).
>  
> > The evidence presented here strongly suggests to me that L4S is not
> benign to existing standards. If it is to be used experimentally, it
> must be contained.
> > If it is to be used internet-wide, then existing incompatible uses
> should be obsoleted.
>  
> You're not the only person who has expressed the view that L4S is not
> able to proceed under RFC 4774 Option 3.
>  
> Everyone - when responding to this message, please keep in mind that
> RFC 4774 is a BCP (Best Current Practice) document, namely BCP 124.
>  
> Thanks, --David
>  
> 
> From: C. M. Heard <[e-mail]> 
> 
> Sent: Tuesday, May 4, 2021 12:40 AM
> 
> To: Black, David
> 
> Cc: TSVWG
> 
> Subject: Scope of the L4S Experiment (was: Guard DSCP)
> 
>  
> 
> [EXTERNAL EMAIL] 
> 
> 
> 
> On Tue, Apr 27, 2021 at 3:57 PM Black, David wrote:
> 
> 
> > 
> > the appropriate L4S experiment scope may be sets of
> > cooperating/participating networks rather than the (originally
> > envisioned) Internet as a whole.
> > 
> > 
> 
>  
> 
> 
> I had certainly understood the intended scope to be sets of
> cooperating/participating networks rather than the Internet as a
> whole. How could it possibly be otherwise, with a change in the
> semantics of CE that is incompatible with existing
>  standards, without at the same time obsoleting those standards?
> 
> 
>  
> 
> 
> When Differentiated Services was introduced by RFC 2474, the existing
> TOS standard was obsoleted, based on good evidence that it was unused
> (there was only one implementation of TOS routing, IIRC, and
> negligible deployment). It didn't get
>  introduced as an experiment.
> 
> 
>  
> 
> 
> When the original experimental incarnation of ECN was specified by
> RFC 2481, it could be introduced as an internet-wide experiment
> because prior standardized uses of the field had been obsoleted on
> good evidence of non-use, and there was
>  good evidence that harm would not be caused to deployed systems.
> 
> 
>  
> 
> 
> The evidence presented here strongly suggests to me that L4S is not
> benign to existing standards. If it is to be used experimentally, it
> must be contained. If it is to be used internet-wide, then existing
> incompatible uses should be obsoleted.
> 
> 
>  
> 
> 
> One or the other, please. Don't deploy L4S internet-wide and call it
> experimental.
> 
> 
>  
> 
> 
> Mike Heard
> 
> 
> 
> 
> 
> 



To reiterate what I wrote on March 26: if there is really so little RFC
3168 ECN deployed in the Internet that it can be safely ignored for an
Internet-wide ECN experiment with incompatible signaling and congestion
response, then the only responsible thing to do is to go through the
process of moving RFC 3168 to historic.

Regards,



  
  


// Steve