Re: [tsvwg] Review comments on a careful read of the L4S ID (#13. RFC4774)

[Bob Briscoe <[e-mail]>]

Gorry, David,

On 06/05/2021 07:52, Gorry Fairhurst wrote:
>
> =================================================================
> ***13. Position with respect to RFC4774 is rather unclear, which 
> motivates a case for alternative semantics for carrier experiments*
>
> This text:
> “The L4S treatment is an experimental track alternative packet marking
> treatment [RFC4774]”
> •RFC4774 states: “The assumption of this document is that when 
> alternate semantics are defined for the ECN field, a codepoint in the 
> diffserv field is used to signal the use of these alternate ECN 
> semantics to the router.” This text and position needs to be 
> clarified, and is being discussed in a tsvwg email thread.
> =================================================================
>

[BB] RFC4774 does not say anything that implies that a DSCP is 
recommended / required / preferred as a way to signal alternative ECN 
semantics. The RFC itself is very clear that DSCP is just an example. At 
the end of Section 3 of RFC4774, after the above quote, it says:

    We note that this discussion does not exclude the possibility of
    using other methods, including out-of-band mechanisms, for signalling
    the use of alternate semantics for the ECN field.  The considerations
    in the rest of this document apply regardless of the method used to
    signal the use of alternate semantics for the ECN field.

Also quoting from Section 2:

        As an example, in most of the proposals for alternate ECN
        semantics, a diffserv field is used to specify the use of
        alternate ECN semantics.

Proposed resolution: No text changes. Although if something else 
underlies this concern, I'd be happy to fix. Please advise.




-- 
________________________________________________________________
Bob Briscoe                               http://bobbriscoe.net/