Re: [tsvwg] Alissa Cooper's Discuss on draft-ietf-tsvwg-rfc5405bis-18: (with DISCUSS)

[Gorry Fairhurst <[e-mail]>]

See below.

On 12/10/2016 15:49, Alissa Cooper wrote:
> Alissa Cooper has entered the following ballot position for
> draft-ietf-tsvwg-rfc5405bis-18: Discuss
>
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> ----------------------------------------------------------------------
> DISCUSS:
> ----------------------------------------------------------------------
>
> = Section 3.17 =
>
> "An application sending ECN-capable datagrams MUST provide an
>        appropriate congestion reaction when it receives feedback
>        indicating that congestion has been experienced.  This must result
>        in reduction of the sending rate by the UDP congestion control
>        method (see Section 3.1) that is not less than the reaction of TCP
>        under equivalent conditions."
>
> Is the second "must" meant to be normative? If so, this worries me a bit.
> RFC 6679 I believe retains flexibility for endpoints to react to
> congestion in ways that are different from TCP and dependent on specific
> codecs, topologies, and other factors. RFC 3551 provides a lot of
> qualification in the requirements it places around equivalence to TCP's
> behavior. So I would be concerned about how this requirement, if
> normative, would affect RTP and other protocols.
>
> If it's not meant to be normative, I would suggest using "ought to" or
> some other word.
I don't think the second "must" is a normative, because that would make 
it potentially contradict other RFCs (as you say). I think it describes 
the principle for design, so "ought to" would reflect that.

Gorry