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

From: "Alissa Cooper" <[email-masked]>
Date: Wed, 12 Oct 2016 06:49:27 -0700

Alissa Cooper has entered the following ballot position for
draft-ietf-tsvwg-rfc5405bis-18: Discuss

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DISCUSS:
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= 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.

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From: Gorry Fairhurst <[email-masked]>
Date: Wed, 12 Oct 2016 18:49:52 +0200

See below.

> https://datatracker.ietf.org/doc/draft-ietf-tsvwg-rfc5405bis/
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

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From: "Eggert, Lars" <[email-masked]>
Date: Fri, 14 Oct 2016 13:22:16 +0000

Applied

> On 2016-10-12, at 18:49, Gorry Fairhurst <[email-masked]> wrote:
> 
> See below.
> 
> 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
> 
>