Subject: [AVTCORE] Martin Duke's No Objection on draft-ietf-avtcore-multi-party-rtt-mix-17: (with COMMENT)

From: Martin Duke via Datatracker <[email-masked]>
Date: Mon, 10 May 2021 14:30:22 -0700

Martin Duke has entered the following ballot position for
draft-ietf-avtcore-multi-party-rtt-mix-17: No Objection

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COMMENT:
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- It is not completely clear to me what the actions in the case of congestion
are. RFC 4103 RECOMMENDS four steps, the first is going from 300 to 500ms. So
what is the hiearchy here. My guess is:

Step 1. Senders MUST go from 300ms to 2 seconds
Step 2. Senders SHOULD (further?) limit the number of characters sent
Step 3. Senders SHOULD go from 2 seconds to 5 seconds
Step 4. Senders SHOULD exclude nodes from the session

Is this correct?

- Assuming it is correct, I don't understand the motivation behind the
congestion considerations in Section 8.

The first and third paragraphs make perfect sense to me. But if the total
traffic to a receiver, regardless of the number of senders, remains limited to
1 packet / 300ms, I don't see why you would change the RFC 4103 guidance of
500ms up to 2 seconds. This isn't a DISCUSS because you're welcome to be more
conservative, but I would like to understand your reasoning.

No need to reply to the comments below:

- In (3.16) and (4.2.2), you mention various privacy-sensitive fields and then
say "Integrity SHALL be considered..." I think you mean confidentiality?
Integrity means the data hasn't been altered by an attacker.

- It would be helpful to clarify in this draft that the CPS limit applies only
to new, not redundant, text, assuming that is in fact the case.

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From: Gunnar Hellström <[email-masked]>
Date: Mon, 17 May 2021 23:15:35 +0200

Martin,

Thanks for the review,

Please see my responses inline.

> https://datatracker.ietf.org/doc/draft-ietf-avtcore-multi-party-rtt-mix/

[GH] First, I should clarify that the values are per source in the 
communication to one receiver.
You are right that it is not very logical to require an increase to a 
fixed time of 2 seconds. It does not help much, and the third action is 
anyway according to RFC 4103 an increase to an interval between 0.5 and 
5 seconds.

Therefore, I suggest to replace the second sentence of section 8, so 
that the section begins:

"The congestion considerations and recommended actions from [RFC4103]  
are also valid in multiparty situations.

The time values SHALL then be applied per source of text sent to a 
receiver."

> Integrity means the data hasn't been altered by an attacker.
[GH] Right, I meant "confidentiality". Modified.
> to new, not redundant, text, assuming that is in fact the case.
[GH] Thanks, yes. I propose to insert the following sentence after the 
first sentence in section 3.22: "The actual rate is calculated without 
regard to any redundant text transmission and is in the multiparty case 
evaluated for all sources contributing to transmission to a receiver."

[GH] I will submit version -18 with the changes indicated above, 
together with edits because of Lars Eggert's nit findings, but am 
prepared to do further changes if needed on the congestion consideration 
wording.

Thanks,

Gunnar

>
> _______________________________________________
> Audio/Video Transport Core Maintenance
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-- 
Gunnar Hellström
GHAccess
[email-masked]

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From: Gunnar Hellström <[email-masked]>
Date: Mon, 17 May 2021 23:29:27 +0200

The new version mentioned in a recent mail answering the comments by 
both Martin Duke and Lars Eggert is available.

The IETF datatracker status page for this draft is:
https://datatracker.ietf.org/doc/draft-ietf-avtcore-multi-party-rtt-mix/

There is also an HTML version available at:
https://www.ietf.org/archive/id/draft-ietf-avtcore-multi-party-rtt-mix-18.html

A diff from the previous version is available at:
https://www.ietf.org/rfcdiff?url2=draft-ietf-avtcore-multi-party-rtt-mix-18

Please note that it may take a couple of minutes from the time of submission
until the htmlized version and diff are available at tools.ietf.org.

Internet-Drafts are also available by anonymous FTP at:
ftp://ftp.ietf.org/internet-drafts/

Regards
Gunnar

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From: Martin Duke <[email-masked]>
Date: Tue, 18 May 2021 07:35:37 -0700

LGTM

On Mon, May 17, 2021 at 2:29 PM Gunnar Hellström <
[email-masked]> wrote:

> > Please refer to
> https://www.ietf.org/iesg/statement/discuss-criteria.html