Re: [xrblock] AD Evaluation of draft-ietf-xrblock-rtcweb-rtcp-xr-metrics-06

Ben Campbell <ben@nostrum.com> Thu, 02 November 2017 15:24 UTC

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Date: Thu, 2 Nov 2017 10:24:19 -0500
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Cc: Varun Singh <varun@callstats.io>, "draft-ietf-xrblock-rtcweb-rtcp-xr-metrics.all@ietf.org" <draft-ietf-xrblock-rtcweb-rtcp-xr-metrics.all@ietf.org>, xrblock <xrblock@ietf.org>
To: Dan Romascanu <dromasca@gmail.com>, Roni Even <roni.even@huawei.com>, "Huangyihong (Rachel)" <rachel.huang@huawei.com>
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Subject: Re: [xrblock] AD Evaluation of draft-ietf-xrblock-rtcweb-rtcp-xr-metrics-06
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Thanks, that sounds good to me.

Is there a specific W3C document that references (or plans to reference) this? I ask because I expect people to ask if the draft has already “done its job”; that is, if it’s still relevant to publish as an RFC.

Ben.

> On Nov 2, 2017, at 7:15 AM, Dan Romascanu <dromasca@gmail.com> wrote:
> 
> I agree.
> 
> Regards,
> 
> Dan
> 
> 
> 
> On Thu, Nov 2, 2017 at 7:25 AM, Roni Even <roni.even@huawei.com> wrote:
> Hi
> Just to clarify, the individual draft started as an Informational draft and just before becoming a WG draft it was changed to standard track. We see no WG decision for this and as Rachel said, Informational is OK
> Roni
> 
> > -----Original Message-----
> > From: xrblock [mailto:xrblock-bounces@ietf.org] On Behalf Of Huangyihong
> > (Rachel)
> > Sent: יום ה 02 נובמבר 2017 12:01
> > To: Ben Campbell; Varun Singh
> > Cc: draft-ietf-xrblock-rtcweb-rtcp-xr-metrics.all@ietf.org; xrblock
> > Subject: Re: [xrblock] AD Evaluation of draft-ietf-xrblock-rtcweb-rtcp-xr-
> > metrics-06
> >
> > Hi Ben,
> >
> > After discussion among the co-authors, we reached the consensus to make it
> > informational. W3C stats API still refers to it, but in an informational way.
> > We'll submit a new version to address your comments.
> >
> > BR,
> > Rachel
> >
> > > -----Original Message-----
> > > From: Ben Campbell [mailto:ben@nostrum.com]
> > > Sent: Friday, October 13, 2017 5:52 AM
> > > To: Varun Singh
> > > Cc: draft-ietf-xrblock-rtcweb-rtcp-xr-metrics.all@ietf.org; xrblock
> > > Subject: Re: [xrblock] AD Evaluation of
> > > draft-ietf-xrblock-rtcweb-rtcp-xr-metrics-06
> > >
> > > >
> > > > On Oct 8, 2017, at 8:11 AM, Varun Singh <varun@callstats.io> wrote:
> > > >
> > > > Hi Ben,
> > > >
> > > > See inline.
> > > >
> > > >> On Tue, Oct 3, 2017 at 12:28 AM, Ben Campbell <ben@nostrum.com>
> > > wrote:
> > > >> Hi,
> > > >>
> > > >> This is my AD Evaluation of
> > > >> draft-ietf-xrblock-rtcweb-rtcp-xr-metrics-06. I
> > > would like to resolve at least the substantive comments prior to IETF LC.
> > > >>
> > > >> Thanks!
> > > >>
> > > >> Ben.
> > > >> —————————
> > > >>
> > > >> Substantive:
> > > >>
> > > >> - General: If I understand correctly, this document lists and
> > > >> describes XR
> > > metrics that a WebRTC application might choose to negotiate and expose
> > > via the WebRTC API. It does not define any new XR metrics. That brings
> > > up two
> > > questions:
> > > >>
> > > >> 1) Why is this specific to WebRTC? For the most parts, all the
> > > >> arguments
> > > here would apply to any sort of RTP endpoint.
> > > >>
> > > >
> > > > This draft was created initially as an input to RTCWEB and later as
> > > > an input to WebRTC Statistics API. Hence the use of WebRTC in the
> > > > title and the introduction. We could add to the introduction: "In
> > > > general, the metrics listed in this document can be exposed by any
> > > > real-time communications endpoint." Or something along those lines
> > > >
> > > >
> > > >> 2) Why is this standards track? This sort of material is typically
> > > >> informational,
> > > or occasionally a BCP. There are a small number of 2119 keywords, but
> > > I’m not sure they are needed or appropriate. (Specifics below.) My
> > > initial instinct is that this should be informational.
> > > >>
> > > >
> > > > The reason until recently (perhaps still exist) is that this was an
> > > > input from the IETF to W3C, I am not sure if there was an official
> > > > liaison statements sent to them? nonetheless, the W3C Statistics API
> > > > document needed a specification needed (a specification in any
> > > > standards body would suffice) for metrics to be accepted into the
> > > > W3C document.
> > >
> > > To make sure I understand:That API document will reference this one?
> > > Do they require that specification to be standards track?
> > >
> > > Was there discussion in xrblock about standards track verses BCP?
> > >
> > > >
> > > > In practice, it helped that I was the co-author of both the IETF and
> > > > W3C document and hence was able to make the case for the metrics in
> > > > W3C.
> > >
> > > Is that case already made? That is, does the need for a published RFC
> > > still exist?
> > >
> > > >
> > > >> - General: This needs an IANA considerations section, even if it
> > > >> just contains
> > > the statement to the effect of “This document makes no requests for
> > IANA”.
> > > >>
> > > >> - 1, last paragraph: “ The document also creates a registry
> > > >> containing
> > > identifiers from the metrics reported in the RTCP Sender, Receiver,
> > > and Extended Reports.”
> > > >
> > > > This should be removed. Thanks for pointing this out.
> > > >
> > > >>
> > > >> It doesn’t actually do that. I understand from the shepherd’s
> > > >> report that
> > > this was intentionally removed.
> > > >>
> > > >> — “All identifiers proposed in this document are RECOMMENDED to be
> > > >> implemented by an endpoint.  An endpoint MAY choose not to expose
> > > >> an identifier if it does not implement the corresponding RTCP
> > > >> Report. “
> > > >>
> > > >> Does the “RECOMMENDED” apply to all endpoints or just WebRTC
> > > >> endpoints? If the latter, doesn’t that requirement belong (or need
> > > >> to
> > > >> update) some requirement from an RTCWEB (maybe rtp-usage)
> > document,
> > > >> or even the API itself? (I suspect that this draft does not have
> > > >> standing to state this normatively.) What is meant by “MAY choose
> > > >> not to expose”. Is that talking about via the WebRTC API? If so,
> > > >> isn’t that up to the API definition? (That is, it shouldn’t be
> > > >> normative
> > > >> here.)
> > > >>
> > > >
> > > > It should be applicable to any endpoint, although it is pertinent or
> > > > timely for the WebRTC endpoint to expose these.
> > > > The purpose of the statement was to highlight that if the
> > > > middlebox/endpoint sends RTCP XRs then it should expose the data
> > > > available via the API.
> > > >
> > > > I am open to changing to a non-normative lower case guidance if that
> > > > would be more suitable, although if this document is making
> > > > recommendations to the W3C document -- wouldn't we keep the
> > uppercase?
> > >
> > > In general, 2119 keywords are better used when we are talking about
> > > interoperability issues in a protocol. I suggest switching to lower
> > > case unless there’s some reason to believe the W3C won’t pay attention
> > > unless it’s in all-caps. (I don’t think that’s usually the case.)
> > >
> > > >
> > > > co-authors, what do you think?
> > > >
> > > >> -2: If this document keeps the normative keywords, please use the
> > > >> updated boilerplate from RFC 8174. (I note that there are at least
> > > >> some uncapitalized “may”s that do not seem normative.)
> > > >>
> > > >
> > > > depending on the above, we should fix these to uppercase.
> > > >
> > > >> - 5.2.2, last paragraph: “The following metrics can also be considered…”
> > > >> Be considered by whom? Implementors? API designers?
> > > >>
> > > >
> > > > Both.
> > > >
> > > >> - 6, first paragraph: “In practice the application MUST be able to
> > > >> query the
> > > statistic identifiers on both an incoming (remote) and outgoing
> > > (local) media stream.”
> > > >> What does the MUST requirement apply to? The WebRTC API? This
> > seems
> > > more like a statement of fact that “ the application needs to be able…”
> > > >>
> > > >
> > > > correct, "needs to" is better.
> > > >
> > > >> -8: "Therefore encryption procedures, such as the ones suggested
> > > >> for a
> > > Secure RTCP (SRTCP), need to be used.”
> > > >> The text should describe the reasons encryption is needed. Also, is
> > > >> this a
> > > new normative requirement, or a restatement of an existing requirement?
> > > >>
> > > >
> > > > I believe it is restatement alluding to the guidance in the
> > > > corresponding RTCP XRs.
> > > >
> > > >> Editorial:
> > > >>
> > > >> -1, paragraph 1:" If sufficient information (metrics or statistics)
> > > >> are provided to the applications, it can attempt to improve the
> > > >> media quality. “
> > > >>
> > > >> s / “are provided” / “is provided”
> > > >> s / applications / application
> > > >>
> > > >> -3, 2nd paragraph: It would help to clarify that the references to
> > > >> section 5
> > > and 6 are to this document, not RFC 3611.
> > > >>
> > > >> — 3rd paragraph: "At the moment…”
> > > >> Please clarify that is at the time of writing (not reading)
> > > >>
> > > >> -5, 2nd paragraph: “ Application impact metrics mainly collect the
> > > >> information in the viewpoint of application … “ s / in / from Also,
> > > >> please expand “FEC” on first mention.
> > > >>
> > > >> - 5.1.1, first paragraph: “ Duplicate packets may be a result of
> > > >> network
> > > delays, which causes the sender to retransmit the original packets.”
> > > >> s/ :delays, which” / “delays that”
> > > >>
> > > >> — last paragraph: "For those RTCWEB services with jitter buffer…”
> > > >> s/buffer/buffers
> > > >>
> > > >> - 5.1.2, first paragraph:
> > > >> First sentence is a comma splice.
> > > >> — “some transitory nature of the impairments”
> > > >> Should this say “the transitory nature of some impairments”?
> > > >> — “ Distributed burst provides a higher subjective quality”
> > > >> “Burst distribution …”?
> > > >> — Last paragraph: “ Hence, if WebRTC application”
> > > >> Missing article (or should application be plural?)
> > > >>
> > > >> - 5.2.1, title: Should “Discard” be “Discarded”?
> > > >>
> > > >> -7: Please clarify that this is at the time of this writing.
> > > >>
> > > >
> > > > Thanks for your feedback and suggestions, we will fix these.
> > > >
> > > > Regards,
> > > > Varun
> > > >
> > > >
> > > > --
> > > > Founder, CEO, callstats.io
> > > > http://www.callstats.io
> > > >
> > > > Interested in networking, media quality, and diagnostics.
> > > > We are hiring!: www.callstats.io/jobs/
> >
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