Re: [ippm] WGLC for draft-ietf-ippm-responsiveness

[Will Hawkins <[e-mail]>]

Bjorn,

I am sorry for not responding sooner! See inline.

On Thu, Dec 21, 2023 at 5:41 AM Bjørn Ivar Teigen <[e-mail]> wrote:
>
> Hello IPPM,
>
>
> I've read draft-ietf-ippm-responsiveness-03. The draft is well-written and easy to read in my opinion. I consider the contribution novel and useful.
>
>
> Please find my comments and questions inline below:
>
>
>
> IP Performance Measurement                                     C. Paasch
> Internet-Draft                                                  R. Meyer
> Intended status: Standards Track                             S. Cheshire
> Expires: 22 April 2024                                        Apple Inc.
>                                                               W. Hawkins
>                                                 University of Cincinnati
>                                                          20 October 2023
>
>                 Responsiveness under Working Conditions
>                    draft-ietf-ippm-responsiveness-03
>
> Abstract
>
> .....
>
> 4.1.1.  Single-flow vs multi-flow
>
> .....
>
>    One of the configuration parameters for the test is an upper bound on
>    the number of parallel load-generating connections.  We recommend a
>    default value for this parameter of 16.
>
>
> Question: What is the rationale for choosing 16 as the upper bound?


Thank you for the question! I will defer to Christoph and Stuart for
their answer re: the upper bound. I have heard them explain the
rationale in the past but cannot seem to recall the specifics! I don't
want to say something incorrect.

>
> .....
>
> 7.  Responsiveness Test Server Discovery
>
>    .....
>
>    Consider this example scenario: A user has a cable modem service
>    offering 100 Mb/s download speed, connected via gigabit Ethernet to
>    one or more Wi-Fi access points in their home, which then offer
>    service to Wi-Fi client devices at different rates depending on
>    distance, interference from other traffic, etc.  By having the cable
>    modem itself host a Responsiveness Test Server instance, the user can
>    then run a test between the cable modem and their computer or
>    smartphone, to help isolate whether bufferbloat they are experiencing
>    is occurring in equipment inside the home (like their Wi-Fi access
>    points) or somewhere outside the home.
>
>
> Comment: It might be useful to add some reflections about how measurements to different points can be compared.
>
> For arguments sake, let's say we measure towards two hypothetical servers and get RPM to an ISP-hosted server of 500, and RPM to the cable modem of 3000.
>
> How can those values be compared or otherwise reasoned about?

I agree that this is an excellent point. While not in the spec, one of
the available RPM clients does contain the concept of a "relative RPM"
score. The relative RPM score 1. calculates the RPM on an unloaded
connection, 2. calculates the RPM under working conditions, and then
3. computes the change. That calculation removes the "absolute"ness of
RPM but does seem to address the point that you raise.

Again, however, the relative RPM score is a non-standard feature
present in only one of the clients. We did not discuss adding it to
the spec itself.

As above, I will defer to Stuart and Christoph for additional context.

Thank you for the feedback!
Will


>
>
> Best regards,
>
> Bjørn Ivar Teigen
>
>
> On Tue, 5 Dec 2023 at 19:10, Marcus Ihlar <marcus.ihlar=[e-mail]> wrote:
>>
>>
>>
>> Hello IPPM,
>>
>>
>>
>> This email starts a Working Group Last Call for " Responsiveness under Working Conditions”, draft-ietf-ippm-responsiveness.
>>
>>
>>
>> https://datatracker.ietf.org/doc/draft-ietf-ippm-responsiveness/
>>
>> https://www.ietf.org/archive/id/draft-ietf-ippm-responsiveness-03.html
>>
>>
>>
>> Please review the document and send your comments in response to this email, along with whether you think the document is ready to progress.
>>
>>
>>
>> Please send your reviews and feedback by Friday, December 22.
>>
>>
>>
>> BR,
>>
>> Marcus & Tommy
>>
>>
>>
>> _______________________________________________
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>
>
>
> --
> Bjørn Ivar Teigen, Ph.D.
> Head of Research
> [phone] | [e-mail] | www.domos.ai
>
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