Re: [rmcat] Fw: New Version Notification for draft-hayes-rmcat-sbd-00.txt

[Simone Ferlin-Oliveira <[e-mail]>]

Hi Stefan,

Thanks for your comments.

Would you have any traces of such WiFi cases you mention?
We plan to run other tests with the algorithm. I have already an
implementation and we are testing it with wired/3G/4G at the moment.

Simone (co-author)

On 22 October 2014 16:36, Stefan Holmer <[e-mail]> wrote:
> Nice draft! I have a few comments:
>
> You're mentioning that skewness would require all delay measurements to be
> stored, and therefore you're computing some different metric which is
> related to skew. I wonder if it shouldn't be possible to more accurately
> estimate the skew from a histogram instead? That way you at least won't need
> to store all delay measurements. Might not be worth the trouble if your
> metric works well.
>
> As mentioned by Mirja, it seems a bit error prone to use the max of the OWD
> (also, shouldn't it be max_T(OWD)?) when computing the PDV.
>
> Somewhat related to this, I wonder if you have any plans to test this
> algorithm on WiFi? I have seen many cases of WiFi with a lot of contention
> and/or interference, where the delay gets skewed not because lack of
> bandwidth, but because of lower layer retransmissions or because the access
> point was busy serving someone else for a moment. I wonder if that can cause
> you to incorrectly detect shared bottlenecks, where in reality there was
> only a shared WiFi... Now that I think of it, the WiFi effect should result
> in positive skewness, while you're looking for negative skewness, so you may
> be ok here. :)
>
> It would be good to have the diff() operation defined somewhere. Is it the
> diff between successive measurements, or the diff between the flows?
>
> /Stefan
>
>
> On Fri, Oct 10, 2014 at 5:37 PM, David Hayes <[e-mail]> wrote:
>>
>> Dear All,
>>
>> We have just submitted of our initial shared bottleneck detection
>> draft and will value your comments and suggestions.
>>
>> Regards,
>>
>> David
>>
>> Begin forwarded message:
>>
>> Date: Fri, 10 Oct 2014 08:17:57 -0700
>> From: <[e-mail]>
>> To: Michael Welzl <[e-mail]>, David Hayes
>> <[e-mail]>, Michael Welzl <[e-mail]>, Simone Ferlin
>> <[e-mail]>, Simone Ferlin <[e-mail]>, David Hayes
>> <[e-mail]> Subject: New Version Notification for
>> draft-hayes-rmcat-sbd-00.txt
>>
>>
>>
>> A new version of I-D, draft-hayes-rmcat-sbd-00.txt
>> has been successfully submitted by David Hayes and posted to the
>> IETF repository.
>>
>> Name:           draft-hayes-rmcat-sbd
>> Revision:       00
>> Title:          Shared Bottleneck Detection for Coupled
>> Congestion Control for RTP Media. Document date:        2014-10-10
>> Group:          Individual Submission
>> Pages:          12
>> URL:
>> http://www.ietf.org/internet-drafts/draft-hayes-rmcat-sbd-00.txt
>> Status:         https://datatracker.ietf.org/doc/draft-hayes-rmcat-sbd/
>> Htmlized:       http://tools.ietf.org/html/draft-hayes-rmcat-sbd-00
>>
>>
>> Abstract:
>>    This document describes a mechanism to detect whether end-to-end data
>>    flows share a common bottleneck.  It relies on summary statistics
>>    that are calculated by a data receiver based on continuous
>>    measurements and regularly fed to a grouping algorithm that runs
>>    wherever the knowledge is needed.  This mechanism complements the
>>    coupled congestion control mechanism in draft-welzl-rmcat-coupled-cc.
>>
>>
>>
>>
>> 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.
>>
>> The IETF Secretariat
>>
>>
>>
>> --
>>
>> -------------------------
>> David Hayes
>> [e-mail]
>> Department of Informatics
>> University of Oslo
>>
>