Subject: Re: [OPSAWG] Feedback on draft-www-opsawg-yang-vpn-service-pm

From: Qin Wu <[email-masked]>
Date: Tue, 15 Dec 2020 01:25:04 +0000

Good catch, Greg, the difference is the granularity of the percentile, supporting five 9s seems reasonable to me. I am happy to align with the percentile defined in STAMP YANG model.

-Qin
发件人: [email-masked] [mailto:[email-masked]]
发送时间: 2020年12月15日 4:32
收件人: Qin Wu <[email-masked]>
抄送: [email-masked]; jclarke=[email-masked]; [email-masked]
主题: Re:[OPSAWG] Feedback on draft-www-opsawg-yang-vpn-service-pm

Hi Qin,

thank you for the detailed analysis of advantages of using percentiles compared with an average metric. I've noticed that in the draft the percentile is defined as

  typedef percentile {

    type decimal64 {

      fraction-digits 2;

    }

    description

      "The nth percentile of a set of data is the

       value at which n percent of the data is below it.";

  }

Doesn't that limit the ability of request the reported percentile, e.g., five 9s? I can reference the STAMP YANG data model<https://datatracker.ietf.org/doc/draft-ietf-ippm-stamp-yang/?include_text=1> where:

   typedef percentile {

     type decimal64 {

       fraction-digits 5;

     }

     description

       "Percentile is a measure used in statistics

       indicating the value below which a given

       percentage of observations in a group of

       observations fall.";

   }

Regards,

Greg Mirsky

Sr. Standardization Expert
预研标准部/有线研究院/有线产品经营部 Standard Preresearch Dept./Wireline Product R&D Institute/Wireline Product Operation Division

E: [email-masked]<mailto:[email-masked]>
www.zte.com.cn<http://www.zte.com.cn/>

Original Mail
Sender: QinWu
To: [email-masked];Joe<mailto:[email-masked];Joe> Clarke (jclarke);opsawg;
Date: 2020/12/14 07:33
Subject: Re: [OPSAWG] Feedback on draft-www-opsawg-yang-vpn-service-pm
Thanks Med for clarification, we discussed the downside of using average before, i.e., hide outlier, which is more appropriate for relative even distribution.
That is why we introduce percentiles. 3 percentiles value can be 50 percentile,75 percentile,95 percentile which is configured by setting low-percentile,middle-percentile, high-percentile under nt:link
     augment /nw:networks/nw:network/nt:link:
       +--rw low-percentile                    percentile
       +--rw high-percentile                   percentile
       +--rw middle-percentile                 percentile
Then high-delay-percentile, high-jitter-percentile, etc can be used to report the measured delay value, jitter value corresponding to specific percentile value, i.e., high-percentile, low-percentile, middle-percentile.
As Med clarified we have defined default value for them.
Regarding the counter, I tend to agree, in addition, I think counter32 is sufficient for discard, error, unknown protocol related statistics, which is similar to
What is defined in ietf-interfaces.

-Qin
-----邮件原件-----
发件人: OPSAWG [mailto:[email-masked]] 代表 [email-masked]<mailto:[email-masked]>
发送时间: 2020年12月14日 22:58
收件人: Joe Clarke (jclarke) <jclarke=[email-masked]<mailto:jclarke=[email-masked]>>; opsawg <[email-masked]<mailto:[email-masked]>>
主题: Re: [OPSAWG] Feedback on draft-www-opsawg-yang-vpn-service-pm

Hi Joe, all,

Thank you for sharing these comments.

Instead of sharing avg values, we do think that sharing percentile values is more useful. Up to 3 sets of percentiles can be shared for each performance metric: low (e.g., 5.00), mid (50.00), or high (90.00). The exact percentile value to characterize low/mid/high is configurable. Otherwise, default values will be used (will update the module + explain the behavior in the text).

If all *-percentile parameters are set to 0.00, this means that no percentile-related nodes will be reported for a given performance metric (one-way delay, one-way delay variation). Only peak/min/current values can be reported.

Fully agree with your comment on the counters.

More text will be added to describe the intended behavior.

Cheers,
Med

> -----Message d'origine-----
> De : OPSAWG [mailto:[email-masked]] De la part de Joe Clarke
> (jclarke) Envoyé : vendredi 11 décembre 2020 21:28 À : opsawg
> <[email-masked]<mailto:[email-masked]>> Objet : [OPSAWG] Feedback on
> draft-www-opsawg-yang-vpn-service-pm
>
> During the IETF109 opsawg session, this draft was presented, and I was
> concerned that a lot of its work had happened amongst the authors of
> the L2NM/L3NM et al work.  I hadn’t seen a lot of discussion on this
> list.
>
> I wanted to kick off some discussion around it.
>
> As contributor:
>
> I think this work is useful and complements the VPN NM work nicely.
> I had a few questions/comments as I read the -02 version of this
> draft.  First, the percentile leafs use the word “percentile” to
> define what it is.  I think some more wording around what is meant by
> the low/middle/high percentiles would be useful.  One can piece this
> together by reading through the YANG module, but I would like to see
> some explanatory text in the body of the document that explains the
> percentile breakdowns.  Examples of this would also be helpful.
>
> What would happen if you set all percentile leafs to 0.00?  Would that
> only affect the delay and jitter leafs?  Again, I think some
> clarifying text is needed here as to how to use these data points.
>
> I’m also curious about some of the tp-telemetry-attributes counters.
> Why are the octets, unicast, and nunicast counters 32-bit?  I think
> they should be 64-bit to be in line with ietf-interfaces.  And for all
> of these leafs, why are they uint instead of counter?  They seem to be
> counters in reading the descriptions.  The same counter questions
> applies to those -count leafs under loss-statistics.
>
> Joe
> _______________________________________________
> OPSAWG mailing list
> [email-masked]<mailto:[email-masked]>
> https://www.ietf.org/mailman/listinfo/opsawg

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