Re: [Teas] What SLOs and SLEs should be in the Slicing Service Model?

Isn't it important to distinguish between "these are things I expect you 
to do, measure, and report" and "these are things I would like you to do 
even though they are not measurable or reportable"?

Yours,
Joel

On 3/23/2022 10:08 AM, mohamed.boucadair@orange.com wrote:
> Hi all,
> 
> This message actually triggers a companion comment I have on the SLO/SLE taxonomy. From the service modeling standpoint, I suggest that we don't inherit that taxonomy for various reasons:
> 
> * Things would be much simpler if we just focus on service requirements without making an assumption how such requirement is expressed and whether it is quantified/quantitative/qualitative/measurable/etc. Whether/how a specific service requirement is covered by service assurance/fulfillment can be part of the slice service definition itself.
> 
> * What we may tag as an SLE today because of the technology limitations, may not stay as such forever. It may be true that an "expectation" may not be easily assessed using current techniques (and thus be tagged as SLE), but this does not prevent that innovative means would be defined in the future (which means that it is an SLO, not an SLE anymore).
> 
> * We are artificially adding extra complexity for the modelling part as service requirement will need to be classified based as SLO or SLEs.
> 
> * I remember that Kiran agreed at least to not import that taxonomy into the data model when we were discussing the call for adoption of the slice definition:
> 
> ==(the full message from Kiran can be found in the archives)===
> "However, it should not imply that NBI models are required to have SLE/SLO indicators and I totally agreed with your comments on draft-wd-teas-ietf-network-slice-nbi-yang-03"
> ==
> 
> Cheers,
> Med
> 
>> -----Message d'origine-----
>> De : Teas <teas-bounces@ietf.org> De la part de Adrian Farrel
>> Envoyé : mercredi 23 mars 2022 14:47
>> À : 'TEAS WG' <teas@ietf.org>
>> Objet : [Teas] What SLOs and SLEs should be in the Slicing Service
>> Model?
>>
>> Hi,
>>
>> Sorry for my audio being a mess in TEAS today.
>>
>> I believe I heard the discussion between Kireeti and Reza correctly, and
>> there was some follow-up in the chat.
>>
>> I agree that "Protection" is a realisation feature and so it qualifies
>> as an SLE, if at all.
>> But "Reliability" is clearly an SLO. Usually expressed as maximum down-
>> time per unit of time, or maximum lost traffic.
>>
>> There was one thing that I *think* I heard. This was Reza saying that
>> the service YANG model was only including the SLOs and SLEs noted in the
>> framework. Maybe I misheard "only" because I think that might be a
>> mistake.
>> The YANG model should certainly be interested in what the framework
>> says, but it is not a requirement that all SLOs and SLEs in the
>> framework be in the model if the authors find that there is no interest
>> in implementing them, and there should certainly be no limitation about
>> including additional SLOs or SLEs in the YANG model. Indeed, the SLOs
>> and SLEs listed in the framework are presented as examples.
>>
>> Cheers,
>> Adrian
>>
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> 
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