Re: [Teas] I-D Action: draft-nsdt-teas-transport-slice-definition-03.txt

[Kiran Makhijani <[e-mail]>]

Hi Joel,
My apologies, I could not reply sooner. Many thanks for paying attention to the document and reviewing it.
Please see inline.
Cheers
Kiran

> -----Original Message-----
> From: Teas <[e-mail]> On Behalf Of Joel Halpern
> Sent: Sunday, July 12, 2020 9:00 PM
> To: [e-mail]
> Subject: Re: [Teas] I-D Action: draft-nsdt-teas-transport-slice-definition-03.txt
> 
> My thanks to the design team for the update to this document.  It is much
> improved.
> 
> I a  unable to understand the third paragraph of section 4.1.2.  I do not know
> what maximum occupancy refers to.  It seems to be talking about some kind of
> notion of objectives applying to subsets of traffic within a slice.  But I can't tell.
> 
[KM] Maximum occupancy implies that when transport slice will 'max out' or overall limit on the slice after which it becomes best effort (may not meet its SLOs). For example, a slice can support 20 flows each with 10 Mbps data rate but 21st flow may or may not get desired bandwidth and it is not an SLO violation. There could be different kinds of limits using objectives such as number of flows, total bandwidth, or may also be other things that a user could ask for such as, max number of addresses, nf instances, etc (this part is coming from NF related resources). This is important for both network operators and transport slice controllers to plan resource allocations better.

> Appendix A.1 is labeled as discussion, and as such appears to be trying to be
> informative rather than normative.  However, the last paragraph of introduces
> things a customer may ask for (i.e. SLOs) that are not described in the rest of
> the document, and do not actually seem to me to be appropriate.  I wowuld ask
> that the last paragraph of section A.1 be stricken.

[KM] Actually, we are saying these are 'not' SLOs and the customer may have specific asks (optionally).  Examples in this paragraph help in clarifying meanings of isolations, linking with VPN+  and may also be input to NBI. Considering this could be our top-level document, we/I prefer to provide some linkage to later documents. An upshot of doing this is we will not have to repeat the discussions we had - since it is already agreed upon and can be referred to. 
> 
> Some minor comments:
> 
> At one point the SLA is defined (I believe reasonably)as the contract 5that
> describes the SLOs with the consequences for missing them.  Then in section
> 4.1 it says "all SLOs combine to form the SLA".  Believe you mean "form the
> objective portion of the SLA"  or "contribute to the SLA"
> or something, since the contractual and consequence aspects of the SLA are
> outside of the SLOs?
[KM] Yes, that is correct. We should add this statement ( contractual aspects of the SLAS are outside the scope) to improve the text.
> 
> Given that availability is defined in terms of the other SLOs (quite
> reasonable) and that some of those may not be directly measurable), it seems
> that availability should itself be considered indirectly measurable?
>
[KM] Since we define it as "uptime to total_time", it is measurable, however that may be.

> nit - Given that the earlier text says that this is only an initial list, there is no
> need to include a bullet in the aspects that says "Other objectives could be
> specified".  It is true.  But has already been stated above.

[KM] :-) It is there to separate measurable vs non-measurable asks. If the nsdt agrees, I don't mind removing the sub-heading.

> In section 4.2 on transport service endpoints, the text seems to say that an
> endpoint has a specific kind of connectivity (P2P, P2MP, ...).
> It seems perfectly valid for a single TSE to be using both P2P and P2MP
> communication.  It seems rather odd to have to consider it to be two TSEs.
> From later text, it is the slice, not the endpoint, which as a particular
> connectivity type.

[KM] Agree.  It is not supposed to imply 2 TSEs. If I understood correctly, you think 'MP2MP' does not make sense. Am I right? If yes, then at least I was thinking of direction of the traffic flow. i.e., traffic could flow out to different TSEs or flow in from different TSE sources. We will discuss how to improve the text - add explanation or remove MP2MP.

> 
> I wonder if the "Transport Slice Realization endpoint" is useful?  Given that
> many things are in both the sample TSE list and the sample TSRE list, it is going
> to be hard to tell them apart.  And as far as I can tell, the TSRE is internal to the
> transport, and therefore outside the scope of this document?  The
> differentiation in the diagram that follows the description does not seem to
> line up with the description, and leaves me more confused.
[KM] Yes, it is internal to transport. The reason we have them is to highlight the 1:N mappings. There may be more than one TSRE mapped to one TSE. Todo: need to think about improving the figure.
> 
> Yours,
> Joel
> 
> On 7/12/2020 10:49 PM, [e-mail] wrote:
> >
> > A New Internet-Draft is available from the on-line Internet-Drafts directories.
> >
> >
> >          Title           : IETF Definition of Transport Slice
> >          Authors         : Reza Rokui
> >                            Shunsuke Homma
> >                            Kiran Makhijani
> >                            Luis M. Contreras
> >                            Jeff Tantsura
> > 	Filename        : draft-nsdt-teas-transport-slice-definition-03.txt
> > 	Pages           : 21
> > 	Date            : 2020-07-12
> >
> > Abstract:
> >     This document describes the definition of a slice in the transport
> >     networks and its characteristics.  The purpose here is to bring
> >     clarity and a common understanding of the transport slice concept and
> >     describe related terms and their meaning.  It explains how transport
> >     slices can be used in combination with end to end network slices, or
> >     independently.
> >
> >
> > The IETF datatracker status page for this draft is:
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