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

Joel Halpern <jmh@joelhalpern.com> Mon, 13 July 2020 03:59 UTC

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From: Joel Halpern <jmh@joelhalpern.com>
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Subject: Re: [Teas] I-D Action: draft-nsdt-teas-transport-slice-definition-03.txt
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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.

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.

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?

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?

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.

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.

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.

Yours,
Joel

On 7/12/2020 10:49 PM, internet-drafts@ietf.org 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:
> https://datatracker.ietf.org/doc/draft-nsdt-teas-transport-slice-definition/
> 
> There are also htmlized versions available at:
> https://tools.ietf.org/html/draft-nsdt-teas-transport-slice-definition-03
> https://datatracker.ietf.org/doc/html/draft-nsdt-teas-transport-slice-definition-03
> 
> A diff from the previous version is available at:
> https://www.ietf.org/rfcdiff?url2=draft-nsdt-teas-transport-slice-definition-03
> 
> 
> 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.
> 
> Internet-Drafts are also available by anonymous FTP at:
> ftp://ftp.ietf.org/internet-drafts/
> 
> 
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