Re: [Int-dir] Intdir telechat review of draft-ietf-tvr-use-cases-05

[Yingzhen Qu <[e-mail]>]

Hi Pascal,

Thanks for the review and comments. Please see my answers below.

Thanks,
Yingzhen

On Wed, Feb 21, 2024 at 8:43 AM Pascal Thubert via Datatracker <
[e-mail]> wrote:

> Reviewer: Pascal Thubert
> Review result: Ready with Issues
>
> I am an assigned INT directorate reviewer for draft-ietf-tvr-use-cases
> (05).
> These comments were written primarily for the benefit of the Internet Area
> Directors. Document editors and shepherd(s) should treat these comments
> just
> like they would treat comments from any other IETF contributors and resolve
> them along with any other Last Call comments that have been received. For
> more
> details on the INT Directorate, see
> https://datatracker.ietf.org/group/intdir/about/
> <https://datatracker.ietf.org/group/intdir/about/>."
>
> For non-INT Area document, the reviewer must give a recommendation as to
> how
> the INT ADs are to complete the ballot on the document and the reason for
> that
> recommendation.
>
> I believe that the document is very well written and highly readable.
>
> My comments may be seen as a matter of taste and ignored, or/and be
> considered
> out of scope.
>
> My main concern is that despite a "Routing Impacts" subsection in all main
> groups of use cases, there's no text on the scope of routing impact.
>
> - Is the impact local like FRR in which case it can be understood?
> - Or is it more global in which cases the impact is harder to assess in
> advance? - flows may be rerouted paths that are loaded differently from the
> original, meaning that there's a measurable impact at the time of the
> switch,
> for the better or the worse - How, when can the impact be gradual? - Is the
> impact a complete reroute of the flow or a variation of the load balancing?
>
> Background fo rthe questions: Rick and myself have a strong RAW background.
> Contrary to the examples given (and the WG ovbjectives), RAW is reactive
> (OAM
> based); but once a decision is made, it seems that the RAW methods are
> applicable in certain listed use cases and may provide a smpooth solution
> to
> the local TVR use cases.
>
> Related comment is that the "Routing Impacts" subsections are not
> comparable
> from one use case to the other. Again I'd have loved comparable items like
> the
> above to be discussed so we figure if we are looking for common or separate
> solutions.
>
> [Yingzhen]: As we know, Fast Reroute (FRR) is a local mechanism designed
to handle unexpected node or link failures, and there might be policies for
determining which traffic should be switched to the backup path. However,
this falls outside the scope of TVR's charter and this document. Scheduled
maintenance, such as link shutdowns, is within scope. Ultimately, how
routing protocols handle these scheduled events is up to the protocols,
including deciding whether a 'one size fits all' solution is appropriate.
One of the objectives of the use case document is to clarify the cases
considered by TVR.

Secondary, on :
>                                 "To the extent that the relative mobility
>                                 between and among nodes in the network can
> be
>                                 understood in advance, the associated loss
> and
>                                 establishment of adjacencies can also be
>                                 planned for."
>
> This is clearly discussing radios. Most radios use cases depend not only
> on the
> relative position, but also the rest of the environment that may obstruct
> and /
> or interfere with the signal. Suggestion:
>
>                                 "To the extent that the relative mobility
>                                 between and among nodes in the network and
> the
>                                 impacts of the environment on the signal
>                                 propagation can be understood in advance,
> the
>                                 associated loss and establishment of
>                                 adjacencies can also be planned for."
>
> [Yingzhen]: thanks for the suggested text. I've published version -06 with
the suggested changes.


> Many thanks again for this document, great and informational read
>
>