Re: [netmod] WG adoption poll draft-bjorklund-netmod-rfc7227bis-00

["t.petch" <[e-mail]>]

----- Original Message -----
From: "Ladislav Lhotka" <[e-mail]>
Sent: Tuesday, September 19, 2017 2:37 PM

> Martin Bjorklund <[e-mail]> writes:
>
> > Ladislav Lhotka <[e-mail]> wrote:
> >> Hi,
> >>
> >> I support the adoption but I propose two conceptual changes:
> >>
> >> 1. Introduce a new module name and namespace so that it is not
> >> necessary to carry along the deprecated baggage. If readability is
> >> the primary concern, this is IMO the way to go. Instead of
> >> "ietf-ip-2", I'd suggest something like "ietf- ip-nmda".
> >>
> >> 2. Avoid obsoleting RFC 7277. I believe the old modules may
continue
> >> to be used
> >> in areas where NMDA is an overkill, such as open source home
> >> routers.
> >
> > Why wouldn't NMDA be appropriate in an open source home router?
Note
> > that the new model really just have a single tree instead of two
> > trees, so the data that needs to be instrumented is more or less the
> > same.
>
> It is quite likely that some parts of the data models will be
> implemented only as configuration but not state data. In the "old
style"
> modules it is easy to add a deviation for the node(s) under -state but
> in NMDA style this is not possible because we only have one node.
>
> There are subtle differences in the schemas for configuration and
state
> data that the NMDA concept doesn't address. If you want another
example,
> ietf-routing-2 has the "router-id" leaf that is conditional via the
> "router-id" feature. If this feature is not supported, router-id
cannot
> be explicitly configured (it is assigned by the system) but in state
data
> "router-id" needs IMO be present in any case. But the if-feature
> isn't able to differentiate between configuration and state data if
> there is only one node for both.

So add a second node!  I think that the idea that NMDA eliminates all
duplication of config and state is a myth; there will still be
duplication where the life cycle of the data diverges, ie it is not
really duplication! I think too that the twin trees approach, while
clumsy, was easy to create; the NMDA approach is more subtle, more
complex, easier to get wrong.

I recall that in the initial stages of discussion of this issue there
was a proposal for an object to have potentially eight different
characteristics so what NMDA gives us at present is limited and will not
solve all the issues of needing more than one node.

Tom Petch








>
> >
> > In fact, if we claim that the new architecture is not appropriate
for
> > some devices I think we have failed, especially if the conclusion is
> > that we need to maintain two versions of all modules going forward.
>
> I am not asking for this but, on the other hand, if NMDA versions used
a new
> module name and namespace (my item #1, which is what ietf-routing-2
> does), then I don't see any pressing need for obsoleting the old style
> modules.
>
> Lada
>
> >
> >
> > /martin
> >
> >
> >
> >
> >
> >
> >> NMDA
> >> implementors should be aware of the new modules but there is no
need to
> >> eradicate the old data models.
> >>
> >> #2 applies also to other modules for which the NMDA version is
underway.
> >>
> >> Lada
> >>
> >> PS. The subject is wrong, it shoud be -rfc7277bis-
> >>
> >> Lou Berger píše v Po 18. 09. 2017 v 10:33 -0400:
> >> > All,
> >> >
> >> > This is start of a two week poll on making
> >> > draft-bjorklund-netmod-rfc7227bis-00 a working group document.
Please
> >> > send email to the list indicating "yes/support" or "no/do not
support".
> >> > If indicating no, please state your reservations with the
document.  If
> >> > yes, please also feel free to provide comments you'd like to see
> >> > addressed once the document is a WG document.
> >> >
> >> > The poll ends Oct 2.
> >> >
> >> > Thanks,
> >> >
> >> > Lou (and Kent)
> >> >
> >> > _______________________________________________
> >> > netmod mailing list
> >> > [e-mail]
> >> > https://www.ietf.org/mailman/listinfo/netmod
> >> --
> >> Ladislav Lhotka
> >> Head, CZ.NIC Labs
> >> PGP Key ID: 0xB8F92B08A9F76C67
> >>
> >> _______________________________________________
> >> netmod mailing list
> >> [e-mail]
> >> https://www.ietf.org/mailman/listinfo/netmod
>
> --
> Ladislav Lhotka
> Head, CZ.NIC Labs
> PGP Key ID: 0xB8F92B08A9F76C67
>
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