Re: [netmod] WG adoption poll draft-bjorklund-netmod-rfc7227bis-00
Ladislav Lhotka <lhotka@nic.cz> Thu, 21 September 2017 11:38 UTC
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From: Ladislav Lhotka <lhotka@nic.cz>
To: Robert Wilton <rwilton@cisco.com>, netmod@ietf.org
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Date: Wed, 20 Sep 2017 16:33:24 +0200
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Subject: Re: [netmod] WG adoption poll draft-bjorklund-netmod-rfc7227bis-00
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Robert Wilton <rwilton@cisco.com> writes: > On 19/09/2017 15:07, Ladislav Lhotka wrote: >> Robert Wilton píše v Út 19. 09. 2017 v 14:49 +0100: >>> Hi Lada, >>> >>> >>> On 19/09/2017 14:37, Ladislav Lhotka wrote: >>>> Martin Bjorklund <mbj@tail-f.com> writes: >>>> >>>>> Ladislav Lhotka <lhotka@nic.cz> 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. >>> The new YANG library allows different sets of modules to be available >>> for <conventional> datastores vs <operational>. The operational >>> datastore can also have different features supported and different >>> deviations vs the conventional datastores. >> OK, I missed the 7895bis draft, sorry. Then there could be differences in >> mandatory/optional (e.g. a node is optional in configuration but mandatory in >> state data) or the data type of a leaf can differ. How can these be handled? > If the data type of the leaf can differ, then normally this should be > modeled as two separate leaves. Do you have a concrete example of > this? So, for example, duplex and duplex-state? And <operational> will have both as siblings? > > If some data is mandatory in config, but not necessarily mandatory in > <operational> then normally it can be marked as mandatory true, since > optional is allowed to violate this constraint if necessary, but > implementations would generally be expected to conform to the constraint > if possible. > > For the reverse case, we can't express that. I think that you would > have to leave out the "mandatory: true" constraint. Again, can you > provide a concrete example of this please? That makes it a bit easier > to reason about. This should be quite typical: a config leaf is optional and if it is not configured, the system sets it to some value (as in the case of router-id). But in state data it is mandatory so that the client can see what the system chose. Lada > > Thanks, > Rob > > >> >> Lada >> >>> So, the device can make the same deviations to remove the state leaves >>> from <operational>. Or if they don't want to support the module in >>> operational at all then a device could just list it as being supported >>> in the conventional datastores and not <operational>. >>> >>>> 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. >>> The new YANG library also supports this: >>> >>> The "router-id" feature would be disabled for the conventional >>> datastores, but enabled for <operational>. >>> >>>>> 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. >>> I think that creating a "-2" versions of these models at this time might >>> be a mistake. I actually think that the "deprecate state leaves" -> >>> "obsolete state leaves" -> "delete state leaves" path is a better choice. >>> >>> Thanks, >>> Rob >>> >>> >>>> 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 >>>>>>> netmod@ietf.org >>>>>>> https://www.ietf.org/mailman/listinfo/netmod >>>>>> -- >>>>>> Ladislav Lhotka >>>>>> Head, CZ.NIC Labs >>>>>> PGP Key ID: 0xB8F92B08A9F76C67 >>>>>> >>>>>> _______________________________________________ >>>>>> netmod mailing list >>>>>> netmod@ietf.org >>>>>> https://www.ietf.org/mailman/listinfo/netmod >>> _______________________________________________ >>> netmod mailing list >>> netmod@ietf.org >>> https://www.ietf.org/mailman/listinfo/netmod > -- Ladislav Lhotka Head, CZ.NIC Labs PGP Key ID: 0xB8F92B08A9F76C67
- [netmod] WG adoption poll draft-bjorklund-netmod-… Lou Berger
- Re: [netmod] WG adoption poll draft-bjorklund-net… Ladislav Lhotka
- Re: [netmod] WG adoption poll draft-bjorklund-net… Martin Bjorklund
- Re: [netmod] WG adoption poll draft-bjorklund-net… Juergen Schoenwaelder
- Re: [netmod] WG adoption poll draft-bjorklund-net… Ladislav Lhotka
- Re: [netmod] WG adoption poll draft-bjorklund-net… Robert Wilton
- Re: [netmod] WG adoption poll draft-bjorklund-net… Ladislav Lhotka
- Re: [netmod] WG adoption poll draft-bjorklund-net… Robert Wilton
- Re: [netmod] WG adoption poll draft-bjorklund-net… t.petch
- Re: [netmod] WG adoption poll draft-bjorklund-net… Robert Wilton
- Re: [netmod] WG adoption poll draft-bjorklund-net… t.petch
- Re: [netmod] WG adoption poll draft-bjorklund-net… Robert Wilton
- Re: [netmod] WG adoption poll draft-bjorklund-net… Ladislav Lhotka
- Re: [netmod] WG adoption poll draft-bjorklund-net… Ladislav Lhotka
- Re: [netmod] WG adoption poll draft-bjorklund-net… Robert Wilton
- Re: [netmod] WG adoption poll draft-bjorklund-net… Juergen Schoenwaelder
- Re: [netmod] WG adoption poll draft-bjorklund-net… Ladislav Lhotka
- Re: [netmod] WG adoption poll draft-bjorklund-net… Martin Bjorklund
- Re: [netmod] WG adoption poll draft-bjorklund-net… Ladislav Lhotka
- Re: [netmod] WG adoption poll draft-bjorklund-net… Martin Bjorklund