Re: [netmod] Schema Mount Point Instance Yang Library Clarification

Ladislav Lhotka <lhotka@nic.cz> Thu, 25 April 2019 07:21 UTC

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From: Ladislav Lhotka <lhotka@nic.cz>
To: Rohit R Ranade <rohitrranade@huawei.com>, "netmod@ietf.org" <netmod@ietf.org>
Date: Thu, 25 Apr 2019 09:21:47 +0200
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Subject: Re: [netmod] Schema Mount Point Instance Yang Library Clarification
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On Wed, 2019-04-24 at 08:52 +0000, Rohit R Ranade wrote:
> Hi Lada,
> 
> Thank you for your response. Please find inline.
> 
> -----Original Message-----
> From: Ladislav Lhotka [mailto:lhotka@nic.cz] 
> Sent: 24 April 2019 12:40
> To: Rohit R Ranade <rohitrranade@huawei.com>om>; netmod@ietf.org
> Subject: Re: [netmod] Schema Mount Point Instance Yang Library Clarification
> 
> Hi Rohit,
> 
> Rohit R Ranade <rohitrranade@huawei.com> writes:
> 
> > Hi All,
> > 
> > In https://tools.ietf.org/html/rfc8528#section-4, a below example is 
> > shown for parent references,
> > 
> > "
> >      +--rw interfaces
> >      |  +--rw interface* [name]
> >      |     ...
> >      +--rw network-instances
> >         +--rw network-instance* [name]
> >            +--rw name
> >            +--mp root
> >               +--rw routing
> >                  ...
> > 
> > "
> > Consider a simple case where the ietf-routing module and ietf-ospf module
> > are mounted as part of network-instance of a L3vpn. Also consider that for
> > ietf-ospf , it has some interface configuration as shown below.
> > This needs parent-references , since the interface configuration is in the
> > parent data-tree of mount-point.
> > 
> > module: ietf-ospf
> >    augment /rt:routing/rt:control-plane-protocols/
> >             rt:control-plane-protocol:
> >      +--rw ospf
> >         +--rw areas
> >         |  +--rw area* [area-id]
> >         |     +--rw interfaces
> >         |        +--rw interface* [name]
> >         |           +--rw name     if:interface-ref
> > 
> > Since the YANG library "under" the mount-point-instance has to be 
> > complete, I was thinking that the YANG library under the mount-point 
> > will have the "ietf-interfaces" YANG module. Since the 
> > "ietf-interfaces" module under the network-instance mount-point may 
> > not make sense,  the "conformance-type" for it will be "import"
> > instead of "implement".
> 
> Yes, I think this is correct: the ietf-ospf module imports the ietf-interfaces 
> module, so the latter has to be specified in the YANG library of the mounted
> schema with "import" conformance.
> 
> > Another statement though confuses me , where the argument of 
> > "presence" statement of "shared-schema", ""The mounted schema together 
> > with the 'parent-reference'
> >                 make up the schema for this mount point.";"  ==> Does
> 
> This is wrong, parent-reference adds nothing to the schema, only to the
> accessible tree for XPath evaluations.
> [Rohit R Ranade] So this needs to be corrected by an errata ?

This sentence is in the module text, so it would require a new revision in order
to be really effective. My suggestion is to wait until more (and possibly more
substantial) changes accumulate.

Lada 

> 
> Lada
> 
> > this mean that YANG Library of the mount-point-instance should not 
> > have "ietf-interfaces" in this case ? This may make the client work 
> > complicated.
> > 
> > 
> > With Regards,
> > Rohit
> > _______________________________________________
> > netmod mailing list
> > netmod@ietf.org
> > https://www.ietf.org/mailman/listinfo/netmod
> 
> --
> Ladislav Lhotka
> Head, CZ.NIC Labs
> PGP Key ID: 0xB8F92B08A9F76C67
-- 
Ladislav Lhotka
Head, CZ.NIC Labs
PGP Key ID: 0xB8F92B08A9F76C67