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

Ladislav Lhotka <lhotka@nic.cz> Wed, 24 April 2019 07:10 UTC

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From: Ladislav Lhotka <lhotka@nic.cz>
To: Rohit R Ranade <rohitrranade@huawei.com>, "netmod\@ietf.org" <netmod@ietf.org>
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Date: Wed, 24 Apr 2019 09:09:58 +0200
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Subject: Re: [netmod] Schema Mount Point Instance Yang Library Clarification
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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.

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