On Wed, May 19, 2021 at 11:22 AM Italo Busi <[email protected]> wrote:
> Then, what would be the difference between an optional and a mandatory > data node? > > > Do not confuse "mandatory to implement" with "mandatory that a node be present". Mandatory to implement is easy: If there is an if-feature conditional that is applied to a node or one of its ancestors, then it is optional to implement. Otherwise it is mandatory to implement. > In some RFC8795 implementations, the support or not support of a data node > may also depend on the specific network-type so in this case the data node > cannot be marked as not-supported > > > This is a different issue. Server capabilities specific to a data model should be handled in a related module. Italo > > > Andy > *From:* Andy Bierman [mailto:[email protected]] > *Sent:* mercoledì 19 maggio 2021 19:35 > *To:* Italo Busi <[email protected]> > *Cc:* [email protected]; [email protected] > *Subject:* Re: [netmod] Question about optional data nodes in YANG > > > > > > > > On Wed, May 19, 2021 at 10:12 AM Italo Busi <[email protected]> wrote: > > We have got a question about how to deal with YANG optional data nodes and > in particular how can a client know which optional data node has been > implemented by a server. > > > > We think that there is no issue with config=false data nodes. When the > client retrieves a YANG tree from the operational datastore it will not get > the data nodes that are not implemented by the server, as reported in > section 5.3 of RFC8342: > > > > If no value is returned for a given node, then > > this implies that the node is not used by the device. > > > > Is our understanding correct? > > > > > > > > The server is expected to advertise a deviation for not-supported for > every subtree > > it does not implement. > > > > https://datatracker.ietf.org/doc/html/rfc7950#section-7.20.3.2 > > > > > > deviation /base:system/base:daytime { > > deviate not-supported; > > } > > > > > > Andy > > > > > > > > The doubt we have is about the config=true data nodes. > > > > How can the client know whether the server supports the configuration of > an optional config=true data node before trying to configure them and > getting an error message? > > > > We understand that it is possible to know whether a YANG model or a > feature of the YANG model (i.e. a group of data nodes) is supported by the > server. The question is rather on specific data nodes with config=true. > > > > We have found scenarios where it could be useful to implement a sub-set of > optional data nodes (profile) of an IETF standard YANG model, but it is not > very clear how a client can understand which profile has been implemented > by the server. > > > > Some examples of profiles of an IETF standard YANG model are provided in: > > > > https://datatracker.ietf.org/doc/html/draft-busi-teas-te-topology-profiles > > > > Thanks, Aihua and Italo > > > > _______________________________________________ > netmod mailing list > [email protected] > https://www.ietf.org/mailman/listinfo/netmod > >
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