Re: [netmod] Question on intefaces-state model

On 06/12/2017 08:31 PM, Andy Bierman wrote:

>
>
> On Mon, Jun 12, 2017 at 10:21 AM, Juergen Schoenwaelder 
> <j.schoenwaelder@jacobs-university.de 
> <mailto:j.schoenwaelder@jacobs-university.de>> wrote:
>
>     On Fri, Jun 09, 2017 at 10:55:20AM +0000, Bogaert, Bart (Nokia -
>     BE/Antwerp) wrote:
>     >
>     > We have a question regarding the statistics container as defined
>     in the
>     > interfaces-state model.  This container defines one mandatory leaf
>     > (discontinuity-time) while all other leafs are optional.  What
>     is the
>     > rationale behind this leaf being mandatory and not an optional
>     field?
>     >
>     > It does not make a lot of sense to return a discontinuity-time
>     value and no
>     > counters if none of the counters are relevant for a specific
>     interface.
>     >
>     > Another alternative could be to add, via a deviation, a when
>     clause to the
>     > container indicating for which ifType(s) the container is (or is
>     not)
>     > present. But that would lead to not supporting the IETF
>     interfaces model to
>     > the full extent.
>     >
>
The alternative which we use is to not have 
/interfaces-state/interface/statistics container for the interfaces 
without counters. The container is mandatory=false.
>
>
>     The discontinuity-time is relevant for _any_ counter associated with
>     an interface, regardless whether the counter is defined in the
>     interfaces model or elsewhere. I have a hard time to imagine an
>     interface that has zero counters.
>
There are some though. Optical amplifiers and similar equipment that 
does not have counters - the status data is only signal levels.
>
> The mandatory-stmt is very confusing for config=false nodes. 
> Mandatory=true means
> an <rpc-reply> must contain an instance of the mandatory leaf.
>
> Mandatory=false does not mean optional-to-implement although it sure
> looks that way for config=false nodes.  Only if-feature can make a 
> node optional to implement.
If we take serial interface with hardware that only has in-octets and 
out-octets counters I would expect to only find these two in 
/interfaces-state/interface/statistics +  discontinuity-time. Do you say 
the rest of the counters must be present (e.g. allways 0) for proper 
implementation of ietf-interfaces?

Vladimir
>
>
>
> /js
>
>
> Andy
>
>     --
>     Juergen Schoenwaelder           Jacobs University Bremen gGmbH
>     Phone: +49 421 200 3587         Campus Ring 1 | 28759 Bremen | Germany
>     Fax:   +49 421 200 3103         <http://www.jacobs-university.de/
>     <http://www.jacobs-university.de/>>
>
>     _______________________________________________
>     netmod mailing list
>     netmod@ietf.org <mailto:netmod@ietf.org>
>     https://www.ietf.org/mailman/listinfo/netmod
>     <https://www.ietf.org/mailman/listinfo/netmod>
>
>
>
>
> _______________________________________________
> netmod mailing list
> netmod@ietf.org
> https://www.ietf.org/mailman/listinfo/netmod