Re: [yang-doctors] Identities vs enums

[Juergen Schoenwaelder <[e-mail]>]

On Wed, Aug 23, 2017 at 12:46:37PM -0700, Andy Bierman wrote:
> On Sun, Aug 20, 2017 at 1:03 AM, Juergen Schoenwaelder <
> [e-mail]> wrote:
> 
> > On Sat, Aug 19, 2017 at 07:02:04PM +0000, Acee Lindem (acee) wrote:
> > > All,
> > > In the context iana-routing-types.yang, we’ve been having a discussion
> > of the merits of identities vs enums. We’ve followed the lead of RFC 7224
> > and used identities which allow augmentation. However, for IANA code
> > points, there could be merit in having the type represent the actual
> > numeric value. Any thoughts on this?
> > >
> > > In the next version of YANG, it would be useful for a base identity to
> > allow it to have a "base-type" (mutually exclusive of "identity-ref"). For
> > all identities a "base-value" would be allowed as long as it conformed to
> > the constraints of the actual or inherited (via “identity-ref”) “base-type”.
> > >
> >
> > The question here really is who is charge of controlling assignments
> > of a name space.
> >
> > - If there is a single authority controlling the assignments, an enum
> >   works fine.
> >
> > - If the assignments are not controlled by a single authority, an
> >   identity works fine.
> >
> > We sometimes have situations that are somewhere in between, i.e., a
> > central authority controlling assignments but delegating parts of the
> > name space to other authoritities. I agree, we do not have good
> > support to model this explicitly in YANG today.
> >
> >
> I think Acee is asking about a new feature that does not exist in YANG,
> which is to add
> an enum value-stmt to an identity-stmt somehow.  Seems like a valid
> use-case.

Identities can be without a central authority controlling assignments
- so there is little hope that values assigned to identities carry a
useful meaning unless there is a mechanism to partition and delegate
number spaces along the identity hierarchy.

/js

-- 
Juergen Schoenwaelder           Jacobs University Bremen gGmbH
Phone: [phone]         Campus Ring 1 | 28759 Bremen | Germany
Fax:   [phone]         <http://www.jacobs-university.de/>