"fengchong (C)" <[email protected]> writes:

> Hi all,
>
>     I notice an identity named 'interface-type' was defined in RFC
> 7223 ( A YANG Data Model for Interface Management). This identity is
> an abstract identity, vendors can define their real Identity based
> it. But it's lack of a means to identify this identity
> 'interface-type' is abstract, so 'interface-type' can be accepted as
> valid value of the leaf based this identity.

In fact, the identity that's specified as "base" in an "identityref"
type is NOT a valid value, so the base identity is abstract.

This wasn't clear in the original RFC 6020 so it was clarified in this erratum:

https://www.rfc-editor.org/errata_search.php?rfc=6020&eid=3470

Section 7.18.2 in draft-ietf-netmod-rfc6020bis-07 has this text:

   The derivation of identities has the following properties:

   o  It is irreflexive, which means that an identity is not derived
      from itself.

   …

In XPath expressions, it is possible to treat an identity as being
abstract or not by using either derived-from() or derived-from-or-self()
function.

Lada

>    So I suggest add 'abstract' statement as 'identity's sub statement in 
> YANG1.1. This statement is optional, default value is false.
> If abstract identity is defined, 'abstract true' MUST be defined, and this 
> identity's name cannot be accepted as valid value of the leaf
> based this identity .
> For example:
>
>      identity interface-type {
>
>        abstract true;
>
>        description
>
>          "Base identity from which specific interface types are
>
>           derived.";
>
>      }
> _______________________________________________
> netmod mailing list
> [email protected]
> https://www.ietf.org/mailman/listinfo/netmod

-- 
Ladislav Lhotka, CZ.NIC Labs
PGP Key ID: E74E8C0C

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