Identityref pointing to base identity is not valid

[alexandrustancu]

I've found the following scenario in the core-model, detailed below.

Context: the switch-selection-reason leaf is an identityref, pointing to the SWITCH_STATE_REASON base identity.

The problem is that the core-model defines only the base identity, SWITCH_STATE_REASON and no other identities that extent this base one.

In the device implementation of the core-model, the leaf switch-selection-reason will need to have a valid value. But no other identities besides the base identity SWITCH_STATE_REASON are defined in the core-model. This means that if a device implements only the core-model, it cannot provide a valid value for the switch-selection-reason, because having a reference to the base identity is not a valid value. According to the YANG RFC 6020: "Valid values for an identityref are any identities derived from the identityref's base identity."

This means that the core-model needs to define another identity derived from the base identity SWITCH_STATE_REASON.

Proposed solution: define a new identity derived from the base identity. All other base identities defined in the core-model have such derived identities, except for the SWITCH_STATE_REASON.

E.g.:

identity SWITCH_STATE_REASON_NONE { base SWITCH_STATE_REASON; description "No reason"; }

Otherwise, a device that implements the core-model might be unable to provide a valid YANG, according to RFC 6020.

[openBackhaul]

Added the following segments manually to core-model-1-4 YANG

  identity ROUTE_SELECTION_REASON_NONE {
    base ROUTE_SELECTION_REASON;
    description
      "No reason";
  }

and

  identity SWITCH_STATE_REASON_NONE {
    base SWITCH_STATE_REASON;
    description
      "No reason";
  }

Entries have to be made in the UML as well.

[PrathibaJee]

• In UML2YANG tool , the pruning and refactoring section of core-model is having the neccessary code changes to include the identities,
  • ROUTE_SELECTION_REASON_NONE
  • SWITCH_STATE_REASON_NONE.
• We also generated a ReleaseCandidate#1 for the core-model and able to see the identities.
• This will be available if we generate and publish a new release of the core-model-1-4.

[openBackhaul]

Implemented as decided.