Background

Each time a new PNF is connected to the network, or reseted to factory settings, a PNF registration process is expected to happen.
Within this process, a VES pnfRegistration event is sent from a PNF instance to the ONAP/DCAE/VES collector.
In order to support Nomadic PNF use-case of a broader BBS use-case, an initial registration of a PNF needs to be distinguished from a re-registration.

Initial registration happens, when a PNF instance registers with ONAP for the first time (it was not used as a resource in any active service instance before).
Generally re-registration happens, when a PNF, that has been used previously in an active service instance, to deliver a service is re-connected or reset, and attempts to register again with ONAP with a pnfRegistration VES event.

Goal

The goal of this page is to summarize and prioritize the criteria, when a registration attempt is considered an initial registration and when - a Re-Registration.
All registration cases, which do not match with re-registration criteria will be considered "initial registrations".

Service/Resource instance state machine

SO project defined the State Machines, related to the service and resource (PNF/VNF) instances life-cycle.
The state machines are defined here. For PNFs, the state machine (simplified is stated as follows):

Register (when a PNF instance is created) → Registered (after initial pnfRegistration) → Assign → Assigned → ConfigAssign → ConfigAssigned → Configure → Configured → Active

Note:

At this moment (ONAP/Casablanca release), the orchestration states are not managed by the PNF PnP building block (state machine was not defined before).
Setting proper states within the PNF PnP BB according to this State Machine will probably be added at the beginning of ONAP/El Alto release.

Re-Registration criteria

The following criteria need to be applied (in the order given here), when evaluation, if a registration attempt is a Re-Registration:

1. If a registration attempt is executed for a PNF Instance, which has an existing entry in the ONAP/AAI, and when that PNF instance is associated with an active (orchestration-status==active) service instance
   → Re-Registration

2. If a registration attempt is executed for a PNF Instance, which has an existing entry in the ONAP/AAI, and when that PNF instance`s orchestration-status field is set to "Registered"
   → Re-Registration (possible starting from ONAP/El Alto release, when a PNF mgmt state machine is implemented)