doc: ospfd / ospf6d: document RFC 9129 ietf-ospf config-write scope

Replace the older "operational data only" sections in doc/user/ospfd.rst
and doc/user/ospf6d.rst with a YANG / NETCONF Support entry that lists
every config-write leaf the ietf-ospf series now supports plus the
deliberate scope gaps:

  * redistribute and default-information-originate remain legacy-CLI
    only (RFC 9129 / RFC 8349 leave them to a separate import / export
    mechanism).
  * Per-address overrides (e.g. `ip ospf cost N A.B.C.D`) have no RFC
    9129 counterpart; YANG is strictly per-interface.
  * FRR-specific NSSA augments (translator-role, suppress-fa,
    default-information-originate) are not in the RFC 9129 area
    grouping; they remain legacy-CLI-only.
  * `router ospf [vrf NAME]` instance creation is still CLI-only;
    YANG operations that target a non-existent instance are rejected
    at VALIDATE with a clear error pointing at `router ospf`.
  * ospf6d has no per-area stub default-cost knob; the leaf is not
    implemented (mgmtd reports "no backend handles this path"). This
    matches the existing v3 CLI surface, not a regression introduced
    by this conversion.
  * ospf6 interface-type rejects non-broadcast and hybrid at VALIDATE
    (ospf6d only accepts broadcast, point-to-point and
    point-to-multipoint).

Adds a worked example showing mgmt set-config / commit apply for the
explicit-router-id leaf so operators see the end-to-end mgmtd path.
Documents the frr-deviations-ietf-routing-ospf interface-name leafref
relaxation and the restoration of referential checks inside the
per-interface callbacks.

Signed-off-by: lamestllama <eric@eparsonage.com>

Author: lamestllama

doc/user/ospf6d.rst

@@ -933,21 +933,46 @@ Showing OSPF6 information
    This command shows the graceful-restart helper details including helper
    configuration parameters.
 
-YANG Operational Data
----------------------
-
-OSPFv3 operational state is available through the standard :rfc:`9129`
-``ietf-ospf`` YANG model. The current support is operational data only; OSPFv3
-configuration is still managed through the existing FRR CLI.
+YANG / NETCONF Support
+----------------------
 
-The following example retrieves the OSPFv3 instance from the mgmtd operational
-datastore:
+OSPFv3 operational state and a subset of OSPFv3 configuration are exposed
+through the standard :rfc:`9129` ``ietf-ospf`` YANG model. The OSPFv3
+instance itself remains owned by the legacy ``router ospf6`` CLI, but
+per-area, per-interface and per-instance configuration leaves are routed
+through the mgmtd northbound and can be read, set, and committed through
+NETCONF / RESTCONF / ``vtysh``'s ``mgmt`` subcommands as well as the legacy
+CLI.
+
+The supported set mirrors the OSPFv2 side documented in :ref:`ospfd`, with
+two v3-specific gaps:
+
+* ``areas/area/default-cost``: ospf6d has no per-area stub default-cost
+  knob, so this leaf is not implemented. Setting it via YANG is rejected
+  by mgmtd as ``no backend handles this path``. This matches FRR's existing
+  v3 CLI surface (which has no ``area X default-cost`` equivalent) and is a
+  pre-existing v2/v3 feature gap, not introduced by this conversion.
+* ``interface-type``: RFC 9129 declares ``broadcast``, ``non-broadcast``,
+  ``point-to-multipoint``, ``point-to-point`` and ``hybrid``. ospf6d only
+  accepts ``broadcast``, ``point-to-point`` and ``point-to-multipoint``;
+  the NB callback rejects ``non-broadcast`` and ``hybrid`` at VALIDATE
+  with a clear error.
+
+Otherwise the set of supported leaves (router-id, area lifecycle,
+area-type, area summary, ranges, per-interface attachment, cost,
+hello-interval, dead-interval, retransmit-interval, priority, mtu-ignore,
+passive, preference) is identical to OSPFv2.
+
+Examples
+~~~~~~~~
+
+Retrieve the OSPFv3 instance from the operational datastore:
 
 .. code-block:: shell
 
    vtysh -c 'show mgmt get-data /ietf-routing:routing/control-plane-protocols/control-plane-protocol[type="ietf-ospf:ospfv3"][name="default"] datastore operational'
 
-To retrieve the merged operational datastore, including the OSPFv3 protocol
+Retrieve the merged operational datastore, including the OSPFv3 protocol
 entry and the ``ietf-interfaces`` data used by OSPF interface leafrefs:
 
 .. code-block:: shell

doc/user/ospfd.rst

@@ -1083,27 +1083,91 @@ Showing Information
    Displays the Graceful Restart Helper details including helper
    config changes.
 
-YANG Operational Data
----------------------
-
-OSPF operational state is available through the standard :rfc:`9129`
-``ietf-ospf`` YANG model. The current support is operational data only; OSPF
-configuration is still managed through the existing FRR CLI.
+YANG / NETCONF Support
+----------------------
 
-The following example retrieves the OSPFv2 instance from the mgmtd operational
-datastore:
+OSPF operational state and a subset of OSPF configuration are exposed through
+the standard :rfc:`9129` ``ietf-ospf`` YANG model.  The OSPF instance itself
+remains owned by the legacy ``router ospf`` CLI, but per-area, per-interface
+and per-instance configuration leaves are routed through the mgmtd northbound
+so they can be read, set and committed via NETCONF / RESTCONF / ``vtysh``'s
+``mgmt`` subcommands as well as the legacy CLI.
+
+Supported configuration leaves
+~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+
+Under ``/ietf-routing:routing/control-plane-protocols/control-plane-protocol[type='ietf-ospf:ospfv2']/ietf-ospf:ospf``:
+
+* ``explicit-router-id``
+* ``preference/{all,intra-area,inter-area,internal,external}`` (admin distance)
+* ``areas/area`` (list create / destroy keyed by ``area-id``)
+* ``areas/area/area-type`` (``normal-area``, ``stub-area``, ``nssa-area``)
+* ``areas/area/summary`` (totally-stubby toggle; RFC 9129 inverts FRR's
+  ``no-summary`` sense)
+* ``areas/area/default-cost`` (stub / NSSA only)
+* ``areas/area/ranges/range`` (list create / destroy), with ``advertise``
+  and ``cost`` leaves
+* ``areas/area/interfaces/interface`` (list create / destroy: assigns an
+  interface to the area), plus the per-interface leaves
+  ``cost``, ``hello-interval``, ``dead-interval``, ``retransmit-interval``,
+  ``priority``, ``mtu-ignore``, ``interface-type``, ``passive``
+
+Out of scope for this slice
+~~~~~~~~~~~~~~~~~~~~~~~~~~~
+
+* ``redistribute`` and ``default-information-originate`` are FRR-specific
+  concepts that RFC 9129 / :rfc:`8349` leave to a separate import / export
+  mechanism. They stay reachable through the legacy CLI on the
+  direct-mutation path.
+* Per-address overrides (e.g. ``ip ospf cost N A.B.C.D``) have no RFC 9129
+  counterpart; the YANG model is strictly per-interface. The legacy CLI
+  with an explicit address argument continues to use direct mutation.
+* FRR-specific area NSSA augments (translator-role,
+  default-information-originate, suppress-fa) are not in the RFC 9129 area
+  grouping; they remain legacy-CLI-only.
+* The ``router ospf [vrf NAME]`` instance creation step is still
+  CLI-only; YANG operations that target a non-existent instance are
+  rejected at VALIDATE with a clear error pointing at ``router ospf``.
+
+Examples
+~~~~~~~~
+
+Retrieve the OSPFv2 instance from the operational datastore:
 
 .. code-block:: shell
 
    vtysh -c 'show mgmt get-data /ietf-routing:routing/control-plane-protocols/control-plane-protocol[type="ietf-ospf:ospfv2"][name="default"] datastore operational'
 
-To retrieve the merged operational datastore, including the OSPF protocol
+Retrieve the merged operational datastore, including the OSPF protocol
 entry and the ``ietf-interfaces`` data used by OSPF interface leafrefs:
 
 .. code-block:: shell
 
    vtysh -c 'show mgmt get-data /* datastore operational'
 
+Set the router-id through mgmtd, then commit:
+
+.. code-block:: shell
+
+   vtysh -c 'configure terminal file-lock'                 \
+         -c 'mgmt set-config /ietf-routing:routing/control-plane-protocols/control-plane-protocol[type="ietf-ospf:ospfv2"][name="default"]/ietf-ospf:ospf/explicit-router-id "10.0.0.1"' \
+         -c 'mgmt commit apply'
+
+The corresponding ``ospf router-id 10.0.0.1`` legacy CLI command takes the
+same path through the northbound; both surfaces converge on the same
+candidate datastore.
+
+Interface leafref relaxation
+~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+
+RFC 9129's per-interface entry keys on a leafref into
+``/ietf-interfaces:interfaces/interface/name``. The
+``frr-deviations-ietf-routing-ospf`` deviation relaxes this so OSPF config
+can be staged ahead of interface plumbing (useful when emitting config from
+an external orchestrator). The relaxation removes libyang's referential
+check; the NB callbacks restore it themselves, rejecting unknown interface
+names at VALIDATE with a clear error.
+
 .. _opaque-lsa:
 
 Opaque LSA