+See:
+* Upstream spec document: https://specs.openstack.org/openstack/nova-specs/specs/mitaka/implemented/get-valid-server-state.html
+* Upstream Compute API reference document: https://developer.openstack.org/api-ref/compute
+* Doctor Get Valid Server State Manual: https://git.opnfv.org/doctor/tree/docs/development/manuals/get-valid-server-state.rst
+
+Port data plane status update
+-----------------------------
+
+Port data plane status can be changed/updated in the case of issues in the underlying data plane
+affecting connectivity from/to Neutron ports.
+
+See:
+* Upstream spec document: https://specs.openstack.org/openstack/neutron-specs/specs/pike/port-data-plane-status.html
+* Upstream Networking API reference document: https://developer.openstack.org/api-ref/network
+
+Doctor driver (Congress)
+------------------------
+
+The Doctor driver can be notified about NFVI failures that have been detected by monitoring systems.
+
+See:
+* Upstream spec document: https://specs.openstack.org/openstack/congress-specs/specs/mitaka/push-type-datasource-driver.html
+* Congress official documentation: https://docs.openstack.org/congress/latest
+
+Event API (Vitrage)
+-------------------
+With this API, monitoring systems can push events to the Doctor datasource.
+
+See:
+* Upstream spec document: https://specs.openstack.org/openstack/vitrage-specs/specs/ocata/event-api.html
+* Vitrage official documentation: https://docs.openstack.org/vitrage/latest
+
+Doctor datasource (Vitrage)
+---------------------------
+After receiving events from monitoring systems, the Doctor datasource identifies the affected resources based on the resource topology.
+
+See:
+* Upstream spec document: https://specs.openstack.org/openstack/vitrage-specs/specs/ocata/doctor-datasource.html
+