diff --git a/api-ref/source/v2/networks.inc b/api-ref/source/v2/networks.inc
index 19298272a..3273fcd46 100644
--- a/api-ref/source/v2/networks.inc
+++ b/api-ref/source/v2/networks.inc
@@ -47,6 +47,14 @@ The ``floatingip-autodelete-internal`` shim extension signals that the
 update of a network's ``router:external`` attribute from ``true`` to
 ``false`` autodeletes the unused Floating IPs of that network.
 
+HA extension
+============
+
+The ``network-ha`` extension allows to pass a boolean parameter during the
+network creation. If ``true`` is passed, a ``ha_router_networks`` database
+register will be created along with the ``network`` register. This field is
+not visible and, initially, not meant to be supported in the CLI.
+
 L2 adjacency extension
 ======================
 
diff --git a/api-ref/source/v2/parameters.yaml b/api-ref/source/v2/parameters.yaml
index 579244918..640cf9878 100644
--- a/api-ref/source/v2/parameters.yaml
+++ b/api-ref/source/v2/parameters.yaml
@@ -4768,6 +4768,12 @@ network-admin_state_up-request:
   in: body
   required: false
   type: boolean
+network-ha:
+  description: |
+    The high availability input flag when creating a network.
+  in: body
+  required: false
+  type: boolean
 network-id:
   description: |
     The ID of the network.
diff --git a/neutron_lib/api/definitions/__init__.py b/neutron_lib/api/definitions/__init__.py
index cecb501b0..deec31936 100644
--- a/neutron_lib/api/definitions/__init__.py
+++ b/neutron_lib/api/definitions/__init__.py
@@ -80,6 +80,7 @@ from neutron_lib.api.definitions import multiprovidernet
 from neutron_lib.api.definitions import network
 from neutron_lib.api.definitions import network_availability_zone
 from neutron_lib.api.definitions import network_cascade_delete
+from neutron_lib.api.definitions import network_ha
 from neutron_lib.api.definitions import network_ip_availability
 from neutron_lib.api.definitions import network_mtu
 from neutron_lib.api.definitions import network_mtu_writable
@@ -228,6 +229,7 @@ _ALL_API_DEFINITIONS = {
     network,
     network_availability_zone,
     network_cascade_delete,
+    network_ha,
     network_ip_availability,
     network_mtu,
     network_mtu_writable,
diff --git a/neutron_lib/api/definitions/network_ha.py b/neutron_lib/api/definitions/network_ha.py
new file mode 100644
index 000000000..4fde6f3ce
--- /dev/null
+++ b/neutron_lib/api/definitions/network_ha.py
@@ -0,0 +1,43 @@
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+#    http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or
+# implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+
+from neutron_lib.api import converters
+from neutron_lib.api.definitions import l3
+from neutron_lib.api.definitions import network
+
+ALIAS = 'network_ha'
+IS_SHIM_EXTENSION = False
+IS_STANDARD_ATTR_EXTENSION = False
+NAME = 'Network HA creation flag'
+API_PREFIX = ''
+DESCRIPTION = 'Network high availability creation flag.'
+UPDATED_TIMESTAMP = '2023-04-27T10:00:00-00:00'
+RESOURCE_NAME = network.RESOURCE_NAME
+COLLECTION_NAME = network.COLLECTION_NAME
+HA = 'ha'
+RESOURCE_ATTRIBUTE_MAP = {
+    COLLECTION_NAME: {
+        HA: {
+            'allow_post': True,
+            'allow_put': False,
+            'is_visible': False,
+            'default': False,
+            'convert_to': converters.convert_to_boolean,
+        },
+    }
+}
+SUB_RESOURCE_ATTRIBUTE_MAP = {}
+ACTION_MAP = {}
+REQUIRED_EXTENSIONS = [l3.ALIAS]
+OPTIONAL_EXTENSIONS = []
+ACTION_STATUS = {}
diff --git a/neutron_lib/db/model_base.py b/neutron_lib/db/model_base.py
index 699084a65..23300d38d 100644
--- a/neutron_lib/db/model_base.py
+++ b/neutron_lib/db/model_base.py
@@ -62,6 +62,14 @@ class HasProjectPrimaryKey(HasProject):
                            nullable=False, primary_key=True)
 
 
+class HasProjectPrimaryUniqueKey(HasProject):
+    """Project mixin, add to subclasses that have a user."""
+
+    # NOTE: project_id is just a free form string
+    project_id = sa.Column(sa.String(db_const.PROJECT_ID_FIELD_SIZE),
+                           nullable=False, primary_key=True, unique=True)
+
+
 class HasId(object):
     """id mixin, add to subclasses that have an id."""
 
diff --git a/releasenotes/notes/network-ha-e6e0c3202b084762.yaml b/releasenotes/notes/network-ha-e6e0c3202b084762.yaml
new file mode 100644
index 000000000..2a6f8f7c4
--- /dev/null
+++ b/releasenotes/notes/network-ha-e6e0c3202b084762.yaml
@@ -0,0 +1,8 @@
+---
+features:
+  - |
+    New API definition: ``network-ha``. This boolean field can be used only
+    during the network creation. If enabled, the Neutron server will create
+    a ``ha_router_networks`` register, that binds the project with the network
+    and represents the only high availability network that can be created per
+    project.