diff --git a/neutron/services/trunk/constants.py b/neutron/services/trunk/constants.py
index 84bcc39b113..227e9fe6e53 100644
--- a/neutron/services/trunk/constants.py
+++ b/neutron/services/trunk/constants.py
@@ -79,3 +79,4 @@ TRUNK_SUBPORT_OWNER = 'trunk:subport'
 
 # String literals for segmentation types
 VLAN = 'vlan'
+INHERIT = 'inherit'
diff --git a/neutron/services/trunk/rules.py b/neutron/services/trunk/rules.py
index d6a9c91d7e3..1e90e4a1e65 100644
--- a/neutron/services/trunk/rules.py
+++ b/neutron/services/trunk/rules.py
@@ -14,6 +14,7 @@
 
 from neutron_lib.api import converters
 from neutron_lib.api.definitions import portbindings
+from neutron_lib.api.definitions import provider_net as provider
 from neutron_lib.api import validators
 from neutron_lib import exceptions as n_exc
 from neutron_lib.plugins import directory
@@ -22,6 +23,7 @@ from neutron._i18n import _
 from neutron.common import utils as n_utils
 from neutron.objects import trunk as trunk_objects
 from neutron.plugins.ml2 import driver_api as api
+from neutron.services.trunk import constants
 from neutron.services.trunk import exceptions as trunk_exc
 from neutron.services.trunk import utils
 
@@ -165,11 +167,41 @@ class SubPortsValidator(object):
 
         if trunk_validation:
             trunk_port_mtu = self._get_port_mtu(context, self.trunk_port_id)
+            self._prepare_subports(context)
             return [self._validate(context, s, trunk_port_mtu)
                     for s in self.subports]
         else:
             return self.subports
 
+    def _prepare_subports(self, context):
+        """Update subports segmentation details if INHERIT is requested."""
+        port_ids = {
+            s['port_id']: i
+            for i, s in enumerate(self.subports)
+            if s.get('segmentation_type') == constants.INHERIT
+        }
+        core_plugin = directory.get_plugin()
+        if not port_ids:
+            return
+        elif not n_utils.is_extension_supported(core_plugin, provider.ALIAS):
+            msg = _("Cannot accept segmentation type %s") % constants.INHERIT
+            raise n_exc.InvalidInput(error_message=msg)
+
+        ports = core_plugin.get_ports(context, filters={'id': port_ids})
+        # this assumes a user does not try to trunk the same network
+        # more than once.
+        network_port_map = {
+            x['network_id']: {'port_id': x['id']}
+            for x in ports
+        }
+        networks = core_plugin.get_networks(
+            context.elevated(), filters={'id': network_port_map})
+        for net in networks:
+            port = network_port_map[net['id']]
+            port.update({'segmentation_id': net[provider.SEGMENTATION_ID],
+                         'segmentation_type': net[provider.NETWORK_TYPE]})
+            self.subports[port_ids[port['port_id']]] = port
+
     def _get_port_mtu(self, context, port_id):
         """
         Return MTU for the network where the given port belongs to.
diff --git a/neutron/tests/contrib/gate_hook.sh b/neutron/tests/contrib/gate_hook.sh
index 820879e0ed6..c1b7e4f8dd9 100644
--- a/neutron/tests/contrib/gate_hook.sh
+++ b/neutron/tests/contrib/gate_hook.sh
@@ -91,6 +91,7 @@ case $VENV in
     load_rc_hook qos
     load_rc_hook trunk
     load_conf_hook mtu
+    load_conf_hook vlan_provider
     load_conf_hook osprofiler
     if [[ "$VENV" =~ "dsvm-scenario" ]]; then
         load_rc_hook ubuntu_image
diff --git a/neutron/tests/contrib/hooks/vlan_provider b/neutron/tests/contrib/hooks/vlan_provider
new file mode 100644
index 00000000000..e6815c94e84
--- /dev/null
+++ b/neutron/tests/contrib/hooks/vlan_provider
@@ -0,0 +1,9 @@
+[[test-config|$TEMPEST_CONFIG]]
+
+[neutron_plugin_options]
+provider_vlans=foo,
+
+[[post-config|/$Q_PLUGIN_CONF_FILE]]
+
+[ml2_type_vlan]
+network_vlan_ranges = foo:1:10
diff --git a/neutron/tests/tempest/api/test_trunk.py b/neutron/tests/tempest/api/test_trunk.py
index 62290c91cc8..647e3dd109b 100644
--- a/neutron/tests/tempest/api/test_trunk.py
+++ b/neutron/tests/tempest/api/test_trunk.py
@@ -220,6 +220,53 @@ class TrunkTestJSON(TrunkTestJSONBase):
         self.assertEqual(1, len(observed_subports))
 
 
+class TrunkTestInheritJSONBase(TrunkTestJSONBase):
+
+    required_extensions = ['provider', 'trunk']
+
+    @classmethod
+    def skip_checks(cls):
+        super(TrunkTestInheritJSONBase, cls).skip_checks()
+        for ext in cls.required_extensions:
+            if not test.is_extension_enabled(ext, 'network'):
+                msg = "%s extension not enabled." % ext
+                raise cls.skipException(msg)
+        if not config.CONF.neutron_plugin_options.provider_vlans:
+            raise cls.skipException("No provider VLAN networks available")
+
+    def create_provider_network(self):
+        foo_net = config.CONF.neutron_plugin_options.provider_vlans[0]
+        post_body = {'network_name': data_utils.rand_name('vlan-net-'),
+                     'provider:network_type': 'vlan',
+                     'provider:physical_network': foo_net}
+        return self.create_shared_network(**post_body)
+
+    @decorators.idempotent_id('0f05d98e-41f5-4629-dada-9aee269c9602')
+    def test_add_subport(self):
+        trunk_network = self.create_provider_network()
+        trunk_port = self.create_port(trunk_network)
+        subport_networks = [
+            self.create_provider_network(),
+            self.create_provider_network(),
+        ]
+        subport1 = self.create_port(subport_networks[0])
+        subport2 = self.create_port(subport_networks[1])
+        subports = [{'port_id': subport1['id'],
+                     'segmentation_type': 'inherit',
+                     'segmentation_id': subport1['id']},
+                    {'port_id': subport2['id'],
+                     'segmentation_type': 'inherit',
+                     'segmentation_id': subport2['id']}]
+        trunk = self.client.create_trunk(trunk_port['id'], subports)['trunk']
+        self.trunks.append(trunk)
+        # Validate that subport got segmentation details from the network
+        for i in range(2):
+            self.assertEqual(subport_networks[i]['provider:network_type'],
+                             trunk['sub_ports'][i]['segmentation_type'])
+            self.assertEqual(subport_networks[i]['provider:segmentation_id'],
+                             trunk['sub_ports'][i]['segmentation_id'])
+
+
 class TrunkTestMtusJSONBase(TrunkTestJSONBase):
 
     required_extensions = ['provider', 'trunk']
diff --git a/neutron/tests/tempest/api/test_trunk_negative.py b/neutron/tests/tempest/api/test_trunk_negative.py
index 585ef52f3c9..f3497bb9a59 100644
--- a/neutron/tests/tempest/api/test_trunk_negative.py
+++ b/neutron/tests/tempest/api/test_trunk_negative.py
@@ -102,6 +102,18 @@ class TrunkTestJSON(test_trunk.TrunkTestJSONBase):
                           [{'segmentation_type': 'vlan',
                             'segmentation_id': 3}])
 
+    @test.attr(type='negative')
+    @decorators.idempotent_id('40aed9be-e976-47d0-dada-bde2c7e74e57')
+    def test_create_subport_invalid_inherit_network_segmentation_type(self):
+        trunk = self._create_trunk_with_network_and_parent([])
+        subport_network = self.create_network()
+        parent_port = self.create_port(subport_network)
+        self.assertRaises(lib_exc.BadRequest, self.client.add_subports,
+                          trunk['trunk']['id'],
+                          [{'port_id': parent_port['id'],
+                            'segmentation_type': 'inherit',
+                            'segmentation_id': -1}])
+
     @test.attr(type='negative')
     @decorators.idempotent_id('40aed9be-e976-47d0-a555-bde2c7e74e57')
     def test_create_trunk_duplicate_subport_segmentation_ids(self):
diff --git a/neutron/tests/tempest/config.py b/neutron/tests/tempest/config.py
index 479d9093d07..5a9ac77c5cf 100644
--- a/neutron/tests/tempest/config.py
+++ b/neutron/tests/tempest/config.py
@@ -19,6 +19,9 @@ CONF = config.CONF
 
 
 NeutronPluginOptions = [
+    cfg.ListOpt('provider_vlans',
+                default=[],
+                help='List of provider networks available in the deployment.'),
     cfg.BoolOpt('specify_floating_ip_address_available',
                 default=True,
                 help='Allow passing an IP Address of the floating ip when '
diff --git a/neutron/tests/unit/services/trunk/test_rules.py b/neutron/tests/unit/services/trunk/test_rules.py
index f3314a6a961..7776aaab461 100644
--- a/neutron/tests/unit/services/trunk/test_rules.py
+++ b/neutron/tests/unit/services/trunk/test_rules.py
@@ -44,6 +44,8 @@ class SubPortsValidatorTestCase(base.BaseTestCase):
 
         mock.patch.object(rules.SubPortsValidator, '_get_port_mtu',
                           return_value=None).start()
+        mock.patch.object(rules.SubPortsValidator, '_prepare_subports',
+                          return_value=None).start()
 
     def test_validate_subport_subport_and_trunk_shared_port_id(self):
         shared_id = uuidutils.generate_uuid()
@@ -124,6 +126,26 @@ class SubPortsValidatorTestCase(base.BaseTestCase):
                           self.context, basic_validation=True)
 
 
+class SubPortsValidatorPrepareTestCase(base.BaseTestCase):
+
+    def setUp(self):
+        super(SubPortsValidatorPrepareTestCase, self).setUp()
+        self.segmentation_types = {constants.VLAN: utils.is_valid_vlan_tag}
+        self.context = mock.ANY
+
+        mock.patch.object(rules.SubPortsValidator, '_get_port_mtu',
+                          return_value=None).start()
+
+    def test__prepare_subports_raise_no_provider_ext(self):
+        validator = rules.SubPortsValidator(
+            self.segmentation_types,
+            [{'port_id': uuidutils.generate_uuid(),
+              'segmentation_type': 'inherit'}])
+        self.assertRaises(n_exc.InvalidInput,
+                          validator._prepare_subports,
+                          self.context)
+
+
 class SubPortsValidatorMtuSanityTestCase(test_plugin.Ml2PluginV2TestCase):
 
     def setUp(self):
diff --git a/releasenotes/notes/trunk_inherit-455dc74b9fa22dad.yaml b/releasenotes/notes/trunk_inherit-455dc74b9fa22dad.yaml
new file mode 100644
index 00000000000..e1f198faf1a
--- /dev/null
+++ b/releasenotes/notes/trunk_inherit-455dc74b9fa22dad.yaml
@@ -0,0 +1,7 @@
+---
+features:
+  - Subport segmentation details can now accept ``inherit`` as segmentation
+    type during a trunk creation/update request.  The trunk plugin will
+    determine the segmentation type and ID and replace them with those of
+    the network to which the port is connected.  Only single-segment VLAN
+    networks are set to have expected and correct results at this point.