diff --git a/gbp/neutron/db/grouppolicy/group_policy_db.py b/gbp/neutron/db/grouppolicy/group_policy_db.py
index f6f8e6bf9..25a5ddfd8 100644
--- a/gbp/neutron/db/grouppolicy/group_policy_db.py
+++ b/gbp/neutron/db/grouppolicy/group_policy_db.py
@@ -738,6 +738,7 @@ class GroupPolicyDbPlugin(gpolicy.GroupPolicyPluginBase,
                     external_segment_id=es_db.id,
                     destination=rt['destination'],
                     nexthop=rt['nexthop'] or ADDRESS_NOT_SPECIFIED)
+
                 es_db.external_routes.append(target)
 
     def _set_ess_for_l3p(self, context, l3p_db, es_dict):
@@ -1555,10 +1556,17 @@ class GroupPolicyDbPlugin(gpolicy.GroupPolicyPluginBase,
         return self._make_external_policy_dict(ep_db)
 
     @log.log
-    def get_external_policies(self, context, filters=None, fields=None):
+    def get_external_policies(self, context, filters=None, fields=None,
+                              sorts=None, limit=None, marker=None,
+                              page_reverse=False):
+        marker_obj = self._get_marker_obj(context, 'external_policy', limit,
+                                          marker)
         return self._get_collection(context, ExternalPolicy,
                                     self._make_external_policy_dict,
-                                    filters=filters, fields=fields)
+                                    filters=filters, fields=fields,
+                                    sorts=sorts, limit=limit,
+                                    marker_obj=marker_obj,
+                                    page_reverse=page_reverse)
 
     @log.log
     def get_external_policies_count(self, context, filters=None):
@@ -1608,10 +1616,17 @@ class GroupPolicyDbPlugin(gpolicy.GroupPolicyPluginBase,
         return self._make_external_segment_dict(es_db)
 
     @log.log
-    def get_external_segments(self, context, filters=None, fields=None):
+    def get_external_segments(self, context, filters=None, fields=None,
+                              sorts=None, limit=None, marker=None,
+                              page_reverse=False):
+        marker_obj = self._get_marker_obj(context, 'external_segment', limit,
+                                          marker)
         return self._get_collection(context, ExternalSegment,
                                     self._make_external_segment_dict,
-                                    filters=filters, fields=fields)
+                                    filters=filters, fields=fields,
+                                    sorts=sorts, limit=limit,
+                                    marker_obj=marker_obj,
+                                    page_reverse=page_reverse)
 
     @log.log
     def get_external_segments_count(self, context, filters=None):
@@ -1655,10 +1670,17 @@ class GroupPolicyDbPlugin(gpolicy.GroupPolicyPluginBase,
         return self._make_nat_pool_dict(np_db)
 
     @log.log
-    def get_nat_pools(self, context, filters=None, fields=None):
+    def get_nat_pools(self, context, filters=None, fields=None,
+                      sorts=None, limit=None, marker=None,
+                      page_reverse=False):
+        marker_obj = self._get_marker_obj(context, 'nat_pool', limit,
+                                          marker)
         return self._get_collection(context, NATPool,
                                     self._make_nat_pool_dict,
-                                    filters=filters, fields=fields)
+                                    filters=filters, fields=fields,
+                                    sorts=sorts, limit=limit,
+                                    marker_obj=marker_obj,
+                                    page_reverse=page_reverse)
 
     @log.log
     def get_nat_pools_count(self, context, filters=None):
diff --git a/gbp/neutron/services/grouppolicy/common/exceptions.py b/gbp/neutron/services/grouppolicy/common/exceptions.py
index 0b7a6224f..db8d9a15b 100644
--- a/gbp/neutron/services/grouppolicy/common/exceptions.py
+++ b/gbp/neutron/services/grouppolicy/common/exceptions.py
@@ -108,3 +108,23 @@ class InvalidSharedAttributeUpdate(GroupPolicyBadRequest):
     message = _("Invalid shared attribute update. Shared resource %(id)s is"
                 "referenced by %(rid)s, which is either shared or owned by a "
                 "different tenant.")
+
+
+class ExternalRouteOverlapsWithL3PIpPool(GroupPolicyBadRequest):
+    message = _("Destination %(destination)s for ES %(es_id)s overlaps with "
+                "L3P %(l3p_id)s.")
+
+
+class ExternalSegmentSubnetOverlapsWithL3PIpPool(GroupPolicyBadRequest):
+    message = _("Subnet %(subnet)s for ES %(es_id)s overlaps with "
+                "L3P %(l3p_id)s.")
+
+
+class ExternalRouteNextHopNotInExternalSegment(GroupPolicyBadRequest):
+    message = _("One or more external routes' nexthop are not part of "
+                "subnet %(cidr)s.")
+
+
+class InvalidL3PExternalIPAddress(GroupPolicyBadRequest):
+    message = _("Address %(ip)s allocated for l3p %(l3p_id)s on segment "
+                "%(es_id)s doesn't belong to the segment subnet %(es_cidr)s")
diff --git a/gbp/neutron/services/grouppolicy/extension_manager.py b/gbp/neutron/services/grouppolicy/extension_manager.py
index 99fe3e391..c4a6a1182 100644
--- a/gbp/neutron/services/grouppolicy/extension_manager.py
+++ b/gbp/neutron/services/grouppolicy/extension_manager.py
@@ -1,17 +1,15 @@
-# Copyright (c) 2014 OpenStack Foundation
-# All Rights Reserved.
+# 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
 #
-#    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
 #
-#         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.
+# 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.openstack.common import log
 from oslo.config import cfg
@@ -209,3 +207,48 @@ class ExtensionManager(stevedore.named.NamedExtensionManager):
         """Call all extension drivers to extend NSP dictionary."""
         for driver in self.ordered_ext_drivers:
             driver.obj.extend_network_service_policy_dict(session, result)
+
+    def process_create_external_segment(self, session, data, result):
+        """Call all extension drivers during EP creation."""
+        self._call_on_ext_drivers("process_create_external_segment",
+                                  session, data, result)
+
+    def process_update_external_segment(self, session, data, result):
+        """Call all extension drivers during EP update."""
+        self._call_on_ext_drivers("process_update_external_segment",
+                                  session, data, result)
+
+    def extend_external_segment_dict(self, session, result):
+        """Call all extension drivers to extend EP dictionary."""
+        for driver in self.ordered_ext_drivers:
+            driver.obj.extend_external_segment_dict(session, result)
+
+    def process_create_external_policy(self, session, data, result):
+        """Call all extension drivers during EP creation."""
+        self._call_on_ext_drivers("process_create_external_policy",
+                                  session, data, result)
+
+    def process_update_external_policy(self, session, data, result):
+        """Call all extension drivers during EP update."""
+        self._call_on_ext_drivers("process_update_external_policy",
+                                  session, data, result)
+
+    def extend_external_policy_dict(self, session, result):
+        """Call all extension drivers to extend EP dictionary."""
+        for driver in self.ordered_ext_drivers:
+            driver.obj.extend_external_policy_dict(session, result)
+
+    def process_create_nat_pool(self, session, data, result):
+        """Call all extension drivers during NP creation."""
+        self._call_on_ext_drivers("process_create_nat_pool",
+                                  session, data, result)
+
+    def process_update_nat_pool(self, session, data, result):
+        """Call all extension drivers during NP update."""
+        self._call_on_ext_drivers("process_update_nat_pool",
+                                  session, data, result)
+
+    def extend_nat_pool_dict(self, session, result):
+        """Call all extension drivers to extend NP dictionary."""
+        for driver in self.ordered_ext_drivers:
+            driver.obj.extend_nat_pool_dict(session, result)
\ No newline at end of file
diff --git a/gbp/neutron/services/grouppolicy/group_policy_context.py b/gbp/neutron/services/grouppolicy/group_policy_context.py
index 17e773300..eb8762e68 100644
--- a/gbp/neutron/services/grouppolicy/group_policy_context.py
+++ b/gbp/neutron/services/grouppolicy/group_policy_context.py
@@ -20,6 +20,21 @@ class GroupPolicyContext(object):
         self._plugin_context = plugin_context
 
 
+class BaseResouceContext(GroupPolicyContext):
+    def __init__(self, plugin, plugin_context, resource, original=None):
+        super(BaseResouceContext, self).__init__(plugin, plugin_context)
+        self._resource = resource
+        self._original = original
+
+    @property
+    def current(self):
+        return self._resource
+
+    @property
+    def original(self):
+        return self._original
+
+
 class PolicyTargetContext(GroupPolicyContext, api.PolicyTargetContext):
 
     def __init__(self, plugin, plugin_context, policy_target,
@@ -211,3 +226,15 @@ class PolicyRuleSetContext(GroupPolicyContext, api.PolicyRuleSetContext):
     @property
     def original(self):
         return self._original_policy_rule_set
+
+
+class ExternalSegmentContext(BaseResouceContext, api.ExternalSegmentContext):
+    pass
+
+
+class ExternalPolicyContext(BaseResouceContext, api.ExternalPolicyContext):
+    pass
+
+
+class NatPoolContext(BaseResouceContext, api.NatPoolContext):
+    pass
\ No newline at end of file
diff --git a/gbp/neutron/services/grouppolicy/group_policy_driver_api.py b/gbp/neutron/services/grouppolicy/group_policy_driver_api.py
index af145640c..f082076f4 100644
--- a/gbp/neutron/services/grouppolicy/group_policy_driver_api.py
+++ b/gbp/neutron/services/grouppolicy/group_policy_driver_api.py
@@ -357,6 +357,102 @@ class PolicyRuleSetContext(object):
         pass
 
 
+@six.add_metaclass(abc.ABCMeta)
+class ExternalSegmentContext(object):
+
+    """Context passed to policy engine for external_segment resource.
+
+    A ExternalSegmentContext instance wraps an external_segment
+    resource.
+    It provides helper methods for accessing other relevant information.
+    Results from expensive operations are cached for convenient access.
+    """
+
+    @abc.abstractproperty
+    def current(self):
+        """Return the current state of the external_segment.
+
+        Return the current state of the external_segment, as defined by
+        GroupPolicyPlugin.create_external_segment.
+        """
+        pass
+
+    @abc.abstractproperty
+    def original(self):
+        """Return the original state of the external_segment.
+
+        Return the original state of the external_segment, prior to a
+        call to update_external_segment. Method is only valid within
+        calls to update_external_segment_precommit and
+        update_external_segment_postcommit.
+        """
+        pass
+
+
+@six.add_metaclass(abc.ABCMeta)
+class ExternalPolicyContext(object):
+
+    """Context passed to policy engine for external_policy resource.
+
+    A ExternalPolicyContext instance wraps an external_policy
+    resource.
+    It provides helper methods for accessing other relevant information.
+    Results from expensive operations are cached for convenient access.
+    """
+
+    @abc.abstractproperty
+    def current(self):
+        """Return the current state of the external_policy.
+
+        Return the current state of the external_policy, as defined by
+        GroupPolicyPlugin.create_external_policy.
+        """
+        pass
+
+    @abc.abstractproperty
+    def original(self):
+        """Return the original state of the external_policy.
+
+        Return the original state of the external_policy, prior to a
+        call to update_external_policy. Method is only valid within
+        calls to update_external_policy_precommit and
+        update_external_policy_postcommit.
+        """
+        pass
+
+
+@six.add_metaclass(abc.ABCMeta)
+class NatPoolContext(object):
+
+    """Context passed to policy engine for nat_pool resource.
+
+    A NatPoolContext instance wraps an nat_pool
+    resource.
+    It provides helper methods for accessing other relevant information.
+    Results from expensive operations are cached for convenient access.
+    """
+
+    @abc.abstractproperty
+    def current(self):
+        """Return the current state of the nat_pool.
+
+        Return the current state of the nat_pool, as defined by
+        GroupPolicyPlugin.create_nat_pool.
+        """
+        pass
+
+    @abc.abstractproperty
+    def original(self):
+        """Return the original state of the nat_pool.
+
+        Return the original state of the nat_pool, prior to a
+        call to update_nat_pool. Method is only valid within
+        calls to update_nat_pool_precommit and
+        update_nat_pool_postcommit.
+        """
+        pass
+
+
 @six.add_metaclass(abc.ABCMeta)
 class PolicyDriver(object):
     """Define stable abstract interface for Group Policy drivers.
@@ -843,6 +939,162 @@ class PolicyDriver(object):
         """
         pass
 
+    def create_external_segment_precommit(self, context):
+        """Allocate resources for a new network service policy.
+
+        :param context: ExternalSegmentContext instance describing the
+        new network service policy.
+        """
+        pass
+
+    def create_external_segment_postcommit(self, context):
+        """Create a network service policy.
+
+        :param context: ExternalSegmentContext instance describing the
+        new network service policy.
+        """
+        pass
+
+    def update_external_segment_precommit(self, context):
+        """Update resources of a network service policy.
+
+        :param context: ExternalSegmentContext instance describing the
+        new state of the ExternalSegment, as well as the original state
+        prior to the update_external_segment call.
+        """
+        pass
+
+    def update_external_segment_postcommit(self, context):
+        """Update a network service policy.
+
+        :param context: ExternalSegmentContext instance describing the
+        new state of the ExternalSegment, as well as the original state
+        prior to the update_external_segment call.
+        """
+        pass
+
+    def delete_external_segment_precommit(self, context):
+        """Delete resources for a network service policy.
+
+        :param context: ExternalSegmentContext instance describing the
+        current state of the ExternalSegment, prior to the call to
+        delete it.
+        """
+        pass
+
+    def delete_external_segment_postcommit(self, context):
+        """Delete a network service policy.
+
+        :param context: ExternalSegmentContext instance describing the
+        current state of the ExternalSegment, prior to the call to
+        delete it.
+        """
+        pass
+
+    def create_external_policy_precommit(self, context):
+        """Allocate resources for a new network service policy.
+
+        :param context: ExternalPolicyContext instance describing the
+        new network service policy.
+        """
+        pass
+
+    def create_external_policy_postcommit(self, context):
+        """Create a network service policy.
+
+        :param context: ExternalPolicyContext instance describing the
+        new network service policy.
+        """
+        pass
+
+    def update_external_policy_precommit(self, context):
+        """Update resources of a network service policy.
+
+        :param context: ExternalPolicyContext instance describing the
+        new state of the ExternalPolicy, as well as the original state
+        prior to the update_external_policy call.
+        """
+        pass
+
+    def update_external_policy_postcommit(self, context):
+        """Update a network service policy.
+
+        :param context: ExternalPolicyContext instance describing the
+        new state of the ExternalPolicy, as well as the original state
+        prior to the update_external_policy call.
+        """
+        pass
+
+    def delete_external_policy_precommit(self, context):
+        """Delete resources for a network service policy.
+
+        :param context: ExternalPolicyContext instance describing the
+        current state of the ExternalPolicy, prior to the call to
+        delete it.
+        """
+        pass
+
+    def delete_external_policy_postcommit(self, context):
+        """Delete a network service policy.
+
+        :param context: ExternalPolicyContext instance describing the
+        current state of the ExternalPolicy, prior to the call to
+        delete it.
+        """
+        pass
+
+    def create_nat_pool_precommit(self, context):
+        """Allocate resources for a new network service policy.
+
+        :param context: NatPoolContext instance describing the
+        new network service policy.
+        """
+        pass
+
+    def create_nat_pool_postcommit(self, context):
+        """Create a network service policy.
+
+        :param context: NatPoolContext instance describing the
+        new network service policy.
+        """
+        pass
+
+    def update_nat_pool_precommit(self, context):
+        """Update resources of a network service policy.
+
+        :param context: NatPoolContext instance describing the
+        new state of the NatPool, as well as the original state
+        prior to the update_nat_pool call.
+        """
+        pass
+
+    def update_nat_pool_postcommit(self, context):
+        """Update a network service policy.
+
+        :param context: NatPoolContext instance describing the
+        new state of the NatPool, as well as the original state
+        prior to the update_nat_pool call.
+        """
+        pass
+
+    def delete_nat_pool_precommit(self, context):
+        """Delete resources for a network service policy.
+
+        :param context: NatPoolContext instance describing the
+        current state of the NatPool, prior to the call to
+        delete it.
+        """
+        pass
+
+    def delete_nat_pool_postcommit(self, context):
+        """Delete a network service policy.
+
+        :param context: NatPoolContext instance describing the
+        current state of the NatPool, prior to the call to
+        delete it.
+        """
+        pass
+
 
 @six.add_metaclass(abc.ABCMeta)
 class ExtensionDriver(object):
@@ -1248,3 +1500,129 @@ class ExtensionDriver(object):
         network_service_policy operation.
         """
         pass
+
+    def process_create_external_segment(self, session, data, result):
+        """Process extended attributes for external_segment creation.
+
+        :param session: database session
+        :param data: dictionary of incoming external_segment data
+        :param result: external_segment dictionary to extend
+
+        Called inside transaction context on session to validate and
+        persist any extended external_segment attributes defined
+        by this driver. Extended attribute values must also be added
+        to result.
+        """
+        pass
+
+    def process_update_external_segment(self, session, data, result):
+        """Process extended attributes for external_segment update.
+
+        :param session: database session
+        :param data: dictionary of incoming external_segment data
+        :param result: external_segment dictionary to extend
+
+        Called inside transaction context on session to validate and
+        update any extended external_segment attributes defined by this
+        driver. Extended attribute values, whether updated or not,
+        must also be added to result.
+        """
+        pass
+
+    def extend_external_segment_dict(self, session, result):
+        """Add extended attributes to external_segment dictionary.
+
+        :param session: database session
+        :param result: external_segment dictionary to extend
+
+        Called inside transaction context on session to add any
+        extended attributes defined by this driver to a
+        external_segment dictionary to be used for mechanism
+        driver calls and/or returned as the result of a
+        external_segment operation.
+        """
+        pass
+
+    def process_create_external_policy(self, session, data, result):
+        """Process extended attributes for external_policy creation.
+
+        :param session: database session
+        :param data: dictionary of incoming external_policy data
+        :param result: external_policy dictionary to extend
+
+        Called inside transaction context on session to validate and
+        persist any extended external_policy attributes defined
+        by this driver. Extended attribute values must also be added
+        to result.
+        """
+        pass
+
+    def process_update_external_policy(self, session, data, result):
+        """Process extended attributes for external_policy update.
+
+        :param session: database session
+        :param data: dictionary of incoming external_policy data
+        :param result: external_policy dictionary to extend
+
+        Called inside transaction context on session to validate and
+        update any extended external_policy attributes defined by this
+        driver. Extended attribute values, whether updated or not,
+        must also be added to result.
+        """
+        pass
+
+    def extend_external_policy_dict(self, session, result):
+        """Add extended attributes to external_policy dictionary.
+
+        :param session: database session
+        :param result: external_policy dictionary to extend
+
+        Called inside transaction context on session to add any
+        extended attributes defined by this driver to a
+        external_policy dictionary to be used for mechanism
+        driver calls and/or returned as the result of a
+        external_policy operation.
+        """
+        pass
+
+    def process_create_nat_pool(self, session, data, result):
+        """Process extended attributes for nat_pool creation.
+
+        :param session: database session
+        :param data: dictionary of incoming nat_pool data
+        :param result: nat_pool dictionary to extend
+
+        Called inside transaction context on session to validate and
+        persist any extended nat_pool attributes defined
+        by this driver. Extended attribute values must also be added
+        to result.
+        """
+        pass
+
+    def process_update_nat_pool(self, session, data, result):
+        """Process extended attributes for nat_pool update.
+
+        :param session: database session
+        :param data: dictionary of incoming nat_pool data
+        :param result: nat_pool dictionary to extend
+
+        Called inside transaction context on session to validate and
+        update any extended nat_pool attributes defined by this
+        driver. Extended attribute values, whether updated or not,
+        must also be added to result.
+        """
+        pass
+
+    def extend_nat_pool_dict(self, session, result):
+        """Add extended attributes to nat_pool dictionary.
+
+        :param session: database session
+        :param result: nat_pool dictionary to extend
+
+        Called inside transaction context on session to add any
+        extended attributes defined by this driver to a
+        nat_pool dictionary to be used for mechanism
+        driver calls and/or returned as the result of a
+        nat_pool operation.
+        """
+        pass
\ No newline at end of file
diff --git a/gbp/neutron/services/grouppolicy/plugin.py b/gbp/neutron/services/grouppolicy/plugin.py
index 378346e29..69ac22285 100644
--- a/gbp/neutron/services/grouppolicy/plugin.py
+++ b/gbp/neutron/services/grouppolicy/plugin.py
@@ -10,11 +10,14 @@
 #    License for the specific language governing permissions and limitations
 #    under the License.
 
+import netaddr
+
 from neutron.api.v2 import attributes as nattr
 from neutron.common import log
 from neutron.openstack.common import excutils
 from neutron.openstack.common import log as logging
 
+from gbp.neutron.db.grouppolicy import group_policy_db as gdb
 from gbp.neutron.db.grouppolicy import group_policy_mapping_db
 from gbp.neutron.services.grouppolicy.common import exceptions as gp_exc
 from gbp.neutron.services.grouppolicy import extension_manager as ext_manager
@@ -54,7 +57,8 @@ class GroupPolicyPlugin(group_policy_mapping_db.GroupPolicyMappingDbPlugin):
     # <attribute> is the field on the <to_check> dictionary that can be used
     # to retrieve the UUID/s of the specific object <type>
 
-    usage_graph = {'l3_policy': {},
+    usage_graph = {'l3_policy': {'external_segments':
+                                 'external_segment'},
                    'l2_policy': {'l3_policy_id': 'l3_policy'},
                    'policy_target_group': {
                        'network_service_policy_id': 'network_service_policy',
@@ -70,6 +74,13 @@ class GroupPolicyPlugin(group_policy_mapping_db.GroupPolicyMappingDbPlugin):
                    'policy_rule_set': {
                        'parent_id': 'policy_rule_set',
                        'policy_rules': 'policy_rule'},
+                   'external_segment': {},
+                   'external_policy': {
+                       'external_segments': 'external_segment',
+                       'provided_policy_rule_sets': 'policy_rule_set',
+                       'consumed_policy_rule_sets': 'policy_rule_set'},
+                   'nat_pool': {'external_segment_id':
+                                'external_segment'}
                    }
     _plurals = None
 
@@ -101,7 +112,7 @@ class GroupPolicyPlugin(group_policy_mapping_db.GroupPolicyMappingDbPlugin):
     def _validate_shared_update(self, context, original, updated, identity):
         if updated.get('shared'):
             # Even though the shared attribute may not be changed, the objects
-            # it is referring to might. For this reason we run the reference
+            # it is referring to might. For this reson we run the reference
             # validation every time a shared resource is updated
             # TODO(ivar): run only when relevant updates happen
             self._validate_shared_create(context, updated, identity)
@@ -139,6 +150,10 @@ class GroupPolicyPlugin(group_policy_mapping_db.GroupPolicyMappingDbPlugin):
             context, obj, self.get_policy_target_groups, 'id',
             obj['providing_policy_target_groups'] +
             obj['consuming_policy_target_groups'])
+        self._check_shared_or_different_tenant(
+            context, obj, self.get_external_policies, 'id',
+            obj['providing_external_policies'] +
+            obj['consuming_external_policies'])
 
     def _validate_policy_classifier_unshare(self, context, obj):
         self._check_shared_or_different_tenant(
@@ -154,6 +169,85 @@ class GroupPolicyPlugin(group_policy_mapping_db.GroupPolicyMappingDbPlugin):
         self._check_shared_or_different_tenant(
             context, obj, self.get_policy_rules, 'id', r_ids)
 
+    def _validate_external_segment_unshare(self, context, obj):
+        self._check_shared_or_different_tenant(
+            context, obj, self.get_l3_policies, 'id', obj['l3_policies'])
+        self._check_shared_or_different_tenant(
+            context, obj, self.get_external_policies, 'id',
+            obj['external_policies'])
+        self._check_shared_or_different_tenant(
+            context, obj, self.get_nat_pools, 'external_segment_id')
+
+    def _validate_external_policy_unshare(self, context, obj):
+        pass
+
+    def _validate_nat_pool_unshare(self, context, obj):
+        pass
+
+    def _validate_routes(self, context, current, original=None):
+        if original:
+            added = (set((x['destination'], x['nexthop']) for x in
+                         current['external_routes']) -
+                     set((x['destination'], x['nexthop']) for x in
+                         original['external_routes']))
+        else:
+            added = set((x['destination'], x['nexthop']) for x in
+                        current['external_routes'])
+        if added:
+            # Verify new ones don't overlap with the existing L3P
+            added_dest = set(x[0] for x in added)
+            # Remove default routes
+            added_dest.discard('0.0.0.0/0')
+            added_dest.discard('::/0')
+            added_ipset = netaddr.IPSet(added_dest)
+            if current['l3_policies']:
+                l3ps = self.get_l3_policies(
+                    context, filters={'id': current['l3_policies']})
+                for l3p in l3ps:
+                    if netaddr.IPSet([l3p['ip_pool']]) & added_ipset:
+                        raise gp_exc.ExternalRouteOverlapsWithL3PIpPool(
+                            destination=added_dest, l3p_id=l3p['id'],
+                            es_id=current['id'])
+            # Verify NH in ES pool
+            added_nexthop = netaddr.IPSet(x[1] for x in added if x[1])
+            es_subnet = netaddr.IPSet([current['cidr']])
+            if added_nexthop & es_subnet != added_nexthop:
+                raise gp_exc.ExternalRouteNextHopNotInExternalSegment(
+                    cidr=current['cidr'])
+
+    def _validate_l3p_es(self, context, current, original=None):
+        if original:
+            added = (set(current['external_segments'].keys()) -
+                     set(original['external_segments'].keys()))
+        else:
+            added = set(current['external_segments'].keys())
+        if added:
+            es_list = self.get_external_segments(context,
+                                                 filters={'id': added})
+            l3p_ipset = netaddr.IPSet([current['ip_pool']])
+            for es in es_list:
+                # Verify no route overlap
+                dest_set = set(x['destination'] for x in
+                               es['external_routes'])
+                dest_set.discard('0.0.0.0/0')
+                dest_set.discard('::/0')
+                if l3p_ipset & netaddr.IPSet(dest_set):
+                    raise gp_exc.ExternalRouteOverlapsWithL3PIpPool(
+                        destination=dest_set, l3p_id=current['id'],
+                        es_id=es['id'])
+                # Verify segment CIDR doesn't overlap with L3P's
+                if l3p_ipset & netaddr.IPSet([es['cidr']]):
+                    raise gp_exc.ExternalSegmentSubnetOverlapsWithL3PIpPool(
+                        subnet=es['cidr'], l3p_id=current['id'],
+                        es_id=current['id'])
+                # Verify allocated address correctly in subnet
+                for addr in current['external_segments'][es['id']]:
+                    if addr != gdb.ADDRESS_NOT_SPECIFIED:
+                        if addr not in netaddr.IPNetwork(es['cidr']):
+                            raise gp_exc.InvalidL3PExternalIPAddress(
+                                ip=addr, es_id=es['id'], l3p_id=current['id'],
+                                es_cidr=es['cidr'])
+
     def __init__(self):
         self.extension_manager = ext_manager.ExtensionManager()
         self.policy_driver_manager = manager.PolicyDriverManager()
@@ -547,6 +641,7 @@ class GroupPolicyPlugin(group_policy_mapping_db.GroupPolicyMappingDbPlugin):
             self.extension_manager.process_create_l3_policy(
                 session, l3_policy, result)
             self._validate_shared_create(context, result, 'l3_policy')
+            self._validate_l3p_es(context, result)
             policy_context = p_context.L3PolicyContext(self, context,
                                                        result)
             self.policy_driver_manager.create_l3_policy_precommit(
@@ -575,6 +670,8 @@ class GroupPolicyPlugin(group_policy_mapping_db.GroupPolicyMappingDbPlugin):
                 session, l3_policy, updated_l3_policy)
             self._validate_shared_update(context, original_l3_policy,
                                          updated_l3_policy, 'l3_policy')
+            self._validate_l3p_es(context, updated_l3_policy,
+                                  original_l3_policy)
             policy_context = p_context.L3PolicyContext(
                 self, context, updated_l3_policy,
                 original_l3_policy=original_l3_policy)
@@ -995,3 +1092,291 @@ class GroupPolicyPlugin(group_policy_mapping_db.GroupPolicyMappingDbPlugin):
                 self.extension_manager.extend_policy_rule_set_dict(
                     session, result)
         return [self._fields(result, fields) for result in results]
+
+    @log.log
+    def create_external_segment(self, context, external_segment):
+        session = context.session
+        with session.begin(subtransactions=True):
+            result = super(GroupPolicyPlugin,
+                           self).create_external_segment(context,
+                                                         external_segment)
+            self.extension_manager.process_create_external_segment(
+                session, external_segment, result)
+            self._validate_shared_create(context, result,
+                                         'external_segment')
+            self._validate_routes(context, result)
+            policy_context = p_context.ExternalSegmentContext(
+                self, context, result)
+            (self.policy_driver_manager.
+             create_external_segment_precommit(policy_context))
+
+        try:
+            (self.policy_driver_manager.
+             create_external_segment_postcommit(policy_context))
+        except gp_exc.GroupPolicyDriverError:
+            with excutils.save_and_reraise_exception():
+                LOG.error(_("create_external_segment_postcommit "
+                            "failed, deleting external_segment "
+                            "'%s'"), result['id'])
+                self.delete_external_segment(context, result['id'])
+
+        return result
+
+    @log.log
+    def update_external_segment(self, context, external_segment_id,
+                                external_segment):
+        session = context.session
+        with session.begin(subtransactions=True):
+            original_external_segment = super(
+                GroupPolicyPlugin, self).get_external_segment(
+                    context, external_segment_id)
+            updated_external_segment = super(
+                GroupPolicyPlugin, self).update_external_segment(
+                    context, external_segment_id,
+                    external_segment)
+            self.extension_manager.process_update_external_segment(
+                session, external_segment, updated_external_segment)
+            self._validate_shared_update(
+                context, original_external_segment,
+                updated_external_segment, 'external_segment')
+            self._validate_routes(context, updated_external_segment,
+                                  original_external_segment)
+            # TODO(ivar): Validate Routes' GW in es subnet
+            policy_context = p_context.ExternalSegmentContext(
+                self, context, updated_external_segment,
+                original_external_segment)
+            (self.policy_driver_manager.
+             update_external_segment_precommit(policy_context))
+
+        self.policy_driver_manager.update_external_segment_postcommit(
+            policy_context)
+        return updated_external_segment
+
+    @log.log
+    def delete_external_segment(self, context, external_segment_id):
+        session = context.session
+        with session.begin(subtransactions=True):
+            es = self.get_external_segment(context, external_segment_id)
+            if es['l3_policies'] or es['nat_pools'] or es['external_policies']:
+                return False
+            policy_context = p_context.ExternalSegmentContext(
+                self, context, es)
+            (self.policy_driver_manager.
+             delete_external_segment_precommit(policy_context))
+            super(GroupPolicyPlugin, self).delete_external_segment(
+                context, external_segment_id)
+
+        try:
+            (self.policy_driver_manager.
+             delete_external_segment_postcommit(policy_context))
+        except gp_exc.GroupPolicyDriverError:
+            with excutils.save_and_reraise_exception():
+                LOG.error(_("delete_external_segment_postcommit "
+                            "failed, deleting external_segment '%s'"),
+                          external_segment_id)
+        return True
+
+    def get_external_segment(self, context, external_segment_id, fields=None):
+        session = context.session
+        with session.begin(subtransactions=True):
+            result = super(GroupPolicyPlugin, self).get_external_segment(
+                context, external_segment_id, None)
+            self.extension_manager.extend_external_segment_dict(session,
+                                                                result)
+        return self._fields(result, fields)
+
+    def get_external_segments(self, context, filters=None, fields=None,
+                              sorts=None, limit=None, marker=None,
+                              page_reverse=False):
+        session = context.session
+        with session.begin(subtransactions=True):
+            results = super(GroupPolicyPlugin, self).get_external_segments(
+                context, filters, None, sorts, limit, marker, page_reverse)
+            for result in results:
+                self.extension_manager.extend_external_segment_dict(
+                    session, result)
+        return [self._fields(result, fields) for result in results]
+
+    @log.log
+    def create_external_policy(self, context, external_policy):
+        session = context.session
+        with session.begin(subtransactions=True):
+            result = super(GroupPolicyPlugin,
+                           self).create_external_policy(
+                               context, external_policy)
+            self.extension_manager.process_create_external_policy(
+                session, external_policy, result)
+            self._validate_shared_create(context, result,
+                                         'external_policy')
+            policy_context = p_context.ExternalPolicyContext(
+                self, context, result)
+            (self.policy_driver_manager.
+             create_external_policy_precommit(policy_context))
+
+        try:
+            (self.policy_driver_manager.
+             create_external_policy_postcommit(policy_context))
+        except gp_exc.GroupPolicyDriverError:
+            with excutils.save_and_reraise_exception():
+                LOG.error(_("create_external_policy_postcommit "
+                            "failed, deleting external_policy "
+                            "'%s'"), result['id'])
+                self.delete_external_policy(context, result['id'])
+
+        return result
+
+    @log.log
+    def update_external_policy(self, context, external_policy_id,
+                               external_policy):
+        session = context.session
+        with session.begin(subtransactions=True):
+            original_external_policy = super(
+                GroupPolicyPlugin, self).get_external_policy(
+                    context, external_policy_id)
+            updated_external_policy = super(
+                GroupPolicyPlugin, self).update_external_policy(
+                    context, external_policy_id,
+                    external_policy)
+            self.extension_manager.process_update_external_policy(
+                session, external_policy, updated_external_policy)
+            self._validate_shared_update(
+                context, original_external_policy,
+                updated_external_policy, 'external_policy')
+            policy_context = p_context.ExternalPolicyContext(
+                self, context, updated_external_policy,
+                original_external_policy)
+            (self.policy_driver_manager.
+             update_external_policy_precommit(policy_context))
+
+        self.policy_driver_manager.update_external_policy_postcommit(
+            policy_context)
+        return updated_external_policy
+
+    @log.log
+    def delete_external_policy(self, context, external_policy_id,
+                               check_unused=False):
+        session = context.session
+        with session.begin(subtransactions=True):
+            es = self.get_external_policy(context, external_policy_id)
+            policy_context = p_context.ExternalPolicyContext(
+                self, context, es)
+            (self.policy_driver_manager.
+             delete_external_policy_precommit(policy_context))
+            super(GroupPolicyPlugin, self).delete_external_policy(
+                context, external_policy_id)
+
+        try:
+            (self.policy_driver_manager.
+             delete_external_policy_postcommit(policy_context))
+        except gp_exc.GroupPolicyDriverError:
+            with excutils.save_and_reraise_exception():
+                LOG.error(_("delete_external_policy_postcommit "
+                            "failed, deleting external_policy '%s'"),
+                          external_policy_id)
+        return True
+
+    def get_external_policy(self, context, external_policy_id, fields=None):
+        session = context.session
+        with session.begin(subtransactions=True):
+            result = super(GroupPolicyPlugin, self).get_external_policy(
+                context, external_policy_id, None)
+            self.extension_manager.extend_external_policy_dict(session,
+                                                               result)
+        return self._fields(result, fields)
+
+    def get_external_policies(self, context, filters=None, fields=None,
+                              sorts=None, limit=None, marker=None,
+                              page_reverse=False):
+        session = context.session
+        with session.begin(subtransactions=True):
+            results = super(GroupPolicyPlugin, self).get_external_policies(
+                context, filters, None, sorts, limit, marker, page_reverse)
+            for result in results:
+                self.extension_manager.extend_external_policy_dict(
+                    session, result)
+        return [self._fields(result, fields) for result in results]
+
+    @log.log
+    def create_nat_pool(self, context, nat_pool):
+        session = context.session
+        with session.begin(subtransactions=True):
+            result = super(GroupPolicyPlugin, self).create_nat_pool(
+                context, nat_pool)
+            self.extension_manager.process_create_nat_pool(session, nat_pool,
+                                                           result)
+            self._validate_shared_create(context, result, 'nat_pool')
+            policy_context = p_context.NatPoolContext(self, context, result)
+            (self.policy_driver_manager.
+             create_nat_pool_precommit(policy_context))
+
+        try:
+            (self.policy_driver_manager.
+             create_nat_pool_postcommit(policy_context))
+        except gp_exc.GroupPolicyDriverError:
+            with excutils.save_and_reraise_exception():
+                LOG.error(_("create_nat_pool_postcommit failed, deleting "
+                            "nat_pool '%s'"), result['id'])
+                self.delete_nat_pool(context, result['id'])
+
+        return result
+
+    @log.log
+    def update_nat_pool(self, context, nat_pool_id, nat_pool):
+        session = context.session
+        with session.begin(subtransactions=True):
+            original_nat_pool = super(
+                GroupPolicyPlugin, self).get_nat_pool(context, nat_pool_id)
+            updated_nat_pool = super(
+                GroupPolicyPlugin, self).update_nat_pool(context, nat_pool_id,
+                                                         nat_pool)
+            self.extension_manager.process_update_nat_pool(
+                session, nat_pool, updated_nat_pool)
+            self._validate_shared_update(context, original_nat_pool,
+                                         updated_nat_pool, 'nat_pool')
+            policy_context = p_context.NatPoolContext(
+                self, context, updated_nat_pool, original_nat_pool)
+            (self.policy_driver_manager.
+             update_nat_pool_precommit(policy_context))
+
+        self.policy_driver_manager.update_nat_pool_postcommit(policy_context)
+        return updated_nat_pool
+
+    @log.log
+    def delete_nat_pool(self, context, nat_pool_id, check_unused=False):
+        session = context.session
+        with session.begin(subtransactions=True):
+            es = self.get_nat_pool(context, nat_pool_id)
+            policy_context = p_context.NatPoolContext(self, context, es)
+            (self.policy_driver_manager.delete_nat_pool_precommit(
+                policy_context))
+            super(GroupPolicyPlugin, self).delete_nat_pool(context,
+                                                           nat_pool_id)
+
+        try:
+            (self.policy_driver_manager.
+             delete_nat_pool_postcommit(policy_context))
+        except gp_exc.GroupPolicyDriverError:
+            with excutils.save_and_reraise_exception():
+                LOG.error(_("delete_nat_pool_postcommit failed, deleting "
+                            "nat_pool '%s'"), nat_pool_id)
+        return True
+
+    def get_nat_pool(self, context, nat_pool_id, fields=None):
+        session = context.session
+        with session.begin(subtransactions=True):
+            result = super(GroupPolicyPlugin, self).get_nat_pool(
+                context, nat_pool_id, None)
+            self.extension_manager.extend_nat_pool_dict(session, result)
+        return self._fields(result, fields)
+
+    def get_nat_pools(self, context, filters=None, fields=None,
+                      sorts=None, limit=None, marker=None,
+                      page_reverse=False):
+        session = context.session
+        with session.begin(subtransactions=True):
+            results = super(GroupPolicyPlugin, self).get_nat_pools(
+                context, filters, None, sorts, limit, marker, page_reverse)
+            for result in results:
+                self.extension_manager.extend_nat_pool_dict(
+                    session, result)
+        return [self._fields(result, fields) for result in results]
\ No newline at end of file
diff --git a/gbp/neutron/services/grouppolicy/policy_driver_manager.py b/gbp/neutron/services/grouppolicy/policy_driver_manager.py
index 0648c90b9..54d118fce 100644
--- a/gbp/neutron/services/grouppolicy/policy_driver_manager.py
+++ b/gbp/neutron/services/grouppolicy/policy_driver_manager.py
@@ -310,3 +310,70 @@ class PolicyDriverManager(stevedore.named.NamedExtensionManager):
     def delete_policy_rule_set_postcommit(self, context):
         self._call_on_drivers("delete_policy_rule_set_postcommit", context,
                               continue_on_failure=True)
+
+    def create_external_segment_precommit(self, context):
+        self._call_on_drivers("create_external_segment_precommit",
+                              context)
+
+    def create_external_segment_postcommit(self, context):
+        self._call_on_drivers("create_external_segment_postcommit",
+                              context)
+
+    def update_external_segment_precommit(self, context):
+        self._call_on_drivers("update_external_segment_precommit",
+                              context)
+
+    def update_external_segment_postcommit(self, context):
+        self._call_on_drivers("update_external_segment_postcommit",
+                              context)
+
+    def delete_external_segment_precommit(self, context):
+        self._call_on_drivers("delete_external_segment_precommit",
+                              context)
+
+    def delete_external_segment_postcommit(self, context):
+        self._call_on_drivers("delete_external_segment_postcommit",
+                              context, continue_on_failure=True)
+
+    def create_external_policy_precommit(self, context):
+        self._call_on_drivers("create_external_policy_precommit",
+                              context)
+
+    def create_external_policy_postcommit(self, context):
+        self._call_on_drivers("create_external_policy_postcommit",
+                              context)
+
+    def update_external_policy_precommit(self, context):
+        self._call_on_drivers("update_external_policy_precommit",
+                              context)
+
+    def update_external_policy_postcommit(self, context):
+        self._call_on_drivers("update_external_policy_postcommit",
+                              context)
+
+    def delete_external_policy_precommit(self, context):
+        self._call_on_drivers("delete_external_policy_precommit",
+                              context)
+
+    def delete_external_policy_postcommit(self, context):
+        self._call_on_drivers("delete_external_policy_postcommit",
+                              context, continue_on_failure=True)
+
+    def create_nat_pool_precommit(self, context):
+        self._call_on_drivers("create_nat_pool_precommit", context)
+
+    def create_nat_pool_postcommit(self, context):
+        self._call_on_drivers("create_nat_pool_postcommit", context)
+
+    def update_nat_pool_precommit(self, context):
+        self._call_on_drivers("update_nat_pool_precommit", context)
+
+    def update_nat_pool_postcommit(self, context):
+        self._call_on_drivers("update_nat_pool_postcommit", context)
+
+    def delete_nat_pool_precommit(self, context):
+        self._call_on_drivers("delete_nat_pool_precommit", context)
+
+    def delete_nat_pool_postcommit(self, context):
+        self._call_on_drivers("delete_nat_pool_postcommit", context,
+                              continue_on_failure=True)
\ No newline at end of file
diff --git a/gbp/neutron/tests/unit/services/grouppolicy/extensions/test_extension.py b/gbp/neutron/tests/unit/services/grouppolicy/extensions/test_extension.py
index 954f409a6..627d09e12 100644
--- a/gbp/neutron/tests/unit/services/grouppolicy/extensions/test_extension.py
+++ b/gbp/neutron/tests/unit/services/grouppolicy/extensions/test_extension.py
@@ -80,6 +80,27 @@ EXTENDED_ATTRIBUTES_2_0 = {
                           'is_visible': True,
                           'enforce_policy': True},
     },
+    gp.EXTERNAL_SEGMENTS: {
+        'es_extension': {'allow_post': True,
+                         'allow_put': True,
+                         'default': attr.ATTR_NOT_SPECIFIED,
+                         'is_visible': True,
+                         'enforce_policy': True},
+    },
+    gp.EXTERNAL_POLICIES: {
+        'ep_extension': {'allow_post': True,
+                         'allow_put': True,
+                         'default': attr.ATTR_NOT_SPECIFIED,
+                         'is_visible': True,
+                         'enforce_policy': True},
+    },
+    gp.NAT_POOLS: {
+        'np_extension': {'allow_post': True,
+                         'allow_put': True,
+                         'default': attr.ATTR_NOT_SPECIFIED,
+                         'is_visible': True,
+                         'enforce_policy': True},
+    },
 }
 
 
diff --git a/gbp/neutron/tests/unit/services/grouppolicy/test_extension_driver_api.py b/gbp/neutron/tests/unit/services/grouppolicy/test_extension_driver_api.py
index aa66d8b0a..9f516c06a 100644
--- a/gbp/neutron/tests/unit/services/grouppolicy/test_extension_driver_api.py
+++ b/gbp/neutron/tests/unit/services/grouppolicy/test_extension_driver_api.py
@@ -373,6 +373,55 @@ class ExtensionDriverTestCase(
         val = res['network_service_policy']['nsp_extension']
         self.assertEqual("def", val)
 
+    def test_es_attr(self):
+        self._test_attr('external_segment')
+
+    def test_ep_attr(self):
+        self._test_attr('external_policy')
+
+    def test_np_attr(self):
+        self._test_attr('nat_pool')
+
+    def _test_attr(self, type):
+        # Test create with default value.
+        acronim = _acronim(type)
+        plural = self._get_resource_plural(type)
+        obj = getattr(self, 'create_%s' % type)()
+        id = obj[type]['id']
+        val = obj[type][acronim + '_extension']
+        self.assertEqual("", val)
+        req = self.new_show_request(plural, id)
+        res = self.deserialize(self.fmt, req.get_response(self.ext_api))
+        val = res[type][acronim + '_extension']
+        self.assertEqual("", val)
+
+        # Test list.
+        res = self._list(plural)
+        val = res[plural][0][acronim + '_extension']
+        self.assertEqual("", val)
+
+        # Test create with explict value.
+        kwargs = {acronim + '_extension': "abc"}
+        obj = getattr(self, 'create_%s' % type)(**kwargs)
+        id = obj[type]['id']
+        val = obj[type][acronim + '_extension']
+        self.assertEqual("abc", val)
+        req = self.new_show_request(plural, id)
+        res = self.deserialize(self.fmt, req.get_response(self.ext_api))
+        val = res[type][acronim + '_extension']
+        self.assertEqual("abc", val)
+
+        # Test update.
+        data = {type: {acronim + '_extension': "def"}}
+        req = self.new_update_request(plural, data, id)
+        res = self.deserialize(self.fmt, req.get_response(self.ext_api))
+        val = res[type][acronim + '_extension']
+        self.assertEqual("def", val)
+        req = self.new_show_request(plural, id)
+        res = self.deserialize(self.fmt, req.get_response(self.ext_api))
+        val = res[type][acronim + '_extension']
+        self.assertEqual("def", val)
+
 
 class TestPolicyTargetExtension(model_base.BASEV2):
     __tablename__ = 'test_policy_target_extension'
@@ -455,6 +504,33 @@ class TestNetworkServicePolicyExtension(model_base.BASEV2):
     value = sa.Column(sa.String(64))
 
 
+class TestExternalSegmentExtension(model_base.BASEV2):
+    __tablename__ = 'test_external_segment_extension'
+    es_id = sa.Column(sa.String(36),
+                      sa.ForeignKey('gp_external_segments.id',
+                                    ondelete="CASCADE"),
+                      primary_key=True)
+    value = sa.Column(sa.String(64))
+
+
+class TestExternalPolicyExtension(model_base.BASEV2):
+    __tablename__ = 'test_external_policy_extension'
+    ep_id = sa.Column(sa.String(36),
+                      sa.ForeignKey('gp_external_policies.id',
+                                    ondelete="CASCADE"),
+                      primary_key=True)
+    value = sa.Column(sa.String(64))
+
+
+class TestNatPoolExtension(model_base.BASEV2):
+    __tablename__ = 'test_nat_pool_extension'
+    np_id = sa.Column(sa.String(36),
+                      sa.ForeignKey('gp_nat_pools.id',
+                                    ondelete="CASCADE"),
+                      primary_key=True)
+    value = sa.Column(sa.String(64))
+
+
 class TestExtensionDriver(api.ExtensionDriver):
     _supported_extension_alias = 'test_extension'
 
@@ -677,3 +753,67 @@ class TestExtensionDriver(api.ExtensionDriver):
                   filter_by(nsp_id=result['id']).
                   one())
         result['nsp_extension'] = record.value
+
+    def process_create_external_segment(self, session, data, result):
+        self._process_create(session, data, result, 'external_segment',
+                             TestExternalSegmentExtension)
+
+    def process_update_external_segment(self, session, data, result):
+        self._process_update(session, data, result, 'external_segment',
+                             TestExternalSegmentExtension)
+
+    def extend_external_segment_dict(self, session, result):
+        self._extend(session, result, 'external_segment',
+                     TestExternalSegmentExtension)
+
+    def process_create_external_policy(self, session, data, result):
+        self._process_create(session, data, result, 'external_policy',
+                             TestExternalPolicyExtension)
+
+    def process_update_external_policy(self, session, data, result):
+        self._process_update(session, data, result, 'external_policy',
+                             TestExternalPolicyExtension)
+
+    def extend_external_policy_dict(self, session, result):
+        self._extend(session, result, 'external_policy',
+                     TestExternalPolicyExtension)
+
+    def process_create_nat_pool(self, session, data, result):
+        self._process_create(session, data, result, 'nat_pool',
+                             TestNatPoolExtension)
+
+    def process_update_nat_pool(self, session, data, result):
+        self._process_update(session, data, result, 'nat_pool',
+                             TestNatPoolExtension)
+
+    def extend_nat_pool_dict(self, session, result):
+        self._extend(session, result, 'nat_pool', TestNatPoolExtension)
+
+    def _process_create(self, session, data, result, type, klass):
+        acronim = _acronim(type)
+        value = data[type][acronim + '_extension']
+        if not attributes.is_attr_set(value):
+            value = ''
+        kwargs = {acronim + '_id': result['id'], 'value': value}
+        record = klass(**kwargs)
+        session.add(record)
+        result[acronim + '_extension'] = value
+
+    def _process_update(self, session, data, result, type, klass):
+        acronim = _acronim(type)
+        kwargs = {acronim + '_id': result['id']}
+        record = session.query(klass).filter_by(**kwargs).one()
+        value = data[type].get(acronim + '_extension')
+        if value and value != record.value:
+            record.value = value
+        result[acronim + '_extension'] = record.value
+
+    def _extend(self, session, result, type, klass):
+        acronim = _acronim(type)
+        kwargs = {acronim + '_id': result['id']}
+        record = session.query(klass).filter_by(**kwargs).one()
+        result[acronim + '_extension'] = record.value
+
+
+def _acronim(type):
+    return ''.join([x[0] for x in type.split('_')])
\ No newline at end of file
diff --git a/gbp/neutron/tests/unit/services/grouppolicy/test_grouppolicy_plugin.py b/gbp/neutron/tests/unit/services/grouppolicy/test_grouppolicy_plugin.py
index 578ac2399..09d8c5fe7 100644
--- a/gbp/neutron/tests/unit/services/grouppolicy/test_grouppolicy_plugin.py
+++ b/gbp/neutron/tests/unit/services/grouppolicy/test_grouppolicy_plugin.py
@@ -90,8 +90,20 @@ class GroupPolicyPluginTestCase(tgpmdb.GroupPolicyMappingDbTestCase):
         return self.create_policy_rule_set(policy_rules=[pr['id']],
                                     **kwargs)['policy_rule_set']
 
-    def _update_gbp_resource(self, id, type, plural, expected_res_status=None,
-                             **kwargs):
+    def _create_external_policy_on_shared(self, **kwargs):
+        es = self.create_external_segment(shared=True)
+        return self.create_external_policy(
+            external_segments=[es['external_segment']['id']],
+            **kwargs)['external_policy']
+
+    def _create_nat_pool_on_shared(self, **kwargs):
+        es = self.create_external_segment(shared=True)
+        return self.create_nat_pool(
+            external_segment_id=es['external_segment']['id'],
+            **kwargs)['nat_pool']
+
+    def _update_gbp_resource_full_response(
+            self, id, type, plural, expected_res_status=None, **kwargs):
         data = {type: kwargs}
         # Create PT with bound port
         req = self.new_update_request(plural, data, id, self.fmt)
@@ -101,11 +113,20 @@ class GroupPolicyPluginTestCase(tgpmdb.GroupPolicyMappingDbTestCase):
             self.assertEqual(res.status_int, expected_res_status)
         elif res.status_int >= webob.exc.HTTPClientError.code:
             raise webob.exc.HTTPClientError(code=res.status_int)
-        return self.deserialize(self.fmt, res).get(type)
+        return self.deserialize(self.fmt, res)
+
+    def _update_gbp_resource(self, id, type, plural, expected_res_status=None,
+                             **kwargs):
+        return self._update_gbp_resource_full_response(
+            id, type, plural, expected_res_status=expected_res_status,
+            **kwargs).get(type)
 
 
 class TestL3Policy(GroupPolicyPluginTestCase):
 
+    def _get_es_dict(self, es, addr=None):
+        return {es['external_segment']['id']: addr or []}
+
     def test_shared_l3_policy_create(self):
         # Verify default is False
         l3p = self.create_l3_policy()
@@ -114,6 +135,30 @@ class TestL3Policy(GroupPolicyPluginTestCase):
         l3p = self.create_l3_policy(shared=True)
         self.assertEqual(True, l3p['l3_policy']['shared'])
 
+    def test_shared_l3p_create_with_es(self):
+        def combination(l3p, es):
+            return {'l3p': l3p, 'es': es}
+        allowed = [combination(False, False), combination(True, True),
+                   combination(False, True)]
+        for shared in allowed:
+            es = self.create_external_segment(
+                cidr='172.0.0.0/8', shared=shared['es'])
+            es_dict = self._get_es_dict(es, ['172.0.0.2', '172.0.0.3'])
+            l3p = self.create_l3_policy(
+                external_segments=es_dict, shared=shared['l3p'],
+                expected_res_status=201)['l3_policy']
+            # Verify create successful
+            self.assertEqual(es_dict, l3p['external_segments'])
+
+    def test_shared_l3p_create_with_es_negative(self):
+        # Not allowed: Unshared ES with shared L3P
+        es = self.create_external_segment(cidr='172.0.0.0/8')
+        es_dict = self._get_es_dict(es, ['172.0.0.2', '172.0.0.3'])
+        res = self.create_l3_policy(external_segments=es_dict,
+                                    shared=True, expected_res_status=400)
+        self.assertEqual('SharedResourceReferenceError',
+                         res['NeutronError']['type'])
+
     def test_shared_l3_policy_update(self):
         l3p = self.create_l3_policy()['l3_policy']
         # Accept share if nothing referenced
@@ -124,6 +169,36 @@ class TestL3Policy(GroupPolicyPluginTestCase):
         self.create_l2_policy(l3_policy_id=l3p['id'])
         self._update_gbp_resource(l3p['id'], 'l3_policy', 'l3_policies',
                                   expected_res_status=200, shared=False)
+        es = self.create_external_segment(cidr='172.0.0.0/8')
+        es_dict = self._get_es_dict(es, ['172.0.0.2', '172.0.0.3'])
+        # Set ES
+        l3p = self._update_gbp_resource(l3p['id'], 'l3_policy', 'l3_policies',
+                                        expected_res_status=200,
+                                        external_segments=es_dict)
+        self.assertEqual(es_dict, l3p['external_segments'])
+
+        # Share ES
+        self._update_gbp_resource(
+            es['external_segment']['id'], 'external_segment',
+            'external_segments', expected_res_status=200, shared=True)
+
+        # Verify sharing/unsharing successful
+        for shared in [True, False]:
+            self._update_gbp_resource(l3p['id'], 'l3_policy', 'l3_policies',
+                                      expected_res_status=200, shared=shared)
+
+        # Remove ES
+        l3p = self._update_gbp_resource(l3p['id'], 'l3_policy', 'l3_policies',
+                                        expected_res_status=200,
+                                        external_segments={})
+        self.assertEqual({}, l3p['external_segments'])
+        # Verify ES update with sharing successful
+        l3p = self._update_gbp_resource(l3p['id'], 'l3_policy', 'l3_policies',
+                                        expected_res_status=200,
+                                        external_segments=es_dict,
+                                        shared=True)
+        # Verify ES correctly set
+        self.assertEqual(es_dict, l3p['external_segments'])
 
     def test_shared_l3_policy_update_negative(self):
         l3p = self.create_l3_policy(shared=True)['l3_policy']
@@ -140,6 +215,69 @@ class TestL3Policy(GroupPolicyPluginTestCase):
         self._update_gbp_resource(l3p['id'], 'l3_policy', 'l3_policies',
                                   expected_res_status=400, shared=False)
 
+        es = self.create_external_segment(cidr='172.0.0.0/8')
+        es_dict = self._get_es_dict(es, ['172.0.0.2', '172.0.0.3'])
+        res = self._update_gbp_resource_full_response(
+            l3p['id'], 'l3_policy', 'l3_policies', expected_res_status=400,
+            external_segments=es_dict, shared=True)
+        self.assertEqual('SharedResourceReferenceError',
+                         res['NeutronError']['type'])
+
+    def test_create_with_es_negative(self):
+        attrs = {'external_routes': [{'destination': '10.160.0.0/16',
+                                     'nexthop': '172.1.1.1'}],
+                 'cidr': '172.1.1.0/24'}
+        es = self.create_external_segment(**attrs)['external_segment']
+        # Overlapping pool
+        attrs = {'ip_pool': '172.1.1.0/20',
+                 'external_segments': {es['id']: ['172.1.1.2']}}
+        res = self.create_l3_policy(expected_res_status=400, **attrs)
+        self.assertEqual('ExternalSegmentSubnetOverlapsWithL3PIpPool',
+                         res['NeutronError']['type'])
+        # Overlapping route
+        attrs['ip_pool'] = '10.160.1.0/24'
+        res = self.create_l3_policy(expected_res_status=400, **attrs)
+        self.assertEqual('ExternalRouteOverlapsWithL3PIpPool',
+                         res['NeutronError']['type'])
+        # Allocated address not in pool
+        attrs = {'ip_pool': '192.168.0.0/24',
+                 'external_segments': {es['id']: ['172.1.2.2']}}
+        res = self.create_l3_policy(expected_res_status=400, **attrs)
+        self.assertEqual('InvalidL3PExternalIPAddress',
+                         res['NeutronError']['type'])
+
+    def test_update_with_es_negative(self):
+        attrs = {'external_routes': [{'destination': '10.160.0.0/16',
+                                     'nexthop': '172.1.1.1'}],
+                 'cidr': '172.1.1.0/24'}
+        es = self.create_external_segment(**attrs)['external_segment']
+
+        # Overlapping pool
+        l3p = self.create_l3_policy(ip_pool='172.1.1.0/20')['l3_policy']
+        attrs = {'external_segments': {es['id']: ['172.1.1.2']}}
+        res = self._update_gbp_resource_full_response(
+            l3p['id'], 'l3_policy', 'l3_policies', expected_res_status=400,
+            **attrs)
+        self.assertEqual('ExternalSegmentSubnetOverlapsWithL3PIpPool',
+                         res['NeutronError']['type'])
+
+        # Overlapping route
+        l3p = self.create_l3_policy(ip_pool='10.160.1.0/24')['l3_policy']
+        res = self._update_gbp_resource_full_response(
+            l3p['id'], 'l3_policy', 'l3_policies', expected_res_status=400,
+            **attrs)
+        self.assertEqual('ExternalRouteOverlapsWithL3PIpPool',
+                         res['NeutronError']['type'])
+
+        # Allocated address not in pool
+        l3p = self.create_l3_policy(ip_pool='192.168.0.0/24')['l3_policy']
+        attrs = {'external_segments': {es['id']: ['172.1.2.2']}}
+        res = self._update_gbp_resource_full_response(
+            l3p['id'], 'l3_policy', 'l3_policies', expected_res_status=400,
+            **attrs)
+        self.assertEqual('InvalidL3PExternalIPAddress',
+                         res['NeutronError']['type'])
+
 
 class TestL2Policy(GroupPolicyPluginTestCase):
 
@@ -474,6 +612,184 @@ class TestPolicyTargetGroup(GroupPolicyPluginTestCase):
                                    expected_res_status=201)
 
 
+class TestExternalSegment(GroupPolicyPluginTestCase):
+
+    def test_shared_es_create(self):
+        # Verify default is False
+        es = self.create_external_segment()
+        self.assertEqual(False, es['external_segment']['shared'])
+        # Verify shared True created without errors
+        es = self.create_external_segment(shared=True)
+        self.assertEqual(True, es['external_segment']['shared'])
+
+    def test_shared_es_update(self):
+        es = self.create_external_segment()['external_segment']
+        for shared in [True, False]:
+            self._update_gbp_resource(
+                es['id'], 'external_segment',
+                'external_segments', expected_res_status=200,
+                shared=shared)
+
+    def test_create_routes(self):
+        attrs = {'external_routes': [{'destination': '0.0.0.0/0',
+                                     'nexthop': '172.1.0.1'}],
+                 'cidr': '172.1.0.0/24'}
+        self.create_external_segment(expected_res_status=201, **attrs)
+
+    def test_routes_negative(self):
+        # Verify wrong NH
+        attrs = {'external_routes': [{'destination': '0.0.0.0/0',
+                                     'nexthop': '172.1.1.1'}],
+                 'cidr': '172.1.0.0/24'}
+        res = self.create_external_segment(expected_res_status=400, **attrs)
+        self.assertEqual('ExternalRouteNextHopNotInExternalSegment',
+                         res['NeutronError']['type'])
+        attrs['cidr'] = '172.1.1.0/24'
+        es = self.create_external_segment(**attrs)['external_segment']
+        self.create_l3_policy(
+            ip_pool='192.160.0.0/16',
+            external_segments={es['id']: ['172.1.1.2']})['l3_policy']
+
+        # Verify refused because overlapping with L3P
+        attrs = {'external_routes': [{'destination': '192.168.2.0/0',
+                                     'nexthop': '172.1.1.1'}]}
+        res = self._update_gbp_resource_full_response(
+            es['id'], 'external_segment', 'external_segments',
+            expected_res_status=400, **attrs)
+        self.assertEqual('ExternalRouteOverlapsWithL3PIpPool',
+                         res['NeutronError']['type'])
+
+
+class TestExternalPolicy(GroupPolicyPluginTestCase):
+
+    def test_shared_ep_create(self):
+        es = self.create_external_segment(
+            shared=True)['external_segment']
+        esns = self.create_external_segment(
+        )['external_segment']
+
+        prs = self._create_policy_rule_set_on_shared(shared=True)
+        prsns = self._create_policy_rule_set_on_shared()
+
+        # Verify non-shared ep providing and consuming shared and non shared
+        # policy_rule_sets
+        ep = self.create_external_policy(
+            external_segments=[es['id']], expected_res_status=201)
+        self.assertEqual(False, ep['external_policy']['shared'])
+        ep = self.create_external_policy(
+            external_segments=[es['id']],
+            provided_policy_rule_sets={prs['id']: '', prsns['id']: ''},
+            consumed_policy_rule_sets={prs['id']: '', prsns['id']: ''},
+            expected_res_status=201)
+        self.assertEqual(False, ep['external_policy']['shared'])
+
+        # Verify shared True created without errors by providing/consuming
+        # shared policy_rule_sets
+        ep = self.create_external_policy(
+            external_segments=[es['id']], shared=True,
+            expected_res_status=201)
+        self.assertEqual(True, ep['external_policy']['shared'])
+        ep = self.create_external_policy(
+            external_segments=[es['id']],
+            provided_policy_rule_sets={prs['id']: ''},
+            consumed_policy_rule_sets={prs['id']: ''}, shared=True,
+            expected_res_status=201)
+        self.assertEqual(True, ep['external_policy']['shared'])
+
+        # Verify not shared created without error on not shared es
+        self.create_external_policy(
+            external_segments=[esns['id']], expected_res_status=201)
+
+    def test_shared_ep_update(self):
+        ep = self._create_external_policy_on_shared()
+        self._update_gbp_resource(
+            ep['id'], 'external_policy', 'external_policies',
+            expected_res_status=200, shared=True)
+        self._update_gbp_resource(
+            ep['id'], 'external_policy', 'external_policies',
+            expected_res_status=200, shared=False)
+
+    def test_shared_ep_create_negative(self):
+        es = self.create_external_segment()['external_segment']
+        prs = self._create_policy_rule_set_on_shared()
+        # Verify shared EP fails on non-shared es
+        res = self.create_external_policy(
+            external_segments=[es['id']], shared=True,
+            expected_res_status=400)
+        self.assertEqual('SharedResourceReferenceError',
+                         res['NeutronError']['type'])
+        # Verify shared EP fails to provide/consume non shared
+        # policy_rule_sets
+        res = self.create_external_policy(
+            shared=True, provided_policy_rule_sets={prs['id']: ''},
+            consumed_policy_rule_sets={prs['id']: ''},
+            expected_res_status=400)
+        self.assertEqual('SharedResourceReferenceError',
+                         res['NeutronError']['type'])
+
+    def test_shared_ep_update_negative(self):
+        ep = self._create_external_policy_on_shared(shared=True)
+        # Verify update to non shared ES fails
+        es = self.create_external_segment()['external_segment']
+        self._update_gbp_resource(
+            ep['id'], 'external_policy', 'external_policies',
+            expected_res_status=400, external_segments=[es['id']])
+
+        # Verify update to non shared provided PRS fails
+        prs = self._create_policy_rule_set_on_shared()
+        self._update_gbp_resource(
+            ep['id'], 'external_policy', 'external_policies',
+            expected_res_status=400,
+            provided_policy_rule_sets={prs['id']: ''})
+        # Verify update to non shared consumed PRS fails
+        self._update_gbp_resource(
+            ep['id'], 'external_policy', 'external_policies',
+            expected_res_status=400,
+            consumed_policy_rule_sets={prs['id']: ''})
+
+
+class TestNatPool(GroupPolicyPluginTestCase):
+
+    def test_nat_pool_shared_create(self):
+        def combination(np, es):
+            return {'np': np, 'es': es}
+        allowed = [combination(False, False), combination(True, True),
+                   combination(False, True)]
+        for shared in allowed:
+            es = self.create_external_segment(
+                shared=shared['es'])['external_segment']
+            self.create_nat_pool(external_segment_id=es['id'],
+                                 shared=shared['np'], expected_res_status=201)
+
+    def test_nat_pool_shared_create_negative(self):
+        es = self.create_external_segment(
+            shared=False)['external_segment']
+        res = self.create_nat_pool(external_segment_id=es['id'],
+                                   shared=True, expected_res_status=400)
+        self.assertEqual('SharedResourceReferenceError',
+                         res['NeutronError']['type'])
+
+    def test_nat_pool_shared_update(self):
+        np = self.create_nat_pool(shared=False)['nat_pool']
+        for shared in [False, True]:
+            es = self.create_external_segment(
+                shared=shared)['external_segment']
+            self._update_gbp_resource(
+                np['id'], 'nat_pool', 'nat_pools', expected_res_status=200,
+                external_segment_id=es['id'])
+        np = self.create_nat_pool(shared=True)['nat_pool']
+        es = self.create_external_segment(
+            shared=True)['external_segment']
+        # Verify shared NP on shared ES
+        self._update_gbp_resource(
+            np['id'], 'nat_pool', 'nat_pools', expected_res_status=200,
+            external_segment_id=es['id'])
+        # Verify unshare NP
+        self._update_gbp_resource(
+            np['id'], 'nat_pool', 'nat_pools', expected_res_status=200,
+            shared=False)
+
+
 class TestGroupPolicyPluginGroupResources(
         GroupPolicyPluginTestCase, tgpdb.TestGroupResources):