diff --git a/gbpautomation/heat/engine/resources/grouppolicy.py b/gbpautomation/heat/engine/resources/grouppolicy.py
index 9db4582..d5f6112 100644
--- a/gbpautomation/heat/engine/resources/grouppolicy.py
+++ b/gbpautomation/heat/engine/resources/grouppolicy.py
@@ -368,8 +368,8 @@ class L3Policy(gbpresource.GBPResource):
             update_allowed=True
         ),
         EXTERNAL_SEGMENTS: properties.Schema(
-            properties.Schema.MAP,
-            _('External segments of L3 policy.'),
+            properties.Schema.LIST,
+            _('External segments for L3 policy.'),
             update_allowed=True
         ),
         SHARED: properties.Schema(
@@ -392,6 +392,21 @@ class L3Policy(gbpresource.GBPResource):
             if self.properties.get(key) is not None:
                 props[key] = self.properties.get(key)
 
+        external_segments_dict = {}
+        props_external_segments = props.get(
+            'external_segments', [])
+
+        for prop_external_segment in props_external_segments:
+            external_segment_id = (
+                prop_external_segment['external_segment_id'])
+            allocated_address = (
+                prop_external_segment['allocated_address'])
+            external_segments_dict.update({external_segment_id:
+                                           allocated_address})
+
+        if external_segments_dict:
+            props['external_segments'] = external_segments_dict
+
         l3_policy = client.create_l3_policy(
             {'l3_policy': props})['l3_policy']
 
@@ -411,6 +426,20 @@ class L3Policy(gbpresource.GBPResource):
 
     def handle_update(self, json_snippet, tmpl_diff, prop_diff):
         if prop_diff:
+            external_segments_dict = {}
+            props_external_segments = prop_diff.get(
+                'external_segments', [])
+
+            for prop_external_segment in props_external_segments:
+                external_segment_id = (
+                    prop_external_segment['external_segment_id'])
+                allocated_address = (
+                    prop_external_segment['allocated_address'])
+                external_segments_dict.update({external_segment_id:
+                                               allocated_address})
+
+            if external_segments_dict:
+                prop_diff['external_segments'] = external_segments_dict
             self.grouppolicy().update_l3_policy(
                 self.resource_id, {'l3_policy': prop_diff})
 
diff --git a/gbpautomation/heat/tests/test_grouppolicy.py b/gbpautomation/heat/tests/test_grouppolicy.py
index a99e672..c192d80 100644
--- a/gbpautomation/heat/tests/test_grouppolicy.py
+++ b/gbpautomation/heat/tests/test_grouppolicy.py
@@ -104,6 +104,10 @@ l3_policy_template = '''
         "description": "test L3 policy resource",
         "ip_version": "4",
         "ip_pool": "10.20.20.0",
+        "external_segments": [
+            {"external_segment_id": "es1",
+             "allocated_address": "1.1.1.1"},
+        ],
         "subnet_prefix_length": 24,
         "shared": True
       }
@@ -720,6 +724,7 @@ class L3PolicyTest(HeatTestCase):
                 "ip_version": "4",
                 "ip_pool": "10.20.20.0",
                 "subnet_prefix_length": 24,
+                "external_segments": {"es1": "1.1.1.1"},
                 "shared": True
             }
         }).AndReturn({'l3_policy': {'id': '5678'}})
@@ -745,6 +750,7 @@ class L3PolicyTest(HeatTestCase):
                 "ip_version": "4",
                 "ip_pool": "10.20.20.0",
                 "subnet_prefix_length": 24,
+                "external_segments": {"es1": "1.1.1.1"},
                 "shared": True
             }
         }).AndRaise(grouppolicy.NeutronClientException())
@@ -807,12 +813,17 @@ class L3PolicyTest(HeatTestCase):
     def test_update(self):
         rsrc = self.create_l3_policy()
         gbpclient.Client.update_l3_policy(
-            '5678', {'l3_policy': {'subnet_prefix_length': 28}})
+            '5678', {'l3_policy': {'subnet_prefix_length': 28,
+                                   'external_segments':
+                                   {'es2': '2.1.1.1'}}})
         self.m.ReplayAll()
         scheduler.TaskRunner(rsrc.create)()
 
         update_template = copy.deepcopy(rsrc.t)
         update_template['Properties']['subnet_prefix_length'] = 28
+        update_template['Properties']['external_segments'] = [
+            {'external_segment_id': 'es2',
+             'allocated_address': '2.1.1.1'}]
         scheduler.TaskRunner(rsrc.update, update_template)()
 
         self.m.VerifyAll()