diff --git a/gbpservice/neutron/services/sfc/aim/sfc_driver.py b/gbpservice/neutron/services/sfc/aim/sfc_driver.py
index 61cd65a63..8265b2a71 100644
--- a/gbpservice/neutron/services/sfc/aim/sfc_driver.py
+++ b/gbpservice/neutron/services/sfc/aim/sfc_driver.py
@@ -45,6 +45,7 @@ FLOWC_DST = 'dst'
 LOG = logging.getLogger(__name__)
 PHYSDOM_TYPE = 'PhysDom'
 SUPPORTED_DOM_TYPES = [PHYSDOM_TYPE]
+DEFAULT_SUBNETS = ['128.0.0.0/1', '0.0.0.0/1', '8000::/1', '::/1']
 MAX_PPGS_PER_CHAIN = 3
 
 
@@ -597,26 +598,20 @@ class SfcAIMDriver(SfcAIMDriverBase):
         cidr = netaddr.IPNetwork(cidr)
         l3out = self.aim_mech._get_svi_net_l3out(net)
         if l3out:
-            if cidr.prefixlen == 0:
-                # Use default External Network
-                ext_net = self.aim_mech._get_svi_default_external_epg(net)
-                ext_net_db = self.aim.get(aim_ctx, ext_net)
-                if not ext_net_db:
-                    raise exceptions.DefaultExternalNetworkNotFound(
-                        id=net['id'])
-            else:
-                # Create ExternalNetwork and ExternalSubnet on the proper
-                # L3Out. Return the External network
-                ext_net = aim_resource.ExternalNetwork(
-                    tenant_name=l3out.tenant_name, l3out_name=l3out.name,
-                    name=flc_aid)
+            # Create ExternalNetwork and ExternalSubnet on the proper
+            # L3Out. Return the External network
+            ext_net = aim_resource.ExternalNetwork(
+                tenant_name=l3out.tenant_name, l3out_name=l3out.name,
+                name=flc_aid)
+            ext_net_db = self.aim.get(aim_ctx, ext_net)
+            if not ext_net_db:
+                ext_net_db = self.aim.create(aim_ctx, ext_net)
+            subnets = [str(cidr)] if cidr.prefixlen != 0 else DEFAULT_SUBNETS
+            for sub in subnets:
                 ext_sub = aim_resource.ExternalSubnet(
                     tenant_name=ext_net.tenant_name,
                     l3out_name=ext_net.l3out_name,
-                    external_network_name=ext_net.name, cidr=str(cidr))
-                ext_net_db = self.aim.get(aim_ctx, ext_net)
-                if not ext_net_db:
-                    ext_net_db = self.aim.create(aim_ctx, ext_net)
+                    external_network_name=ext_net.name, cidr=sub)
                 ext_sub_db = self.aim.get(aim_ctx, ext_sub)
                 if not ext_sub_db:
                     self.aim.create(aim_ctx, ext_sub)
@@ -644,14 +639,10 @@ class SfcAIMDriver(SfcAIMDriverBase):
         cidr = netaddr.IPNetwork(cidr)
         ext_net = None
         if l3out:
-            if cidr.prefixlen != 0:
-                ext_net = aim_resource.ExternalNetwork(
-                    tenant_name=l3out.tenant_name, l3out_name=l3out.name,
-                    name=flc_aid)
-                epg = self.aim.get(aim_ctx, ext_net)
-            else:
-                epg = self.aim.get(
-                    aim_ctx, self.aim_mech._get_svi_default_external_epg(net))
+            ext_net = aim_resource.ExternalNetwork(
+                tenant_name=l3out.tenant_name, l3out_name=l3out.name,
+                name=flc_aid)
+            epg = self.aim.get(aim_ctx, ext_net)
         else:
             epg = self.aim.get(aim_ctx, self.aim_mech._get_epg_by_network_id(
                 plugin_context.session, net['id']))
@@ -977,7 +968,11 @@ class SfcAIMDriver(SfcAIMDriverBase):
         else:
             cidr = flowc['destination_ip_prefix']
             net = self._get_flowc_dst_network(plugin_context, flowc)
-        cidr = aim_utils.sanitize_display_name(cidr)
+        cidr = netaddr.IPNetwork(cidr)
+        if cidr.prefixlen == 0:
+            cidr = 'default'
+        else:
+            cidr = aim_utils.sanitize_display_name(str(cidr))
         name = self.name_mapper.network(plugin_context.session, net['id'],
                                         prefix=cidr + '_')
         return name
diff --git a/gbpservice/neutron/tests/unit/services/sfc/test_aim_sfc_driver.py b/gbpservice/neutron/tests/unit/services/sfc/test_aim_sfc_driver.py
index caf0b8ab8..ae07c8c48 100644
--- a/gbpservice/neutron/tests/unit/services/sfc/test_aim_sfc_driver.py
+++ b/gbpservice/neutron/tests/unit/services/sfc/test_aim_sfc_driver.py
@@ -436,21 +436,26 @@ class TestAIMServiceFunctionChainingBase(test_aim_base.AIMBaseTestCase):
                     # DN extension for external networks.
                     ext = aim_res.ExternalNetwork.from_dn(
                         net['apic:distinguished_names']['ExternalNetwork'])
+                    name_prefix = cidr.replace('/', '_')
+                    subnets = [cidr]
                     if cidr in ['0.0.0.0/0', '::/0']:
                         # use default external EPG
-                        ext_net = self.aim_mgr.get(ctx, ext)
-                    else:
-                        ext_net = self.aim_mgr.get(
-                            ctx, aim_res.ExternalNetwork(
-                                tenant_name=ext.tenant_name,
-                                l3out_name=ext.l3out_name,
-                                name=cidr.replace(
-                                    '/', '_') + '_' + 'net_' + net['id']))
-                    ext_sub = self.aim_mgr.get(ctx, aim_res.ExternalSubnet(
-                        tenant_name=ext.tenant_name, l3out_name=ext.l3out_name,
-                        external_network_name=ext_net.name, cidr=cidr))
+                        name_prefix = 'default'
+                        subnets = ['128.0.0.0/1', '0.0.0.0/1', '8000::/1',
+                                   '::/1']
+                    ext_net = self.aim_mgr.get(
+                        ctx, aim_res.ExternalNetwork(
+                            tenant_name=ext.tenant_name,
+                            l3out_name=ext.l3out_name,
+                            name=name_prefix + '_' + 'net_' + net['id']))
+                    for sub in subnets:
+                        ext_sub = self.aim_mgr.get(ctx, aim_res.ExternalSubnet(
+                            tenant_name=ext.tenant_name,
+                            l3out_name=ext.l3out_name,
+                            external_network_name=ext_net.name, cidr=sub))
+                        self.assertIsNotNone(ext_sub)
+
                     self.assertIsNotNone(ext_net)
-                    self.assertIsNotNone(ext_sub)
                     self.assertTrue(
                         contract.name in (ext_net.consumed_contract_names if
                                           pref == 'src_' else