diff --git a/neutron_tempest_plugin/api/base.py b/neutron_tempest_plugin/api/base.py
index 7f056d1..7af3711 100644
--- a/neutron_tempest_plugin/api/base.py
+++ b/neutron_tempest_plugin/api/base.py
@@ -875,9 +875,10 @@
                                            association['fixed_port_id'])
 
     @classmethod
-    def create_router_interface(cls, router_id, subnet_id):
+    def create_router_interface(cls, router_id, subnet_id, client=None):
         """Wrapper utility that returns a router interface."""
-        interface = cls.client.add_router_interface_with_subnet_id(
+        client = client or cls.client
+        interface = client.add_router_interface_with_subnet_id(
             router_id, subnet_id)
         return interface
 
@@ -1350,13 +1351,14 @@
 
     @classmethod
     def create_provider_network(cls, physnet_name, start_segmentation_id,
-                                max_attempts=30):
+                                max_attempts=30, external=False):
         segmentation_id = start_segmentation_id
         for attempts in range(max_attempts):
             try:
                 return cls.create_network(
                     name=data_utils.rand_name('test_net'),
-                    shared=True,
+                    shared=not external,
+                    external=external,
                     provider_network_type='vlan',
                     provider_physical_network=physnet_name,
                     provider_segmentation_id=segmentation_id)
diff --git a/neutron_tempest_plugin/api/test_routers.py b/neutron_tempest_plugin/api/test_routers.py
index 66cea78..7758b1a 100644
--- a/neutron_tempest_plugin/api/test_routers.py
+++ b/neutron_tempest_plugin/api/test_routers.py
@@ -329,13 +329,10 @@
 class ExternalGWMultihomingRoutersTest(base_routers.BaseRouterTest):
 
     @classmethod
+    @tutils.requires_ext(extension="external-gateway-multihoming",
+                         service="network")
     def setUpClass(cls):
         super().setUpClass()
-        ext_alias = 'external-gateway-multihoming'
-        try:
-            cls.client.get_extension(ext_alias)
-        except lib_exc.NotFound:
-            raise cls.skipException(f'{ext_alias} extension not available.')
 
     @decorators.idempotent_id('33e9a156-a83f-435f-90ee-1a49dc9c350d')
     def test_create_router_enable_default_route_ecmp(self):