diff --git a/whitebox_neutron_tempest_plugin/config.py b/whitebox_neutron_tempest_plugin/config.py
index 09e194e..3702bb3 100644
--- a/whitebox_neutron_tempest_plugin/config.py
+++ b/whitebox_neutron_tempest_plugin/config.py
@@ -125,11 +125,9 @@ WhiteboxNeutronPluginOptions = [
                help="Bridge dedicated for external network. It is used for "
                     "capturing traffic for routing tests."),
     cfg.StrOpt('node_ext_interface',
-               default=None,
-               help='Physical interface of a node that is connected to the'
-                    'external network. In case the value is set to None the '
-                    'interface name will be discovered from a list of '
-                    'interfaces under bridge connected to external network'),
+               default='eth1',
+               help='Physical interface of a node that is connected to the '
+                    'external network.'),
     cfg.IntOpt('minbw_placement_nic_kbps_egress',
                default=None,
                help='BW configured per NIC for the minimum BW placement '
diff --git a/whitebox_neutron_tempest_plugin/tests/scenario/base.py b/whitebox_neutron_tempest_plugin/tests/scenario/base.py
index 91bfb1f..4e50e1b 100644
--- a/whitebox_neutron_tempest_plugin/tests/scenario/base.py
+++ b/whitebox_neutron_tempest_plugin/tests/scenario/base.py
@@ -1056,14 +1056,6 @@ class TrafficFlowTest(BaseTempestWhiteboxTestCase):
                     node['ovs_pod'] = line.split()[1]
 
     def _start_captures(self, filters, interface=None):
-        def get_interface(client):
-            interfaces = client.exec_command(
-                "sudo ovs-vsctl list-ports " + WB_CONF.ext_bridge +
-                r"| grep 'eth\|enp\|ens' | grep -v veth " +
-                "|| true").strip().split()
-            if interfaces:
-                return ','.join(interfaces)
-
         for node in self.nodes:
             if not (node['is_controller'] or
                     node['is_compute'] or
@@ -1081,10 +1073,8 @@ class TrafficFlowTest(BaseTempestWhiteboxTestCase):
                 command_prefix = ''
                 if interface:
                     capture_interface = interface
-                elif WB_CONF.node_ext_interface:
-                    capture_interface = WB_CONF.node_ext_interface
                 else:
-                    capture_interface = get_interface(node['client'])
+                    capture_interface = WB_CONF.node_ext_interface
             node['capture'] = capture.TcpdumpCapture(
                 capture_client, capture_interface, filters, command_prefix)
             self.useFixture(node['capture'])