diff --git a/zaza/openstack/charm_tests/dragent/configure.py b/zaza/openstack/charm_tests/dragent/configure.py
index b9588d4..79c1720 100644
--- a/zaza/openstack/charm_tests/dragent/configure.py
+++ b/zaza/openstack/charm_tests/dragent/configure.py
@@ -41,8 +41,9 @@ def setup():
     :returns: None
     :rtype: None
     """
-    # Reuse the existing network configuration code.
-    basic_overcloud_network()
+    # Reuse the existing network configuration code but ask for a separate
+    # service subnet to be created for FIPs.
+    basic_overcloud_network(use_separate_fip_subnet=True)
 
     # Get a keystone session
     keystone_session = openstack_utils.get_overcloud_keystone_session()
diff --git a/zaza/openstack/charm_tests/neutron/setup.py b/zaza/openstack/charm_tests/neutron/setup.py
index d6a1ab2..f81590d 100644
--- a/zaza/openstack/charm_tests/neutron/setup.py
+++ b/zaza/openstack/charm_tests/neutron/setup.py
@@ -68,6 +68,17 @@ DEFAULT_UNDERCLOUD_NETWORK_CONFIG = {
     "default_gateway": "10.5.0.1",
 }
 
+# For Neutron Dynamic Tests it is useful to avoid relying on the directly
+# connected routes and instead using the advertised routes on the southbound
+# path and default routes on the northbound path. To do that, a separate
+# service subnet may be optionally created to force Neutron to use that instead
+# of the external network subnet without concrete service IPs which is used as
+# a fallback only.
+DEFAULT_FIP_SERVICE_SUBNET_CONFIG = {
+    "fip_service_subnet_name": openstack_utils.FIP_SERVICE_SUBNET_NAME,
+    "fip_service_subnet_cidr": "100.64.0.0/24"
+}
+
 
 def undercloud_and_charm_setup(limit_gws=None):
     """Perform undercloud and charm setup for network plumbing.
@@ -111,7 +122,7 @@ def undercloud_and_charm_setup(limit_gws=None):
                         .format(provider_type))
 
 
-def basic_overcloud_network(limit_gws=None):
+def basic_overcloud_network(limit_gws=None, use_separate_fip_subnet=False):
     """Run setup for neutron networking.
 
     Configure the following:
@@ -119,6 +130,10 @@ def basic_overcloud_network(limit_gws=None):
 
     :param limit_gws: Limit the number of gateways that get a port attached
     :type limit_gws: int
+    :param use_separate_fip_subnet: Use a separate service subnet for floating
+                                    ips instead of relying on the external
+                                    network subnet for FIP allocations.
+    :type use_separate_fip_subnet: bool
     """
     cli_utils.setup_logging()
 
@@ -128,6 +143,10 @@ def basic_overcloud_network(limit_gws=None):
     network_config.update(OVERCLOUD_NETWORK_CONFIG)
     # Default undercloud settings
     network_config.update(DEFAULT_UNDERCLOUD_NETWORK_CONFIG)
+
+    if use_separate_fip_subnet:
+        network_config.update(DEFAULT_FIP_SERVICE_SUBNET_CONFIG)
+
     # Environment specific settings
     network_config.update(generic_utils.get_undercloud_env_vars())
 
diff --git a/zaza/openstack/configure/network.py b/zaza/openstack/configure/network.py
index 20cde9f..33fab27 100755
--- a/zaza/openstack/configure/network.py
+++ b/zaza/openstack/configure/network.py
@@ -132,6 +132,23 @@ def setup_sdn(network_config, keystone_session=None):
         neutron_client,
         project_id,
         network_config["external_net_name"])
+
+    # If a separate service subnet for FIPs is requested, create one. This is
+    # useful for testing dynamic routing scenarios to avoid relying on directly
+    # connected routes to the external network subnet.
+    if network_config.get('fip_service_subnet_name'):
+        openstack_utils.create_provider_subnet(
+            neutron_client,
+            project_id,
+            ext_network,
+            subnet_name=network_config["fip_service_subnet_name"],
+            cidr=network_config["fip_service_subnet_cidr"],
+            # Disable DHCP as we don't need a metadata port serving this
+            # subnet while Neutron would fail to allocate a fixed IP for it
+            # with a service subnet constraint below.
+            dhcp=False,
+            service_types=['network:floatingip']
+        )
     openstack_utils.create_provider_subnet(
         neutron_client,
         project_id,
diff --git a/zaza/openstack/utilities/openstack.py b/zaza/openstack/utilities/openstack.py
index df540e5..19f8ce9 100644
--- a/zaza/openstack/utilities/openstack.py
+++ b/zaza/openstack/utilities/openstack.py
@@ -199,6 +199,9 @@ KEYSTONE_REMOTE_CACERT = (
 # Network/router names
 EXT_NET = os.environ.get('TEST_EXT_NET', 'ext_net')
 EXT_NET_SUBNET = os.environ.get('TEST_EXT_NET_SUBNET', 'ext_net_subnet')
+# An optional service subnet for FIPs is necessary.
+FIP_SERVICE_SUBNET_NAME = os.environ.get('TEST_FIP_SERVICE_SUBNET_NAME',
+                                         'fip_service_subnet')
 PRIVATE_NET = os.environ.get('TEST_PRIVATE_NET', 'private')
 PRIVATE_NET_SUBNET = os.environ.get('TEST_PRIVATE_NET_SUBNET',
                                     'private_subnet')
@@ -1301,7 +1304,7 @@ def create_provider_subnet(neutron_client, project_id, network,
                            subnet_name=EXT_NET_SUBNET,
                            default_gateway=None, cidr=None,
                            start_floating_ip=None, end_floating_ip=None,
-                           dhcp=False):
+                           dhcp=False, service_types=None):
     """Create the provider subnet.
 
     :param neutron_client: Authenticated neutronclient
@@ -1322,6 +1325,8 @@ def create_provider_subnet(neutron_client, project_id, network,
     :type end_floating_ip: string or None
     :param dhcp: Run DHCP on this subnet
     :type dhcp: boolean
+    :param service_types: Optional subnet service types
+    :type service_types: List[str]
     :returns: Subnet object
     :rtype: dict
     """
@@ -1345,6 +1350,8 @@ def create_provider_subnet(neutron_client, project_id, network,
                 'end': end_floating_ip,
             }
             subnet_msg['allocation_pools'] = [allocation_pool]
+        if service_types:
+            subnet_msg['service_types'] = service_types
 
         logging.info('Creating new subnet')
         subnet = neutron_client.create_subnet({'subnet': subnet_msg})['subnet']