diff --git a/neutron/conf/plugins/ml2/config.py b/neutron/conf/plugins/ml2/config.py
index cd56ee6794a..651ec614b9b 100644
--- a/neutron/conf/plugins/ml2/config.py
+++ b/neutron/conf/plugins/ml2/config.py
@@ -51,13 +51,13 @@ ml2_opts = [
                       'This option allows specifying a physical network MTU '
                       'value that differs from the default global_physnet_mtu '
                       'value.')),
-    cfg.ListOpt('physical_network_mtus',
-                default=[],
-                help=_("A list of mappings of physical networks to MTU "
-                       "values. The format of the mapping is "
-                       "<physnet>:<mtu val>. This mapping allows "
-                       "specifying a physical network MTU value that "
-                       "differs from the default global_physnet_mtu value.")),
+    cfg.DictOpt('physical_network_mtus',
+                default={},
+                help=_("Mappings of physical networks to MTU values. "
+                       "The format of the mapping is <physnet>:<mtu val>. "
+                       "This mapping allows specifying a physical network MTU "
+                       "value that differs from "
+                       "the default global_physnet_mtu value.")),
     cfg.StrOpt('external_network_type',
                help=_("Default network type for external networks when no "
                       "provider attributes are specified. By default it is "
diff --git a/neutron/plugins/ml2/drivers/helpers.py b/neutron/plugins/ml2/drivers/helpers.py
index 276665f8e1b..c5cd3c339cd 100644
--- a/neutron/plugins/ml2/drivers/helpers.py
+++ b/neutron/plugins/ml2/drivers/helpers.py
@@ -22,7 +22,6 @@ from neutron_lib.plugins import constants as plugin_constants
 from neutron_lib.plugins import directory
 from neutron_lib.plugins.ml2 import api
 from neutron_lib.plugins import utils as p_utils
-from neutron_lib.utils import helpers
 from oslo_config import cfg
 from oslo_db import exception as db_exc
 from oslo_log import log
@@ -37,13 +36,7 @@ class BaseTypeDriver(api.ML2TypeDriver):
     """BaseTypeDriver for functions common to Segment and flat."""
 
     def __init__(self):
-        try:
-            self.physnet_mtus = helpers.parse_mappings(
-                cfg.CONF.ml2.physical_network_mtus, unique_values=False
-            )
-        except Exception as e:
-            LOG.error("Failed to parse physical_network_mtus: %s", e)
-            self.physnet_mtus = []
+        self.physnet_mtus = cfg.CONF.ml2.physical_network_mtus
 
     def get_mtu(self, physical_network=None):
         return p_utils.get_deployment_physnet_mtu()
diff --git a/neutron/tests/unit/plugins/ml2/drivers/test_type_flat.py b/neutron/tests/unit/plugins/ml2/drivers/test_type_flat.py
index 89f4d17038b..0a9bccf4a44 100644
--- a/neutron/tests/unit/plugins/ml2/drivers/test_type_flat.py
+++ b/neutron/tests/unit/plugins/ml2/drivers/test_type_flat.py
@@ -38,7 +38,7 @@ class FlatTypeTest(testlib_api.SqlTestCase):
                               group='ml2_type_flat')
         self.driver = type_flat.FlatTypeDriver()
         self.context = context.Context()
-        self.driver.physnet_mtus = []
+        self.driver.physnet_mtus = {}
 
     def _get_allocation(self, context, segment):
         return flat_obj.FlatAllocation.get_object(
@@ -145,23 +145,13 @@ class FlatTypeTest(testlib_api.SqlTestCase):
         self.driver.physnet_mtus = {}
         self.assertEqual(0, self.driver.get_mtu('physnet1'))
 
-    def test_parse_physical_network_mtus(self):
-        cfg.CONF.set_override(
-            'physical_network_mtus',
-            ['physnet1:1500', 'physnet2:1500', 'physnet3:9000'],
-            group='ml2')
-        driver = type_flat.FlatTypeDriver()
-        self.assertEqual('1500', driver.physnet_mtus['physnet1'])
-        self.assertEqual('1500', driver.physnet_mtus['physnet2'])
-        self.assertEqual('9000', driver.physnet_mtus['physnet3'])
-
 
 class FlatTypeDefaultTest(base.BaseTestCase):
 
     def setUp(self):
         super().setUp()
         self.driver = type_flat.FlatTypeDriver()
-        self.driver.physnet_mtus = []
+        self.driver.physnet_mtus = {}
 
     def test_validate_provider_segment_default(self):
         segment = {api.NETWORK_TYPE: p_const.TYPE_FLAT,
diff --git a/neutron/tests/unit/plugins/ml2/drivers/test_type_vlan.py b/neutron/tests/unit/plugins/ml2/drivers/test_type_vlan.py
index 6fa0ffe3ca5..9a7349617df 100644
--- a/neutron/tests/unit/plugins/ml2/drivers/test_type_vlan.py
+++ b/neutron/tests/unit/plugins/ml2/drivers/test_type_vlan.py
@@ -66,7 +66,7 @@ class VlanTypeTest(testlib_api.SqlTestCase):
         self.driver = type_vlan.VlanTypeDriver()
         self.driver._sync_vlan_allocations()
         self.context = context.Context()
-        self.driver.physnet_mtus = []
+        self.driver.physnet_mtus = {}
         self.setup_coreplugin(CORE_PLUGIN)
 
     def test_parse_network_exception_handling(self):
@@ -328,7 +328,7 @@ class VlanTypeAllocationTest(testlib_api.SqlTestCase):
                               ranges,
                               group='ml2_type_vlan')
         driver = type_vlan.VlanTypeDriver()
-        driver.physnet_mtus = []
+        driver.physnet_mtus = {}
         driver._sync_vlan_allocations()
         # swap config order from DB order after sync has happened to
         # ensure config order is followed and not DB order