diff --git a/releasenotes/notes/port-physnet-cidr-map-463a1639aba45832.yaml b/releasenotes/notes/port-physnet-cidr-map-463a1639aba45832.yaml
new file mode 100644
index 000000000..77886d7de
--- /dev/null
+++ b/releasenotes/notes/port-physnet-cidr-map-463a1639aba45832.yaml
@@ -0,0 +1,6 @@
+---
+fixes:
+  - |
+    The undercloud install now configures ironic inspector to automatically
+    populate the physical_network field on baremetal provisioning ports. See
+    bug `1870529 <https://launchpad.net/bugs/1870529>`_.
diff --git a/tripleoclient/tests/v1/undercloud/test_config.py b/tripleoclient/tests/v1/undercloud/test_config.py
index a245215d3..e17b9f1ea 100644
--- a/tripleoclient/tests/v1/undercloud/test_config.py
+++ b/tripleoclient/tests/v1/undercloud/test_config.py
@@ -184,6 +184,7 @@ class TestNetworkSettings(TestBaseNetworkSettings):
                  'tag': 'ctlplane-subnet',
                  'mtu': 1500}],
             'MasqueradeNetworks': {},
+            'PortPhysnetCidrMap': {'192.168.24.0/24': 'ctlplane'},
             'UndercloudCtlplaneSubnets': {
                 'ctlplane-subnet': {
                     'AllocationPools': [
@@ -230,6 +231,7 @@ class TestNetworkSettings(TestBaseNetworkSettings):
                  'tag': 'ctlplane-subnet',
                  'mtu': 1500}],
             'MasqueradeNetworks': {},
+            'PortPhysnetCidrMap': {'fd12:3456:789a:1::/64': 'ctlplane'},
             'UndercloudCtlplaneSubnets': {
                 'ctlplane-subnet': {
                     'AllocationPools': [
@@ -279,6 +281,7 @@ class TestNetworkSettings(TestBaseNetworkSettings):
                  'tag': 'ctlplane-subnet',
                  'mtu': 1500}],
             'MasqueradeNetworks': {},
+            'PortPhysnetCidrMap': {'fd12:3456:789a:1::/64': 'ctlplane'},
             'UndercloudCtlplaneSubnets': {
                 'ctlplane-subnet': {
                     'AllocationPools': [
@@ -356,6 +359,7 @@ class TestNetworkSettings(TestBaseNetworkSettings):
                  'tag': 'ctlplane-subnet',
                  'mtu': 1500}],
             'MasqueradeNetworks': {},
+            'PortPhysnetCidrMap': {'192.168.24.0/24': 'ctlplane'},
             'UndercloudCtlplaneSubnets': {
                 'ctlplane-subnet': {
                     'AllocationPools': [
@@ -386,6 +390,7 @@ class TestNetworkSettings(TestBaseNetworkSettings):
                  'tag': 'ctlplane-subnet',
                  'mtu': 1500}],
             'MasqueradeNetworks': {},
+            'PortPhysnetCidrMap': {'192.168.10.0/24': 'ctlplane'},
             'UndercloudCtlplaneSubnets': {
                 'ctlplane-subnet': {
                     'AllocationPools': [
@@ -418,6 +423,7 @@ class TestNetworkSettings(TestBaseNetworkSettings):
                  'tag': 'ctlplane-subnet',
                  'mtu': 1500}],
             'MasqueradeNetworks': {},
+            'PortPhysnetCidrMap': {'192.168.10.0/24': 'ctlplane'},
             'UndercloudCtlplaneSubnets': {
                 'ctlplane-subnet': {
                     'AllocationPools': [
@@ -449,6 +455,7 @@ class TestNetworkSettings(TestBaseNetworkSettings):
                  'tag': 'ctlplane-subnet',
                  'mtu': 1500}],
             'MasqueradeNetworks': {},
+            'PortPhysnetCidrMap': {'192.168.24.0/24': 'ctlplane'},
             'UndercloudCtlplaneSubnets': {
                 'ctlplane-subnet': {
                     'AllocationPools': [
@@ -478,6 +485,7 @@ class TestNetworkSettings(TestBaseNetworkSettings):
                  'tag': 'ctlplane-subnet',
                  'mtu': 1500}],
             'MasqueradeNetworks': {},
+            'PortPhysnetCidrMap': {'192.168.24.0/24': 'ctlplane'},
             'UndercloudCtlplaneSubnets': {
                 'ctlplane-subnet': {
                     'AllocationPools': [
@@ -508,6 +516,7 @@ class TestNetworkSettings(TestBaseNetworkSettings):
                  'tag': 'ctlplane-subnet',
                  'mtu': 1500}],
             'MasqueradeNetworks': {},
+            'PortPhysnetCidrMap': {'192.168.24.0/24': 'ctlplane'},
             'UndercloudCtlplaneSubnets': {
                 'ctlplane-subnet': {
                     'AllocationPools': [
@@ -585,6 +594,9 @@ class TestNetworkSettings(TestBaseNetworkSettings):
                 '192.168.24.0/24': ['192.168.24.0/24',
                                     '192.168.10.0/24',
                                     '192.168.20.0/24']},
+            'PortPhysnetCidrMap': {'192.168.10.0/24': 'subnet1',
+                                   '192.168.20.0/24': 'subnet2',
+                                   '192.168.24.0/24': 'ctlplane'},
             'UndercloudCtlplaneSubnets': {
                 # The ctlplane-subnet subnet have defaults
                 'ctlplane-subnet': {
@@ -662,6 +674,9 @@ class TestNetworkSettings(TestBaseNetworkSettings):
                  'mtu': 1500}
             ],
             'MasqueradeNetworks': {},
+            'PortPhysnetCidrMap': {'192.168.10.0/24': 'subnet1',
+                                   '192.168.20.0/24': 'subnet2',
+                                   '192.168.24.0/24': 'ctlplane'},
             'UndercloudCtlplaneSubnets': {
                 # The ctlplane-subnet subnet have defaults
                 'ctlplane-subnet': {
@@ -721,6 +736,8 @@ class TestNetworkSettings(TestBaseNetworkSettings):
                  'mtu': 1500},
             ],
             'MasqueradeNetworks': {},
+            'PortPhysnetCidrMap': {'192.168.10.0/24': 'subnet1',
+                                   '192.168.24.0/24': 'ctlplane'},
             'UndercloudCtlplaneSubnets': {
                 # The ctlplane-subnet subnet have defaults
                 'ctlplane-subnet': {
@@ -773,6 +790,8 @@ class TestNetworkSettings(TestBaseNetworkSettings):
                  'mtu': 1500},
             ],
             'MasqueradeNetworks': {},
+            'PortPhysnetCidrMap': {'192.168.10.0/24': 'subnet1',
+                                   '192.168.24.0/24': 'ctlplane'},
             'UndercloudCtlplaneSubnets': {
                 # The ctlplane-subnet subnet have defaults
                 'ctlplane-subnet': {
@@ -854,6 +873,9 @@ class TestNetworkSettings(TestBaseNetworkSettings):
                  'mtu': 1500}
             ],
             'MasqueradeNetworks': {},
+            'PortPhysnetCidrMap': {'192.168.10.0/24': 'subnet1',
+                                   '192.168.20.0/24': 'subnet2',
+                                   '192.168.24.0/24': 'ctlplane'},
             'UndercloudCtlplaneSubnets': {
                 # The ctlplane-subnet subnet have defaults
                 'ctlplane-subnet': {
diff --git a/tripleoclient/v1/undercloud_config.py b/tripleoclient/v1/undercloud_config.py
index 135d961d1..255fef763 100644
--- a/tripleoclient/v1/undercloud_config.py
+++ b/tripleoclient/v1/undercloud_config.py
@@ -354,10 +354,23 @@ def _calculate_allocation_pools(subnet):
             for ip_range in list(ip_set.iter_ipranges())]
 
 
+def _generate_inspection_physnet_cidr_map():
+    cidr_map = {}
+    for subnet in CONF.subnets:
+        s = CONF.get(subnet)
+        if subnet == str(CONF.local_subnet):
+            cidr_map[s.cidr] = 'ctlplane'
+        else:
+            cidr_map[s.cidr] = subnet
+
+    return cidr_map
+
+
 def _process_network_args(env):
     """Populate the environment with network configuration."""
 
     env['IronicInspectorSubnets'] = _generate_inspection_subnets()
+    env['PortPhysnetCidrMap'] = _generate_inspection_physnet_cidr_map()
     env['ControlPlaneStaticRoutes'] = _generate_subnets_static_routes()
     env['UndercloudCtlplaneSubnets'] = {}
     env['UndercloudCtlplaneIPv6AddressMode'] = CONF['ipv6_address_mode']