diff --git a/environments/net-bond-with-vlans-no-external.yaml b/environments/net-bond-with-vlans-no-external.yaml
index 75959a0b01..cc27d4f009 100644
--- a/environments/net-bond-with-vlans-no-external.yaml
+++ b/environments/net-bond-with-vlans-no-external.yaml
@@ -20,7 +20,3 @@ resource_registry:
   OS::TripleO::Controller::Net::SoftwareConfig: ../network/config/bond-with-vlans/controller-no-external.yaml
   OS::TripleO::ObjectStorage::Net::SoftwareConfig: ../network/config/bond-with-vlans/swift-storage.yaml
   OS::TripleO::CephStorage::Net::SoftwareConfig: ../network/config/bond-with-vlans/ceph-storage.yaml
-
-# NOTE: with no external interface we should be able to use the
-# default Neutron l3_agent.ini setting for the external bridge (br-ex)
-# i.e. No need to set:  NeutronExternalNetworkBridge: "''"
diff --git a/environments/net-bond-with-vlans-v6.yaml b/environments/net-bond-with-vlans-v6.yaml
index 73dda3d932..dc6fdfe370 100644
--- a/environments/net-bond-with-vlans-v6.yaml
+++ b/environments/net-bond-with-vlans-v6.yaml
@@ -12,9 +12,3 @@ resource_registry:
   OS::TripleO::Controller::Net::SoftwareConfig: ../network/config/bond-with-vlans/controller-v6.yaml
   OS::TripleO::ObjectStorage::Net::SoftwareConfig: ../network/config/bond-with-vlans/swift-storage.yaml
   OS::TripleO::CephStorage::Net::SoftwareConfig: ../network/config/bond-with-vlans/ceph-storage.yaml
-
-parameter_defaults:
-  # This sets 'external_network_bridge' in l3_agent.ini to an empty string
-  # so that external networks act like provider bridge networks (they
-  # will plug into br-int instead of br-ex)
-  NeutronExternalNetworkBridge: "''"
diff --git a/environments/net-bond-with-vlans.yaml b/environments/net-bond-with-vlans.yaml
index de8f8f749b..38c31cac0a 100644
--- a/environments/net-bond-with-vlans.yaml
+++ b/environments/net-bond-with-vlans.yaml
@@ -11,9 +11,3 @@ resource_registry:
   OS::TripleO::Controller::Net::SoftwareConfig: ../network/config/bond-with-vlans/controller.yaml
   OS::TripleO::ObjectStorage::Net::SoftwareConfig: ../network/config/bond-with-vlans/swift-storage.yaml
   OS::TripleO::CephStorage::Net::SoftwareConfig: ../network/config/bond-with-vlans/ceph-storage.yaml
-
-parameter_defaults:
-  # This sets 'external_network_bridge' in l3_agent.ini to an empty string
-  # so that external networks act like provider bridge networks (they
-  # will plug into br-int instead of br-ex)
-  NeutronExternalNetworkBridge: "''"
diff --git a/environments/net-single-nic-linux-bridge-with-vlans.yaml b/environments/net-single-nic-linux-bridge-with-vlans.yaml
index fd80bb9bc2..f34cfb9292 100644
--- a/environments/net-single-nic-linux-bridge-with-vlans.yaml
+++ b/environments/net-single-nic-linux-bridge-with-vlans.yaml
@@ -11,9 +11,3 @@ resource_registry:
     OS::TripleO::Controller::Net::SoftwareConfig: ../network/config/single-nic-linux-bridge-vlans/controller.yaml
     OS::TripleO::ObjectStorage::Net::SoftwareConfig: ../network/config/single-nic-linux-bridge-vlans/swift-storage.yaml
     OS::TripleO::CephStorage::Net::SoftwareConfig: ../network/config/single-nic-linux-bridge-vlans/ceph-storage.yaml
-
-parameter_defaults:
-  # This sets 'external_network_bridge' in l3_agent.ini to an empty string
-  # so that external networks act like provider bridge networks (they
-  # will plug into br-int instead of br-ex)
-  NeutronExternalNetworkBridge: "''"
diff --git a/environments/net-single-nic-with-vlans-no-external.yaml b/environments/net-single-nic-with-vlans-no-external.yaml
index c7594b3201..65d3813794 100644
--- a/environments/net-single-nic-with-vlans-no-external.yaml
+++ b/environments/net-single-nic-with-vlans-no-external.yaml
@@ -19,7 +19,3 @@ resource_registry:
   OS::TripleO::Controller::Net::SoftwareConfig: ../network/config/single-nic-vlans/controller-no-external.yaml
   OS::TripleO::ObjectStorage::Net::SoftwareConfig: ../network/config/single-nic-vlans/swift-storage.yaml
   OS::TripleO::CephStorage::Net::SoftwareConfig: ../network/config/single-nic-vlans/ceph-storage.yaml
-
-# NOTE: with no external interface we should be able to use the
-# default Neutron l3_agent.ini setting for the external bridge (br-ex)
-# i.e. No need to set:  NeutronExternalNetworkBridge: "''"
diff --git a/environments/net-single-nic-with-vlans-v6.yaml b/environments/net-single-nic-with-vlans-v6.yaml
index 8210bad3d1..966e5fe9d4 100644
--- a/environments/net-single-nic-with-vlans-v6.yaml
+++ b/environments/net-single-nic-with-vlans-v6.yaml
@@ -11,9 +11,3 @@ resource_registry:
   OS::TripleO::Controller::Net::SoftwareConfig: ../network/config/single-nic-vlans/controller-v6.yaml
   OS::TripleO::ObjectStorage::Net::SoftwareConfig: ../network/config/single-nic-vlans/swift-storage.yaml
   OS::TripleO::CephStorage::Net::SoftwareConfig: ../network/config/single-nic-vlans/ceph-storage.yaml
-
-parameter_defaults:
-  # This sets 'external_network_bridge' in l3_agent.ini to an empty string
-  # so that external networks act like provider bridge networks (they
-  # will plug into br-int instead of br-ex)
-  NeutronExternalNetworkBridge: "''"
diff --git a/environments/net-single-nic-with-vlans.yaml b/environments/net-single-nic-with-vlans.yaml
index a61bc6e187..b087b3e4cc 100644
--- a/environments/net-single-nic-with-vlans.yaml
+++ b/environments/net-single-nic-with-vlans.yaml
@@ -11,9 +11,3 @@ resource_registry:
   OS::TripleO::Controller::Net::SoftwareConfig: ../network/config/single-nic-vlans/controller.yaml
   OS::TripleO::ObjectStorage::Net::SoftwareConfig: ../network/config/single-nic-vlans/swift-storage.yaml
   OS::TripleO::CephStorage::Net::SoftwareConfig: ../network/config/single-nic-vlans/ceph-storage.yaml
-
-parameter_defaults:
-  # This sets 'external_network_bridge' in l3_agent.ini to an empty string
-  # so that external networks act like provider bridge networks (they
-  # will plug into br-int instead of br-ex)
-  NeutronExternalNetworkBridge: "''"
diff --git a/environments/network-environment.yaml b/environments/network-environment.yaml
index b02fc198bb..c5e2a5883c 100644
--- a/environments/network-environment.yaml
+++ b/environments/network-environment.yaml
@@ -48,8 +48,6 @@ parameter_defaults:
   # ManagementInterfaceDefaultRoute: 10.0.1.1
   # Define the DNS servers (maximum 2) for the overcloud nodes
   DnsServers: ["8.8.8.8","8.8.4.4"]
-  # Set to empty string to enable multiple external networks or VLANs
-  NeutronExternalNetworkBridge: "''"
   # List of Neutron network types for tenant networks (will be used in order)
   NeutronNetworkType: 'vxlan,vlan'
   # The tunnel type for the tenant network (vxlan or gre). Set to '' to disable tunneling.
diff --git a/puppet/services/neutron-l3-compute-dvr.yaml b/puppet/services/neutron-l3-compute-dvr.yaml
index b6c2911605..fef3199200 100644
--- a/puppet/services/neutron-l3-compute-dvr.yaml
+++ b/puppet/services/neutron-l3-compute-dvr.yaml
@@ -22,10 +22,6 @@ parameters:
   Debug:
     type: string
     default: ''
-  NeutronExternalNetworkBridge:
-    description: Name of bridge used for external network traffic.
-    type: string
-    default: 'br-ex'
   MonitoringSubscriptionNeutronL3Dvr:
     default: 'overcloud-neutron-l3-dvr'
     type: string
@@ -35,6 +31,19 @@ parameters:
       tag: openstack.neutron.agent.l3-compute
       path: /var/log/neutron/l3-agent.log
 
+  # DEPRECATED: the following options are deprecated and are currently maintained
+  # for backwards compatibility. They will be removed in the Pike cycle.
+  NeutronExternalNetworkBridge:
+    description: Name of bridge used for external network traffic. Usually L2
+                 agent handles port wiring into external bridge, and hence the
+                 parameter should be unset.
+    type: string
+    default: ''
+
+conditions:
+
+  external_network_bridge_empty: {equals : [{get_param: NeutronExternalNetworkBridge}, "''"]}
+
 resources:
 
   NeutronBase:
@@ -56,7 +65,11 @@ outputs:
       config_settings:
         map_merge:
           - get_attr: [NeutronBase, role_data, config_settings]
-          - neutron::agents::l3::external_network_bridge: {get_param: NeutronExternalNetworkBridge}
-            neutron::agents::l3::agent_mode : 'dvr'
+          - neutron::agents::l3::agent_mode : 'dvr'
+          -
+            if:
+            - external_network_bridge_empty
+            - {}
+            - neutron::agents::l3::external_network_bridge: {get_param: NeutronExternalNetworkBridge}
       step_config: |
         include tripleo::profile::base::neutron::l3
diff --git a/puppet/services/neutron-l3.yaml b/puppet/services/neutron-l3.yaml
index a2157555c7..919947808f 100644
--- a/puppet/services/neutron-l3.yaml
+++ b/puppet/services/neutron-l3.yaml
@@ -21,10 +21,6 @@ parameters:
   Debug:
     type: string
     default: ''
-  NeutronExternalNetworkBridge:
-    description: Name of bridge used for external network traffic.
-    type: string
-    default: 'br-ex'
   NeutronL3AgentMode:
     description: |
       Agent mode for L3 agent. Must be one of legacy or dvr_snat.
@@ -43,6 +39,15 @@ parameters:
       tag: openstack.neutron.agent.l3
       path: /var/log/neutron/l3-agent.log
 
+  # DEPRECATED: the following options are deprecated and are currently maintained
+  # for backwards compatibility. They will be removed in the Pike cycle.
+  NeutronExternalNetworkBridge:
+    description: Name of bridge used for external network traffic. Usually L2
+                 agent handles port wiring into external bridge, and hence the
+                 parameter should be unset.
+    type: string
+    default: ''
+
 conditions:
 
   external_network_bridge_empty: {equals : [{get_param: NeutronExternalNetworkBridge}, "''"]}