diff --git a/apps/openstacknetworking/app/src/main/java/org/onosproject/openstacknetworking/impl/DistributedOpenstackNetworkStore.java b/apps/openstacknetworking/app/src/main/java/org/onosproject/openstacknetworking/impl/DistributedOpenstackNetworkStore.java
index 3581580..04ca594 100644
--- a/apps/openstacknetworking/app/src/main/java/org/onosproject/openstacknetworking/impl/DistributedOpenstackNetworkStore.java
+++ b/apps/openstacknetworking/app/src/main/java/org/onosproject/openstacknetworking/impl/DistributedOpenstackNetworkStore.java
@@ -93,6 +93,8 @@
     private static final String ERR_NOT_FOUND = " does not exist";
     private static final String ERR_DUPLICATE = " already exists";
 
+    private static final long TIMEOUT_MS = 2000; // wait for 2s
+
     private static final KryoNamespace SERIALIZER_NEUTRON_L2 = KryoNamespace.newBuilder()
             .register(KryoNamespaces.API)
             .register(Network.class)
@@ -275,11 +277,21 @@
 
         log.debug("Prepare OpenStack port remove");
 
+        long timeoutExpiredMs = System.currentTimeMillis() + TIMEOUT_MS;
+
         while (true) {
+
+            long waitMs = timeoutExpiredMs - System.currentTimeMillis();
+
             if (preCommitPortService.subscriberCountByEventType(
                     portId, OPENSTACK_PORT_PRE_REMOVE) == 0) {
                 break;
             }
+
+            if (waitMs <= 0) {
+                log.debug("Timeout waiting for port removal.");
+                break;
+            }
         }
 
         Versioned<Port> osPort = osPortStore.remove(portId);
diff --git a/apps/openstacknetworking/app/src/main/java/org/onosproject/openstacknetworking/impl/InstancePortManager.java b/apps/openstacknetworking/app/src/main/java/org/onosproject/openstacknetworking/impl/InstancePortManager.java
index 9878de0..3f204fb 100644
--- a/apps/openstacknetworking/app/src/main/java/org/onosproject/openstacknetworking/impl/InstancePortManager.java
+++ b/apps/openstacknetworking/app/src/main/java/org/onosproject/openstacknetworking/impl/InstancePortManager.java
@@ -146,6 +146,13 @@
         checkArgument(!Strings.isNullOrEmpty(instancePort.portId()),
                                                     ERR_NULL_INSTANCE_PORT_ID);
 
+        // in case OpenStack removes the port prior to OVS, we will not update
+        // the instance port as it does not exist in the store
+        if (instancePortStore.instancePort(instancePort.portId()) == null) {
+            log.warn("Unable to update instance port {}, as it does not exist", instancePort.portId());
+            return;
+        }
+
         instancePortStore.updateInstancePort(instancePort);
         log.info(String.format(MSG_INSTANCE_PORT, instancePort.portId(), MSG_UPDATED));
     }
diff --git a/apps/openstacknetworking/app/src/main/java/org/onosproject/openstacknetworking/impl/OpenstackRoutingArpHandler.java b/apps/openstacknetworking/app/src/main/java/org/onosproject/openstacknetworking/impl/OpenstackRoutingArpHandler.java
index 9e47a0c..d751c03 100644
--- a/apps/openstacknetworking/app/src/main/java/org/onosproject/openstacknetworking/impl/OpenstackRoutingArpHandler.java
+++ b/apps/openstacknetworking/app/src/main/java/org/onosproject/openstacknetworking/impl/OpenstackRoutingArpHandler.java
@@ -15,6 +15,7 @@
  */
 package org.onosproject.openstacknetworking.impl;
 
+import com.google.common.base.Strings;
 import com.google.common.collect.ImmutableSet;
 import com.google.common.collect.Sets;
 import org.apache.felix.scr.annotations.Activate;
@@ -430,6 +431,12 @@
                 return;
             }
 
+            if (portId == null || fip.getPortId() == null) {
+                log.trace("Unknown target ARP request for {}, ignore it",
+                        fip.getFloatingIpAddress());
+                return;
+            }
+
             InstancePort instPort = instancePortService.instancePort(portId);
             MacAddress targetMac = instPort.macAddress();
 
@@ -521,40 +528,46 @@
                     );
                     break;
                 case OPENSTACK_FLOATING_IP_ASSOCIATED:
-                    eventExecutor.execute(() -> {
-                        NetFloatingIP osFip = event.floatingIp();
-
-                        // associate a floating IP with an existing VM
-                        setFloatingIpArpRule(event.floatingIp(), event.portId(), completedGws, true);
-                    });
+                    if (getValidPortId(event) != null) {
+                        eventExecutor.execute(() -> {
+                            // associate a floating IP with an existing VM
+                            setFloatingIpArpRule(event.floatingIp(), getValidPortId(event),
+                                    completedGws, true);
+                        });
+                    }
                     break;
                 case OPENSTACK_FLOATING_IP_DISASSOCIATED:
-                    eventExecutor.execute(() -> {
-                        NetFloatingIP osFip = event.floatingIp();
-
-                        // associate a floating IP with an existing VM
-                        setFloatingIpArpRule(event.floatingIp(), event.portId(), completedGws, false);
-                    });
+                    if (getValidPortId(event) != null) {
+                        eventExecutor.execute(() -> {
+                            // disassociate a floating IP with an existing VM
+                            setFloatingIpArpRule(event.floatingIp(), getValidPortId(event),
+                                    completedGws, false);
+                        });
+                    }
                     break;
                 case OPENSTACK_FLOATING_IP_CREATED:
-                    eventExecutor.execute(() -> {
-                        NetFloatingIP osFip = event.floatingIp();
-
-                        // during floating IP creation, if the floating IP is
-                        // associated with any port of VM, then we will set
-                        // floating IP related ARP rules to gateway node
-                        setFloatingIpArpRule(osFip, event.portId(), completedGws, true);
-                    });
+                    // during floating IP creation, if the floating IP is
+                    // associated with any port of VM, then we will set
+                    // floating IP related ARP rules to gateway node
+                    if (getValidPortId(event) != null) {
+                        eventExecutor.execute(() -> {
+                            // associate a floating IP with an existing VM
+                            setFloatingIpArpRule(event.floatingIp(), getValidPortId(event),
+                                    completedGws, true);
+                        });
+                    }
                     break;
                 case OPENSTACK_FLOATING_IP_REMOVED:
-                    eventExecutor.execute(() -> {
-                        NetFloatingIP osFip = event.floatingIp();
-
-                        // during floating IP deletion, if the floating IP is
-                        // still associated with any port of VM, then we will
-                        // remove floating IP related ARP rules from gateway node
-                        setFloatingIpArpRule(event.floatingIp(), event.portId(), completedGws, false);
-                    });
+                    // during floating IP deletion, if the floating IP is
+                    // still associated with any port of VM, then we will
+                    // remove floating IP related ARP rules from gateway node
+                    if (getValidPortId(event) != null) {
+                        eventExecutor.execute(() -> {
+                            // associate a floating IP with an existing VM
+                            setFloatingIpArpRule(event.floatingIp(), getValidPortId(event),
+                                    completedGws, false);
+                        });
+                    }
                     break;
                 default:
                     // do nothing for the other events
@@ -562,6 +575,21 @@
             }
         }
 
+        private String getValidPortId(OpenstackRouterEvent event) {
+            NetFloatingIP osFip = event.floatingIp();
+            String portId = osFip.getPortId();
+
+            if (Strings.isNullOrEmpty(portId)) {
+                portId = event.portId();
+            }
+
+            if (portId != null && instancePortService.instancePort(portId) != null) {
+                return portId;
+            }
+
+            return null;
+        }
+
         private Set<IP> getExternalGatewaySnatIps(ExternalGateway extGw) {
             return osNetworkAdminService.ports().stream()
                     .filter(port ->
diff --git a/apps/openstacknetworking/app/src/main/java/org/onosproject/openstacknetworking/impl/OpenstackRoutingFloatingIpHandler.java b/apps/openstacknetworking/app/src/main/java/org/onosproject/openstacknetworking/impl/OpenstackRoutingFloatingIpHandler.java
index 73e9f19..f20eb51 100644
--- a/apps/openstacknetworking/app/src/main/java/org/onosproject/openstacknetworking/impl/OpenstackRoutingFloatingIpHandler.java
+++ b/apps/openstacknetworking/app/src/main/java/org/onosproject/openstacknetworking/impl/OpenstackRoutingFloatingIpHandler.java
@@ -90,7 +90,6 @@
 import static org.onosproject.openstacknetworking.util.OpenstackNetworkingUtil.swapStaleLocation;
 import static org.onosproject.openstacknetworking.util.RulePopulatorUtil.buildExtension;
 import static org.onosproject.openstacknode.api.OpenstackNode.NodeType.GATEWAY;
-import static org.openstack4j.model.network.NetworkType.FLAT;
 
 /**
  * Handles OpenStack floating IP events.
@@ -204,11 +203,11 @@
         if (install) {
             preCommitPortService.subscribePreCommit(osPort.getId(),
                     OPENSTACK_PORT_PRE_REMOVE, this.getClass().getName());
-            log.info("Subscribed the port pre-remove event");
+            log.info("Subscribed the port {} on listening pre-remove event", osPort.getId());
         } else {
             preCommitPortService.unsubscribePreCommit(osPort.getId(),
                     OPENSTACK_PORT_PRE_REMOVE, this.getClass().getName());
-            log.info("Unsubscribed the port pre-remove event");
+            log.info("Unsubscribed the port {} on listening pre-remove event", osPort.getId());
         }
 
         updateComputeNodeRules(instPort, osNet, gateway, install);
@@ -690,6 +689,12 @@
                             if (osNetworkService.port(osFip.getPortId()) != null) {
                                 disassociateFloatingIp(osFip, osFip.getPortId());
                             }
+
+                            // since we skip floating IP disassociation, we need to
+                            // manually unsubscribe the port pre-remove event
+                            preCommitPortService.unsubscribePreCommit(osFip.getPortId(),
+                                    OPENSTACK_PORT_PRE_REMOVE, this.getClass().getName());
+                            log.info("Unsubscribed the port {} on listening pre-remove event", osFip.getPortId());
                         }
                         log.info("Removed floating IP {}", osFip.getFloatingIpAddress());
                     });
@@ -945,8 +950,7 @@
         public boolean isRelevant(OpenstackNetworkEvent event) {
             // do not allow to proceed without leadership
             NodeId leader = leadershipService.getLeader(appId.name());
-            return Objects.equals(localNodeId, leader) &&
-                    event.subject().getNetworkType() != FLAT;
+            return Objects.equals(localNodeId, leader);
         }
 
         @Override
diff --git a/apps/openstacknetworking/app/src/test/java/org/onosproject/openstacknetworking/impl/InstancePortManagerTest.java b/apps/openstacknetworking/app/src/test/java/org/onosproject/openstacknetworking/impl/InstancePortManagerTest.java
index d7f0291..3f191a4 100644
--- a/apps/openstacknetworking/app/src/test/java/org/onosproject/openstacknetworking/impl/InstancePortManagerTest.java
+++ b/apps/openstacknetworking/app/src/test/java/org/onosproject/openstacknetworking/impl/InstancePortManagerTest.java
@@ -296,7 +296,7 @@
     /**
      * Tests if updating an unregistered instance port fails with an exception.
      */
-    @Test(expected = IllegalArgumentException.class)
+    @Test
     public void testUpdateUnregisteredInstancePort() {
         target.updateInstancePort(instancePort1);
     }