diff --git a/apps/segmentrouting/src/main/java/org/onosproject/segmentrouting/DefaultRoutingHandler.java b/apps/segmentrouting/src/main/java/org/onosproject/segmentrouting/DefaultRoutingHandler.java
index 1324795..82f991a 100644
--- a/apps/segmentrouting/src/main/java/org/onosproject/segmentrouting/DefaultRoutingHandler.java
+++ b/apps/segmentrouting/src/main/java/org/onosproject/segmentrouting/DefaultRoutingHandler.java
@@ -47,7 +47,7 @@
  * routing rule population.
  */
 public class DefaultRoutingHandler {
-    private static final int MAX_RETRY_ATTEMPTS = 5;
+    private static final int MAX_RETRY_ATTEMPTS = 25;
     private static final String ECMPSPG_MISSING = "ECMP shortest path graph not found";
     private static Logger log = LoggerFactory.getLogger(DefaultRoutingHandler.class);
 
@@ -212,11 +212,11 @@
                 log.trace("repopulateRoutingRulesForRoutes: running ECMP graph for device {}", link.get(0));
                 EcmpShortestPathGraph ecmpSpg = new EcmpShortestPathGraph(link.get(0), srManager);
                 if (populateEcmpRoutingRules(link.get(0), ecmpSpg, ImmutableSet.of())) {
-                    log.debug("Populating flow rules from {} to all is successful",
+                    log.debug("Populating flow rules from all to dest:{} is successful",
                               link.get(0));
                     currentEcmpSpgMap.put(link.get(0), ecmpSpg);
                 } else {
-                    log.warn("Failed to populate the flow rules from {} to all", link.get(0));
+                    log.warn("Failed to populate the flow rules from all to dest:{}", link.get(0));
                     return false;
                 }
             } else {
@@ -463,9 +463,9 @@
     /**
      * Populate ECMP rules for subnets from target to destination via nexthops.
      *
-     * @param targetSw Device ID of target switch
-     * @param destSw Device ID of destination switch
-     * @param nextHops List of next hops
+     * @param targetSw Device ID of target switch in which rules will be programmed
+     * @param destSw Device ID of final destination switch to which the rules will forward
+     * @param nextHops List of next hops via which destSw will be reached
      * @param subnets Subnets to be populated. If empty, populate all configured subnets.
      * @return true if succeed
      */
@@ -647,6 +647,8 @@
 
         @Override
         public void run() {
+            log.info("RETRY FILTER ATTEMPT# {} for dev:{}",
+                     MAX_RETRY_ATTEMPTS - attempts, devId);
             boolean success = rulePopulator.populateRouterMacVlanFilters(devId);
             if (!success && --attempts > 0) {
                 executorService.schedule(this, 200, TimeUnit.MILLISECONDS);
diff --git a/apps/segmentrouting/src/main/java/org/onosproject/segmentrouting/RoutingRulePopulator.java b/apps/segmentrouting/src/main/java/org/onosproject/segmentrouting/RoutingRulePopulator.java
index 0ddffa4..3542ec9 100644
--- a/apps/segmentrouting/src/main/java/org/onosproject/segmentrouting/RoutingRulePopulator.java
+++ b/apps/segmentrouting/src/main/java/org/onosproject/segmentrouting/RoutingRulePopulator.java
@@ -244,7 +244,8 @@
     }
 
     /**
-     * Populates IP flow rules for the router IP address.
+     * Populates IP flow rules for an IP prefix in the target device. The prefix
+     * is reachable via destination device.
      *
      * @param deviceId target device ID to set the rules
      * @param ipPrefix the IP address of the destination router
@@ -312,9 +313,11 @@
                 ipPrefix,
                 deviceId);
         ObjectiveContext context = new DefaultObjectiveContext(
-                (objective) -> log.debug("IP rule for router {} populated", ipPrefix),
+                (objective) -> log.debug("IP rule for router {} populated in dev:{}",
+                                         ipPrefix, deviceId),
                 (objective, error) ->
-                        log.warn("Failed to populate IP rule for router {}: {}", ipPrefix, error));
+                        log.warn("Failed to populate IP rule for router {}: {} in dev:{}",
+                                 ipPrefix, error, deviceId));
         srManager.flowObjectiveService.forward(deviceId, fwdBuilder.add(context));
         rulePopulationCounter.incrementAndGet();
 
@@ -356,14 +359,15 @@
     }
 
     /**
-     * Populates MPLS flow rules to all routers.
+     * Populates MPLS flow rules in the target device to point towards the
+     * destination device.
      *
-     * @param deviceId target device ID of the switch to set the rules
+     * @param targetSwId target device ID of the switch to set the rules
      * @param destSwId destination switch device ID
      * @param nextHops next hops switch ID list
      * @return true if all rules are set successfully, false otherwise
      */
-    public boolean populateMplsRule(DeviceId deviceId, DeviceId destSwId,
+    public boolean populateMplsRule(DeviceId targetSwId, DeviceId destSwId,
                                     Set<DeviceId> nextHops) {
         int segmentId;
         try {
@@ -392,11 +396,11 @@
         // If the next hop is the destination router for the segment, do pop
         if (nextHops.size() == 1 && destSwId.equals(nextHops.toArray()[0])) {
             log.debug("populateMplsRule: Installing MPLS forwarding objective for "
-                    + "label {} in switch {} with pop", segmentId, deviceId);
+                    + "label {} in switch {} with pop", segmentId, targetSwId);
 
             // bos pop case (php)
             ForwardingObjective.Builder fwdObjBosBuilder =
-                    getMplsForwardingObjective(deviceId,
+                    getMplsForwardingObjective(targetSwId,
                                                nextHops,
                                                true,
                                                true,
@@ -416,13 +420,13 @@
         } else {
             // next hop is not destination, SR CONTINUE case (swap with self)
             log.debug("Installing MPLS forwarding objective for "
-                    + "label {} in switch {} without pop", segmentId, deviceId);
+                    + "label {} in switch {} without pop", segmentId, targetSwId);
 
             // continue case with bos - this does get triggered in edge routers
             // and in core routers - driver can handle depending on availability
             // of MPLS ECMP or not
             ForwardingObjective.Builder fwdObjBosBuilder =
-                    getMplsForwardingObjective(deviceId,
+                    getMplsForwardingObjective(targetSwId,
                                                nextHops,
                                                false,
                                                true,
@@ -441,17 +445,23 @@
                                                false); */
 
         }
-
+        // XXX when other cases above are implemented check for validity of
+        // debug messages below
         for (ForwardingObjective.Builder fwdObjBuilder : fwdObjBuilders) {
             ((Builder) ((Builder) fwdObjBuilder.fromApp(srManager.appId)
                     .makePermanent()).withSelector(selector)
                     .withPriority(SegmentRoutingService.DEFAULT_PRIORITY))
                     .withFlag(ForwardingObjective.Flag.SPECIFIC);
             ObjectiveContext context = new DefaultObjectiveContext(
-                    (objective) -> log.debug("MPLS rule for SID {} populated", segmentId),
+                    (objective) -> log.debug("MPLS rule {} for SID {} populated in dev:{} ",
+                                             objective.id(), segmentId, targetSwId),
                     (objective, error) ->
-                            log.warn("Failed to populate MPLS rule for SID {}: {}", segmentId, error));
-            srManager.flowObjectiveService.forward(deviceId, fwdObjBuilder.add(context));
+                            log.warn("Failed to populate MPLS rule {} for SID {}: {} in dev:{}",
+                                     objective.id(), segmentId, error, targetSwId));
+            ForwardingObjective fob = fwdObjBuilder.add(context);
+            log.debug("Sending MPLS fwd obj {} for SID {}-> next {} in sw: {}",
+                      fob.id(), segmentId, fob.nextId(), targetSwId);
+            srManager.flowObjectiveService.forward(targetSwId, fob);
             rulePopulationCounter.incrementAndGet();
         }
 
@@ -493,13 +503,16 @@
         // packets will be hashed or not.
         fwdBuilder.withTreatment(tbuilder.build());
         NeighborSet ns = new NeighborSet(nextHops);
-        log.debug("Trying to get a nextObjid for mpls rule on device:{} to ns:{}",
+        log.debug("Trying to get a nextObjId for mpls rule on device:{} to ns:{}",
                  deviceId, ns);
 
         int nextId = srManager.getNextObjectiveId(deviceId, ns, meta);
         if (nextId <= 0) {
             log.warn("No next objective in {} for ns: {}", deviceId, ns);
             return null;
+        } else {
+            log.debug("nextObjId found:{} for mpls rule on device:{} to ns:{}",
+                      nextId, deviceId, ns);
         }
 
         fwdBuilder.nextStep(nextId);
@@ -537,40 +550,54 @@
                      deviceId);
             return false;
         }
-
+        int disabledPorts = 0, suppressedPorts = 0, filteredPorts = 0;
         for (Port port : devPorts) {
             ConnectPoint connectPoint = new ConnectPoint(deviceId, port.number());
             // TODO: Handles dynamic port events when we are ready for dynamic config
             SegmentRoutingAppConfig appConfig = srManager.cfgService
                     .getConfig(srManager.appId, SegmentRoutingAppConfig.class);
-            if ((appConfig == null || !appConfig.suppressSubnet().contains(connectPoint)) &&
-                    port.isEnabled()) {
-                Ip4Prefix portSubnet = config.getPortSubnet(deviceId, port.number());
-                VlanId assignedVlan = (portSubnet == null)
-                        ? VlanId.vlanId(SegmentRoutingManager.ASSIGNED_VLAN_NO_SUBNET)
-                        : srManager.getSubnetAssignedVlanId(deviceId, portSubnet);
+            if (!port.isEnabled()) {
+                disabledPorts++;
+                continue;
+            }
+            if (appConfig != null && appConfig.suppressSubnet().contains(connectPoint)) {
+                suppressedPorts++;
+                continue;
+            }
+            Ip4Prefix portSubnet = config.getPortSubnet(deviceId, port.number());
+            VlanId assignedVlan = (portSubnet == null)
+                    ? VlanId.vlanId(SegmentRoutingManager.ASSIGNED_VLAN_NO_SUBNET)
+                    : srManager.getSubnetAssignedVlanId(deviceId, portSubnet);
 
-                FilteringObjective.Builder fob = DefaultFilteringObjective.builder();
-                fob.withKey(Criteria.matchInPort(port.number()))
+            FilteringObjective.Builder fob = DefaultFilteringObjective.builder();
+            fob.withKey(Criteria.matchInPort(port.number()))
                 .addCondition(Criteria.matchEthDst(deviceMac))
                 .addCondition(Criteria.matchVlanId(VlanId.NONE))
                 .withPriority(SegmentRoutingService.DEFAULT_PRIORITY);
-                // vlan assignment is valid only if this instance is master
-                if (srManager.mastershipService.isLocalMaster(deviceId)) {
-                    TrafficTreatment tt = DefaultTrafficTreatment.builder()
-                            .pushVlan().setVlanId(assignedVlan).build();
-                    fob.withMeta(tt);
-                }
-                fob.permit().fromApp(srManager.appId);
-                log.debug("Sending filtering objective for dev/port:{}/{}", deviceId, port);
-                ObjectiveContext context = new DefaultObjectiveContext(
-                        (objective) -> log.debug("Filter for {} populated", connectPoint),
-                        (objective, error) ->
-                                log.warn("Failed to populate filter for {}: {}", connectPoint, error));
-                srManager.flowObjectiveService.filter(deviceId, fob.add(context));
+            // vlan assignment is valid only if this instance is master
+            if (srManager.mastershipService.isLocalMaster(deviceId)) {
+                TrafficTreatment tt = DefaultTrafficTreatment.builder()
+                        .pushVlan().setVlanId(assignedVlan).build();
+                fob.withMeta(tt);
             }
+            fob.permit().fromApp(srManager.appId);
+            log.debug("Sending filtering objective for dev/port:{}/{}", deviceId, port);
+            filteredPorts++;
+            ObjectiveContext context = new DefaultObjectiveContext(
+                (objective) -> log.debug("Filter for {} populated", connectPoint),
+                (objective, error) ->
+                log.warn("Failed to populate filter for {}: {}", connectPoint, error));
+            srManager.flowObjectiveService.filter(deviceId, fob.add(context));
         }
-        return true;
+        log.info("Filtering on dev:{}, disabledPorts:{}, suppressedPorts:{}, filteredPorts:{}",
+                  deviceId, disabledPorts, suppressedPorts, filteredPorts);
+        // XXX With this check, there is a chance that not all the ports that
+        // should be filtered actually get filtered as long as one of them does.
+        // Note there is no PORT_UPDATED event that makes the port go from disabled
+        // to enabled state, because the ports comes enabled from the switch.
+        // Check ONOS core, where the port becoming available and being declared
+        // enabled is possibly not atomic.
+        return (filteredPorts > 0) ? true : false;
     }
 
     /**
diff --git a/core/net/src/main/java/org/onosproject/net/flowobjective/impl/FlowObjectiveManager.java b/core/net/src/main/java/org/onosproject/net/flowobjective/impl/FlowObjectiveManager.java
index b6c748a..6933c07 100644
--- a/core/net/src/main/java/org/onosproject/net/flowobjective/impl/FlowObjectiveManager.java
+++ b/core/net/src/main/java/org/onosproject/net/flowobjective/impl/FlowObjectiveManager.java
@@ -239,7 +239,8 @@
     private boolean queueObjective(DeviceId deviceId, ForwardingObjective fwd) {
         if (fwd.nextId() != null &&
                 flowObjectiveStore.getNextGroup(fwd.nextId()) == null) {
-            log.trace("Queuing forwarding objective for nextId {}", fwd.nextId());
+            log.debug("Queuing forwarding objective {} for nextId {} meant for device {}",
+                      fwd.id(), fwd.nextId(), deviceId);
             // TODO: change to computeIfAbsent
             Set<PendingNext> newset = Collections.newSetFromMap(
                                           new ConcurrentHashMap<PendingNext, Boolean>());
@@ -398,7 +399,7 @@
                 Set<PendingNext> pending = pendingForwards.remove(event.subject());
 
                 if (pending == null) {
-                    log.warn("Nothing pending for this obj event {}", event);
+                    log.debug("Nothing pending for this obj event {}", event);
                     return;
                 }
 
@@ -457,7 +458,7 @@
     public List<String> getNextMappings() {
         List<String> mappings = new ArrayList<>();
         Map<Integer, NextGroup> allnexts = flowObjectiveStore.getAllGroups();
-        // XXX if the NextGroup upon decoding stored info of the deviceId
+        // XXX if the NextGroup after de-serialization actually stored info of the deviceId
         // then info on any nextObj could be retrieved from one controller instance.
         // Right now the drivers on one instance can only fetch for next-ids that came
         // to them.
diff --git a/core/store/dist/src/main/java/org/onosproject/store/flowobjective/impl/DistributedFlowObjectiveStore.java b/core/store/dist/src/main/java/org/onosproject/store/flowobjective/impl/DistributedFlowObjectiveStore.java
index 957523c..b5a57cd 100644
--- a/core/store/dist/src/main/java/org/onosproject/store/flowobjective/impl/DistributedFlowObjectiveStore.java
+++ b/core/store/dist/src/main/java/org/onosproject/store/flowobjective/impl/DistributedFlowObjectiveStore.java
@@ -30,15 +30,22 @@
 import org.onosproject.store.AbstractStore;
 import org.onosproject.store.service.AtomicCounter;
 import org.onosproject.store.service.ConsistentMap;
+import org.onosproject.store.service.MapEvent;
+import org.onosproject.store.service.MapEventListener;
 import org.onosproject.store.service.Serializer;
 import org.onosproject.store.service.StorageService;
 import org.onosproject.store.service.Versioned;
 import org.slf4j.Logger;
 
+import static org.onlab.util.Tools.groupedThreads;
 import static org.slf4j.LoggerFactory.getLogger;
 
 import java.util.HashMap;
 import java.util.Map;
+import java.util.concurrent.BlockingQueue;
+import java.util.concurrent.ExecutorService;
+import java.util.concurrent.Executors;
+import java.util.concurrent.LinkedBlockingQueue;
 
 /**
  * Manages the inventory of created next groups.
@@ -57,9 +64,16 @@
     protected StorageService storageService;
 
     private AtomicCounter nextIds;
+    private MapEventListener<Integer, byte[]> mapListener = new NextGroupListener();
+    // event queue to separate map-listener threads from event-handler threads (tpool)
+    private BlockingQueue<ObjectiveEvent> eventQ;
+    private ExecutorService tpool;
 
     @Activate
     public void activate() {
+        tpool = Executors.newFixedThreadPool(4, groupedThreads("onos/flobj-notifier", "%d", log));
+        eventQ = new LinkedBlockingQueue<ObjectiveEvent>();
+        tpool.execute(new FlowObjectiveNotifier());
         nextGroups = storageService.<Integer, byte[]>consistentMapBuilder()
                 .withName("flowobjective-groups")
                 .withSerializer(Serializer.using(
@@ -68,7 +82,7 @@
                                 .register(Versioned.class)
                                 .build("DistributedFlowObjectiveStore")))
                 .build();
-
+        nextGroups.addListener(mapListener);
         nextIds = storageService.getAtomicCounter("next-objective-counter");
         log.info("Started");
     }
@@ -76,6 +90,7 @@
 
     @Deactivate
     public void deactivate() {
+        tpool.shutdown();
         log.info("Stopped");
     }
 
@@ -120,4 +135,37 @@
     public int allocateNextId() {
         return (int) nextIds.incrementAndGet();
     }
+
+    private class FlowObjectiveNotifier implements Runnable {
+        @Override
+        public void run() {
+            try {
+                while (!Thread.currentThread().isInterrupted()) {
+                    notifyDelegate(eventQ.take());
+                }
+            } catch (InterruptedException ex) {
+                Thread.currentThread().interrupt();
+            }
+        }
+    }
+
+    private class NextGroupListener implements MapEventListener<Integer, byte[]> {
+        @Override
+        public void event(MapEvent<Integer, byte[]> event) {
+            switch (event.type()) {
+            case INSERT:
+                eventQ.add(new ObjectiveEvent(ObjectiveEvent.Type.ADD, event.key()));
+                break;
+            case REMOVE:
+                eventQ.add(new ObjectiveEvent(ObjectiveEvent.Type.REMOVE, event.key()));
+                break;
+            case UPDATE:
+                // TODO Introduce UPDATE ObjectiveEvent when the map is being updated
+                break;
+            default:
+                break;
+            }
+        }
+    }
+
 }
diff --git a/drivers/default/src/main/java/org/onosproject/driver/pipeline/Ofdpa2Pipeline.java b/drivers/default/src/main/java/org/onosproject/driver/pipeline/Ofdpa2Pipeline.java
index 6f42dbc..d1b285b 100644
--- a/drivers/default/src/main/java/org/onosproject/driver/pipeline/Ofdpa2Pipeline.java
+++ b/drivers/default/src/main/java/org/onosproject/driver/pipeline/Ofdpa2Pipeline.java
@@ -182,6 +182,12 @@
         FlowRuleOperations.Builder flowOpsBuilder = FlowRuleOperations.builder();
 
         rules = processForward(fwd);
+        if (rules == null || rules.isEmpty()) {
+            // Assumes fail message has already been generated to the objective
+            // context. Returning here prevents spurious pass message to be
+            // generated by FlowRule service for empty flowOps.
+            return;
+        }
         switch (fwd.op()) {
             case ADD:
                 rules.stream()
@@ -748,7 +754,7 @@
      *            returned if there is an issue in processing the objective.
      */
     protected Collection<FlowRule> processSpecific(ForwardingObjective fwd) {
-        log.trace("Processing specific fwd objective:{} in dev:{} with next:{}",
+        log.debug("Processing specific fwd objective:{} in dev:{} with next:{}",
                   fwd.id(), deviceId, fwd.nextId());
         boolean isEthTypeObj = isSupportedEthTypeObjective(fwd);
         boolean isEthDstObj = isSupportedEthDstObjective(fwd);
@@ -885,8 +891,8 @@
         if (fwd.nextId() != null) {
             if (forTableId == MPLS_TABLE_1 && !popMpls) {
                 log.warn("SR CONTINUE case cannot be handled as MPLS ECMP "
-                        + "is not implemented in OF-DPA yet. Aborting this flow "
-                        + "in this device {}", deviceId);
+                        + "is not implemented in OF-DPA yet. Aborting this flow {} -> next:{}"
+                        + "in this device {}", fwd.id(), fwd.nextId(), deviceId);
                 // XXX We could convert to forwarding to a single-port, via a
                 // MPLS interface, or a MPLS SWAP (with-same) but that would
                 // have to be handled in the next-objective. Also the pop-mpls
@@ -907,6 +913,11 @@
                     return Collections.emptySet();
                 }
                 tb.deferred().group(group.id());
+            } else {
+                log.warn("Cannot find group for nextId:{} in dev:{}. Aborting fwd:{}",
+                         fwd.nextId(), deviceId, fwd.id());
+                fail(fwd, ObjectiveError.FLOWINSTALLATIONFAILED);
+                return Collections.emptySet();
             }
         }
         tb.transition(ACL_TABLE);
@@ -1063,7 +1074,7 @@
             for (GroupKey gk : gkd) {
                 Group g = groupService.getGroup(deviceId, gk);
                 if (g == null) {
-                    gchain.append("  ERROR").append(" -->");
+                    gchain.append("  NoGrp").append(" -->");
                     continue;
                 }
                 gchain.append("  0x").append(Integer.toHexString(g.id().id()))
@@ -1071,7 +1082,12 @@
                 lastGroup = g;
             }
             // add port information for last group in group-chain
-            for (Instruction i: lastGroup.buckets().buckets().get(0).treatment().allInstructions()) {
+            List<Instruction> lastGroupIns = new ArrayList<Instruction>();
+            if (gchain != null) {
+                lastGroupIns = lastGroup.buckets().buckets().get(0)
+                                    .treatment().allInstructions();
+            }
+            for (Instruction i: lastGroupIns) {
                 if (i instanceof OutputInstruction) {
                     gchain.append(" port:").append(((OutputInstruction) i).port());
                 }