diff --git a/app/src/main/java/org/onosproject/segmentrouting/DefaultRoutingHandler.java b/app/src/main/java/org/onosproject/segmentrouting/DefaultRoutingHandler.java
index 98d5d4a..46d94ed 100644
--- a/app/src/main/java/org/onosproject/segmentrouting/DefaultRoutingHandler.java
+++ b/app/src/main/java/org/onosproject/segmentrouting/DefaultRoutingHandler.java
@@ -787,7 +787,7 @@
      * @param destSw1 Device ID of final destination switch to which the rules will forward
      * @param destSw2 Device ID of paired destination switch to which the rules will forward
      *                A null deviceId indicates packets should only be sent to destSw1
-     * @param nextHops Map indication a list of next hops per destSw
+     * @param nextHops Map of a set of next hops per destSw
      * @param subnets Subnets to be populated. If empty, populate all configured subnets.
      * @return true if it succeeds in populating rules
      */ // refactor
@@ -822,7 +822,8 @@
             subnets = (subnets != null && !subnets.isEmpty())
                             ? Sets.newHashSet(subnets)
                             : Sets.newHashSet(config.getSubnets(destSw1));
-            // XXX -  Rethink this
+            // XXX - Rethink this - ignoring routerIPs in all other switches
+            // even edge to edge switches
             /*subnets.add(dest1RouterIpv4.toIpPrefix());
             if (dest1RouterIpv6 != null) {
                 subnets.add(dest1RouterIpv6.toIpPrefix());
@@ -843,26 +844,6 @@
             if (!result) {
                 return false;
             }
-            /* XXX rethink this
-            IpPrefix routerIpPrefix = destRouterIpv4.toIpPrefix();
-            log.debug("* populateEcmpRoutingRulePartial in device {} towards {} "
-                    + "for router IP {}", targetSw, destSw, routerIpPrefix);
-            result = rulePopulator.populateIpRuleForRouter(targetSw, routerIpPrefix,
-                                                           destSw, nextHops);
-            if (!result) {
-                return false;
-            }
-            // If present we deal with IPv6 loopback.
-            if (destRouterIpv6 != null) {
-                routerIpPrefix = destRouterIpv6.toIpPrefix();
-                log.debug("* populateEcmpRoutingRulePartial in device {} towards {}"
-                        + " for v6 router IP {}", targetSw, destSw, routerIpPrefix);
-                result = rulePopulator.populateIpRuleForRouter(targetSw, routerIpPrefix,
-                                                               destSw, nextHops);
-                if (!result) {
-                    return false;
-                }
-            }*/
         }
 
         if (!targetIsEdge && dest1IsEdge) {
@@ -877,11 +858,20 @@
                 return false;
             }
             if (dest1RouterIpv6 != null) {
-                result = rulePopulator.populateMplsRule(targetSw, destSw1,
-                                                        nextHops.get(destSw1),
-                                                        dest1RouterIpv6);
-                if (!result) {
-                    return false;
+                int v4sid = 0, v6sid = 0;
+                try {
+                    v4sid = config.getIPv4SegmentId(destSw1);
+                    v6sid = config.getIPv6SegmentId(destSw1);
+                } catch (DeviceConfigNotFoundException e) {
+                    log.warn(e.getMessage());
+                }
+                if (v4sid != v6sid) {
+                    result = rulePopulator.populateMplsRule(targetSw, destSw1,
+                                                            nextHops.get(destSw1),
+                                                            dest1RouterIpv6);
+                    if (!result) {
+                        return false;
+                    }
                 }
             }
         }
@@ -1435,11 +1425,26 @@
                     continue;
                 }
                 if (!targetIsEdge && itrIdx > 1) {
-                    // optimization for spines to not use other leaves to get
-                    // to a leaf to avoid loops
-                    log.debug("Avoiding {} hop path for non-edge targetSw:{}"
-                            + " --> dstSw:{}", itrIdx, targetSw, dstSw);
-                    break;
+                    // optimization for spines to not use leaves to get
+                    // to a spine or other leaves
+                    boolean pathdevIsEdge = false;
+                    for (ArrayList<DeviceId> via : swViaMap.get(targetSw)) {
+                        for (DeviceId pathdev : via) {
+                            try {
+                                pathdevIsEdge = srManager.deviceConfiguration
+                                        .isEdgeDevice(pathdev);
+                            } catch (DeviceConfigNotFoundException e) {
+                                log.warn(e.getMessage());
+                            }
+                            if (pathdevIsEdge) {
+                                log.debug("Avoiding {} hop path for non-edge targetSw:{}"
+                                        + " --> dstSw:{} which goes through an edge"
+                                        + " device {} in path {}", itrIdx,
+                                          targetSw, dstSw, pathdev, via);
+                                return ImmutableSet.of();
+                            }
+                        }
+                    }
                 }
                 Set<DeviceId> nextHops = new HashSet<>();
                 for (ArrayList<DeviceId> via : swViaMap.get(targetSw)) {
diff --git a/app/src/main/java/org/onosproject/segmentrouting/LinkHandler.java b/app/src/main/java/org/onosproject/segmentrouting/LinkHandler.java
index be99764..63473a7 100644
--- a/app/src/main/java/org/onosproject/segmentrouting/LinkHandler.java
+++ b/app/src/main/java/org/onosproject/segmentrouting/LinkHandler.java
@@ -105,35 +105,33 @@
         if (!isLinkValid(link)) {
             return;
         }
-        if (srManager.deviceConfiguration == null ||
-                !srManager.deviceConfiguration.isConfigured(link.src().deviceId())) {
-            updateSeenLink(link, true);
-            // XXX revisit - what about devicePortMap
-            log.warn("Source device of this link is not configured.. "
-                    + "not processing further");
-            return;
-        }
-
         // Irrespective of whether the local is a MASTER or not for this device,
         // create group handler instance and push default TTP flow rules if needed,
         // as in a multi-instance setup, instances can initiate groups for any
-        // device.
+        // device. Also update local groupHandler stores.
         DefaultGroupHandler groupHandler = srManager.groupHandlerMap
-                .get(link.src().deviceId());
+                                                .get(link.src().deviceId());
         if (groupHandler != null) {
             groupHandler.portUpForLink(link);
         } else {
-            // XXX revisit/cleanup
             Device device = srManager.deviceService.getDevice(link.src().deviceId());
             if (device != null) {
-                log.warn("processLinkAdded: Link Added "
-                        + "Notification without Device Added "
-                        + "event, still handling it");
+                log.warn("processLinkAdded: Link Added notification without "
+                        + "Device Added event, still handling it");
                 srManager.processDeviceAdded(device);
                 groupHandler = srManager.groupHandlerMap.get(link.src().deviceId());
-                groupHandler.portUpForLink(link);
+                if (groupHandler != null) {
+                    groupHandler.portUpForLink(link);
+                }
             }
         }
+        if (srManager.deviceConfiguration == null ||
+                !srManager.deviceConfiguration.isConfigured(link.src().deviceId())) {
+            updateSeenLink(link, true);
+            log.warn("Source device of this link is not configured.. "
+                    + "not processing further");
+            return;
+        }
 
         /*
          // process link only if it is bidirectional
@@ -221,7 +219,7 @@
         srManager.defaultRoutingHandler
                 .populateRoutingRulesForLinkStatusChange(link, null, null);
 
-        // update local groupHandler stores
+        // attempt rehashing for parallel links
         DefaultGroupHandler groupHandler = srManager.groupHandlerMap
                 .get(link.src().deviceId());
         if (groupHandler != null) {
@@ -236,8 +234,8 @@
                                   .deviceId())) ? "not parallel"
                                                 : "not master");
             }
-            // ensure local stores are updated
-            groupHandler.portDown(link.src().port());
+            // ensure local stores are updated after all rerouting or rehashing
+            groupHandler.portDownForLink(link);
         } else {
             log.warn("group handler not found for dev:{} when removing link: {}",
                      link.src().deviceId(), link);
@@ -273,14 +271,14 @@
             return true;
         }
         try {
-            if (!devConfig.isEdgeDevice(srcId)
+            /*if (!devConfig.isEdgeDevice(srcId)
                     && !devConfig.isEdgeDevice(dstId)) {
                 // ignore links between spines
                 // XXX revisit when handling multi-stage fabrics
                 log.warn("Links between spines not allowed...ignoring "
                         + "link {}", link);
                 return false;
-            }
+            }*/
             if (devConfig.isEdgeDevice(srcId)
                     && devConfig.isEdgeDevice(dstId)) {
                 // ignore links between leaves if they are not pair-links
diff --git a/app/src/main/java/org/onosproject/segmentrouting/RoutingRulePopulator.java b/app/src/main/java/org/onosproject/segmentrouting/RoutingRulePopulator.java
index c152b99..bd57248 100644
--- a/app/src/main/java/org/onosproject/segmentrouting/RoutingRulePopulator.java
+++ b/app/src/main/java/org/onosproject/segmentrouting/RoutingRulePopulator.java
@@ -352,32 +352,25 @@
         DestinationSet ds;
         TrafficTreatment treatment;
 
-        // If the next hop is the same as the final destination, then MPLS label
-        // is not set.
-        /*if (nextHops.size() == 1 && nextHops.toArray()[0].equals(destSw)) {
-            tbuilder.immediate().decNwTtl();
-            ds = new DestinationSet(false, destSw);
-            treatment = tbuilder.build();
-        } else {
-            ds = new DestinationSet(false, segmentId, destSw);
-            treatment = null;
-        }*/
         if (destSw2 == null) {
             // single dst - create destination set based on next-hop
+            // If the next hop is the same as the final destination, then MPLS
+            // label is not set.
             Set<DeviceId> nhd1 = nextHops.get(destSw1);
             if (nhd1.size() == 1 && nhd1.iterator().next().equals(destSw1)) {
                 tbuilder.immediate().decNwTtl();
-                ds = new DestinationSet(false, destSw1);
+                ds = new DestinationSet(false, false, destSw1);
                 treatment = tbuilder.build();
             } else {
-                ds = new DestinationSet(false, segmentId1, destSw1);
+                ds = new DestinationSet(false, false, segmentId1, destSw1);
                 treatment = null;
             }
         } else {
             // dst pair - IP rules for dst-pairs are always from other edge nodes
             // the destination set needs to have both destinations, even if there
             // are no next hops to one of them
-            ds = new DestinationSet(false, segmentId1, destSw1, segmentId2, destSw2);
+            ds = new DestinationSet(false, false, segmentId1, destSw1,
+                                    segmentId2, destSw2);
             treatment = null;
         }
 
@@ -394,7 +387,7 @@
         }
 
         int nextId = grpHandler.getNextObjectiveId(ds, nextHops,
-                                                   metabuilder.build(), true);
+                                                   metabuilder.build(), false);
         if (nextId <= 0) {
             log.warn("No next objective in {} for ds: {}", targetSw, ds);
             return false;
@@ -461,13 +454,75 @@
     }
 
     /**
-     * Deals with !MPLS Bos use case.
+     * Populates MPLS flow rules in the target device to point towards the
+     * destination device.
+     *
+     * @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
+     * @param routerIp the router ip of the destination switch
+     * @return true if all rules are set successfully, false otherwise
+     */
+    boolean populateMplsRule(DeviceId targetSwId, DeviceId destSwId,
+                             Set<DeviceId> nextHops, IpAddress routerIp) {
+        int segmentId;
+        try {
+            if (routerIp.isIp4()) {
+                segmentId = config.getIPv4SegmentId(destSwId);
+            } else {
+                segmentId = config.getIPv6SegmentId(destSwId);
+            }
+        } catch (DeviceConfigNotFoundException e) {
+            log.warn(e.getMessage() + " Aborting populateMplsRule.");
+            return false;
+        }
+
+        List<ForwardingObjective> fwdObjs = new ArrayList<>();
+        Collection<ForwardingObjective> fwdObjsMpls;
+        // Generates the transit rules used by the standard "routing".
+        fwdObjsMpls = handleMpls(targetSwId, destSwId, nextHops, segmentId,
+                                 routerIp, true);
+        if (fwdObjsMpls.isEmpty()) {
+            return false;
+        }
+        fwdObjs.addAll(fwdObjsMpls);
+
+        // Generates the transit rules used by the MPLS Pwaas.
+        int pwSrLabel;
+        try {
+            pwSrLabel = config.getPWRoutingLabel(destSwId);
+        } catch (DeviceConfigNotFoundException e) {
+            log.warn(e.getMessage()
+                    + " Aborting populateMplsRule. No label for PseudoWire traffic.");
+            return false;
+        }
+        fwdObjsMpls = handleMpls(targetSwId, destSwId, nextHops, pwSrLabel,
+                                 routerIp, false);
+        if (fwdObjsMpls.isEmpty()) {
+            return false;
+        }
+        fwdObjs.addAll(fwdObjsMpls);
+
+        for (ForwardingObjective fwdObj : fwdObjs) {
+            log.debug("Sending MPLS fwd obj {} for SID {}-> next {} in sw: {}",
+                      fwdObj.id(), segmentId, fwdObj.nextId(), targetSwId);
+            srManager.flowObjectiveService.forward(targetSwId, fwdObj);
+            rulePopulationCounter.incrementAndGet();
+        }
+
+        return true;
+    }
+
+    /**
+     * Differentiates between popping and swapping labels when building an MPLS
+     * forwarding objective.
      *
      * @param targetSwId the target sw
      * @param destSwId the destination sw
      * @param nextHops the set of next hops
-     * @param segmentId the segmentId to match
-     * @param routerIp the router ip
+     * @param segmentId the segmentId to match representing the destination
+     *            switch
+     * @param routerIp the router ip representing the destination switch
      * @return a collection of fwdobjective
      */
     private Collection<ForwardingObjective> handleMpls(
@@ -497,9 +552,6 @@
             log.debug("populateMplsRule: Installing MPLS forwarding objective for "
                     + "label {} in switch {} with pop to next-hops {}",
                     segmentId, targetSwId, nextHops);
-            // Not-bos pop case (php for the current label). If MPLS-ECMP
-            // has been configured, the application we will request the
-            // installation for an MPLS-ECMP group.
             ForwardingObjective.Builder fwdObjNoBosBuilder =
                     getMplsForwardingObjective(targetSwId,
                                                nextHops,
@@ -507,6 +559,7 @@
                                                isMplsBos,
                                                metabuilder.build(),
                                                routerIp,
+                                               segmentId,
                                                destSwId);
             // Error case, we cannot handle, exit.
             if (fwdObjNoBosBuilder == null) {
@@ -515,13 +568,11 @@
             fwdObjBuilders.add(fwdObjNoBosBuilder);
 
         } else {
-            // next hop is not destination, SR CONTINUE case (swap with self)
+            // next hop is not destination, irrespective of the number of next
+            // hops (1 or more) -- SR CONTINUE case (swap with self)
             log.debug("Installing MPLS forwarding objective for "
                     + "label {} in switch {} without pop to next-hops {}",
                     segmentId, targetSwId, nextHops);
-            // Not-bos pop case. If MPLS-ECMP has been configured, the
-            // application we will request the installation for an MPLS-ECMP
-            // group.
             ForwardingObjective.Builder fwdObjNoBosBuilder =
                     getMplsForwardingObjective(targetSwId,
                                                nextHops,
@@ -529,6 +580,7 @@
                                                isMplsBos,
                                                metabuilder.build(),
                                                routerIp,
+                                               segmentId,
                                                destSwId);
             // Error case, we cannot handle, exit.
             if (fwdObjNoBosBuilder == null) {
@@ -541,7 +593,6 @@
         List<ForwardingObjective> fwdObjs = Lists.newArrayList();
         // We add the final property to the fwdObjs.
         for (ForwardingObjective.Builder fwdObjBuilder : fwdObjBuilders) {
-
             ((Builder) ((Builder) fwdObjBuilder
                     .fromApp(srManager.appId)
                     .makePermanent())
@@ -559,71 +610,25 @@
 
             ForwardingObjective fob = fwdObjBuilder.add(context);
             fwdObjs.add(fob);
-
         }
 
         return fwdObjs;
     }
 
     /**
-     * Populates MPLS flow rules in the target device to point towards the
-     * destination device.
+     * Returns a Forwarding Objective builder for the MPLS rule that references
+     * the desired Next Objective. Creates a DestinationSet that allows the
+     * groupHandler to create or find the required next objective.
      *
-     * @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
-     * @param routerIp the router ip
-     * @return true if all rules are set successfully, false otherwise
+     * @param targetSw the target sw
+     * @param nextHops the set of next hops
+     * @param phpRequired true if penultimate-hop-popping is required
+     * @param isBos true if matched label is bottom-of-stack
+     * @param meta metadata for creating next objective
+     * @param routerIp the router ip representing the destination switch
+     * @param destSw the destination sw
+     * @return the mpls forwarding objective builder
      */
-    boolean populateMplsRule(DeviceId targetSwId, DeviceId destSwId,
-                                    Set<DeviceId> nextHops,
-                                    IpAddress routerIp) {
-
-        int segmentId;
-        try {
-            if (routerIp.isIp4()) {
-                segmentId = config.getIPv4SegmentId(destSwId);
-            } else {
-                segmentId = config.getIPv6SegmentId(destSwId);
-            }
-        } catch (DeviceConfigNotFoundException e) {
-            log.warn(e.getMessage() + " Aborting populateMplsRule.");
-            return false;
-        }
-
-        List<ForwardingObjective> fwdObjs = new ArrayList<>();
-        Collection<ForwardingObjective> fwdObjsMpls;
-        // Generates the transit rules used by the standard "routing".
-        fwdObjsMpls = handleMpls(targetSwId, destSwId, nextHops, segmentId, routerIp, true);
-        if (fwdObjsMpls.isEmpty()) {
-            return false;
-        }
-        fwdObjs.addAll(fwdObjsMpls);
-
-        // Generates the transit rules used by the MPLS Pwaas.
-        int pwSrLabel;
-        try {
-            pwSrLabel = config.getPWRoutingLabel(destSwId);
-        } catch (DeviceConfigNotFoundException e) {
-            log.warn(e.getMessage() + " Aborting populateMplsRule. No label for PseudoWire traffic.");
-            return false;
-        }
-        fwdObjsMpls = handleMpls(targetSwId, destSwId, nextHops, pwSrLabel, routerIp, false);
-        if (fwdObjsMpls.isEmpty()) {
-            return false;
-        }
-        fwdObjs.addAll(fwdObjsMpls);
-
-        for (ForwardingObjective fwdObj : fwdObjs) {
-            log.debug("Sending MPLS fwd obj {} for SID {}-> next {} in sw: {}",
-                      fwdObj.id(), segmentId, fwdObj.nextId(), targetSwId);
-            srManager.flowObjectiveService.forward(targetSwId, fwdObj);
-            rulePopulationCounter.incrementAndGet();
-        }
-
-        return true;
-    }
-
     private ForwardingObjective.Builder getMplsForwardingObjective(
                                              DeviceId targetSw,
                                              Set<DeviceId> nextHops,
@@ -631,13 +636,15 @@
                                              boolean isBos,
                                              TrafficSelector meta,
                                              IpAddress routerIp,
+                                             int segmentId,
                                              DeviceId destSw) {
 
         ForwardingObjective.Builder fwdBuilder = DefaultForwardingObjective
                 .builder().withFlag(ForwardingObjective.Flag.SPECIFIC);
 
         TrafficTreatment.Builder tbuilder = DefaultTrafficTreatment.builder();
-
+        DestinationSet ds = null;
+        boolean simple = false;
         if (phpRequired) {
             // php case - pop should always be flow-action
             log.debug("getMplsForwardingObjective: php required");
@@ -649,49 +656,54 @@
                     tbuilder.deferred().popMpls(EthType.EtherType.IPV6.ethType());
                 }
                 tbuilder.decNwTtl();
+                // standard case -> BoS == True; pop results in IP packet and forwarding
+                // is via an ECMP group
+                ds = new DestinationSet(false, false, destSw);
             } else {
                 tbuilder.deferred().popMpls(EthType.EtherType.MPLS_UNICAST.ethType())
                     .decMplsTtl();
+                // double-label case -> BoS == False, pop results in MPLS packet
+                // depending on configuration we can ECMP this packet or choose one output
+                if (srManager.getMplsEcmp()) {
+                    ds = new DestinationSet(true, false, destSw);
+                } else {
+                    ds = new DestinationSet(true, false, destSw);
+                    simple = true;
+                }
             }
         } else {
             // swap with self case - SR CONTINUE
-            log.debug("getMplsForwardingObjective: php not required");
+            log.debug("getMplsForwardingObjective: swap with self");
             tbuilder.deferred().decMplsTtl();
+            // swap results in MPLS packet with same BoS bit regardless of bit value
+            // depending on configuration we can ECMP this packet or choose one output
+            if (srManager.getMplsEcmp()) {
+                ds = new DestinationSet(false, true, segmentId, destSw);
+            } else {
+                ds = new DestinationSet(false, true, segmentId, destSw);
+                simple = true;
+            }
         }
 
         fwdBuilder.withTreatment(tbuilder.build());
-        // if MPLS-ECMP == True we will build a standard NeighborSet.
-        // Otherwise a RandomNeighborSet.
-        DestinationSet ns = DestinationSet.destinationSet(false, false, destSw);
-        if (!isBos && this.srManager.getMplsEcmp()) {
-            ns = DestinationSet.destinationSet(false, true, destSw);
-        } else if (!isBos && !this.srManager.getMplsEcmp()) {
-            ns = DestinationSet.destinationSet(true, true, destSw);
-        }
-
-        log.debug("Trying to get a nextObjId for mpls rule on device:{} to ns:{}",
-                  targetSw, ns);
+        log.debug("Trying to get a nextObjId for mpls rule on device:{} to ds:{}",
+                  targetSw, ds);
         DefaultGroupHandler gh = srManager.getGroupHandler(targetSw);
         if (gh == null) {
             log.warn("getNextObjectiveId query - groupHandler for device {} "
                     + "not found", targetSw);
             return null;
         }
-        // If BoS == True, all forwarding is via L3 ECMP group.
-        // If Bos == False, the forwarding can be via MPLS-ECMP group or through
-        // MPLS-Interface group. This depends on the configuration of the option
-        // MPLS-ECMP.
-        // The metadata informs the driver that the next-Objective will be used
-        // by MPLS flows and if Bos == False the driver will use MPLS groups.
+
         Map<DeviceId, Set<DeviceId>> dstNextHops = new HashMap<>();
         dstNextHops.put(destSw, nextHops);
-        int nextId = gh.getNextObjectiveId(ns, dstNextHops, meta, isBos);
+        int nextId = gh.getNextObjectiveId(ds, dstNextHops, meta, simple);
         if (nextId <= 0) {
-            log.warn("No next objective in {} for ns: {}", targetSw, ns);
+            log.warn("No next objective in {} for ds: {}", targetSw, ds);
             return null;
         } else {
-            log.debug("nextObjId found:{} for mpls rule on device:{} to ns:{}",
-                      nextId, targetSw, ns);
+            log.debug("nextObjId found:{} for mpls rule on device:{} to ds:{}",
+                      nextId, targetSw, ds);
         }
 
         fwdBuilder.nextStep(nextId);
diff --git a/app/src/main/java/org/onosproject/segmentrouting/SegmentRoutingManager.java b/app/src/main/java/org/onosproject/segmentrouting/SegmentRoutingManager.java
index 559f60c..c6bb015 100644
--- a/app/src/main/java/org/onosproject/segmentrouting/SegmentRoutingManager.java
+++ b/app/src/main/java/org/onosproject/segmentrouting/SegmentRoutingManager.java
@@ -1263,6 +1263,11 @@
             .populateRoutingRulesForLinkStatusChange(null, null, device.id());
         defaultRoutingHandler.purgeEcmpGraph(device.id());
         xConnectHandler.removeDevice(device.id());
+
+        // Cleanup all internal groupHandler stores for this device. Should be
+        // done after all rerouting or rehashing has been completed
+        groupHandlerMap.entrySet()
+            .forEach(entry -> entry.getValue().cleanUpForNeighborDown(device.id()));
     }
 
     private void processPortUpdated(Device device, Port port) {
diff --git a/app/src/main/java/org/onosproject/segmentrouting/TunnelHandler.java b/app/src/main/java/org/onosproject/segmentrouting/TunnelHandler.java
index e18b920..1dd845b 100644
--- a/app/src/main/java/org/onosproject/segmentrouting/TunnelHandler.java
+++ b/app/src/main/java/org/onosproject/segmentrouting/TunnelHandler.java
@@ -222,7 +222,7 @@
             deviceIds.add(config.getDeviceId(sid));
         }
         // For these NeighborSet isMpls is meaningless.
-        DestinationSet ns = new DestinationSet(false,
+        DestinationSet ns = new DestinationSet(false, false,
                                          tunnel.labelIds().get(2),
                                          DeviceId.NONE);
 
diff --git a/app/src/main/java/org/onosproject/segmentrouting/config/DeviceConfiguration.java b/app/src/main/java/org/onosproject/segmentrouting/config/DeviceConfiguration.java
index 7ea430d..070a7ec 100644
--- a/app/src/main/java/org/onosproject/segmentrouting/config/DeviceConfiguration.java
+++ b/app/src/main/java/org/onosproject/segmentrouting/config/DeviceConfiguration.java
@@ -196,7 +196,6 @@
     @Override
     public int getIPv4SegmentId(DeviceId deviceId) throws DeviceConfigNotFoundException {
         SegmentRouterInfo srinfo = deviceConfigMap.get(deviceId);
-        log.info("DEVICE MAP IS {}", deviceConfigMap);
         if (srinfo != null) {
             log.trace("getIPv4SegmentId for device{} is {}", deviceId, srinfo.ipv4NodeSid);
             return srinfo.ipv4NodeSid;
diff --git a/app/src/main/java/org/onosproject/segmentrouting/grouphandler/DefaultGroupHandler.java b/app/src/main/java/org/onosproject/segmentrouting/grouphandler/DefaultGroupHandler.java
index 3cf1331..1e0e6fd 100644
--- a/app/src/main/java/org/onosproject/segmentrouting/grouphandler/DefaultGroupHandler.java
+++ b/app/src/main/java/org/onosproject/segmentrouting/grouphandler/DefaultGroupHandler.java
@@ -188,7 +188,8 @@
     }
 
     /**
-     * Updates local stores for link-src device/port to neighbor (link-dst).
+     * Updates local stores for link-src-device/port to neighbor (link-dst) for
+     * link that has come up.
      *
      * @param link the infrastructure link
      */
@@ -207,11 +208,13 @@
     }
 
     /**
-     * Updates local stores for port that has gone down.
+     * Updates local stores for link-src-device/port to neighbor (link-dst) for
+     * link that has gone down.
      *
-     * @param port port number that has gone down
+     * @param link the infrastructure link
      */
-    public void portDown(PortNumber port) {
+    public void portDownForLink(Link link) {
+        PortNumber port = link.src().port();
         if (portDeviceMap.get(port) == null) {
             log.warn("portDown: unknown port");
             return;
@@ -224,6 +227,18 @@
     }
 
     /**
+     * Cleans up local stores for removed neighbor device.
+     *
+     * @param neighborId the device identifier for the neighbor device
+     */
+    public void cleanUpForNeighborDown(DeviceId neighborId) {
+        Set<PortNumber> ports = devicePortMap.remove(neighborId);
+        if (ports != null) {
+            ports.forEach(p -> portDeviceMap.remove(p));
+        }
+    }
+
+    /**
      * Checks all groups in the src-device of link for neighbor sets that include
      * the dst-device of link, and edits the hash groups according to link up
      * or down. Should only be called by the master instance of the src-switch
@@ -248,8 +263,11 @@
                 .stream()
                 .filter(entry -> entry.getKey().deviceId().equals(deviceId))
                 // Filter out PW transit groups or include them if MPLS ECMP is supported
-                .filter(entry -> !entry.getKey().destinationSet().mplsSet() ||
-                        (entry.getKey().destinationSet().mplsSet() && srManager.getMplsEcmp()))
+                .filter(entry -> !entry.getKey().destinationSet().notBos() ||
+                        (entry.getKey().destinationSet().notBos() && srManager.getMplsEcmp()))
+                // Filter out simple SWAP groups or include them if MPLS ECMP is supported
+                .filter(entry -> !entry.getKey().destinationSet().swap() ||
+                        (entry.getKey().destinationSet().swap() && srManager.getMplsEcmp()))
                 .filter(entry -> entry.getValue().containsNextHop(link.dst().deviceId()))
                 .map(entry -> entry.getKey())
                 .collect(Collectors.toSet());
@@ -452,6 +470,21 @@
             int edgeLabel = dskey.destinationSet().getEdgeLabel(destSw);
             Integer nextId = nhops.nextId();
 
+            // some store elements may not be hashed next-objectives - ignore them
+            if (isSimpleNextObjective(dskey)) {
+                log.debug("Ignoring {} of SIMPLE nextObj for targetSw:{}"
+                        + " -> dstSw:{} with current nextHops:{} to new"
+                        + " nextHops: {} in nextId:{}",
+                          (revoke) ? "removal" : "addition", targetSw, destSw,
+                          currNeighbors, nextHops, nextId);
+                if ((revoke && !nextHops.isEmpty())
+                        || (!revoke && !nextHops.equals(currNeighbors))) {
+                    log.warn("Simple next objective cannot be edited to "
+                            + "move from {} to {}", currNeighbors, nextHops);
+                }
+                continue;
+            }
+
             if (currNeighbors == null || nextHops == null) {
                 log.warn("fixing hash groups but found currNeighbors:{} or nextHops:{}"
                         + " in targetSw:{} for dstSw:{}", currNeighbors, nextHops,
@@ -514,6 +547,7 @@
                                new NextNeighbors(currentNextHops.dstNextHops(),
                                                  currentNextHops.nextId()));
         }
+
         // even if one fails and others succeed, return false so ECMPspg not updated
         return success;
     }
@@ -615,6 +649,18 @@
     }
 
     /**
+     * Returns true if the destination set is meant for swap or multi-labeled
+     * packet transport, and MPLS ECMP is not supported.
+     *
+     * @param dskey the key representing the destination set
+     * @return true if destination set is meant for simple next objectives
+     */
+    boolean isSimpleNextObjective(DestinationSetNextObjectiveStoreKey dskey) {
+        return (dskey.destinationSet().notBos() || dskey.destinationSet().swap())
+                && !srManager.getMplsEcmp();
+    }
+
+    /**
      * Adds or removes a port that has been configured with a vlan to a broadcast group
      * for bridging. Should only be called by the master instance for this device.
      *
@@ -678,23 +724,26 @@
     }
 
     /**
-     * Returns the next objective of type hashed associated with the destination set.
-     * In addition, updates the existing next-objective if new route-route paths found
-     * have resulted in the addition of new next-hops to a particular destination.
-     * If there is no existing next objective for this destination set, this method
-     * would create a next objective and return the nextId. Optionally metadata can be
-     * passed in for the creation of the next objective.
+     * Returns the next objective of type hashed (or simple) associated with the
+     * destination set. In addition, updates the existing next-objective if new
+     * route-paths found have resulted in the addition of new next-hops to a
+     * particular destination. If there is no existing next objective for this
+     * destination set, this method would create a next objective and return the
+     * nextId. Optionally metadata can be passed in for the creation of the next
+     * objective. If the parameter simple is true then a simple next objective
+     * is created instead of a hashed one.
      *
      * @param ds destination set
      * @param nextHops a map of per destination next hops
      * @param meta metadata passed into the creation of a Next Objective
-     * @param isBos if Bos is set
+     * @param simple if true, a simple next objective will be created instead of
+     *            a hashed next objective
      * @return int if found or -1 if there are errors in the creation of the
-     *          neighbor set.
+     *         neighbor set.
      */
     public int getNextObjectiveId(DestinationSet ds,
                                   Map<DeviceId, Set<DeviceId>> nextHops,
-                                  TrafficSelector meta, boolean isBos) {
+                                  TrafficSelector meta, boolean simple) {
         NextNeighbors next = dsNextObjStore.
                 get(new DestinationSetNextObjectiveStoreKey(deviceId, ds));
         if (next == null) {
@@ -708,7 +757,7 @@
                       (nsStoreEntry.getKey().deviceId().equals(deviceId)))
                       .collect(Collectors.toList()));
 
-            createGroupFromDestinationSet(ds, nextHops, meta, isBos);
+            createGroupFromDestinationSet(ds, nextHops, meta, simple);
             next = dsNextObjStore.
                     get(new DestinationSetNextObjectiveStoreKey(deviceId, ds));
             if (next == null) {
@@ -833,39 +882,38 @@
         }
 
         // Update portToDevice database
-        DeviceId prev = portDeviceMap.putIfAbsent(portToNeighbor, neighborId);
+        // should always update as neighbor could have changed on this port
+        DeviceId prev = portDeviceMap.put(portToNeighbor, neighborId);
         if (prev != null) {
-            log.debug("Device: {} port: {} already has neighbor: {} ",
+            log.debug("Device/port: {}/{} previous neighbor: {}, current neighbor: {} ",
                       deviceId, portToNeighbor, prev, neighborId);
         }
     }
 
     /**
      * Creates a NextObjective for a hash group in this device from a given
-     * DestinationSet.
+     * DestinationSet. If the parameter simple is true, a simple next objective
+     * is created instead.
      *
      * @param ds the DestinationSet
      * @param neighbors a map for each destination and its next-hops
      * @param meta metadata passed into the creation of a Next Objective
-     * @param isBos if BoS is set
+     * @param simple if true, a simple next objective will be created instead of
+     *            a hashed next objective
      */
     public void createGroupFromDestinationSet(DestinationSet ds,
                                               Map<DeviceId, Set<DeviceId>> neighbors,
                                               TrafficSelector meta,
-                                              boolean isBos) {
+                                              boolean simple) {
         int nextId = flowObjectiveService.allocateNextId();
-        NextObjective.Type type = NextObjective.Type.HASHED;
+        NextObjective.Type type = (simple) ? NextObjective.Type.SIMPLE
+                                           : NextObjective.Type.HASHED;
         if (neighbors == null || neighbors.isEmpty()) {
             log.warn("createGroupsFromDestinationSet: needs at least one neighbor"
                     + "to create group in dev:{} for ds: {} with next-hops {}",
                     deviceId, ds, neighbors);
             return;
         }
-        // If Bos == False and MPLS-ECMP == false, we have
-        // to use simple group and we will pick a single neighbor for a single dest.
-        if (!isBos && !srManager.getMplsEcmp()) {
-            type = NextObjective.Type.SIMPLE;
-        }
 
         NextObjective.Builder nextObjBuilder = DefaultNextObjective
                 .builder()
@@ -878,7 +926,7 @@
 
         // create treatment buckets for each neighbor for each dst Device
         // except in the special case where we only want to pick a single
-        // neighbor for a simple group
+        // neighbor/port for a simple nextObj
         boolean foundSingleNeighbor = false;
         boolean treatmentAdded = false;
         Map<DeviceId, Set<DeviceId>> dstNextHops = new ConcurrentHashMap<>();
@@ -912,8 +960,8 @@
                 }
                 // For each port to the neighbor, we create a new treatment
                 Set<PortNumber> neighborPorts = devicePortMap.get(neighborId);
-                // In this case we are using a SIMPLE group. We randomly pick a port
-                if (!isBos && !srManager.getMplsEcmp()) {
+                // In this case we need a SIMPLE nextObj. We randomly pick a port
+                if (simple) {
                     int size = devicePortMap.get(neighborId).size();
                     int index = RandomUtils.nextInt(0, size);
                     neighborPorts = Collections.singleton(
@@ -928,9 +976,14 @@
                     tBuilder.setEthDst(neighborMac).setEthSrc(nodeMacAddr);
                     int edgeLabel = ds.getEdgeLabel(dst);
                     if (edgeLabel != DestinationSet.NO_EDGE_LABEL) {
-                        tBuilder.pushMpls()
-                        .copyTtlOut()
-                        .setMpls(MplsLabel.mplsLabel(edgeLabel));
+                        if (simple) {
+                            // swap label case
+                            tBuilder.setMpls(MplsLabel.mplsLabel(edgeLabel));
+                        } else {
+                            // ecmp with label push case
+                            tBuilder.pushMpls().copyTtlOut()
+                                    .setMpls(MplsLabel.mplsLabel(edgeLabel));
+                        }
                     }
                     tBuilder.setOutput(sp);
                     nextObjBuilder.addTreatment(tBuilder.build());
@@ -1395,8 +1448,11 @@
                         .stream()
                         .filter(entry -> entry.getKey().deviceId().equals(deviceId))
                         // Filter out PW transit groups or include them if MPLS ECMP is supported
-                        .filter(entry -> !entry.getKey().destinationSet().mplsSet() ||
-                                (entry.getKey().destinationSet().mplsSet() && srManager.getMplsEcmp()))
+                        .filter(entry -> !entry.getKey().destinationSet().notBos() ||
+                                (entry.getKey().destinationSet().notBos() && srManager.getMplsEcmp()))
+                        // Filter out simple SWAP groups or include them if MPLS ECMP is supported
+                        .filter(entry -> !entry.getKey().destinationSet().swap() ||
+                                (entry.getKey().destinationSet().swap() && srManager.getMplsEcmp()))
                         .map(entry -> entry.getKey())
                         .collect(Collectors.toSet());
                 for (DestinationSetNextObjectiveStoreKey dsKey : dsKeySet) {
@@ -1434,8 +1490,11 @@
                                         + " port/label {}/{} to dst {} via {}",
                                         deviceId, nid, port, edgeLabel,
                                         dstDev, neighbor);
-                                nextObjBuilder.addTreatment(treatmentBuilder(port,
-                                                                neighborMac, edgeLabel));
+                                nextObjBuilder
+                                    .addTreatment(treatmentBuilder(port,
+                                                                   neighborMac,
+                                                                   dsKey.destinationSet().swap(),
+                                                                   edgeLabel));
                             });
                         });
                     });
@@ -1450,16 +1509,22 @@
         }
 
         TrafficTreatment treatmentBuilder(PortNumber outport, MacAddress dstMac,
-                                          int edgeLabel) {
+                                          boolean swap, int edgeLabel) {
             TrafficTreatment.Builder tBuilder =
                     DefaultTrafficTreatment.builder();
             tBuilder.setOutput(outport)
                 .setEthDst(dstMac)
                 .setEthSrc(nodeMacAddr);
             if (edgeLabel != DestinationSet.NO_EDGE_LABEL) {
-                tBuilder.pushMpls()
-                    .copyTtlOut()
-                    .setMpls(MplsLabel.mplsLabel(edgeLabel));
+                if (swap) {
+                    // swap label case
+                    tBuilder.setMpls(MplsLabel.mplsLabel(edgeLabel));
+                } else {
+                    // ecmp with label push case
+                    tBuilder.pushMpls()
+                        .copyTtlOut()
+                        .setMpls(MplsLabel.mplsLabel(edgeLabel));
+                }
             }
             return tBuilder.build();
         }
diff --git a/app/src/main/java/org/onosproject/segmentrouting/grouphandler/DestinationSet.java b/app/src/main/java/org/onosproject/segmentrouting/grouphandler/DestinationSet.java
index 7f839cf..0626bc8 100644
--- a/app/src/main/java/org/onosproject/segmentrouting/grouphandler/DestinationSet.java
+++ b/app/src/main/java/org/onosproject/segmentrouting/grouphandler/DestinationSet.java
@@ -28,15 +28,17 @@
 import static org.slf4j.LoggerFactory.getLogger;
 
 /**
- * Representation of a set of destination switch dpids along with their edge-node
- * labels. Meant to be used as a lookup-key in a hash-map to retrieve an ECMP-group
- * that hashes packets towards a specific destination switch,
- * or paired-destination switches.
+ * Representation of a set of destination switch dpids along with their
+ * edge-node labels. Meant to be used as a lookup-key in a hash-map to retrieve
+ * an ECMP-group that hashes packets towards a specific destination switch, or
+ * paired-destination switches. May also be used to represent cases where the
+ * forwarding does not use ECMP groups (ie SIMPLE next objectives)
  */
 public class DestinationSet {
     public static final int NO_EDGE_LABEL = -1;
     private static final int NOT_ASSIGNED = 0;
-    private boolean mplsSet;
+    private boolean notBos; // XXX replace with enum
+    private boolean swap; // XXX replace with enum
     private final DeviceId dstSw1;
     private final int edgeLabel1;
     private final DeviceId dstSw2;
@@ -48,12 +50,14 @@
     /**
      * Constructor for a single destination with no Edge label.
      *
-     * @param isMplsSet indicates if it is a mpls destination set
+     * @param isNotBos indicates if it is meant for a non bottom-of-stack label
+     * @param isSwap indicates if it is meant for a swap action
      * @param dstSw the destination switch
      */
-    public DestinationSet(boolean isMplsSet, DeviceId dstSw) {
+    public DestinationSet(boolean isNotBos, boolean isSwap, DeviceId dstSw) {
         this.edgeLabel1 = NO_EDGE_LABEL;
-        this.mplsSet = isMplsSet;
+        this.notBos = isNotBos;
+        this.swap = isSwap;
         this.dstSw1 = dstSw;
         this.edgeLabel2 = NOT_ASSIGNED;
         this.dstSw2 = null;
@@ -62,13 +66,15 @@
     /**
      * Constructor for a single destination with Edge label.
      *
-     * @param isMplsSet indicates if it is a mpls destination set
+     * @param isNotBos indicates if it is meant for a non bottom-of-stack label
+     * @param isSwap indicates if it is meant for a swap action
      * @param edgeLabel label to be pushed as part of group operation
      * @param dstSw the destination switch
      */
-    public DestinationSet(boolean isMplsSet,
+    public DestinationSet(boolean isNotBos, boolean isSwap,
                        int edgeLabel, DeviceId dstSw) {
-        this.mplsSet = isMplsSet;
+        this.notBos = isNotBos;
+        this.swap = isSwap;
         this.edgeLabel1 = edgeLabel;
         this.dstSw1 = dstSw;
         this.edgeLabel2 = NOT_ASSIGNED;
@@ -76,19 +82,23 @@
     }
 
     /**
-     * Constructor for paired destination switches and their associated
-     * edge labels.
+     * Constructor for paired destination switches and their associated edge
+     * labels.
      *
-     * @param isMplsSet indicates if it is a mpls destination set
-     * @param edgeLabel1 label to be pushed as part of group operation for dstSw1
+     * @param isNotBos indicates if it is meant for a non bottom-of-stack label
+     * @param isSwap indicates if it is meant for a swap action
+     * @param edgeLabel1 label to be pushed as part of group operation for
+     *            dstSw1
      * @param dstSw1 one of the paired destination switches
-     * @param edgeLabel2 label to be pushed as part of group operation for dstSw2
+     * @param edgeLabel2 label to be pushed as part of group operation for
+     *            dstSw2
      * @param dstSw2 the other paired destination switch
      */
-    public DestinationSet(boolean isMplsSet,
+    public DestinationSet(boolean isNotBos, boolean isSwap,
                           int edgeLabel1, DeviceId dstSw1,
                           int edgeLabel2, DeviceId dstSw2) {
-        this.mplsSet = isMplsSet;
+        this.notBos = isNotBos;
+        this.swap = isSwap;
         if (dstSw1.toString().compareTo(dstSw2.toString()) <= 0) {
             this.edgeLabel1 = edgeLabel1;
             this.dstSw1 = dstSw1;
@@ -108,52 +118,13 @@
     public DestinationSet() {
         this.edgeLabel1 = NOT_ASSIGNED;
         this.edgeLabel2 = NOT_ASSIGNED;
-        this.mplsSet = true;
+        this.notBos = true;
+        this.swap = true;
         this.dstSw1 = DeviceId.NONE;
         this.dstSw2 = DeviceId.NONE;
     }
 
     /**
-     * Factory method for DestinationSet hierarchy.
-     *
-     * @param random the expected behavior.
-     * @param isMplsSet indicates if it is a mpls destination set
-     * @param dstSw the destination switch
-     * @return the destination set object.
-     */
-    public static DestinationSet destinationSet(boolean random,
-                                          boolean isMplsSet, DeviceId dstSw) {
-        return random ? new RandomDestinationSet(dstSw)
-                      : new DestinationSet(isMplsSet, dstSw);
-    }
-
-    /**
-     * Factory method for DestinationSet hierarchy.
-     *
-     * @param random the expected behavior.
-     * @param isMplsSet indicates if it is a mpls destination set
-     * @param edgeLabel label to be pushed as part of group operation
-     * @param dstSw the destination switch
-     * @return the destination set object
-     */
-    public static DestinationSet destinationSet(boolean random,
-                                          boolean isMplsSet, int edgeLabel,
-                                          DeviceId dstSw) {
-        return random ? new RandomDestinationSet(edgeLabel, dstSw)
-                      : new DestinationSet(isMplsSet, edgeLabel, dstSw);
-    }
-
-    /**
-     * Factory method for DestinationSet hierarchy.
-     *
-     * @param random the expected behavior.
-     * @return the destination set object
-     */
-    public static DestinationSet destinationSet(boolean random) {
-        return random ? new RandomDestinationSet() : new DestinationSet();
-    }
-
-    /**
      * Gets the label associated with given destination switch.
      *
      * @param dstSw the destination switch
@@ -183,12 +154,21 @@
     }
 
     /**
-     * Gets the value of mplsSet.
+     * Gets the value of notBos.
      *
-     * @return the value of mplsSet
+     * @return the value of notBos
      */
-    public boolean mplsSet() {
-        return mplsSet;
+    public boolean notBos() {
+        return notBos;
+    }
+
+    /**
+     * Gets the value of swap.
+     *
+     * @return the value of swap
+     */
+    public boolean swap() {
+        return swap;
     }
 
     // The list of destination ids and label are used for comparison.
@@ -202,7 +182,8 @@
         }
         DestinationSet that = (DestinationSet) o;
         boolean equal = (this.edgeLabel1 == that.edgeLabel1 &&
-                            this.mplsSet == that.mplsSet &&
+                            this.notBos == that.notBos &&
+                            this.swap == that.swap &&
                             this.dstSw1.equals(that.dstSw1));
         if (this.dstSw2 != null && that.dstSw2 == null ||
                 this.dstSw2 == null && that.dstSw2 != null) {
@@ -219,15 +200,26 @@
     @Override
     public int hashCode() {
         if (dstSw2 == null) {
-            return Objects.hash(mplsSet, edgeLabel1, dstSw1);
+            return Objects.hash(notBos, swap, edgeLabel1, dstSw1);
         }
-        return Objects.hash(mplsSet, edgeLabel1, dstSw1, edgeLabel2, dstSw2);
+        return Objects.hash(notBos, swap, edgeLabel1, dstSw1, edgeLabel2,
+                            dstSw2);
     }
 
     @Override
     public String toString() {
+        String type;
+        if (!notBos && !swap) {
+            type = "default";
+        } else if (!notBos && swap) {
+            type = "swapbos";
+        } else if (notBos && !swap) {
+            type = "not-bos";
+        } else {
+            type = "swap-nb";
+        }
         ToStringHelper h = toStringHelper(this)
-                                .add("MplsSet", mplsSet)
+                                .add("Type", type)
                                 .add("DstSw1", dstSw1)
                                 .add("Label1", edgeLabel1);
         if (dstSw2 != null) {
diff --git a/app/src/main/java/org/onosproject/segmentrouting/grouphandler/RandomDestinationSet.java b/app/src/main/java/org/onosproject/segmentrouting/grouphandler/RandomDestinationSet.java
deleted file mode 100644
index 3671b03..0000000
--- a/app/src/main/java/org/onosproject/segmentrouting/grouphandler/RandomDestinationSet.java
+++ /dev/null
@@ -1,60 +0,0 @@
-/*
- * Copyright 2016-present Open Networking Foundation
- *
- * Licensed under the Apache License, Version 2.0 (the "License");
- * you may not use this file except in compliance with the License.
- * You may obtain a copy of the License at
- *
- *     http://www.apache.org/licenses/LICENSE-2.0
- *
- * Unless required by applicable law or agreed to in writing, software
- * distributed under the License is distributed on an "AS IS" BASIS,
- * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
- * See the License for the specific language governing permissions and
- * limitations under the License.
- */
-
-package org.onosproject.segmentrouting.grouphandler;
-
-import org.onosproject.net.DeviceId;
-
-/**
- * Extends its super class modifying its internal behavior.
- * Pick a neighbor will pick a random neighbor.
- */
-public class RandomDestinationSet extends DestinationSet {
-
-    public RandomDestinationSet(DeviceId dstSw) {
-        super(true, dstSw);
-    }
-
-    public RandomDestinationSet(int edgeLabel,
-                             DeviceId dstSw) {
-        super(true, edgeLabel, dstSw);
-    }
-
-    public RandomDestinationSet() {
-        super();
-    }
-
-    // XXX revisit the need for this class since neighbors no longer stored here
-    // will be handled when we fix pseudowires for dual-Tor scenarios
-
-
-    /*@Override
-    public DeviceId getFirstNeighbor() {
-        if (getDeviceIds().isEmpty()) {
-            return DeviceId.NONE;
-        }
-        int size = getDeviceIds().size();
-        int index = RandomUtils.nextInt(0, size);
-        return Iterables.get(getDeviceIds(), index);
-    }*/
-
-    @Override
-    public String toString() {
-        return " RandomNeighborset Sw: " //+ getDeviceIds()
-                + " and Label: " //+ getEdgeLabel()
-                + " for destination: "; // + getDestinationSw();
-    }
-}
diff --git a/app/src/main/java/org/onosproject/segmentrouting/mcast/McastHandler.java b/app/src/main/java/org/onosproject/segmentrouting/mcast/McastHandler.java
index cd59ee5..732d884 100644
--- a/app/src/main/java/org/onosproject/segmentrouting/mcast/McastHandler.java
+++ b/app/src/main/java/org/onosproject/segmentrouting/mcast/McastHandler.java
@@ -131,7 +131,7 @@
     private boolean isMcastStable() {
         long last = (long) (lastMcastChange.toEpochMilli() / 1000.0);
         long now = (long) (Instant.now().toEpochMilli() / 1000.0);
-        log.debug("Mcast stable since {}s", now - last);
+        log.trace("Mcast stable since {}s", now - last);
         return (now - last) > MCAST_STABLITY_THRESHOLD;
     }
 
diff --git a/app/src/test/java/org/onosproject/segmentrouting/grouphandler/DestinationSetTest.java b/app/src/test/java/org/onosproject/segmentrouting/grouphandler/DestinationSetTest.java
index f890852..6abf6e3 100644
--- a/app/src/test/java/org/onosproject/segmentrouting/grouphandler/DestinationSetTest.java
+++ b/app/src/test/java/org/onosproject/segmentrouting/grouphandler/DestinationSetTest.java
@@ -23,7 +23,7 @@
 import static org.junit.Assert.assertTrue;
 
 public class DestinationSetTest {
-    DestinationSet ds1, ds2, ds3, ds4;
+    DestinationSet ds1, ds2, ds3, ds4, ds5, ds6;
     DeviceId d201, d202;
     int el201, el202;
 
@@ -33,30 +33,36 @@
         d202 = DeviceId.deviceId("of:0000000000000202");
         el201 = 201;
         el202 = 202;
-        ds1 = new DestinationSet(false, d201);
-        ds2 = new DestinationSet(false, el201, d201);
-        ds3 = new DestinationSet(false, el201, d201, el202, d202);
-        ds4 = new DestinationSet(false,
+        ds1 = new DestinationSet(false, false, d201);
+        ds2 = new DestinationSet(false, false, el201, d201);
+        ds3 = new DestinationSet(false, false, el201, d201, el202, d202);
+        ds4 = new DestinationSet(false, false,
                                  DestinationSet.NO_EDGE_LABEL, d201,
                                  DestinationSet.NO_EDGE_LABEL, d202);
+        ds5 = new DestinationSet(true, false, d201); // not-bos
+        ds6 = new DestinationSet(false, true, el201, d201); // swap group
     }
 
     @Test
     public void testIsValid() {
-        assertTrue(!ds1.mplsSet());
+        assertTrue(!ds1.notBos());
+        assertTrue(!ds1.swap());
         assertTrue(ds1.getEdgeLabel(d201) == DestinationSet.NO_EDGE_LABEL);
         assertTrue(ds1.getDestinationSwitches().size() == 1);
 
-        assertTrue(!ds2.mplsSet());
+        assertTrue(!ds2.notBos());
+        assertTrue(!ds2.swap());
         assertTrue(ds2.getEdgeLabel(d201) == el201);
         assertTrue(ds2.getDestinationSwitches().size() == 1);
 
-        assertTrue(!ds3.mplsSet());
+        assertTrue(!ds3.notBos());
+        assertTrue(!ds3.swap());
         assertTrue(ds3.getEdgeLabel(d201) == el201);
         assertTrue(ds3.getEdgeLabel(d202) == el202);
         assertTrue(ds3.getDestinationSwitches().size() == 2);
 
-        assertTrue(!ds4.mplsSet());
+        assertTrue(!ds4.notBos());
+        assertTrue(!ds4.swap());
         assertTrue(ds4.getEdgeLabel(d201) == DestinationSet.NO_EDGE_LABEL);
         assertTrue(ds4.getEdgeLabel(d202) == DestinationSet.NO_EDGE_LABEL);
         assertTrue(ds4.getDestinationSwitches().size() == 2);
@@ -65,85 +71,104 @@
         assertFalse(ds1.equals(ds4));
         assertFalse(ds3.equals(ds4));
         assertFalse(ds2.equals(ds3));
+        assertFalse(ds1.equals(ds3));
+
+        assertFalse(ds1.equals(ds5));
+        assertFalse(ds2.equals(ds6));
     }
 
 
     @Test
     public void testOneDestinationWithoutLabel() {
-        DestinationSet testds = new DestinationSet(false, d201);
+        DestinationSet testds = new DestinationSet(false, false, d201);
         assertTrue(testds.equals(ds1)); // match
 
-        testds = new DestinationSet(true, d201);
-        assertFalse(testds.equals(ds1)); //wrong mplsSet
+        testds = new DestinationSet(true, false, d201);
+        assertFalse(testds.equals(ds1)); // wrong notBos
+        assertTrue(testds.equals(ds5)); // correct notBos
 
-        testds = new DestinationSet(false, d202);
+        testds = new DestinationSet(false, false, d202);
         assertFalse(testds.equals(ds1)); //wrong device
 
-        testds = new DestinationSet(false, el201, d201);
+        testds = new DestinationSet(false, false, el201, d201);
         assertFalse(testds.equals(ds1)); // wrong label
 
-        testds = new DestinationSet(false, -1, d201, -1, d202);
+        testds = new DestinationSet(false, false, -1, d201, -1, d202);
         assertFalse(testds.equals(ds1)); // 2-devs should not match
+
+        testds = new DestinationSet(false, true, d201);
+        assertFalse(testds.equals(ds1)); // wrong swap
+        assertFalse(testds.equals(ds6)); // wrong label
+
+        testds = new DestinationSet(false, true, el201, d201);
+        assertTrue(testds.equals(ds6)); // correct swap
+
+        testds = new DestinationSet(false, true, DestinationSet.NO_EDGE_LABEL, d201);
+        assertFalse(testds.equals(ds6)); // wrong label
+
+        testds = new DestinationSet(true, true, el201, d201);
+        assertFalse(testds.equals(ds6)); // wrong notbos
     }
 
 
 
     @Test
     public void testOneDestinationWithLabel() {
-        DestinationSet testds = new DestinationSet(false, 203, d202);
+        DestinationSet testds = new DestinationSet(false, false, 203, d202);
         assertFalse(testds.equals(ds2)); //wrong label
 
-        testds = new DestinationSet(true, 201, d201);
-        assertFalse(testds.equals(ds2)); //wrong mplsSet
+        testds = new DestinationSet(true, false, 201, d201);
+        assertFalse(testds.equals(ds2)); // wrong notBos
 
-        testds = new DestinationSet(false, 201, d202);
+        testds = new DestinationSet(false, false, 201, d202);
         assertFalse(testds.equals(ds2)); //wrong device
 
-        testds = new DestinationSet(false, 201, DeviceId.deviceId("of:0000000000000201"));
+        testds = new DestinationSet(false, false, 201,
+                                    DeviceId.deviceId("of:0000000000000201"));
         assertTrue(testds.equals(ds2)); // match
 
-        testds = new DestinationSet(false, d201);
+        testds = new DestinationSet(false, false, d201);
         assertFalse(testds.equals(ds2)); // wrong label
 
-        testds = new DestinationSet(false, el201, d201, el202, d202);
+        testds = new DestinationSet(false, false, el201, d201, el202, d202);
         assertFalse(testds.equals(ds1)); // 2-devs should not match
     }
 
     @Test
     public void testDestPairWithLabel() {
-        DestinationSet testds = new DestinationSet(false, el201, d201, el202, d202);
+        DestinationSet testds = new DestinationSet(false, false, el201, d201, el202, d202);
         assertTrue(testds.equals(ds3)); // match same switches, same order
         assertTrue(testds.hashCode() == ds3.hashCode());
 
-        testds = new DestinationSet(false, el202, d202, el201, d201);
+        testds = new DestinationSet(false, false, el202, d202, el201, d201);
         assertTrue(testds.equals(ds3)); // match same switches, order reversed
         assertTrue(testds.hashCode() == ds3.hashCode());
 
-        testds = new DestinationSet(false, el202, d202);
+        testds = new DestinationSet(false, false, el202, d202);
         assertFalse(testds.equals(ds3)); // one less switch should not match
         assertFalse(testds.hashCode() == ds3.hashCode());
 
-        testds = new DestinationSet(false, el201, d201);
+        testds = new DestinationSet(false, false, el201, d201);
         assertFalse(testds.equals(ds3)); // one less switch should not match
         assertFalse(testds.hashCode() == ds3.hashCode());
 
-        testds = new DestinationSet(false, el201, d201, 0, DeviceId.NONE);
+        testds = new DestinationSet(false, false, el201, d201, 0, DeviceId.NONE);
         assertFalse(testds.equals(ds3)); // one less switch should not match
         assertFalse(testds.hashCode() == ds3.hashCode());
 
-        testds = new DestinationSet(false, el201, d202, el201, d201);
+        testds = new DestinationSet(false, false, el201, d202, el201, d201);
         assertFalse(testds.equals(ds3)); // wrong labels
         assertFalse(testds.hashCode() == ds3.hashCode());
 
-        testds = new DestinationSet(true, el202, d202, el201, d201);
-        assertFalse(testds.equals(ds3)); // wrong mpls set
+        testds = new DestinationSet(true, false, el202, d202, el201, d201);
+        assertFalse(testds.equals(ds3)); // wrong not bos
         assertFalse(testds.hashCode() == ds3.hashCode());
 
-        testds = new DestinationSet(false, el202, d202, el201, d202);
+        testds = new DestinationSet(false, false, el202, d202, el201, d202);
         assertFalse(testds.equals(ds3)); // wrong device
         assertFalse(testds.hashCode() == ds3.hashCode());
 
-        testds = new DestinationSet(false,
+        testds = new DestinationSet(false, false,
                                     el202, DeviceId.deviceId("of:0000000000000205"),
                                     el201, d201);
         assertFalse(testds.equals(ds3)); // wrong device
@@ -152,39 +177,39 @@
 
     @Test
     public void testDestPairWithoutLabel() {
-        DestinationSet testds = new DestinationSet(false, -1, d201, -1, d202);
+        DestinationSet testds = new DestinationSet(false, false, -1, d201, -1, d202);
         assertTrue(testds.equals(ds4)); // match same switches, same order
         assertTrue(testds.hashCode() == ds4.hashCode());
 
-        testds = new DestinationSet(false, -1, d202, -1, d201);
+        testds = new DestinationSet(false, false, -1, d202, -1, d201);
         assertTrue(testds.equals(ds4)); // match same switches, order reversed
         assertTrue(testds.hashCode() == ds4.hashCode());
 
-        testds = new DestinationSet(false, -1, d202);
+        testds = new DestinationSet(false, false, -1, d202);
         assertFalse(testds.equals(ds4)); // one less switch should not match
         assertFalse(testds.hashCode() == ds4.hashCode());
 
-        testds = new DestinationSet(false, -1, d201);
+        testds = new DestinationSet(false, false, -1, d201);
         assertFalse(testds.equals(ds4)); // one less switch should not match
         assertFalse(testds.hashCode() == ds4.hashCode());
 
-        testds = new DestinationSet(false, -1, d201, 0, DeviceId.NONE);
+        testds = new DestinationSet(false, false, -1, d201, 0, DeviceId.NONE);
         assertFalse(testds.equals(ds4)); // one less switch should not match
         assertFalse(testds.hashCode() == ds4.hashCode());
 
-        testds = new DestinationSet(false, el201, d201, -1, d202);
+        testds = new DestinationSet(false, false, el201, d201, -1, d202);
         assertFalse(testds.equals(ds4)); // wrong labels
         assertFalse(testds.hashCode() == ds4.hashCode());
 
-        testds = new DestinationSet(true, -1, d202, -1, d201);
+        testds = new DestinationSet(true, false, -1, d202, -1, d201);
         assertFalse(testds.equals(ds4)); // wrong mpls set
         assertFalse(testds.hashCode() == ds4.hashCode());
 
-        testds = new DestinationSet(false, -1, d202, -1, d202);
+        testds = new DestinationSet(false, false, -1, d202, -1, d202);
         assertFalse(testds.equals(ds4)); // wrong device
         assertFalse(testds.hashCode() == ds4.hashCode());
 
-        testds = new DestinationSet(false,
+        testds = new DestinationSet(false, false,
                                     -1, DeviceId.deviceId("of:0000000000000205"),
                                     -1, d201);
         assertFalse(testds.equals(ds4)); // wrong device