diff --git a/providers/null/src/main/java/org/onosproject/provider/nil/TopologyMutationDriver.java b/providers/null/src/main/java/org/onosproject/provider/nil/TopologyMutationDriver.java
new file mode 100644
index 0000000..ccf7e08
--- /dev/null
+++ b/providers/null/src/main/java/org/onosproject/provider/nil/TopologyMutationDriver.java
@@ -0,0 +1,223 @@
+/*
+ * Copyright 2015 Open Networking Laboratory
+ *
+ * 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.provider.nil;
+
+import com.google.common.collect.Lists;
+import org.onosproject.net.ConnectPoint;
+import org.onosproject.net.device.DeviceService;
+import org.onosproject.net.link.DefaultLinkDescription;
+import org.onosproject.net.link.LinkDescription;
+import org.onosproject.net.link.LinkProviderService;
+import org.onosproject.net.link.LinkService;
+import org.slf4j.Logger;
+import org.slf4j.LoggerFactory;
+
+import java.util.List;
+import java.util.Random;
+import java.util.concurrent.ExecutorService;
+import java.util.stream.Collectors;
+
+import static java.util.concurrent.Executors.newSingleThreadScheduledExecutor;
+import static org.onlab.util.Tools.delay;
+import static org.onlab.util.Tools.groupedThreads;
+import static org.onosproject.net.Link.Type.DIRECT;
+import static org.onosproject.net.MastershipRole.MASTER;
+import static org.onosproject.provider.nil.TopologySimulator.description;
+
+/**
+ * Drives topology mutations at a specified rate of events per second.
+ */
+class TopologyMutationDriver implements Runnable {
+
+    private final Logger log = LoggerFactory.getLogger(getClass());
+
+    private static final int WAIT_DELAY = 2_000;
+    private static final int MAX_DOWN_LINKS = 5;
+
+    private final Random random = new Random();
+
+    private volatile boolean stopped = true;
+
+    private double mutationRate;
+    private int millis, nanos;
+
+    private LinkService linkService;
+    private DeviceService deviceService;
+    private LinkProviderService linkProviderService;
+
+    private List<LinkDescription> activeLinks;
+    private List<LinkDescription> inactiveLinks;
+
+    private final ExecutorService executor =
+            newSingleThreadScheduledExecutor(groupedThreads("onos/null", "topo-mutator"));
+
+    /**
+     * Starts the mutation process.
+     *
+     * @param mutationRate        link events per second
+     * @param linkService         link service
+     * @param deviceService       device service
+     * @param linkProviderService link provider service
+     */
+    void start(double mutationRate,
+               LinkService linkService, DeviceService deviceService,
+               LinkProviderService linkProviderService) {
+        stopped = false;
+        this.linkService = linkService;
+        this.deviceService = deviceService;
+        this.linkProviderService = linkProviderService;
+        activeLinks = reduceLinks();
+        inactiveLinks = Lists.newArrayList();
+        adjustRate(mutationRate);
+        executor.submit(this);
+    }
+
+    /**
+     * Adjusts the topology mutation rate.
+     *
+     * @param mutationRate new topology mutation rate
+     */
+    void adjustRate(double mutationRate) {
+        this.mutationRate = mutationRate;
+        if (mutationRate > 0) {
+            this.millis = (int) (1_000 / mutationRate / 2);
+            this.nanos = (int) (1_000_000 / mutationRate / 2) % 1_000_000;
+        } else {
+            this.millis = 0;
+            this.nanos = 0;
+        }
+        log.info("Settings: millis={}, nanos={}", millis, nanos);
+    }
+
+    /**
+     * Stops the mutation process.
+     */
+    void stop() {
+        stopped = true;
+    }
+
+    /**
+     * Severs the link between the specified end-points in both directions.
+     *
+     * @param one link endpoint
+     * @param two link endpoint
+     */
+    void severLink(ConnectPoint one, ConnectPoint two) {
+        LinkDescription link = new DefaultLinkDescription(one, two, DIRECT);
+        linkProviderService.linkVanished(link);
+        linkProviderService.linkVanished(reverse(link));
+
+    }
+
+    /**
+     * Repairs the link between the specified end-points in both directions.
+     *
+     * @param one link endpoint
+     * @param two link endpoint
+     */
+    void repairLink(ConnectPoint one, ConnectPoint two) {
+        LinkDescription link = new DefaultLinkDescription(one, two, DIRECT);
+        linkProviderService.linkDetected(link);
+        linkProviderService.linkDetected(reverse(link));
+    }
+
+    @Override
+    public void run() {
+        delay(WAIT_DELAY);
+
+        while (!stopped) {
+            if (mutationRate > 0 && inactiveLinks.isEmpty()) {
+                primeInactiveLinks();
+            } else if (mutationRate <= 0 && !inactiveLinks.isEmpty()) {
+                repairInactiveLinks();
+            } else if (inactiveLinks.isEmpty()) {
+                delay(WAIT_DELAY);
+
+            } else {
+                activeLinks.add(repairLink());
+                pause();
+                inactiveLinks.add(severLink());
+                pause();
+            }
+        }
+    }
+
+    // Primes the inactive links with a few random links.
+    private void primeInactiveLinks() {
+        for (int i = 0, n = Math.min(MAX_DOWN_LINKS, activeLinks.size()); i < n; i++) {
+            inactiveLinks.add(severLink());
+        }
+    }
+
+    // Repairs all inactive links.
+    private void repairInactiveLinks() {
+        while (!inactiveLinks.isEmpty()) {
+            repairLink();
+        }
+    }
+
+    // Picks a random active link and severs it.
+    private LinkDescription severLink() {
+        LinkDescription link = getRandomLink(activeLinks);
+        linkProviderService.linkVanished(link);
+        linkProviderService.linkVanished(reverse(link));
+        return link;
+    }
+
+    // Picks a random inactive link and repairs it.
+    private LinkDescription repairLink() {
+        LinkDescription link = getRandomLink(inactiveLinks);
+        linkProviderService.linkDetected(link);
+        linkProviderService.linkDetected(reverse(link));
+        return link;
+    }
+
+    // Produces a reverse of the specified link.
+    private LinkDescription reverse(LinkDescription link) {
+        return new DefaultLinkDescription(link.dst(), link.src(), link.type());
+    }
+
+    // Returns a random link from the specified list of links.
+    private LinkDescription getRandomLink(List<LinkDescription> links) {
+        return links.remove(random.nextInt(links.size()));
+    }
+
+    // Reduces the given list of links to just a single link in each original pair.
+    private List<LinkDescription> reduceLinks() {
+        List<LinkDescription> links = Lists.newArrayList();
+        linkService.getLinks().forEach(link -> links.add(description(link)));
+        return links.stream()
+                .filter(this::isOurLink)
+                .filter(this::isRightDirection)
+                .collect(Collectors.toList());
+    }
+
+    // Returns true if the specified link is ours.
+    private boolean isOurLink(LinkDescription linkDescription) {
+        return deviceService.getRole(linkDescription.src().deviceId()) == MASTER;
+    }
+
+    // Returns true if the link source is greater than the link destination.
+    private boolean isRightDirection(LinkDescription link) {
+        return link.src().deviceId().toString().compareTo(link.dst().deviceId().toString()) > 0;
+    }
+
+    // Pauses the current thread for the pre-computed time of millis & nanos.
+    private void pause() {
+        delay(millis, nanos);
+    }
+
+}