diff --git a/src/main/java/net/floodlightcontroller/core/internal/OFSwitchImpl.java b/src/main/java/net/floodlightcontroller/core/internal/OFSwitchImpl.java
index ce865d8..0bb9f2f 100644
--- a/src/main/java/net/floodlightcontroller/core/internal/OFSwitchImpl.java
+++ b/src/main/java/net/floodlightcontroller/core/internal/OFSwitchImpl.java
@@ -23,10 +23,10 @@
 import java.util.Collection;
 import java.util.Collections;
 import java.util.Date;
-import java.util.HashMap;
 import java.util.LinkedList;
 import java.util.List;
 import java.util.Map;
+import java.util.WeakHashMap;
 import java.util.concurrent.ConcurrentHashMap;
 import java.util.concurrent.ConcurrentMap;
 import java.util.concurrent.Future;
@@ -135,7 +135,7 @@
             new ThreadLocal<Map<OFSwitchImpl, List<OFMessage>>>() {
                 @Override
                 protected Map<OFSwitchImpl, List<OFMessage>> initialValue() {
-                    return new HashMap<OFSwitchImpl, List<OFMessage>>();
+                    return new WeakHashMap<OFSwitchImpl, List<OFMessage>>();
                 }
             };
 
diff --git a/src/main/java/net/floodlightcontroller/util/OFMessageDamper.java b/src/main/java/net/floodlightcontroller/util/OFMessageDamper.java
index 47a92a9..5faf38e 100644
--- a/src/main/java/net/floodlightcontroller/util/OFMessageDamper.java
+++ b/src/main/java/net/floodlightcontroller/util/OFMessageDamper.java
@@ -6,7 +6,10 @@
 
 import java.io.IOException;
 import java.util.EnumSet;
+import java.util.Iterator;
 import java.util.Set;
+import java.util.concurrent.ExecutorService;
+import java.util.concurrent.Executors;
 
 import net.floodlightcontroller.core.FloodlightContext;
 import net.floodlightcontroller.core.IOFSwitch;
@@ -81,6 +84,8 @@
 
     TimedCache<DamperEntry> cache;
     EnumSet<OFType> msgTypesToCache;
+    // executor for invalidate task
+    private static ExecutorService executor = Executors.newFixedThreadPool(1);
 
     /**
      * @param capacity      the maximum number of messages that should be
@@ -147,4 +152,24 @@
             return true;
         }
     }
+
+    /**
+     * Invalidates all the damper cache entries for the specified switch.
+     *
+     * @param sw switch connection to invalidate
+     */
+    public void invalidate(final IOFSwitch sw) {
+        executor.submit(new Runnable() {
+            @Override
+            public void run() {
+                Iterator<DamperEntry> it = cache.getCachedEntries().iterator();
+                while (it.hasNext()) {
+                    DamperEntry entry = it.next();
+                    if (entry.sw == sw) {
+                        it.remove();
+                    }
+                }
+            }
+        });
+   }
 }
diff --git a/src/main/java/net/floodlightcontroller/util/TimedCache.java b/src/main/java/net/floodlightcontroller/util/TimedCache.java
index 2a90f0b..76f1e57 100644
--- a/src/main/java/net/floodlightcontroller/util/TimedCache.java
+++ b/src/main/java/net/floodlightcontroller/util/TimedCache.java
@@ -17,6 +17,7 @@
 
 package net.floodlightcontroller.util;
 
+import java.util.Set;
 import java.util.concurrent.ConcurrentMap;
 
 import com.googlecode.concurrentlinkedhashmap.ConcurrentLinkedHashMap;
@@ -60,7 +61,7 @@
      * @return boolean
      */
     public boolean update(K key) {
-        Long curr = new Long(System.currentTimeMillis());
+        long curr = System.currentTimeMillis();
         Long prev = cache.putIfAbsent(key, curr);
 
         if (prev == null) {
@@ -75,4 +76,15 @@
 
         return true;
     }
+
+    /**
+     * Gets all the cached entries.
+     * <p/>
+     * Modification to the returned set will be reflected to the cache.
+     *
+     * @return cached entries
+     */
+    Set<K> getCachedEntries() {
+        return cache.keySet();
+    }
 }