diff --git a/model/ccnx.h b/model/ccnx.h
index 38c2f74..f87da94 100644
--- a/model/ccnx.h
+++ b/model/ccnx.h
@@ -23,6 +23,7 @@
 
 #include "ns3/object.h"
 #include "ns3/callback.h"
+#include "ns3/traced-callback.h"
 
 namespace ns3 {
 
@@ -79,13 +80,6 @@
 class Ccnx : public Object
 {
 public:
-  enum ForwardingStrategy
-    { 
-      NDN_FLOODING = 1,
-      NDN_BESTROUTE = 2,
-      NDN_RANKING = 3 
-    };
-
   /**
    * \brief Interface ID
    *
@@ -94,48 +88,6 @@
   static TypeId GetTypeId ();
   virtual ~Ccnx ();
 
-  // /**
-  //  * \brief Send an Interest packet to a specified face
-  //  *
-  //  * \param face face where to send this packet
-  //  * \param header Interest header
-  //  * \param packet fully prepared CCNx packet to send
-  //  *
-  //  * Higher-level layers (forwarding strategy in particular) call this
-  //  * method to send a packet down the stack to the MAC and PHY layers.
-  //  */
-  // virtual void
-  // SendInterest (const Ptr<CcnxFace> &face,
-  //               const Ptr<const CcnxInterestHeader> &header,
-  //               const Ptr<Packet> &packet) = 0;
-
-  // /**
-  //  * \brief Send a ContentObject packet to a specified face
-  //  *
-  //  * \param face face where to send this packet
-  //  * \param header ContentObject header
-  //  * \param packet fully prepared CCNx packet to send
-  //  *
-  //  * Higher-level layers (forwarding strategy in particular) call this
-  //  * method to send a packet down the stack to the MAC and PHY layers.
-  //  */
-  // virtual void
-  // SendContentObject (const Ptr<CcnxFace> &face,
-  //                    const Ptr<const CcnxContentObjectHeader> &header,
-  //                    const Ptr<Packet> &packet) = 0;
-
-  // /**
-  //  * \brief Lower layers calls this method after demultiplexing
-  //  *
-  //  * Lower-layer-dependent implementation of CcnxFace will do actual work
-  //  * to set up demultiplexing and call this function as a callback
-  //  *
-  //  * \param face face from which packet came from
-  //  * \param p the packet
-  //  */
-  // virtual void
-  // Receive (const Ptr<CcnxFace> &face, const Ptr<const Packet> &p) = 0;
-
   /**
    * \brief Register a new forwarding strategy to be used by this Ccnx
    * stack
@@ -197,6 +149,64 @@
    */
   virtual Ptr<CcnxFace>
   GetFaceByNetDevice (Ptr<NetDevice> netDevice) const = 0;
+
+
+  /**
+   * \enum DropReason
+   * \brief A reason why the packet has been dropped
+   */
+  enum DropReason
+    {
+      DUPLICATED, // Interests
+      SUPPRESSED, // Interests and Nacks
+      NO_FACES,    // Interests
+      NON_DUPLICATED, // Nacks
+      AFTER_SATISFIED, // Nacks
+      UNSOLICITED      // data
+    };
+  
+protected:
+  ////////////////////////////////////////////////////////////////////
+  ////////////////////////////////////////////////////////////////////
+  ////////////////////////////////////////////////////////////////////
+  
+  // transmittedInterestTrace is inside ForwardingStrategy
+  
+  TracedCallback<Ptr<const CcnxInterestHeader>,
+                 Ptr<const CcnxFace> > m_inInterests;
+
+  TracedCallback<Ptr<const CcnxInterestHeader>,
+                 DropReason,
+                 Ptr<const CcnxFace> > m_dropInterests;
+  
+  ////////////////////////////////////////////////////////////////////
+  ////////////////////////////////////////////////////////////////////
+  ////////////////////////////////////////////////////////////////////
+
+  TracedCallback<Ptr<const CcnxInterestHeader>,
+                 Ptr<const CcnxFace> > m_outNacks;
+
+  TracedCallback<Ptr<const CcnxInterestHeader>,
+                 Ptr<const CcnxFace> > m_inNacks;
+
+  TracedCallback<Ptr<const CcnxInterestHeader>,
+                 DropReason,
+                 Ptr<const CcnxFace> > m_dropNacks;
+
+  ////////////////////////////////////////////////////////////////////
+  ////////////////////////////////////////////////////////////////////
+  ////////////////////////////////////////////////////////////////////
+
+  TracedCallback<Ptr<const CcnxContentObjectHeader>,
+                 bool /*from cache*/,
+                 Ptr<const CcnxFace> > m_outData;
+
+  TracedCallback<Ptr<const CcnxContentObjectHeader>,
+                 Ptr<const CcnxFace> > m_inData;
+
+  TracedCallback<Ptr<const CcnxContentObjectHeader>,
+                  DropReason,
+                  Ptr<const CcnxFace> > m_dropData;  
 };
 
 } // namespace ns3