diff --git a/examples/abilene-topology.cc b/examples/abilene-topology.cc
index a96daf7..c0c1f16 100644
--- a/examples/abilene-topology.cc
+++ b/examples/abilene-topology.cc
@@ -26,6 +26,7 @@
 #include "ns3/point-to-point-grid.h"
 #include "ns3/ipv4-global-routing-helper.h"
 #include "ns3/animation-interface.h"
+#include "ns3/ccnx-l3-protocol.h"
 
 #include <iostream>
 #include <sstream>
@@ -37,6 +38,14 @@
 
 NS_LOG_COMPONENT_DEFINE ("CcnxAbileneTopology");
 
+int transmittedInterests = 0;
+int receivedInterests = 0;
+int droppedInterests = 0;
+
+int transmittedData = 0;
+int receivedData = 0;
+int droppedData = 0;
+
 void PrintTime ()
 {
   NS_LOG_INFO (Simulator::Now ());
@@ -60,11 +69,47 @@
     }
 }
 
+static void OnTransmittedInterest (std::string context, Ptr<const CcnxInterestHeader> header, 
+                                   Ptr<Ccnx> ccnx, Ptr<const CcnxFace> face)
+{
+  transmittedInterests++;
+}
+
+static void OnReceivedInterest (std::string context, Ptr<const CcnxInterestHeader> header, 
+                                Ptr<Ccnx> ccnx, Ptr<const CcnxFace> face)
+{
+  receivedInterests++;
+}
+
+static void OnDroppedInterest (std::string context, Ptr<const CcnxInterestHeader> header, CcnxL3Protocol::DropReason reason,
+                               Ptr<Ccnx> ccnx, Ptr<const CcnxFace> face)
+{
+  droppedInterests++;
+}
+
+static void OnTransmittedData (std::string context, Ptr<const CcnxContentObjectHeader> header, Ptr<const Packet> packet,
+                               CcnxL3Protocol::ContentObjectSource source, Ptr<Ccnx> ccnx, Ptr<const CcnxFace> face)
+{
+    transmittedData++;    
+}
+
+static void OnReceivedData (std::string context, Ptr<const CcnxContentObjectHeader> header, Ptr<const Packet> packet,
+                            Ptr<Ccnx> ccnx, Ptr<const CcnxFace> face)
+{
+    receivedData++;
+}
+
+static void OnDroppedData (std::string context, Ptr<const CcnxContentObjectHeader> header, Ptr<const Packet> packet,
+                           CcnxL3Protocol::DropReason reason, Ptr<Ccnx> ccnx, Ptr<const CcnxFace> face )
+{
+    droppedData++;
+}
+
 int 
 main (int argc, char *argv[])
 {
-  // Packet::EnableChecking();
-  // Packet::EnablePrinting();
+  Packet::EnableChecking();
+  Packet::EnablePrinting();
   string input ("./src/NDNabstraction/examples/abilene-topology.txt");
     
   Time finishTime = Seconds (20.0);
@@ -92,6 +137,13 @@
       return -1;
     }
 
+  int droppedInterests[nodes.GetN()];
+  int congestedInterests[nodes.GetN()];
+  int sentInterests[nodes.GetN()];
+  (void)droppedInterests;
+  (void)sentInterests;
+  (void)congestedInterests;
+    
   SpringMobilityHelper::InstallSprings (reader.LinksBegin (), reader.LinksEnd ());
 
   // InternetStackHelper stack;
@@ -137,9 +189,38 @@
       anim->SetMobilityPollInterval (Seconds (1));
     }
 
+  NS_LOG_INFO ("Configure Tracing.");
+  // first, pcap tracing in non-promiscuous mode
+  //ccnxHelper.EnablePcapAll ("csma-ping", false);
+  // then, print what the packet sink receives.
+  //Config::ConnectWithoutContext ("/NodeList/3/ApplicationList/0/$ns3::PacketSink/Rx", 
+  //                                 MakeCallback (&SinkRx));
+  // finally, print the ping rtts.
+    //Packet::EnablePrinting ();
+  Config::Connect("/NodeList/*/ns3::CcnxL3Protocol/TransmittedInterestTrace",
+                                 MakeCallback (&OnTransmittedInterest));
+  Config::Connect ("/NodeList/*/ns3::CcnxL3Protocol/ReceivedInterestTrace",
+                     MakeCallback (&OnReceivedInterest));
+  Config::Connect ("/NodeList/*/ns3::CcnxL3Protocol/DroppedInterestTrace",
+                     MakeCallback (&OnDroppedInterest));
+    
+  Config::Connect ("/NodeList/*/ns3::CcnxL3Protocol/ReceivedDataTrace",
+                     MakeCallback (&OnReceivedData));
+  Config::Connect ("/NodeList/*/ns3::CcnxL3Protocol/TransmittedDataTrace",
+                     MakeCallback (&OnTransmittedData));
+  Config::Connect ("/NodeList/*/ns3::CcnxL3Protocol/DroppedDataTrace",
+                     MakeCallback (&OnDroppedData));
+
   NS_LOG_INFO ("Run Simulation.");
   Simulator::Run ();
   Simulator::Destroy ();
   NS_LOG_INFO ("Done.");
+
+  NS_LOG_INFO("Total received interests = " << receivedInterests);
+  NS_LOG_INFO("Total transmitted interests = " << transmittedInterests);
+  NS_LOG_INFO("Total dropped interests = " << droppedInterests);
+  NS_LOG_INFO("Total received data = " << receivedData);
+  NS_LOG_INFO("Total transmitted data = " << transmittedData);
+  NS_LOG_INFO("Total dropped data = " << droppedData);
   return 0;
 }