diff --git a/utils/tracers/ndn-cs-tracer.cc b/utils/tracers/ndn-cs-tracer.cc
index 742961f..6cab66f 100644
--- a/utils/tracers/ndn-cs-tracer.cc
+++ b/utils/tracers/ndn-cs-tracer.cc
@@ -15,7 +15,8 @@
  * along with this program; if not, write to the Free Software
  * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
  *
- * Author:  Alexander Afanasyev <alexander.afanasyev@ucla.edu>
+ * Author: Xiaoyan Hu <x......u@gmail.com>
+ *         Alexander Afanasyev <alexander.afanasyev@ucla.edu>
  */
 
 #include "ndn-cs-tracer.h"
@@ -25,18 +26,66 @@
 #include "ns3/names.h"
 #include "ns3/callback.h"
 
-#include <boost/lexical_cast.hpp>
-
+#include "ns3/ndn-app.h"
 #include "ns3/ndn-interest.h"
 #include "ns3/ndn-content-object.h"
+#include "ns3/simulator.h"
+#include "ns3/node-list.h"
+#include "ns3/log.h"
+
+#include <boost/lexical_cast.hpp>
+
+#include <fstream>
+
+NS_LOG_COMPONENT_DEFINE ("ndn.CsTracer");
 
 using namespace std;
 
 namespace ns3 {
 namespace ndn {
-    
-CsTracer::CsTracer (Ptr<Node> node)
+
+
+boost::tuple< boost::shared_ptr<std::ostream>, std::list<Ptr<CsTracer> > >
+CsTracer::InstallAll (const std::string &file, Time averagingPeriod/* = Seconds (0.5)*/)
+{
+  using namespace boost;
+  using namespace std;
+  
+  std::list<Ptr<CsTracer> > tracers;
+  boost::shared_ptr<std::ofstream> outputStream (new std::ofstream ());
+  outputStream->open (file.c_str (), std::ios_base::out | std::ios_base::trunc);
+
+  if (!outputStream->is_open ())
+    return boost::make_tuple (outputStream, tracers);
+
+  for (NodeList::Iterator node = NodeList::Begin ();
+       node != NodeList::End ();
+       node++)
+    {
+      NS_LOG_DEBUG ("Node: " << (*node)->GetId ());
+
+      Ptr<CsTracer> trace = Create<CsTracer> (outputStream, *node);
+      trace->SetAveragingPeriod (averagingPeriod);
+      tracers.push_back (trace);
+    }
+
+  if (tracers.size () > 0)
+    {
+      // *m_l3RateTrace << "# "; // not necessary for R's read.table
+      tracers.front ()->PrintHeader (*outputStream);
+      *outputStream << "\n";
+    }
+
+  return boost::make_tuple (outputStream, tracers);
+}
+
+//////////////////////////////////////////////////////////////////////////////
+//////////////////////////////////////////////////////////////////////////////
+//////////////////////////////////////////////////////////////////////////////
+
+CsTracer::CsTracer (boost::shared_ptr<std::ostream> os, Ptr<Node> node)
 : m_nodePtr (node)
+, m_os (os)
 {
   m_node = boost::lexical_cast<string> (m_nodePtr->GetId ());
 
@@ -49,8 +98,9 @@
     }
 }
 
-CsTracer::CsTracer (const std::string &node)
+CsTracer::CsTracer (boost::shared_ptr<std::ostream> os, const std::string &node)
 : m_node (node)
+, m_os (os)
 {
   Connect ();
 }
@@ -67,7 +117,75 @@
                    MakeCallback (&CsTracer::CacheHits, this));
   Config::Connect ("/NodeList/"+m_node+"/$ns3::ndn::ContentStore/CacheMisses",
                    MakeCallback (&CsTracer::CacheMisses, this));
+
+  Reset ();  
 }
 
+
+void
+CsTracer::SetAveragingPeriod (const Time &period)
+{
+  m_period = period;
+  m_printEvent.Cancel ();
+  m_printEvent = Simulator::Schedule (m_period, &CsTracer::PeriodicPrinter, this);
+}
+
+void
+CsTracer::PeriodicPrinter ()
+{
+  Print (*m_os);
+  Reset ();
+  
+  m_printEvent = Simulator::Schedule (m_period, &CsTracer::PeriodicPrinter, this);
+}
+
+void
+CsTracer::PrintHeader (std::ostream &os) const
+{
+  os << "Time" << "\t"
+
+     << "Node" << "\t"
+
+     << "Type" << "\t"
+     << "Packets" << "\t";
+}
+
+void
+CsTracer::Reset ()
+{
+  m_stats.Reset();
+}
+
+#define PRINTER(printName, fieldName)           \
+  os << time.ToDouble (Time::S) << "\t"         \
+  << m_node << "\t"                             \
+  << printName << "\t"                          \
+  << m_stats.fieldName << "\n";
+
+
+void
+CsTracer::Print (std::ostream &os) const
+{
+  Time time = Simulator::Now ();
+
+  PRINTER ("CacheHits",   m_cacheHits);
+  PRINTER ("CacheMisses", m_cacheMisses);
+}
+
+void 
+CsTracer::CacheHits (std::string context,
+                     Ptr<const InterestHeader>, Ptr<const ContentObjectHeader>)
+{
+  m_stats.m_cacheHits ++;
+}
+
+void 
+CsTracer::CacheMisses (std::string context, 
+                       Ptr<const InterestHeader>)
+{
+  m_stats.m_cacheMisses ++;
+}
+
+
 } // namespace ndn
 } // namespace ns3