diff --git a/model/ndn-common.h b/model/ndn-common.h
index 3581a4c..de21c29 100644
--- a/model/ndn-common.h
+++ b/model/ndn-common.h
@@ -11,7 +11,29 @@
 #ifndef NDN_COMMON_H
 #define NDN_COMMON_H
 
+#include "ns3/nstime.h"
+#include "ns3/simulator.h"
+
+#define NDNSIM_MODE 1
+
 #define NDN_NAMESPACE_BEGIN  namespace ns3 { namespace ndn {
 #define NDN_NAMESPACE_END    } /*ndn*/ } /*ns3*/ 
 
+NDN_NAMESPACE_BEGIN
+
+typedef Time TimeInterval;
+
+namespace time
+{
+
+inline Time
+NowUnixTimestamp ()
+{
+  return Simulator::Now ();
+}
+
+}
+
+NDN_NAMESPACE_END
+
 #endif // NDN_COMMON_H