diff -r d5e55601a7ab src/applications/model/onoff-application.cc
--- a/src/applications/model/onoff-application.cc	Sat Jan 14 08:22:50 2017 -0800
+++ b/src/applications/model/onoff-application.cc	Sun Jan 15 16:36:18 2017 -0800
@@ -41,6 +41,7 @@
 #include "ns3/udp-socket-factory.h"
 #include "ns3/string.h"
 #include "ns3/pointer.h"
+#include "ns3/boolean.h"
 
 namespace ns3 {
 
@@ -59,6 +60,22 @@
                    DataRateValue (DataRate ("500kb/s")),
                    MakeDataRateAccessor (&OnOffApplication::m_cbrRate),
                    MakeDataRateChecker ())
+    .AddAttribute ("RandomSize", "An optional random variable that replaces the use of fixed PacketSize variable",
+                   StringValue ("ns3::ConstantRandomVariable[Constant=512.0]"),
+                   MakePointerAccessor (&OnOffApplication::m_randomSize),
+                   MakePointerChecker <RandomVariableStream>())
+    .AddAttribute ("UseRandomSize", "Flag for whether packet distribution or fixed packet size is used",
+                   BooleanValue (false),
+                   MakeBooleanAccessor (&OnOffApplication::m_useRandomSize),
+                   MakeBooleanChecker ())
+    .AddAttribute ("RandomInterval", "An optional random variable that replaces the use of fixed DataRate",
+                   StringValue ("ns3::ConstantRandomVariable[Constant=512.0]"),
+                   MakePointerAccessor (&OnOffApplication::m_randomInterval),
+                   MakePointerChecker <RandomVariableStream>())
+    .AddAttribute ("UseRandomInterval", "Flag for whether interval distribution or fixed DataRate is used",
+                   BooleanValue (false),
+                   MakeBooleanAccessor (&OnOffApplication::m_useRandomInterval),
+                   MakeBooleanChecker ())
     .AddAttribute ("PacketSize", "The size of packets sent in on state",
                    UintegerValue (512),
                    MakeUintegerAccessor (&OnOffApplication::m_pktSize),
@@ -129,7 +146,9 @@
   NS_LOG_FUNCTION (this << stream);
   m_onTime->SetStream (stream);
   m_offTime->SetStream (stream + 1);
-  return 2;
+  m_randomInterval->SetStream (stream + 2);
+  m_randomSize->SetStream (stream + 3);
+  return 4;
 }
 
 void
@@ -235,8 +254,21 @@
     {
       uint32_t bits = m_pktSize * 8 - m_residualBits;
       NS_LOG_LOGIC ("bits = " << bits);
-      Time nextTime (Seconds (bits /
-                              static_cast<double>(m_cbrRate.GetBitRate ()))); // Time till next packet
+      Time nextTime;
+      // Time till next packet
+      if (m_useRandomInterval)
+        {
+          nextTime = Seconds (m_randomInterval->GetValue ());
+          NS_ASSERT_MSG (nextTime.IsPositive (),
+                                        "Packet interval is unexpectedly zero or negative. "
+                                        "Please verify the configuration of "
+                                        "`ns3::OnOffApplication::RandomInterval` "
+                                        "random variable.");
+        }
+      else
+        {
+          nextTime = Seconds (bits / static_cast<double>(m_cbrRate.GetBitRate ()));
+        }
       NS_LOG_LOGIC ("nextTime = " << nextTime);
       m_sendEvent = Simulator::Schedule (nextTime,
                                          &OnOffApplication::SendPacket, this);
@@ -271,7 +303,20 @@
   NS_LOG_FUNCTION (this);
 
   NS_ASSERT (m_sendEvent.IsExpired ());
-  Ptr<Packet> packet = Create<Packet> (m_pktSize);
+  uint32_t packetSize;
+  if (m_useRandomSize)
+    {
+      packetSize = m_randomSize->GetInteger ();
+      NS_ASSERT_MSG (packetSize > 0, "Packet size was unexpectedly zero. "
+                                     "Please verify the configuration of "
+                                     "`ns3::OnOffApplication::RandomSize` "
+                                     "random variable.");
+    }
+  else
+    {
+      packetSize = m_pktSize;
+    }
+  Ptr<Packet> packet = Create<Packet> (packetSize);
   m_txTrace (packet);
   m_socket->Send (packet);
   m_totBytes += m_pktSize;
diff -r d5e55601a7ab src/applications/model/onoff-application.h
--- a/src/applications/model/onoff-application.h	Sat Jan 14 08:22:50 2017 -0800
+++ b/src/applications/model/onoff-application.h	Sun Jan 15 16:36:18 2017 -0800
@@ -151,6 +151,10 @@
   Ptr<Socket>     m_socket;       //!< Associated socket
   Address         m_peer;         //!< Peer address
   bool            m_connected;    //!< True if connected
+  Ptr<RandomVariableStream>  m_randomSize; //!< rng for packet size distribution
+  bool            m_useRandomSize;    //!< boolean to use packet distribution
+  Ptr<RandomVariableStream>  m_randomInterval;  //!< rng for interarrival time
+  bool            m_useRandomInterval; //!< boolean to use interval distribution
   Ptr<RandomVariableStream>  m_onTime;       //!< rng for On Time
   Ptr<RandomVariableStream>  m_offTime;      //!< rng for Off Time
   DataRate        m_cbrRate;      //!< Rate that data is generated