diff --git a/CHANGES.html b/CHANGES.html
index a5a56dd9a..4d1de5bd2 100644
--- a/CHANGES.html
+++ b/CHANGES.html
@@ -54,6 +54,7 @@ us a note on ns-developers mailing list.</p>
 <h1>Changes from ns-3.30 to ns-3.31</h1>
 <h2>New API:</h2>
 <ul>
+<li> New <b>...FailSafe ()</b> variants of the <b> Config </b> and <b>Config::MatchContainer</b> functions which set Attributes or connect TraceSources.  These all return a boolean indicating if any attributes could be set (or trace sources connected).  These are useful if you are not sure that the requested objects exist, for example in AnimationInterface.</li>
 <li> New attributes for <b> Ipv4L3Protocol</b> have been added to enable RFC 6621-based duplicate packet detection (DPD) (<b>EnableDuplicatePacketDetection</b>) and to control the cache expiration time (<b>DuplicateExpire</b>).</li>
 <li><b> MakeConsistent </b> method of <b> BuildingsHelper </b> class is 
 deprecated and moved to <b> MobilityBuildingInfo </b> class. <b> DoInitialize </b> 
@@ -78,6 +79,7 @@ transmitted.</li>
 </ul>
 <h2>Changes to existing API:</h2>
 <ul>
+<li> Previously the <b>Config::Connect</b> and <b>Config::Set</b> families of functions would fail silently if the attribute or trace source didn't exist on the path given (typically due to spelling errors). Now those functions will throw a fatal error.  If you need the old behavior use the new  <b>...FailSafe ()</b> variants.</li>
 <li>The internal TCP API for <b>TcpCongestionOps</b> has been extended to support the <b>CongControl</b> method to allow for delivery rate estimation feedback to the congestion control mechanism.</li>
 <li>Functions <b>LteEnbPhy::ReceiveUlHarqFeedback</b> and <b>LteUePhy::ReceiveLteDlHarqFeedback</b> are renamed to <b>LteEnbPhy::ReportUlHarqFeedback</b> and <b>LteUePhy::EnqueueDlHarqFeedback</b>, respectively to avoid confusion about their functionality. <b>LteHelper</b> is updated accordingly.</li>
 <li>Now on, instead of <b>uint8_t</b>, <b>uint16_t</b> would be used to store a bandwidth value in LTE.</li>
diff --git a/doc/manual/source/attributes.rst b/doc/manual/source/attributes.rst
index f9a6668a7..71af68381 100644
--- a/doc/manual/source/attributes.rst
+++ b/doc/manual/source/attributes.rst
@@ -463,7 +463,15 @@ default values.::
 
 At this point, we have created a single :cpp:class:`Node` (``n0``)
 and a single :cpp:class:`PointToPointNetDevice` (``net0``),
-and added a :cpp:class:`DropTailQueue` (``q``) to ``net0``.
+added a :cpp:class:`DropTailQueue` (``q``) to ``net0``,
+which will be configured with a queue size limit of 80 packets.
+
+As a final note, the :cpp:func:`Config::Set...()` functions
+will throw an error if the targeted Attribute does not exist at the path
+given.  There are also "fail-safe" versions,
+:cpp:func:`Config::Set...FailSafe()`, if you can't be sure the Attribute
+exists.  The fail-safe versions return `true` if at least one instance
+could be set.
 
 Constructors, Helpers and ObjectFactory
 =======================================
diff --git a/doc/manual/source/tracing.rst b/doc/manual/source/tracing.rst
index 55ca8e5df..76f6b58d7 100644
--- a/doc/manual/source/tracing.rst
+++ b/doc/manual/source/tracing.rst
@@ -294,6 +294,13 @@ congestion window in the TCP socket, the registered callback will be executed
 and the function ``CwndTracer`` will be called printing out the old and new
 values of the TCP congestion window.
 
+As a final note, the :cpp:func:`Config::Connect...()` functions
+will throw an error if the targeted TraceSource does not exist at the path
+given.  There are also "fail-safe" versions,
+:cpp:func:`Config::Connect...FailSafe()`, if you can't be sure the TraceSource
+exists.  The fail-safe versions return `true` if at least one connection
+could be made.
+
 Using the Tracing API
 *********************
 
diff --git a/src/core/model/config.cc b/src/core/model/config.cc
index 25e1942bf..39272882a 100644
--- a/src/core/model/config.cc
+++ b/src/core/model/config.cc
@@ -48,8 +48,8 @@ MatchContainer::MatchContainer (const std::vector<Ptr<Object> > &objects,
                                 const std::vector<std::string> &contexts,
                                 std::string path)
   : m_objects (objects),
-    m_contexts (contexts),
-    m_path (path)
+  m_contexts (contexts),
+  m_path (path)
 {
   NS_LOG_FUNCTION (this << &objects << &contexts << path);
 }
@@ -97,31 +97,63 @@ MatchContainer::Set (std::string name, const AttributeValue &value)
   for (Iterator tmp = Begin (); tmp != End (); ++tmp)
     {
       Ptr<Object> object = *tmp;
+      // Let ObjectBase::SetAttribute raise any errors
       object->SetAttribute (name, value);
     }
 }
+bool
+MatchContainer::SetFailSafe (std::string name, const AttributeValue &value)
+{
+  NS_LOG_FUNCTION (this << name << &value);
+  bool ok = false;
+  for (Iterator tmp = Begin (); tmp != End (); ++tmp)
+    {
+      Ptr<Object> object = *tmp;
+      ok |= object->SetAttributeFailSafe (name, value);
+    }
+  return ok;
+}
 void
 MatchContainer::Connect (std::string name, const CallbackBase &cb)
+{
+  if (!ConnectFailSafe (name, cb))
+    {
+      NS_FATAL_ERROR ("Cound not connect callback to " << name);
+    }
+}
+bool
+MatchContainer::ConnectFailSafe (std::string name, const CallbackBase &cb)
 {
   NS_LOG_FUNCTION (this << name << &cb);
   NS_ASSERT (m_objects.size () == m_contexts.size ());
+  bool ok = false;
   for (uint32_t i = 0; i < m_objects.size (); ++i)
     {
       Ptr<Object> object = m_objects[i];
       std::string ctx = m_contexts[i] + name;
-      object->TraceConnect (name, ctx, cb);
+      ok |= object->TraceConnect (name, ctx, cb);
     }
+  return ok;
 }
 void
 MatchContainer::ConnectWithoutContext (std::string name, const CallbackBase &cb)
+{
+  if (!ConnectWithoutContextFailSafe (name, cb))
+    {
+      NS_FATAL_ERROR ("Could not connect callback to " << name);
+    }
+}
+bool
+MatchContainer::ConnectWithoutContextFailSafe (std::string name, const CallbackBase &cb)
 {
   NS_LOG_FUNCTION (this << name << &cb);
-
+  bool ok = false;
   for (Iterator tmp = Begin (); tmp != End (); ++tmp)
     {
       Ptr<Object> object = *tmp;
-      object->TraceConnectWithoutContext (name, cb);
+      ok |= object->TraceConnectWithoutContext (name, cb);
     }
+  return ok;
 }
 void
 MatchContainer::Disconnect (std::string name, const CallbackBase &cb)
@@ -585,12 +617,16 @@ Resolver::DoArrayResolve (std::string path, const ObjectPtrContainerValue &conta
 class ConfigImpl : public Singleton<ConfigImpl>
 {
 public:
+  // Keep Set and SetFailSafe since their errors are triggered
+  // by the underlying ObjecBase functions.
   /** \copydoc Config::Set() */
   void Set (std::string path, const AttributeValue &value);
-  /** \copydoc Config::ConnectWithoutContext() */
-  void ConnectWithoutContext (std::string path, const CallbackBase &cb);
-  /** \copydoc Config::Connect() */
-  void Connect (std::string path, const CallbackBase &cb);
+  /** \copydoc Config::SetFailSafe() */
+  bool SetFailSafe (std::string path, const AttributeValue &value);
+  /** \copydoc Config::ConnectWithoutContextFailSafe() */
+  bool ConnectWithoutContextFailSafe (std::string path, const CallbackBase &cb);
+  /** \copydoc Config::ConnectFailSafe() */
+  bool ConnectFailSafe (std::string path, const CallbackBase &cb);
   /** \copydoc Config::DisconnectWithoutContext() */
   void DisconnectWithoutContext (std::string path, const CallbackBase &cb);
   /** \copydoc Config::Disconnect() */
@@ -648,21 +684,24 @@ ConfigImpl::Set (std::string path, const AttributeValue &value)
   MatchContainer container = LookupMatches (root);
   container.Set (leaf, value);
 }
-void
-ConfigImpl::ConnectWithoutContext (std::string path, const CallbackBase &cb)
+bool
+ConfigImpl::SetFailSafe (std::string path, const AttributeValue &value)
+{
+  NS_LOG_FUNCTION (this << path << &value);
+
+  std::string root, leaf;
+  ParsePath (path, &root, &leaf);
+  MatchContainer container = LookupMatches (root);
+  return container.SetFailSafe (leaf, value);
+}
+bool
+ConfigImpl::ConnectWithoutContextFailSafe (std::string path, const CallbackBase &cb)
 {
   NS_LOG_FUNCTION (this << path << &cb);
   std::string root, leaf;
   ParsePath (path, &root, &leaf);
   MatchContainer container = LookupMatches (root);
-  if (container.GetN () == 0)
-    {
-      std::size_t lastFwdSlash = root.rfind ("/");
-      NS_LOG_WARN ("Failed to connect " << leaf <<
-                   ", the Requested object name = " << root.substr (lastFwdSlash + 1) <<
-                   " does not exits on path " << root.substr (0, lastFwdSlash));
-    }
-  container.ConnectWithoutContext (leaf, cb);
+  return container.ConnectWithoutContextFailSafe (leaf, cb);
 }
 void
 ConfigImpl::DisconnectWithoutContext (std::string path, const CallbackBase &cb)
@@ -674,28 +713,21 @@ ConfigImpl::DisconnectWithoutContext (std::string path, const CallbackBase &cb)
   if (container.GetN () == 0)
     {
       std::size_t lastFwdSlash = root.rfind ("/");
-      NS_LOG_WARN ("Failed to disconnect " << leaf <<
-                   ", the Requested object name = " << root.substr (lastFwdSlash + 1) <<
-                   " does not exits on path " << root.substr (0, lastFwdSlash));
+      NS_LOG_WARN ("Failed to disconnect " << leaf
+                                           << ", the Requested object name = " << root.substr (lastFwdSlash + 1)
+                                           << " does not exits on path " << root.substr (0, lastFwdSlash));
     }
   container.DisconnectWithoutContext (leaf, cb);
 }
-void
-ConfigImpl::Connect (std::string path, const CallbackBase &cb)
+bool
+ConfigImpl::ConnectFailSafe (std::string path, const CallbackBase &cb)
 {
   NS_LOG_FUNCTION (this << path << &cb);
 
   std::string root, leaf;
   ParsePath (path, &root, &leaf);
   MatchContainer container = LookupMatches (root);
-  if (container.GetN () == 0)
-    {
-      std::size_t lastFwdSlash = root.rfind ("/");
-      NS_LOG_WARN ("Failed to connect " << leaf <<
-                   ", the Requested object name = " << root.substr (lastFwdSlash + 1) <<
-                   " does not exits on path " << root.substr (0, lastFwdSlash));
-    }
-  container.Connect (leaf, cb);
+  return container.ConnectFailSafe (leaf, cb);
 }
 void
 ConfigImpl::Disconnect (std::string path, const CallbackBase &cb)
@@ -708,9 +740,9 @@ ConfigImpl::Disconnect (std::string path, const CallbackBase &cb)
   if (container.GetN () == 0)
     {
       std::size_t lastFwdSlash = root.rfind ("/");
-      NS_LOG_WARN ("Failed to disconnect " << leaf <<
-                   ", the Requested object name = " << root.substr (lastFwdSlash + 1) <<
-                   " does not exits on path " << root.substr (0, lastFwdSlash));
+      NS_LOG_WARN ("Failed to disconnect " << leaf
+                                           << ", the Requested object name = " << root.substr (lastFwdSlash + 1)
+                                           << " does not exits on path " << root.substr (0, lastFwdSlash));
     }
   container.Disconnect (leaf, cb);
 }
@@ -721,10 +753,11 @@ ConfigImpl::LookupMatches (std::string path)
   NS_LOG_FUNCTION (this << path);
   class LookupMatchesResolver : public Resolver
   {
-  public:
+public:
     LookupMatchesResolver (std::string path)
       : Resolver (path)
-    {}
+    {
+    }
     virtual void DoOne (Ptr<Object> object, std::string path)
     {
       m_objects.push_back (object);
@@ -803,12 +836,16 @@ void Reset (void)
       (*i)->ResetInitialValue ();
     }
 }
-
 void Set (std::string path, const AttributeValue &value)
 {
   NS_LOG_FUNCTION (path << &value);
   ConfigImpl::Get ()->Set (path, value);
 }
+bool SetFailSafe (std::string path, const AttributeValue &value)
+{
+  NS_LOG_FUNCTION (path << &value);
+  return ConfigImpl::Get ()->SetFailSafe (path, value);
+}
 void SetDefault (std::string name, const AttributeValue &value)
 {
   NS_LOG_FUNCTION (name << &value);
@@ -862,7 +899,12 @@ bool SetGlobalFailSafe (std::string name, const AttributeValue &value)
 void ConnectWithoutContext (std::string path, const CallbackBase &cb)
 {
   NS_LOG_FUNCTION (path << &cb);
-  ConfigImpl::Get ()->ConnectWithoutContext (path, cb);
+  ConnectWithoutContextFailSafe (path, cb);
+}
+bool ConnectWithoutContextFailSafe (std::string path, const CallbackBase &cb)
+{
+  NS_LOG_FUNCTION (path << &cb);
+  return ConfigImpl::Get ()->ConnectWithoutContextFailSafe (path, cb);
 }
 void DisconnectWithoutContext (std::string path, const CallbackBase &cb)
 {
@@ -873,7 +915,16 @@ void
 Connect (std::string path, const CallbackBase &cb)
 {
   NS_LOG_FUNCTION (path << &cb);
-  ConfigImpl::Get ()->Connect (path, cb);
+  if (!ConnectFailSafe (path, cb))
+    {
+      NS_FATAL_ERROR ("Could not connect callback to " << name);
+    }
+}
+bool
+ConnectFailSafe (std::string path, const CallbackBase &cb)
+{
+  NS_LOG_FUNCTION (path << &cb);
+  return ConfigImpl::Get ()->ConnectFailSafe (path, cb);
 }
 void
 Disconnect (std::string path, const CallbackBase &cb)
diff --git a/src/core/model/config.h b/src/core/model/config.h
index 096ed45d2..1e76d3ab8 100644
--- a/src/core/model/config.h
+++ b/src/core/model/config.h
@@ -65,6 +65,11 @@ void Reset (void);
  * value.
  */
 void Set (std::string path, const AttributeValue &value);
+/**
+ * \copydoc Set()
+ * \return \c true if any matching attributes could be set.
+ */
+bool SetFailSafe (std::string path, const AttributeValue &value);
 /**
  * \ingroup config
  * \param [in] name The full name of the attribute
@@ -112,6 +117,11 @@ bool SetGlobalFailSafe (std::string name, const AttributeValue &value);
  * to them.
  */
 void ConnectWithoutContext (std::string path, const CallbackBase &cb);
+/**
+ * \copydoc ConnectWithoutContext()
+ * \returns \c true if any trace sources could be connected.
+ */
+bool ConnectWithoutContextFailSafe (std::string path, const CallbackBase &cb);
 /**
  * \ingroup config
  * \param [in] path A path to match trace sources.
@@ -131,6 +141,11 @@ void DisconnectWithoutContext (std::string path, const CallbackBase &cb);
  * context string upon trace event notification.
  */
 void Connect (std::string path, const CallbackBase &cb);
+/**
+ * \copydoc Connect()
+ * \returns \c true if any trace sources could be connected.
+ */
+bool ConnectFailSafe (std::string path, const CallbackBase &cb);
 /**
  * \ingroup config
  * \param [in] path A path to match trace sources.
@@ -204,6 +219,11 @@ public:
    * \sa ns3::Config::Set
    */
   void Set (std::string name, const AttributeValue &value);
+  /**
+   * \copydoc Set()
+   * \returns \c true if any attributes could be set.
+   */
+  bool SetFailSafe (std::string name, const AttributeValue &value);
   /**
    * \param [in] name The name of the trace source to connect to
    * \param [in] cb The sink to connect to the trace source
@@ -213,6 +233,11 @@ public:
    * \sa ns3::Config::Connect
    */
   void Connect (std::string name, const CallbackBase &cb);
+  /**
+   * \copydoc Connect()
+   * \returns \c true if any trace sources could be connected.
+   */
+  bool ConnectFailSafe (std::string name, const CallbackBase &cb);
   /**
    * \param [in] name The name of the trace source to connect to
    * \param [in] cb The sink to connect to the trace source
@@ -222,6 +247,11 @@ public:
    * \sa ns3::Config::ConnectWithoutContext
    */
   void ConnectWithoutContext (std::string name, const CallbackBase &cb);
+  /**
+   * \copydoc ConnectWithoutContext()
+   * \returns \c true if any trace sources could be connected.
+   */
+  bool ConnectWithoutContextFailSafe (std::string name, const CallbackBase &cb);
   /**
    * \param [in] name The name of the trace source to disconnect from
    * \param [in] cb The sink to disconnect from the trace source
diff --git a/src/netanim/model/animation-interface.cc b/src/netanim/model/animation-interface.cc
index fd36818ad..09dc26f6e 100644
--- a/src/netanim/model/animation-interface.cc
+++ b/src/netanim/model/animation-interface.cc
@@ -1626,109 +1626,109 @@ void
 AnimationInterface::ConnectCallbacks ()
 {
   // Connect the callbacks
-  Config::Connect ("/ChannelList/*/TxRxPointToPoint",
-                   MakeCallback (&AnimationInterface::DevTxTrace, this));
-  Config::Connect ("/NodeList/*/DeviceList/*/$ns3::WifiNetDevice/Phy/PhyTxPsduBegin",
-                   MakeCallback (&AnimationInterface::WifiPhyTxBeginTrace, this));
-  Config::Connect ("/NodeList/*/DeviceList/*/$ns3::WifiNetDevice/Phy/PhyRxBegin",
-                   MakeCallback (&AnimationInterface::WifiPhyRxBeginTrace, this));
-  Config::ConnectWithoutContext ("/NodeList/*/$ns3::MobilityModel/CourseChange",
-                                 MakeCallback (&AnimationInterface::MobilityCourseChangeTrace, this));
-  Config::Connect ("/NodeList/*/DeviceList/*/$ns3::WimaxNetDevice/Tx",
-                   MakeCallback (&AnimationInterface::WimaxTxTrace, this));
-  Config::Connect ("/NodeList/*/DeviceList/*/$ns3::WimaxNetDevice/Rx",
-                   MakeCallback (&AnimationInterface::WimaxRxTrace, this));
-  Config::Connect ("/NodeList/*/DeviceList/*/$ns3::LteNetDevice/Tx",
-                   MakeCallback (&AnimationInterface::LteTxTrace, this));
-  Config::Connect ("/NodeList/*/DeviceList/*/$ns3::LteNetDevice/Rx",
-                   MakeCallback (&AnimationInterface::LteRxTrace, this));
-  Config::Connect ("/NodeList/*/DeviceList/*/$ns3::CsmaNetDevice/PhyTxBegin",
-                   MakeCallback (&AnimationInterface::CsmaPhyTxBeginTrace, this));
-  Config::Connect ("/NodeList/*/DeviceList/*/$ns3::CsmaNetDevice/PhyTxEnd",
-                   MakeCallback (&AnimationInterface::CsmaPhyTxEndTrace, this));
-  Config::Connect ("/NodeList/*/DeviceList/*/$ns3::CsmaNetDevice/PhyRxEnd",
-                   MakeCallback (&AnimationInterface::CsmaPhyRxEndTrace, this));
-  Config::Connect ("/NodeList/*/DeviceList/*/$ns3::CsmaNetDevice/MacRx",
-                   MakeCallback (&AnimationInterface::CsmaMacRxTrace, this));
-  Config::Connect ("/NodeList/*/DeviceList/*/$ns3::UanNetDevice/Phy/PhyTxBegin",
-                   MakeCallback (&AnimationInterface::UanPhyGenTxTrace, this));
-  Config::Connect ("/NodeList/*/DeviceList/*/$ns3::UanNetDevice/Phy/PhyRxBegin",
-                   MakeCallback (&AnimationInterface::UanPhyGenRxTrace, this));
-  Config::Connect ("/NodeList/*/$ns3::BasicEnergySource/RemainingEnergy",
-                   MakeCallback (&AnimationInterface::RemainingEnergyTrace, this));
-
+  Config::ConnectFailSafe ("/ChannelList/*/TxRxPointToPoint",
+                           MakeCallback (&AnimationInterface::DevTxTrace, this));
+  Config::ConnectFailSafe ("/NodeList/*/DeviceList/*/$ns3::WifiNetDevice/Phy/PhyTxPsduBegin",
+                           MakeCallback (&AnimationInterface::WifiPhyTxBeginTrace, this));
+  Config::ConnectFailSafe ("/NodeList/*/DeviceList/*/$ns3::WifiNetDevice/Phy/PhyRxBegin",
+                           MakeCallback (&AnimationInterface::WifiPhyRxBeginTrace, this));
+  Config::ConnectWithoutContextFailSafe ("/NodeList/*/$ns3::MobilityModel/CourseChange",
+                                         MakeCallback (&AnimationInterface::MobilityCourseChangeTrace, this));
+  Config::ConnectFailSafe ("/NodeList/*/DeviceList/*/$ns3::WimaxNetDevice/Tx",
+                           MakeCallback (&AnimationInterface::WimaxTxTrace, this));
+  Config::ConnectFailSafe ("/NodeList/*/DeviceList/*/$ns3::WimaxNetDevice/Rx",
+                           MakeCallback (&AnimationInterface::WimaxRxTrace, this));
+  Config::ConnectFailSafe ("/NodeList/*/DeviceList/*/$ns3::LteNetDevice/Tx",
+                           MakeCallback (&AnimationInterface::LteTxTrace, this));
+  Config::ConnectFailSafe ("/NodeList/*/DeviceList/*/$ns3::LteNetDevice/Rx",
+                           MakeCallback (&AnimationInterface::LteRxTrace, this));
+  Config::ConnectFailSafe ("/NodeList/*/DeviceList/*/$ns3::CsmaNetDevice/PhyTxBegin",
+                           MakeCallback (&AnimationInterface::CsmaPhyTxBeginTrace, this));
+  Config::ConnectFailSafe ("/NodeList/*/DeviceList/*/$ns3::CsmaNetDevice/PhyTxEnd",
+                           MakeCallback (&AnimationInterface::CsmaPhyTxEndTrace, this));
+  Config::ConnectFailSafe ("/NodeList/*/DeviceList/*/$ns3::CsmaNetDevice/PhyRxEnd",
+                           MakeCallback (&AnimationInterface::CsmaPhyRxEndTrace, this));
+  Config::ConnectFailSafe ("/NodeList/*/DeviceList/*/$ns3::CsmaNetDevice/MacRx",
+                           MakeCallback (&AnimationInterface::CsmaMacRxTrace, this));
+  Config::ConnectFailSafe ("/NodeList/*/DeviceList/*/$ns3::UanNetDevice/Phy/PhyTxBegin",
+                           MakeCallback (&AnimationInterface::UanPhyGenTxTrace, this));
+  Config::ConnectFailSafe ("/NodeList/*/DeviceList/*/$ns3::UanNetDevice/Phy/PhyRxBegin",
+                           MakeCallback (&AnimationInterface::UanPhyGenRxTrace, this));
+  Config::ConnectFailSafe ("/NodeList/*/$ns3::BasicEnergySource/RemainingEnergy",
+                           MakeCallback (&AnimationInterface::RemainingEnergyTrace, this));
+  
   ConnectLte ();
-
-  Config::Connect ("/NodeList/*/$ns3::Ipv4L3Protocol/Tx",
-                   MakeCallback (&AnimationInterface::Ipv4TxTrace, this));
-  Config::Connect ("/NodeList/*/$ns3::Ipv4L3Protocol/Rx",
-                   MakeCallback (&AnimationInterface::Ipv4RxTrace, this));
-  Config::Connect ("/NodeList/*/$ns3::Ipv4L3Protocol/Drop",
-                   MakeCallback (&AnimationInterface::Ipv4DropTrace, this));
-
+  
+  Config::ConnectFailSafe ("/NodeList/*/$ns3::Ipv4L3Protocol/Tx",
+                           MakeCallback (&AnimationInterface::Ipv4TxTrace, this));
+  Config::ConnectFailSafe ("/NodeList/*/$ns3::Ipv4L3Protocol/Rx",
+                           MakeCallback (&AnimationInterface::Ipv4RxTrace, this));
+  Config::ConnectFailSafe ("/NodeList/*/$ns3::Ipv4L3Protocol/Drop",
+                           MakeCallback (&AnimationInterface::Ipv4DropTrace, this));
+  
   // Queue Enqueues
-
-  Config::Connect ("/NodeList/*/DeviceList/*/$ns3::AlohaNoackNetDevice/Queue/Enqueue",
-                   MakeCallback (&AnimationInterface::EnqueueTrace, this));
-  Config::Connect ("/NodeList/*/DeviceList/*/$ns3::CsmaNetDevice/TxQueue/Enqueue",
-                   MakeCallback (&AnimationInterface::EnqueueTrace, this));
-  Config::Connect ("/NodeList/*/DeviceList/*/$ns3::PointToPointNetDevice/TxQueue/Enqueue",
-                   MakeCallback (&AnimationInterface::EnqueueTrace, this));
-
+  
+  Config::ConnectFailSafe ("/NodeList/*/DeviceList/*/$ns3::AlohaNoackNetDevice/Queue/Enqueue",
+                           MakeCallback (&AnimationInterface::EnqueueTrace, this));
+  Config::ConnectFailSafe ("/NodeList/*/DeviceList/*/$ns3::CsmaNetDevice/TxQueue/Enqueue",
+                           MakeCallback (&AnimationInterface::EnqueueTrace, this));
+  Config::ConnectFailSafe ("/NodeList/*/DeviceList/*/$ns3::PointToPointNetDevice/TxQueue/Enqueue",
+                           MakeCallback (&AnimationInterface::EnqueueTrace, this));
+  
   // Queue Dequeues
-
-  Config::Connect ("/NodeList/*/DeviceList/*/$ns3::AlohaNoackNetDevice/Queue/Dequeue",
-                   MakeCallback (&AnimationInterface::DequeueTrace, this));
-  Config::Connect ("/NodeList/*/DeviceList/*/$ns3::CsmaNetDevice/TxQueue/Dequeue",
-                   MakeCallback (&AnimationInterface::DequeueTrace, this));
-  Config::Connect ("/NodeList/*/DeviceList/*/$ns3::PointToPointNetDevice/TxQueue/Dequeue",
-                   MakeCallback (&AnimationInterface::DequeueTrace, this));
-
+  
+  Config::ConnectFailSafe ("/NodeList/*/DeviceList/*/$ns3::AlohaNoackNetDevice/Queue/Dequeue",
+                           MakeCallback (&AnimationInterface::DequeueTrace, this));
+  Config::ConnectFailSafe ("/NodeList/*/DeviceList/*/$ns3::CsmaNetDevice/TxQueue/Dequeue",
+                           MakeCallback (&AnimationInterface::DequeueTrace, this));
+  Config::ConnectFailSafe ("/NodeList/*/DeviceList/*/$ns3::PointToPointNetDevice/TxQueue/Dequeue",
+                           MakeCallback (&AnimationInterface::DequeueTrace, this));
+  
   // Queue Drops
-
-  Config::Connect ("/NodeList/*/DeviceList/*/$ns3::AlohaNoackNetDevice/Queue/Drop",
-                   MakeCallback (&AnimationInterface::QueueDropTrace, this));
-  Config::Connect ("/NodeList/*/DeviceList/*/$ns3::CsmaNetDevice/TxQueue/Drop",
-                   MakeCallback (&AnimationInterface::QueueDropTrace, this));
-  Config::Connect ("/NodeList/*/DeviceList/*/$ns3::PointToPointNetDevice/TxQueue/Drop",
-                   MakeCallback (&AnimationInterface::QueueDropTrace, this));
-
-
+  
+  Config::ConnectFailSafe ("/NodeList/*/DeviceList/*/$ns3::AlohaNoackNetDevice/Queue/Drop",
+                           MakeCallback (&AnimationInterface::QueueDropTrace, this));
+  Config::ConnectFailSafe ("/NodeList/*/DeviceList/*/$ns3::CsmaNetDevice/TxQueue/Drop",
+                           MakeCallback (&AnimationInterface::QueueDropTrace, this));
+  Config::ConnectFailSafe ("/NodeList/*/DeviceList/*/$ns3::PointToPointNetDevice/TxQueue/Drop",
+                           MakeCallback (&AnimationInterface::QueueDropTrace, this));
+  
+  
   // Wifi Mac
-  Config::Connect ("/NodeList/*/DeviceList/*/$ns3::WifiNetDevice/Mac/MacTx",
-                   MakeCallback (&AnimationInterface::WifiMacTxTrace, this));
-  Config::Connect ("/NodeList/*/DeviceList/*/$ns3::WifiNetDevice/Mac/MacTxDrop",
-                   MakeCallback (&AnimationInterface::WifiMacTxDropTrace, this));
-  Config::Connect ("/NodeList/*/DeviceList/*/$ns3::WifiNetDevice/Mac/MacRx",
-                   MakeCallback (&AnimationInterface::WifiMacRxTrace, this));
-  Config::Connect ("/NodeList/*/DeviceList/*/$ns3::WifiNetDevice/Mac/MacRxDrop",
-                   MakeCallback (&AnimationInterface::WifiMacRxDropTrace, this));
-
+  Config::ConnectFailSafe ("/NodeList/*/DeviceList/*/$ns3::WifiNetDevice/Mac/MacTx",
+                           MakeCallback (&AnimationInterface::WifiMacTxTrace, this));
+  Config::ConnectFailSafe ("/NodeList/*/DeviceList/*/$ns3::WifiNetDevice/Mac/MacTxDrop",
+                           MakeCallback (&AnimationInterface::WifiMacTxDropTrace, this));
+  Config::ConnectFailSafe ("/NodeList/*/DeviceList/*/$ns3::WifiNetDevice/Mac/MacRx",
+                           MakeCallback (&AnimationInterface::WifiMacRxTrace, this));
+  Config::ConnectFailSafe ("/NodeList/*/DeviceList/*/$ns3::WifiNetDevice/Mac/MacRxDrop",
+                           MakeCallback (&AnimationInterface::WifiMacRxDropTrace, this));
+  
   // Wifi Phy
-  Config::Connect ("/NodeList/*/DeviceList/*/$ns3::WifiNetDevice/Phy/PhyTxDrop",
-                   MakeCallback (&AnimationInterface::WifiPhyTxDropTrace, this));
-  Config::Connect ("/NodeList/*/DeviceList/*/$ns3::WifiNetDevice/Phy/PhyRxDrop",
-                   MakeCallback (&AnimationInterface::WifiPhyRxDropTrace, this));
-
+  Config::ConnectFailSafe ("/NodeList/*/DeviceList/*/$ns3::WifiNetDevice/Phy/PhyTxDrop",
+                           MakeCallback (&AnimationInterface::WifiPhyTxDropTrace, this));
+  Config::ConnectFailSafe ("/NodeList/*/DeviceList/*/$ns3::WifiNetDevice/Phy/PhyRxDrop",
+                           MakeCallback (&AnimationInterface::WifiPhyRxDropTrace, this));
+  
   // LrWpan
-  Config::Connect ("NodeList/*/DeviceList/*/$ns3::LrWpanNetDevice/Phy/PhyTxBegin",
-                   MakeCallback (&AnimationInterface::LrWpanPhyTxBeginTrace, this));
-  Config::Connect ("NodeList/*/DeviceList/*/$ns3::LrWpanNetDevice/Phy/PhyRxBegin",
-                   MakeCallback (&AnimationInterface::LrWpanPhyRxBeginTrace, this));
-  Config::Connect ("/NodeList/*/DeviceList/*/$ns3::LrWpanNetDevice/Mac/MacTx",
-                   MakeCallback (&AnimationInterface::LrWpanMacTxTrace, this));
-  Config::Connect ("/NodeList/*/DeviceList/*/$ns3::LrWpanNetDevice/Mac/MacTxDrop",
-                   MakeCallback (&AnimationInterface::LrWpanMacTxDropTrace, this));
-  Config::Connect ("/NodeList/*/DeviceList/*/$ns3::LrWpanNetDevice/Mac/MacRx",
-                   MakeCallback (&AnimationInterface::LrWpanMacRxTrace, this));
-  Config::Connect ("/NodeList/*/DeviceList/*/$ns3::LrWpanNetDevice/Mac/MacRxDrop",
-                   MakeCallback (&AnimationInterface::LrWpanMacRxDropTrace, this));
-
+  Config::ConnectFailSafe ("NodeList/*/DeviceList/*/$ns3::LrWpanNetDevice/Phy/PhyTxBegin",
+                           MakeCallback (&AnimationInterface::LrWpanPhyTxBeginTrace, this));
+  Config::ConnectFailSafe ("NodeList/*/DeviceList/*/$ns3::LrWpanNetDevice/Phy/PhyRxBegin",
+                           MakeCallback (&AnimationInterface::LrWpanPhyRxBeginTrace, this));
+  Config::ConnectFailSafe ("/NodeList/*/DeviceList/*/$ns3::LrWpanNetDevice/Mac/MacTx",
+                           MakeCallback (&AnimationInterface::LrWpanMacTxTrace, this));
+  Config::ConnectFailSafe ("/NodeList/*/DeviceList/*/$ns3::LrWpanNetDevice/Mac/MacTxDrop",
+                           MakeCallback (&AnimationInterface::LrWpanMacTxDropTrace, this));
+  Config::ConnectFailSafe ("/NodeList/*/DeviceList/*/$ns3::LrWpanNetDevice/Mac/MacRx",
+                           MakeCallback (&AnimationInterface::LrWpanMacRxTrace, this));
+  Config::ConnectFailSafe ("/NodeList/*/DeviceList/*/$ns3::LrWpanNetDevice/Mac/MacRxDrop",
+                           MakeCallback (&AnimationInterface::LrWpanMacRxDropTrace, this));
+  
   // Wave
-  Config::Connect ("/NodeList/*/DeviceList/*/$ns3::WaveNetDevice/PhyEntities/*/$ns3::WifiPhy/PhyTxBegin",
-                   MakeCallback (&AnimationInterface::WavePhyTxBeginTrace, this));
-  Config::Connect ("/NodeList/*/DeviceList/*/$ns3::WaveNetDevice/PhyEntities/*/$ns3::WifiPhy/PhyRxBegin",
-                   MakeCallback (&AnimationInterface::WavePhyRxBeginTrace, this));
+  Config::ConnectFailSafe ("/NodeList/*/DeviceList/*/$ns3::WaveNetDevice/PhyEntities/*/$ns3::WifiPhy/PhyTxBegin",
+                           MakeCallback (&AnimationInterface::WavePhyTxBeginTrace, this));
+  Config::ConnectFailSafe ("/NodeList/*/DeviceList/*/$ns3::WaveNetDevice/PhyEntities/*/$ns3::WifiPhy/PhyRxBegin",
+                           MakeCallback (&AnimationInterface::WavePhyRxBeginTrace, this));
 }
 
 Vector