--- a/examples/mixed-wireless.cc	Fri Apr 11 11:30:05 2008 -0700
+++ b/examples/mixed-wireless.cc	Sun Apr 13 15:46:17 2008 -0700
@@ -166,7 +166,7 @@
                               "Bounds", Rectangle (0, 1000, 0, 1000),
                               "Speed", ConstantVariable (2000),
                               "Pause", ConstantVariable (0.2));
-  mobility.Layout (backbone);
+  mobility.Install (backbone);
 
   /////////////////////////////////////////////////////////////////////////// 
   //                                                                       //
@@ -178,17 +178,19 @@
   // the "172.16 address space
   ipAddrs.SetBase ("172.16.0.0", "255.255.255.0");
 
+
   for (uint32_t i = 0; i < backboneNodes; ++i)
     {
       NS_LOG_INFO ("Configuring local area network for backbone node " << i);
       //
-      // Create a container to manage the nodes of the LAN.  Pick one of 
-      // the backbone nodes to be part of the LAN and first add it to 
-      // the container.  Then create the rest of the nodes we'll need.
+      // Create a container to manage the nodes of the LAN.  We need
+      // two containers here; one with all of the new nodes, and one
+      // with all of the nodes including new and existing nodes
       //
-      NodeContainer lan;
-      lan.Add (backbone.Get (i));
-      lan.Create (lanNodes - 1);
+      NodeContainer newLanNodes;
+      newLanNodes.Create (lanNodes - 1);
+      // Now, create the container with all nodes on this link
+      NodeContainer lan (backbone.Get (i), newLanNodes);
       //
       // Create the CSMA net devices and install them into the nodes in our 
       // collection.
@@ -198,9 +200,9 @@
       csma.SetChannelParameter ("Delay", MilliSeconds (2));
       NetDeviceContainer lanDevices = csma.Install (lan);
       //
-      // Add the IPv4 protocol stack to the nodes in our container
+      // Add the IPv4 protocol stack to the new LAN nodes
       //
-      internet.Install (lan);
+      internet.Install (newLanNodes);
       //
       // Assign IPv4 addresses to the device drivers (actually to the 
       // associated IPv4 interfaces) we just created.
@@ -227,13 +229,14 @@
     {
       NS_LOG_INFO ("Configuring wireless network for backbone node " << i);
       //
-      // Create a container to manage the nodes of the network.  Pick one of 
-      // the backbone nodes to be part of the network and first add it to 
-      // the container.  Then create the rest of the nodes we'll need.
+      // Create a container to manage the nodes of the LAN.  We need
+      // two containers here; one with all of the new nodes, and one
+      // with all of the nodes including new and existing nodes
       //
-      NodeContainer infra;
-      infra.Add (backbone.Get (i));
-      infra.Create (infraNodes - 1);
+      NodeContainer newInfraNodes;
+      newInfraNodes.Create (infraNodes - 1);
+      // Now, create the container with all nodes on this link
+      NodeContainer infra (backbone.Get (i), newInfraNodes);
       //
       // Create another ad hoc network and devices
       //
@@ -244,7 +247,7 @@
 
       // Add the IPv4 protocol stack to the nodes in our container
       //
-      internet.Install (infra);
+      internet.Install (newInfraNodes);
       //
       // Assign IPv4 addresses to the device drivers (actually to the associated
       // IPv4 interfaces) we just created.
@@ -272,7 +275,7 @@
                                  "Bounds", Rectangle (-25, 25, -25, 25),
                                  "Speed", ConstantVariable (30),
                                  "Pause", ConstantVariable (0.4));
-      mobility.Layout (infra);
+      mobility.Install (infra);
     }
   /////////////////////////////////////////////////////////////////////////// 
   //                                                                       //
@@ -282,7 +285,7 @@
 
   NS_LOG_INFO ("Enabling OLSR routing on all backbone nodes");
   OlsrHelper olsr;
-  olsr.Enable (backbone);
+  olsr.Install (backbone);
 
   /////////////////////////////////////////////////////////////////////////// 
   //                                                                       //

--- a/examples/simple-point-to-point-olsr.cc	Fri Apr 11 11:30:05 2008 -0700
+++ b/examples/simple-point-to-point-olsr.cc	Sun Apr 13 15:46:17 2008 -0700
@@ -120,7 +120,7 @@
   // Enable OLSR
   NS_LOG_INFO ("Enabling OLSR Routing.");
   OlsrHelper olsr;
-  olsr.EnableAll ();
+  olsr.InstallAll ();
 
   // Create the OnOff application to send UDP datagrams of size
   // 210 bytes at a rate of 448 Kb/s

--- a/examples/wifi-adhoc.cc	Fri Apr 11 11:30:05 2008 -0700
+++ b/examples/wifi-adhoc.cc	Sun Apr 13 15:46:17 2008 -0700
@@ -126,7 +126,7 @@
   mobility.SetPositionAllocator (positionAlloc);
   mobility.SetMobilityModel ("ns3::StaticMobilityModel");
 
-  mobility.Layout (c);
+  mobility.Install (c);
 
   PacketSocketAddress socket;
   socket.SetSingleDevice(devices.Get (0)->GetIfIndex ());

--- a/examples/wifi-ap.cc	Fri Apr 11 11:30:05 2008 -0700
+++ b/examples/wifi-ap.cc	Sun Apr 13 15:46:17 2008 -0700
@@ -151,8 +151,8 @@
   wifi.Install (ap, channel);
 
   // mobility.
-  mobility.Layout (stas);
-  mobility.Layout (ap);
+  mobility.Install (stas);
+  mobility.Install (ap);
 
   Simulator::Schedule (Seconds (1.0), &AdvancePosition, ap.Get (0));
 

--- a/samples/main-grid-topology.cc	Fri Apr 11 11:30:05 2008 -0700
+++ b/samples/main-grid-topology.cc	Sun Apr 13 15:46:17 2008 -0700
@@ -37,7 +37,7 @@
   // finalize the setup by attaching to each object
   // in the input array a position and initializing
   // this position with the calculated coordinates.
-  mobility.Layout (nodes);
+  mobility.Install (nodes);
 
   // iterate our nodes and print their position.
   for (NodeContainer::Iterator j = nodes.Begin ();

--- a/samples/main-random-topology.cc	Fri Apr 11 11:30:05 2008 -0700
+++ b/samples/main-random-topology.cc	Sun Apr 13 15:46:17 2008 -0700
@@ -31,7 +31,7 @@
                                  "Y", String ("100.0"),
                                  "Rho", String ("Uniform:0:30"));
   mobility.SetMobilityModel ("ns3::StaticMobilityModel");
-  mobility.Layout (c);
+  mobility.Install (c);
 
   Config::Connect ("/NodeList/*/$ns3::MobilityModelNotifier/CourseChange",
                               MakeCallback (&CourseChange));

--- a/samples/main-random-walk.cc	Fri Apr 11 11:30:05 2008 -0700
+++ b/samples/main-random-walk.cc	Sun Apr 13 15:46:17 2008 -0700
@@ -41,7 +41,7 @@
                              "Time", String ("2s"),
                              "Speed", String ("Constant:1.0"),
                              "Bounds", String ("0:200:0:100"));
-  mobility.LayoutAll ();
+  mobility.InstallAll ();
   Config::Connect ("/NodeList/*/$ns3::MobilityModelNotifier/CourseChange",
                               MakeCallback (&CourseChange));
 

--- a/src/helper/internet-stack-helper.cc	Fri Apr 11 11:30:05 2008 -0700
+++ b/src/helper/internet-stack-helper.cc	Sun Apr 13 15:46:17 2008 -0700
@@ -17,6 +17,10 @@
  *
  * Author: Mathieu Lacage <mathieu.lacage@sophia.inria.fr>
  */
+#include "ns3/assert.h"
+#include "ns3/log.h"
+#include "ns3/object.h"
+#include "ns3/ipv4.h"
 #include "internet-stack-helper.h"
 #include "ns3/internet-stack.h"
 #include "ns3/packet-socket-factory.h"
@@ -33,6 +37,12 @@
   for (NodeContainer::Iterator i = c.Begin (); i != c.End (); ++i)
     {
       Ptr<Node> node = *i;
+      if (node->GetObject<Ipv4> () != 0)
+        {
+          NS_FATAL_ERROR ("InternetStackHelper::Install(): Aggregating " 
+             "an InternetStack to a node with an existing Ipv4 object");
+          return;
+        } 
       AddInternetStack (node);
       Ptr<PacketSocketFactory> factory = CreateObject<PacketSocketFactory> ();
       node->AggregateObject (factory);

--- a/src/helper/internet-stack-helper.h	Fri Apr 11 11:30:05 2008 -0700
+++ b/src/helper/internet-stack-helper.h	Sun Apr 13 15:46:17 2008 -0700
@@ -37,7 +37,10 @@
    * \param c the set of nodes
    *
    * For each node in the input container, aggregate implementations
-   * of the ns3::Ipv4, ns3::Udp, and, ns3::Tcp classes.
+   * of the ns3::Ipv4, ns3::Udp, and, ns3::Tcp classes.  The program
+   * will assert if this method is called on a container with a node
+   * that already has an Ipv4 object aggregated to it.
+   * 
    */
   void Install (NodeContainer c);
 

--- a/src/helper/mobility-helper.cc	Fri Apr 11 11:30:05 2008 -0700
+++ b/src/helper/mobility-helper.cc	Sun Apr 13 15:46:17 2008 -0700
@@ -122,7 +122,7 @@
 }
 
 void 
-MobilityHelper::Layout (NodeContainer c)
+MobilityHelper::Install (NodeContainer c)
 {
   for (NodeContainer::Iterator i = c.Begin (); i != c.End (); ++i)
     {
@@ -167,9 +167,9 @@
 }
 
 void 
-MobilityHelper::LayoutAll (void)
+MobilityHelper::InstallAll (void)
 {
-  Layout (NodeContainer::GetGlobal ());
+  Install (NodeContainer::GetGlobal ());
 }
 
 } // namespace ns3

--- a/src/helper/mobility-helper.h	Fri Apr 11 11:30:05 2008 -0700
+++ b/src/helper/mobility-helper.h	Sun Apr 13 15:46:17 2008 -0700
@@ -34,7 +34,7 @@
 /**
  * \brief assign positions and mobility models to nodes.
  *
- * MobilityHelper::Layout is the most important method here.
+ * MobilityHelper::Install is the most important method here.
  */
 class MobilityHelper
 {
@@ -43,14 +43,14 @@
   ~MobilityHelper ();
 
   /**
-   * After this method is called, every call to MobilityHelper::Layout
+   * After this method is called, every call to MobilityHelper::Install
    * will also attach to the new ns3::MobilityModel an ns3::MobilityModelNotifier
    * which can be used to listen to CourseChange events.
    */
   void EnableNotifier (void);
   /**
    * After this method is called, no ns3::MobilityModelNotifier object will
-   * be associated to any new ns3::MobilityModel created by MobilityHelper::Layout.
+   * be associated to any new ns3::MobilityModel created by MobilityHelper::Install.
    * This will make it impossible to listen to "CourseChange" events from these
    * new ns3::MobilityModel instances.
    */
@@ -60,7 +60,7 @@
    * \param allocator allocate initial node positions
    *
    * Set the position allocator which will be used to allocate
-   * the initial position of every node in MobilityModel::Layout.
+   * the initial position of every node in MobilityModel::Install.
    */
   void SetPositionAllocator (Ptr<PositionAllocator> allocator);
 
@@ -117,7 +117,7 @@
    * \param n9 the name of the attribute to set in the mobility model.
    * \param v9 the value of the attribute to set in the mobility model.
    *
-   * Calls to MobilityHelper::Layout will create an instance of a matching 
+   * Calls to MobilityHelper::Install will create an instance of a matching 
    * mobility model for each node.
    */
   void SetMobilityModel (std::string type,
@@ -136,9 +136,9 @@
    *
    * Push an item on the top of the stack of "reference mobility models".
    * The input item should be a node instance to which a mobility model
-   * has already been aggregated (usually by a call to Layout).
+   * has already been aggregated (usually by a call to Install).
    *
-   * If this this stack is not empty when MobilityHelper::Layout
+   * If this this stack is not empty when MobilityHelper::Install
    * is called, the model from the top of the stack is used
    * to create a ns3::HierarchicalMobilityModel to make the
    * newly-created models define their positions relative to that
@@ -173,13 +173,13 @@
    * ns3::MobilityModelNotifier to generate 'CourseChange' events based on the 
    * boolean flag set by MobilityHelper::EnableNotifier and MobilityHelper::DisableNotifier.
    */
-  void Layout (NodeContainer container);
+  void Install (NodeContainer container);
 
   /**
-   * Perform the work of MobilityHelper::Layout on _all_ nodes which
+   * Perform the work of MobilityHelper::Install on _all_ nodes which
    * exist in the simulation.
    */
-  void LayoutAll (void);
+  void InstallAll (void);
 private:
 
   std::vector<Ptr<MobilityModel> > m_mobilityStack;

--- a/src/helper/ns2-mobility-helper.cc	Fri Apr 11 11:30:05 2008 -0700
+++ b/src/helper/ns2-mobility-helper.cc	Sun Apr 13 15:46:17 2008 -0700
@@ -154,9 +154,9 @@
 }
 
 void 
-Ns2MobilityHelper::Layout (void) const
+Ns2MobilityHelper::Install (void) const
 {
-  Layout (NodeList::Begin (), NodeList::End ());
+  Install (NodeList::Begin (), NodeList::End ());
 }
 
 } // namespace ns3

--- a/src/helper/ns2-mobility-helper.h	Fri Apr 11 11:30:05 2008 -0700
+++ b/src/helper/ns2-mobility-helper.h	Sun Apr 13 15:46:17 2008 -0700
@@ -51,7 +51,7 @@
    * whose nodeId is matches the nodeId of the nodes in the trace
    * file.
    */
-  void Layout (void) const;
+  void Install (void) const;
 
   /**
    * \param begin an iterator which points to the start of the input
@@ -65,7 +65,7 @@
    * the index of the object in the input array.
    */
   template <typename T>
-  void Layout (T begin, T end) const;
+  void Install (T begin, T end) const;
 private:
   class ObjectStore
   {
@@ -86,7 +86,7 @@
 
 template <typename T>
 void 
-Ns2MobilityHelper::Layout (T begin, T end) const
+Ns2MobilityHelper::Install (T begin, T end) const
 {
   class MyObjectStore : public ObjectStore
   {

--- a/src/helper/olsr-helper.cc	Fri Apr 11 11:30:05 2008 -0700
+++ b/src/helper/olsr-helper.cc	Sun Apr 13 15:46:17 2008 -0700
@@ -51,26 +51,32 @@
 }
 
 void 
-OlsrHelper::Enable (NodeContainer container)
+OlsrHelper::Install (NodeContainer container)
 {
   for (NodeContainer::Iterator i = container.Begin (); i != container.End (); ++i)
     {
       Ptr<Node> node = *i;
-      Enable (node);
+      Install (node);
     }
 }
 void 
-OlsrHelper::Enable (Ptr<Node> node)
+OlsrHelper::Install (Ptr<Node> node)
 {
+  if (node->GetObject<olsr::Agent> () != 0)
+    {
+      NS_FATAL_ERROR ("OlsrHelper::Install(): Aggregating "
+         "an Olsr Agent to a node with an existing Olsr Agent");
+      return;
+    }
   Ptr<olsr::Agent> agent = m_agentFactory.Create<olsr::Agent> ();
   agent->SetNode (node);
   node->AggregateObject (agent);
   agent->Start ();
 }
 void 
-OlsrHelper::EnableAll (void)
+OlsrHelper::InstallAll (void)
 {
-  Enable (NodeContainer::GetGlobal ());
+  Install (NodeContainer::GetGlobal ());
 }
 
 } // namespace ns3

--- a/src/helper/olsr-helper.h	Fri Apr 11 11:30:05 2008 -0700
+++ b/src/helper/olsr-helper.h	Sun Apr 13 15:46:17 2008 -0700
@@ -41,9 +41,9 @@
 		 std::string n6 = "", Attribute v6 = Attribute (),
 		 std::string n7 = "", Attribute v7 = Attribute ());
 
-  void Enable (NodeContainer container);
-  void Enable (Ptr<Node> node);
-  void EnableAll (void);
+  void Install (NodeContainer container);
+  void Install (Ptr<Node> node);
+  void InstallAll (void);
 private:
   ObjectFactory m_agentFactory;
 };

--- a/src/internet-node/internet-stack.cc	Fri Apr 11 11:30:05 2008 -0700
+++ b/src/internet-node/internet-stack.cc	Sun Apr 13 15:46:17 2008 -0700
@@ -36,11 +36,6 @@
 void 
 AddInternetStack (Ptr<Node> node)
 {
-  // This may be called on a node with a previously added stack
-  if (node->GetObject<Ipv4> ())
-    {
-      return;
-    }
   Ptr<Ipv4L3Protocol> ipv4 = CreateObject<Ipv4L3Protocol> ();
   Ptr<ArpL3Protocol> arp = CreateObject<ArpL3Protocol> ();
   ipv4->SetNode (node);