diff --git a/SConstruct b/SConstruct
index ff05f4afc..1f243a4a5 100644
--- a/SConstruct
+++ b/SConstruct
@@ -239,6 +239,7 @@ node.add_headers ([
     'header-utils.h',
     'protocol.h',
     'queue.h',
+    'arp-ipv4-interface.h',
     ])
 node.add_inst_headers ([
     'node.h',
@@ -247,7 +248,6 @@ node.add_inst_headers ([
     'ipv4-address.h',
     'net-device.h',
     'net-device-list.h',
-    'arp-ipv4-interface.h',
     'ipv4-interface.h',
     'mac-address.h',
     'ipv4.h',
@@ -275,7 +275,6 @@ p2p.add_sources ([
     'p2p-net-device.cc',
     'p2p-channel.cc',
     'p2p-topology.cc',
-    'p2p-ipv4-interface.cc',
     ])
 p2p.add_headers ([
     'propagator.h',
@@ -284,7 +283,6 @@ p2p.add_inst_headers ([
     'p2p-net-device.h',
     'p2p-channel.h',
     'p2p-topology.h',
-    'p2p-ipv4-interface.h',
     ])
 
 
diff --git a/examples/simple-p2p.cc b/examples/simple-p2p.cc
index d005b12e8..657e2a890 100644
--- a/examples/simple-p2p.cc
+++ b/examples/simple-p2p.cc
@@ -54,7 +54,6 @@
 #include "ns3/p2p-net-device.h"
 #include "ns3/mac-address.h"
 #include "ns3/ipv4-address.h"
-#include "ns3/arp-ipv4-interface.h"
 #include "ns3/ipv4.h"
 #include "ns3/datagram-socket.h"
 #include "ns3/ipv4-route.h"
diff --git a/samples/main-p2p-net-device-if.cc b/samples/main-p2p-net-device-if.cc
index 5dbc3a7d5..4fa3c6731 100644
--- a/samples/main-p2p-net-device-if.cc
+++ b/samples/main-p2p-net-device-if.cc
@@ -22,12 +22,10 @@
 #include "ns3/debug.h"
 #include "ns3/internet-node.h"
 #include "ns3/packet.h"
-#include "ns3/arp-ipv4-interface.h"
 #include "ns3/ipv4-address.h"
 #include "ns3/p2p-channel.h"
 #include "ns3/p2p-net-device.h"
 #include "ns3/drop-tail.h"
-#include "ns3/arp-ipv4-interface.h"
 #include "ns3/ipv4.h"
 #include "ns3/trace-context.h"
 #include "ns3/datagram-socket.h"
@@ -161,45 +159,43 @@ int main (int argc, char *argv[])
   //     vector of Ipv4Interfaces (keyed off of ifIndex)
 
   NS_DEBUG_UNCOND("Adding ARP Interface to InternetNode a");
-  ArpIpv4Interface* arpipv4interfacep = new ArpIpv4Interface(&a, &neta);
-  uint32_t indexA;
-  indexA = (&a)->GetIpv4 ()->AddInterface (arpipv4interfacep);
+  Ipv4 *ipa = (&a)->GetIpv4 ();
+  uint32_t indexA = ipa->AddInterface (&neta);
   NS_DEBUG_UNCOND("Adding Interface " << indexA);
 
 
   // iii) give the interface an IP address
 
   NS_DEBUG_UNCOND("Giving IP address to ARP Interface");
-  arpipv4interfacep->SetAddress(Ipv4Address("10.1.1.1"));
-  arpipv4interfacep->SetNetworkMask(Ipv4Mask("255.255.255.0"));
+  ipa->SetAddress(indexA, Ipv4Address("10.1.1.1"));
+  ipa->SetNetworkMask(indexA, Ipv4Mask("255.255.255.0"));
 
   // iv) set the interface's state to "UP"
 
   NS_DEBUG_UNCOND("Setting ARP interface to UP");
-  arpipv4interfacep->SetUp();
+  ipa->SetUp(indexA);
 
-  a.GetIpv4()->SetDefaultRoute (Ipv4Address ("10.1.1.2"), 1);
+  ipa->SetDefaultRoute (Ipv4Address ("10.1.1.2"), 1);
 
 
   NS_DEBUG_UNCOND("Adding ARP Interface to InternetNode b");
-  ArpIpv4Interface* arpipv4interfacepb = new ArpIpv4Interface(&b, &netb);
-  uint32_t indexB;
-  indexB = (&b)->GetIpv4 ()->AddInterface (arpipv4interfacepb);
+  Ipv4 *ipb = (&b)->GetIpv4 ();
+  uint32_t indexB = ipb->AddInterface (&netb);
   NS_DEBUG_UNCOND("Adding Interface " << indexB);
 
 
   // iii) give the interface an IP address
 
   NS_DEBUG_UNCOND("Giving IP address to ARP Interface");
-  arpipv4interfacepb->SetAddress(Ipv4Address("10.1.1.2"));
-  arpipv4interfacepb->SetNetworkMask(Ipv4Mask("255.255.255.0"));
+  ipb->SetAddress(indexB, Ipv4Address("10.1.1.2"));
+  ipb->SetNetworkMask(indexB, Ipv4Mask("255.255.255.0"));
 
   // iv) set the interface's state to "UP"
 
   NS_DEBUG_UNCOND("Setting ARP interface to UP");
-  arpipv4interfacepb->SetUp();
+  ipb->SetUp(indexB);
 
-  b.GetIpv4()->SetDefaultRoute (Ipv4Address ("10.1.1.1"), 1);
+  ipb->SetDefaultRoute (Ipv4Address ("10.1.1.1"), 1);
 
 
   DatagramSocket *source = new DatagramSocket (&a);
diff --git a/src/devices/p2p/p2p-ipv4-interface.cc b/src/devices/p2p/p2p-ipv4-interface.cc
deleted file mode 100644
index 0bf81288a..000000000
--- a/src/devices/p2p/p2p-ipv4-interface.cc
+++ /dev/null
@@ -1,55 +0,0 @@
-/* -*- Mode: C++; c-file-style: "gnu"; indent-tabs-mode:nil; -*- */
-/*
- * Copyright (c) 2007 INRIA
- * All rights reserved.
- *
- * This program is free software; you can redistribute it and/or modify
- * it under the terms of the GNU General Public License version 2 as
- * published by the Free Software Foundation;
- *
- * This program is distributed in the hope that it will be useful,
- * but WITHOUT ANY WARRANTY; without even the implied warranty of
- * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
- * GNU General Public License for more details.
- *
- * You should have received a copy of the GNU General Public License
- * along with this program; if not, write to the Free Software
- * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
- *
- * Authors: 
- *  Mathieu Lacage <mathieu.lacage@sophia.inria.fr>,
- */
-#include "p2p-ipv4-interface.h"
-
-#include "ns3/packet.h"
-#include "ns3/net-device.h"
-#include "ns3/composite-trace-resolver.h"
-#include "ns3/ipv4.h"
-
-namespace ns3 {
-
-PointToPointIpv4Interface::PointToPointIpv4Interface (Node *node, NetDevice *device)
-  : Ipv4Interface (device),
-    m_node (node)
-{}
-PointToPointIpv4Interface::~PointToPointIpv4Interface ()
-{}
-
-void 
-PointToPointIpv4Interface::SendTo (Packet p, Ipv4Address dest)
-{
-  GetDevice ()->Send (p, GetDevice ()->GetBroadcast (), Ipv4::PROT_NUMBER);
-}
-
-TraceResolver *
-PointToPointIpv4Interface::DoCreateTraceResolver (TraceContext const &context)
-{
-  CompositeTraceResolver *resolver = new CompositeTraceResolver (context);
-  resolver->Add ("netdevice",
-                 MakeCallback (&NetDevice::CreateTraceResolver, GetDevice ()),
-                 PointToPointIpv4Interface::NETDEVICE);
-  return resolver;
-
-}
-
-}//namespace ns3
diff --git a/src/devices/p2p/p2p-ipv4-interface.h b/src/devices/p2p/p2p-ipv4-interface.h
deleted file mode 100644
index 2b0ac0755..000000000
--- a/src/devices/p2p/p2p-ipv4-interface.h
+++ /dev/null
@@ -1,49 +0,0 @@
-/* -*- Mode: C++; c-file-style: "gnu"; indent-tabs-mode:nil; -*- */
-/*
- * Copyright (c) 2007 INRIA
- * All rights reserved.
- *
- * This program is free software; you can redistribute it and/or modify
- * it under the terms of the GNU General Public License version 2 as
- * published by the Free Software Foundation;
- *
- * This program is distributed in the hope that it will be useful,
- * but WITHOUT ANY WARRANTY; without even the implied warranty of
- * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
- * GNU General Public License for more details.
- *
- * You should have received a copy of the GNU General Public License
- * along with this program; if not, write to the Free Software
- * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
- *
- * Authors: 
- *  Mathieu Lacage <mathieu.lacage@sophia.inria.fr>,
- */
-#ifndef POINT_TO_POINT_IPV4_INTERFACE_H
-#define POINT_TO_POINT_IPV4_INTERFACE_H
-
-#include "ns3/ipv4-interface.h"
-
-namespace ns3 {
-
-class Node;
-
-class PointToPointIpv4Interface : public Ipv4Interface
-{
- public:
-  enum TraceType {
-    NETDEVICE,
-  };
-  PointToPointIpv4Interface (Node *node, NetDevice *device);
-  virtual ~PointToPointIpv4Interface ();
-
- private:
-  virtual void SendTo (Packet p, Ipv4Address dest);
-  virtual TraceResolver *DoCreateTraceResolver (TraceContext const &context);
-  Node *m_node;
-};
-
-}//namespace ns3
-
-
-#endif /* ARP_IPV4_INTERFACE_H */
diff --git a/src/devices/p2p/p2p-topology.cc b/src/devices/p2p/p2p-topology.cc
index 16799f70d..02e116f5a 100644
--- a/src/devices/p2p/p2p-topology.cc
+++ b/src/devices/p2p/p2p-topology.cc
@@ -33,7 +33,6 @@
 #include "ns3/ipv4.h"
 #include "ns3/net-device-list.h"
 
-#include "p2p-ipv4-interface.h"
 #include "p2p-channel.h"
 #include "p2p-net-device.h"
 #include "p2p-topology.h"
@@ -67,27 +66,27 @@ PointToPointTopology::AddPointToPointLink(
   PointToPointNetDevice* net1 = new PointToPointNetDevice(n1);
   net1->AddQueue(Queue::Default().Copy());
   ndl1->Add(net1);
-  Ipv4Interface *interf1 = new PointToPointIpv4Interface (n1, net1);
-  uint32_t index1 = n1->GetIpv4 ()->AddInterface (interf1);
+  Ipv4 *ip1 = n1->GetIpv4 ();
+  uint32_t index1 = ip1->AddInterface (net1);
   net1->Attach (channel);
 
-  interf1->SetAddress (addr1);
-  interf1->SetNetworkMask (netmask);
-  interf1->SetUp ();
+  ip1->SetAddress (index1, addr1);
+  ip1->SetNetworkMask (index1, netmask);
+  ip1->SetUp (index1);
 
   PointToPointNetDevice* net2 = new PointToPointNetDevice(n2);
   net2->AddQueue(Queue::Default().Copy());
   ndl2->Add(net2);
-  Ipv4Interface *interf2 = new PointToPointIpv4Interface (n2, net2);
-  uint32_t index2 = n2->GetIpv4 ()->AddInterface (interf2);
+  Ipv4 *ip2 = n2->GetIpv4 ();
+  uint32_t index2 = ip2->AddInterface (net2);
   net2->Attach (channel);
 
-  interf2->SetAddress (addr2);
-  interf2->SetNetworkMask (netmask);
-  interf2->SetUp ();
+  ip2->SetAddress (index2, addr2);
+  ip2->SetNetworkMask (index2, netmask);
+  ip2->SetUp (index2);
 
-  n1->GetIpv4 ()->AddHostRouteTo (addr2, index1);
-  n2->GetIpv4 ()->AddHostRouteTo (addr1, index2);
+  ip1->AddHostRouteTo (addr2, index1);
+  ip2->AddHostRouteTo (addr1, index2);
 
   return channel;
 }
diff --git a/src/node/internet-node.cc b/src/node/internet-node.cc
index cec474eec..4b4eed166 100644
--- a/src/node/internet-node.cc
+++ b/src/node/internet-node.cc
@@ -31,7 +31,6 @@
 #include "udp.h"
 #include "ipv4.h"
 #include "arp.h"
-#include "ipv4-loopback-interface.h"
 
 namespace ns3 {
 
@@ -52,7 +51,6 @@ InternetNode::InternetNode()
   m_l3Demux->Insert (Ipv4 (this));
   m_l3Demux->Insert (Arp (this));
   m_ipv4L4Demux->Insert (Udp (this));
-  SetupLoopback ();
 }
 
 InternetNode::InternetNode (InternetNode const &o)
@@ -61,7 +59,6 @@ InternetNode::InternetNode (InternetNode const &o)
   m_applicationList = new ApplicationList();
   m_l3Demux = o.m_l3Demux->Copy (this);
   m_ipv4L4Demux = o.m_ipv4L4Demux->Copy (this);
-  SetupLoopback ();  
 }
 InternetNode const &
 InternetNode::operator = (InternetNode const &o)
@@ -73,7 +70,6 @@ InternetNode::operator = (InternetNode const &o)
   m_netDevices = new NetDeviceList ();
   m_l3Demux = o.m_l3Demux->Copy (this);
   m_ipv4L4Demux = o.m_ipv4L4Demux->Copy (this);
-  SetupLoopback ();  
   return *this;
 }
 
@@ -91,17 +87,6 @@ InternetNode::SetName (std::string name)
   m_name = name;
 }
 
-void
-InternetNode::SetupLoopback (void)
-{
-  Ipv4LoopbackInterface * interface = new Ipv4LoopbackInterface (this);
-  interface->SetAddress (Ipv4Address::GetLoopback ());
-  interface->SetNetworkMask (Ipv4Mask::GetLoopback ());
-  uint32_t index = GetIpv4 ()->AddInterface (interface);
-  GetIpv4 ()->AddHostRouteTo (Ipv4Address::GetLoopback (), index);
-  interface->SetUp ();
-}
-
 // Copy this node
 InternetNode* 
 InternetNode::Copy() const
diff --git a/src/node/internet-node.h b/src/node/internet-node.h
index 3ef7b1ed8..5cb31702a 100644
--- a/src/node/internet-node.h
+++ b/src/node/internet-node.h
@@ -57,7 +57,6 @@ public:
 
   void SetName(std::string name);
 private:
-  void SetupLoopback (void);
   // Capabilities
   NetDeviceList*   m_netDevices;
   ApplicationList* m_applicationList;
diff --git a/src/node/ipv4.cc b/src/node/ipv4.cc
index 66b207641..d2eb66d40 100644
--- a/src/node/ipv4.cc
+++ b/src/node/ipv4.cc
@@ -31,6 +31,8 @@
 #include "ipv4-header.h"
 #include "ipv4-interface.h"
 #include "ipv4-route.h"
+#include "ipv4-loopback-interface.h"
+#include "arp-ipv4-interface.h"
 // the two following headers are needed for Ipv4::ForwardUp
 #include "node.h"
 #include "ipv4-l4-demux.h"
@@ -48,10 +50,11 @@ Ipv4::Ipv4(Node *node)
     m_identification (0),
     m_defaultRoute (0),
     m_node (node)
-{}
+{
+  SetupLoopback ();
+}
 Ipv4::~Ipv4 ()
 {
-  // XXX I am not sure we are really allowed to do this here.
   for (Ipv4InterfaceList::iterator i = m_interfaces.begin (); i != m_interfaces.end (); i++)
     {
       delete (*i);
@@ -71,6 +74,17 @@ Ipv4::~Ipv4 ()
   delete m_defaultRoute;
 }
 
+void
+Ipv4::SetupLoopback (void)
+{
+  Ipv4LoopbackInterface * interface = new Ipv4LoopbackInterface (m_node);
+  interface->SetAddress (Ipv4Address::GetLoopback ());
+  interface->SetNetworkMask (Ipv4Mask::GetLoopback ());
+  uint32_t index = AddIpv4Interface (interface);
+  AddHostRouteTo (Ipv4Address::GetLoopback (), index);
+  interface->SetUp ();
+}
+
 TraceResolver *
 Ipv4::CreateTraceResolver (TraceContext const &context)
 {
@@ -85,7 +99,7 @@ Ipv4::CreateTraceResolver (TraceContext const &context)
 }
 
 TraceResolver *
-Ipv4::InterfacesCreateTraceResolver (TraceContext const &context)
+Ipv4::InterfacesCreateTraceResolver (TraceContext const &context) const
 {
   ArrayTraceResolver<Ipv4Interface> *resolver = 
     new ArrayTraceResolver<Ipv4Interface> 
@@ -286,7 +300,13 @@ Ipv4::RemoveRoute (uint32_t index)
 
 
 uint32_t 
-Ipv4::AddInterface (Ipv4Interface *interface)
+Ipv4::AddInterface (NetDevice *device)
+{
+  Ipv4Interface *interface = new ArpIpv4Interface (m_node, device);
+  return AddIpv4Interface (interface);
+}
+uint32_t 
+Ipv4::AddIpv4Interface (Ipv4Interface *interface)
 {
   uint32_t index = m_nInterfaces;
   m_interfaces.push_back (interface);
@@ -294,7 +314,7 @@ Ipv4::AddInterface (Ipv4Interface *interface)
   return index;
 }
 Ipv4Interface *
-Ipv4::GetInterface (uint32_t index)
+Ipv4::GetInterface (uint32_t index) const
 {
   uint32_t tmp = 0;
   for (Ipv4InterfaceList::const_iterator i = m_interfaces.begin (); i != m_interfaces.end (); i++)
@@ -308,7 +328,7 @@ Ipv4::GetInterface (uint32_t index)
   return 0;
 }
 uint32_t 
-Ipv4::GetNInterfaces (void)
+Ipv4::GetNInterfaces (void) const
 {
   return m_nInterfaces;
 }
@@ -477,4 +497,54 @@ Ipv4::ForwardUp (Packet p, Ipv4Header const&ip)
   protocol->Receive (p, ip.GetSource (), ip.GetDestination ());
 }
 
+void 
+Ipv4::SetAddress (uint32_t i, Ipv4Address address)
+{
+  Ipv4Interface *interface = GetInterface (i);
+  interface->SetAddress (address);
+}
+void 
+Ipv4::SetNetworkMask (uint32_t i, Ipv4Mask mask)
+{
+  Ipv4Interface *interface = GetInterface (i);
+  interface->SetNetworkMask (mask);
+}
+Ipv4Mask 
+Ipv4::GetNetworkMask (uint32_t i) const
+{
+  Ipv4Interface *interface = GetInterface (i);
+  return interface->GetNetworkMask ();
+}
+Ipv4Address 
+Ipv4::GetAddress (uint32_t i) const
+{
+  Ipv4Interface *interface = GetInterface (i);
+  return interface->GetAddress ();
+}
+uint16_t 
+Ipv4::GetMtu (uint32_t i) const
+{
+  Ipv4Interface *interface = GetInterface (i);
+  return interface->GetMtu ();
+}
+bool 
+Ipv4::IsUp (uint32_t i) const
+{
+  Ipv4Interface *interface = GetInterface (i);
+  return interface->IsUp ();
+}
+void 
+Ipv4::SetUp (uint32_t i)
+{
+  Ipv4Interface *interface = GetInterface (i);
+  interface->SetUp ();
+}
+void 
+Ipv4::SetDown (uint32_t i)
+{
+  Ipv4Interface *interface = GetInterface (i);
+  interface->SetDown ();
+}
+
+
 }//namespace ns3
diff --git a/src/node/ipv4.h b/src/node/ipv4.h
index 548dd2005..63a3272a6 100644
--- a/src/node/ipv4.h
+++ b/src/node/ipv4.h
@@ -164,16 +164,16 @@ public:
    * to disable it, you can invoke Ipv4Interface::SetDown which will
    * make sure that it is never used during packet forwarding.
    */
-  uint32_t AddInterface (Ipv4Interface *interface);
+  uint32_t AddInterface (NetDevice *device);
   /**
    * \param i index of interface to return
    * \returns the requested interface
    */
-  Ipv4Interface * GetInterface (uint32_t i);
+  Ipv4Interface * GetInterface (uint32_t i) const;
   /**
    * \returns the number of interfaces added by the user.
    */
-  uint32_t GetNInterfaces (void);
+  uint32_t GetNInterfaces (void) const;
   /**
    * \param device the device to match
    * \returns the matching interface, zero if not found.
@@ -207,11 +207,23 @@ public:
   void Send (Packet const &packet, Ipv4Address source, 
 	     Ipv4Address destination, uint8_t protocol);
 
+  void SetAddress (uint32_t i, Ipv4Address address);
+  void SetNetworkMask (uint32_t i, Ipv4Mask mask);
+  Ipv4Mask GetNetworkMask (uint32_t t) const;
+  Ipv4Address GetAddress (uint32_t i) const;
+  uint16_t GetMtu (uint32_t i) const;
+  bool IsUp (uint32_t i) const;
+  void SetUp (uint32_t i);
+  void SetDown (uint32_t i);
+
+
  private:
   void SendRealOut (Packet const &packet, Ipv4Header const &ip, Ipv4Route const &route);
   bool Forwarding (Packet const &packet, Ipv4Header &ipHeader, NetDevice &device);
   void ForwardUp (Packet p, Ipv4Header const&ip);
-  TraceResolver *InterfacesCreateTraceResolver (TraceContext const &context);
+  uint32_t AddIpv4Interface (Ipv4Interface *interface);
+  void SetupLoopback (void);
+  TraceResolver *InterfacesCreateTraceResolver (TraceContext const &context) const;
 
   typedef std::list<Ipv4Interface*> Ipv4InterfaceList;
   typedef std::list<Ipv4Route *> HostRoutes;
diff --git a/src/node/l3-demux.cc b/src/node/l3-demux.cc
index 091674597..8dae35096 100644
--- a/src/node/l3-demux.cc
+++ b/src/node/l3-demux.cc
@@ -41,15 +41,15 @@ L3Demux::~L3Demux()
 }
 
 TraceResolver *
-L3Demux::CreateTraceResolver (TraceContext const &context)
+L3Demux::CreateTraceResolver (TraceContext const &context) const
 {
   CompositeTraceResolver *resolver = new CompositeTraceResolver (context);
   for (L3Map_t::const_iterator i = m_protocols.begin(); i != m_protocols.end(); ++i)
     {
       std::string protValue;
       std::ostringstream oss (protValue);
-      oss << (i->second)->GetProtocolNumber ();
-      ProtocolTraceType context = (i->second)->GetProtocolNumber ();
+      oss << i->second->GetProtocolNumber ();
+      ProtocolTraceType context = i->second->GetProtocolNumber ();
       resolver->Add (protValue, 
                      MakeCallback (&L3Protocol::CreateTraceResolver, i->second),
                      context);
diff --git a/src/node/l3-demux.h b/src/node/l3-demux.h
index 5b9ccdbaf..30384ca11 100644
--- a/src/node/l3-demux.h
+++ b/src/node/l3-demux.h
@@ -59,7 +59,7 @@ public:
    *          performed in this object. The caller must
    *          delete the returned object.
    */
-  TraceResolver *CreateTraceResolver (TraceContext const &context);
+  TraceResolver *CreateTraceResolver (TraceContext const &context) const;
 
 
   /**