diff --git a/src/internet-node/rtt-estimator.cc b/src/internet-node/rtt-estimator.cc
index 8a6d07a20..0e7801ac5 100644
--- a/src/internet-node/rtt-estimator.cc
+++ b/src/internet-node/rtt-estimator.cc
@@ -29,7 +29,7 @@
 
 #include "rtt-estimator.h"
 #include "ns3/simulator.h"
-#include "ns3/type-id-default-value.h"
+#include "ns3/double.h"
 
 namespace ns3{
 
@@ -40,19 +40,21 @@ TypeId
 RttEstimator::GetTypeId (void)
 {
   static TypeId tid = TypeId ("RttEstimator")
-    .SetParent<Object> ();
+    .SetParent<Object> ()
+    .AddAttribute ("MaxMultiplier", 
+                   "XXX",
+                   Double (64.0),
+                   MakeDoubleAccessor (&RttEstimator::m_maxMultiplier),
+                   MakeDoubleChecker<double> ())
+    .AddAttribute ("InitialEstimation", 
+                   "XXX",
+                   Seconds (1.0),
+                   MakeTimeAccessor (&RttEstimator::est),
+                   MakeTimeChecker ())
+    ;
   return tid;
 }
 
-//Default values
-TypeIdDefaultValue RttEstimator::defaultTid ("RttEstimator",
-                                             "Tahoe round trip time estimation",
-                                             RttEstimator::GetTypeId (), "RttMeanDeviation");
-NumericDefaultValue<double> RttEstimator::defaultMaxMultiplier ("RttMaxMultiplier","",64.0);
-
-// RttEstimator Static Member variables
-Time        RttEstimator::initialEstimate = Seconds (1.0); // Default initial estimate
-
 //RttHistory methods
 RttHistory::RttHistory (SequenceNumber s, uint32_t c, Time t)
   : seq (s), count (c), time (t), retx (false)
@@ -66,7 +68,7 @@ RttHistory::RttHistory (const RttHistory& h)
 
 // Base class methods
 
-RttEstimator::RttEstimator () : next (1), history (), est (initialEstimate),
+RttEstimator::RttEstimator () : next (1), history (),
     nSamples (0), multiplier (1.0) 
 { 
   //note next=1 everywhere since first segment will have sequence 1
@@ -142,7 +144,7 @@ void RttEstimator::ClearSent ()
 
 void RttEstimator::IncreaseMultiplier ()
 {
-  multiplier = std::min (multiplier * 2.0, defaultMaxMultiplier.GetValue ());
+  multiplier = std::min (multiplier * 2.0, m_maxMultiplier);
 }
 
 void RttEstimator::ResetMultiplier ()
@@ -153,24 +155,13 @@ void RttEstimator::ResetMultiplier ()
 void RttEstimator::Reset ()
 { // Reset to initial state
   next = 1;
-  est = initialEstimate;
+  est = Seconds (1.0); // XXX: we should go back to the 'initial value' here. Need to add support in Object for this.
   history.clear ();         // Remove all info from the history
   nSamples = 0;
   ResetMultiplier ();
 }
 
-// Base class, static methods
-void RttEstimator::InitialEstimate (Time e)
-{ // Set a new default initial estimate
-  initialEstimate = e;
-}
 
-Ptr<RttEstimator> RttEstimator::CreateDefault ()
-{
-  TypeId tid = defaultTid.GetValue ();
-  Ptr<RttEstimator> rtte = tid.CreateObject (0.1, initialEstimate)->GetObject<RttEstimator> ();
-  return rtte;
-}
 
 //-----------------------------------------------------------------------------
 //-----------------------------------------------------------------------------
@@ -183,13 +174,18 @@ RttMeanDeviation::GetTypeId (void)
 {
   static TypeId tid = TypeId ("RttMeanDeviation")
     .SetParent<RttEstimator> ()
-    .AddConstructor<RttMeanDeviation, double> ()
-    .AddConstructor<RttMeanDeviation, double, Time> ();
+    .AddConstructor<RttMeanDeviation> ()
+    .AddAttribute ("Gain",
+                   "XXX",
+                   Double (0.1),
+                   MakeDoubleAccessor (&RttMeanDeviation::gain),
+                   MakeDoubleChecker<double> ())
+    ;
   return tid;
 }
 
-RttMeanDeviation::RttMeanDeviation(double g) :
-  gain (g), variance (ns3::Seconds(0)) 
+RttMeanDeviation::RttMeanDeviation() :
+  variance (ns3::Seconds(0)) 
 { 
 }
 
@@ -198,11 +194,6 @@ RttMeanDeviation::RttMeanDeviation (const RttMeanDeviation& c)
 {
 }
 
-RttMeanDeviation::RttMeanDeviation (double g, Time e) : 
-  RttEstimator (e), gain (g), variance (ns3::Seconds(0)) 
-{ 
-}
-
 void RttMeanDeviation::Measurement (Time m)
 {
   if (nSamples)
diff --git a/src/internet-node/rtt-estimator.h b/src/internet-node/rtt-estimator.h
index 3161f8b8b..695727648 100644
--- a/src/internet-node/rtt-estimator.h
+++ b/src/internet-node/rtt-estimator.h
@@ -71,19 +71,12 @@ public:
 private:
   SequenceNumber        next;    // Next expected sequence to be sent
   RttHistory_t history; // List of sent packet
+  double m_maxMultiplier;
+  Time m_initialEstimate;
 public:
   Time       est;     // Current estimate
   uint32_t      nSamples;// Number of samples
   double       multiplier;   // RTO Multiplier
-public:
-  static void InitialEstimate(Time);
-  static Ptr<RttEstimator> CreateDefault();      // Retrieve current default
-
-  static TypeIdDefaultValue defaultTid;
-  static NumericDefaultValue<double> defaultMaxMultiplier;
-
-private:
-  static Time initialEstimate;       // Default initial estimate
 };
 
 // The "Mean-Deviation" estimator, as discussed by Van Jacobson
@@ -96,16 +89,8 @@ class RttMeanDeviation : public RttEstimator {
 public :
   static TypeId GetTypeId (void);
 
-    //Doc:Desc Constructor for {\tt RttMeanDeviation} specifying the gain factor for the
-    //Doc:Desc estimator.
-    //Doc:Arg1 Gain factor.
-  RttMeanDeviation (double g);
+  RttMeanDeviation ();
 
-    //Doc:Desc Constructor for {\tt RttMeanDeviation} specifying the gain factor
-    //Doc:Desc and the initial estimate.
-    //Doc:Arg1 Gain factor.
-    //Doc:Arg2 Initial estimate.
-  RttMeanDeviation (double g, Time e);
 
   //Doc:Method
   RttMeanDeviation (const RttMeanDeviation&); // Copy constructor
diff --git a/src/internet-node/tcp-header.cc b/src/internet-node/tcp-header.cc
index 15905d71e..ff06b06e6 100644
--- a/src/internet-node/tcp-header.cc
+++ b/src/internet-node/tcp-header.cc
@@ -44,11 +44,10 @@ TcpHeader::TcpHeader ()
     m_ackNumber (0),
     m_length (5),
     m_flags (0),
-    m_windowSize (Tcp::defaultAdvWin.GetValue ()),
+    m_windowSize (0),
     m_checksum (0),
     m_urgentPointer (0)
-{
-}
+{}
 
 TcpHeader::~TcpHeader ()
 {}
diff --git a/src/internet-node/tcp-l4-protocol.cc b/src/internet-node/tcp-l4-protocol.cc
index 0f1ebddff..1a0464503 100644
--- a/src/internet-node/tcp-l4-protocol.cc
+++ b/src/internet-node/tcp-l4-protocol.cc
@@ -311,6 +311,14 @@ static TcpStateMachine tcpStateMachine; //only instance of a TcpStateMachine
 /* see http://www.iana.org/assignments/protocol-numbers */
 const uint8_t TcpL4Protocol::PROT_NUMBER = 6;
 
+ObjectFactory
+TcpL4Protocol::GetDefaultRttEstimatorFactory (void)
+{
+  ObjectFactory factory;
+  factory.SetTypeId ("RttMeanDeviation");
+  return factory;
+}
+
 TypeId 
 TcpL4Protocol::GetTypeId (void)
 {
@@ -321,6 +329,11 @@ TcpL4Protocol::GetTypeId (void)
                    Ptr<Node> (0),
                    MakePtrAccessor (&TcpL4Protocol::m_node),
                    MakePtrChecker<Node> ())
+    .AddAttribute ("RttEstimatorFactory",
+                   "How RttEstimator objects are created.",
+                   GetDefaultRttEstimatorFactory (),
+                   MakeObjectFactoryAccessor (&TcpL4Protocol::m_rttFactory),
+                   MakeObjectFactoryChecker ())
     ;
   return tid;
 }
@@ -365,7 +378,8 @@ Ptr<Socket>
 TcpL4Protocol::CreateSocket (void)
 {
   NS_LOG_FUNCTION;
-  Ptr<Socket> socket = Create<TcpSocket> (m_node, this);
+  Ptr<RttEstimator> rtt = m_rttFactory.Create<RttEstimator> ();
+  Ptr<Socket> socket = CreateObject<TcpSocket> (m_node, this, rtt);
   return socket;
 }
 
diff --git a/src/internet-node/tcp-l4-protocol.h b/src/internet-node/tcp-l4-protocol.h
index 73bfb8e97..583d325f1 100644
--- a/src/internet-node/tcp-l4-protocol.h
+++ b/src/internet-node/tcp-l4-protocol.h
@@ -26,6 +26,7 @@
 #include "ns3/packet.h"
 #include "ns3/ipv4-address.h"
 #include "ns3/ptr.h"
+#include "ns3/object-factory.h"
 #include "ipv4-end-point-demux.h"
 #include "ipv4-l4-protocol.h"
 #include "ipv4-interface.h"
@@ -103,10 +104,12 @@ protected:
 private:
   Ptr<Node> m_node;
   Ipv4EndPointDemux *m_endPoints;
+  ObjectFactory m_rttFactory;
 private:
   friend class TcpSocket;
   void SendPacket (Ptr<Packet>, TcpHeader,
                   Ipv4Address, Ipv4Address);
+  static ObjectFactory GetDefaultRttEstimatorFactory (void);
 };
 
 }; // namespace ns3
diff --git a/src/internet-node/tcp-socket.cc b/src/internet-node/tcp-socket.cc
index f2d8ad4cd..dcac0ef18 100644
--- a/src/internet-node/tcp-socket.cc
+++ b/src/internet-node/tcp-socket.cc
@@ -31,7 +31,6 @@
 #include "tcp-typedefs.h"
 #include "ns3/simulator.h"
 #include "ns3/packet.h"
-#include "ns3/default-value.h"
 
 #include <algorithm>
 
@@ -41,7 +40,7 @@ using namespace std;
 
 namespace ns3 {
 
-TcpSocket::TcpSocket (Ptr<Node> node, Ptr<TcpL4Protocol> tcp)
+  TcpSocket::TcpSocket (Ptr<Node> node, Ptr<TcpL4Protocol> tcp, Ptr<RttEstimator> rtt)
   : m_skipRetxResched (false),
     m_dupAckCount (0),
     m_endPoint (0),
@@ -62,19 +61,22 @@ TcpSocket::TcpSocket (Ptr<Node> node, Ptr<TcpL4Protocol> tcp)
     m_lastRxAck (0),
     m_nextRxSequence (0),
     m_pendingData (0),
-    m_segmentSize (Tcp::defaultSegSize.GetValue()),
-    m_rxWindowSize (Tcp::defaultAdvWin.GetValue()),
-    m_advertisedWindowSize (Tcp::defaultAdvWin.GetValue()),
-    m_cWnd (Tcp::defaultInitialCWnd.GetValue() * m_segmentSize),
-    m_ssThresh (Tcp::defaultSSThresh.GetValue()),
-    m_initialCWnd (Tcp::defaultInitialCWnd.GetValue()),
-    m_rtt (RttEstimator::CreateDefault()),
-    m_lastMeasuredRtt (Seconds(0.0)),
-    m_cnTimeout (Seconds (Tcp::defaultConnTimeout.GetValue ())),
-    m_cnCount (Tcp::defaultConnCount.GetValue ())
+    m_rtt (rtt),
+    m_lastMeasuredRtt (Seconds(0.0))
 {
   NS_LOG_FUNCTION;
   NS_LOG_PARAMS (this<<node<<tcp);
+  
+  Ptr<Tcp> t = node->GetObject<Tcp> ();
+  m_segmentSize = t->GetDefaultSegSize ();
+  m_rxWindowSize = t->GetDefaultAdvWin ();
+  m_advertisedWindowSize = t->GetDefaultAdvWin ();
+  m_cWnd = t->GetDefaultInitialCwnd () * m_segmentSize;
+  m_ssThresh = t->GetDefaultSsThresh ();
+  m_initialCWnd = t->GetDefaultInitialCwnd ();
+  m_cnTimeout = Seconds (t->GetDefaultConnTimeout ());
+  m_cnCount = t->GetDefaultConnCount ();
+
 }
 
 TcpSocket::~TcpSocket ()
diff --git a/src/internet-node/tcp-socket.h b/src/internet-node/tcp-socket.h
index 3a7970fe8..4f9f0fde9 100644
--- a/src/internet-node/tcp-socket.h
+++ b/src/internet-node/tcp-socket.h
@@ -45,7 +45,7 @@ public:
   /**
    * Create an unbound tcp socket.
    */
-  TcpSocket (Ptr<Node> node, Ptr<TcpL4Protocol> tcp);
+  TcpSocket (Ptr<Node> node, Ptr<TcpL4Protocol> tcp, Ptr<RttEstimator> rtt);
   virtual ~TcpSocket ();
 
   virtual enum SocketErrno GetErrno (void) const;
diff --git a/src/node/tcp.cc b/src/node/tcp.cc
index 55a0927a3..6bc15e884 100644
--- a/src/node/tcp.cc
+++ b/src/node/tcp.cc
@@ -18,58 +18,100 @@
  * Author: Raj Bhattacharjea <raj.b@gatech.edu>
  */
 #include "tcp.h"
+#include "ns3/uinteger.h"
 
 namespace ns3 {
 
-NumericDefaultValue<uint32_t>       Tcp::defaultSegSize
-("TcpDefaultSegmentSize",
-"Default TCP maximum segment size in bytes (may be adjusted based on MTU discovery)",
-536);
-
-NumericDefaultValue<uint32_t>       Tcp::defaultAdvWin
-("TcpDefaultAdvertisedWindowSize",
-"Default TCP advertised window size (bytes)",
-0xffff);
-
-NumericDefaultValue<uint32_t>       Tcp::defaultSSThresh
-("TcpDefaultSlowStartThreshold",
-"Default TCP slow start threshold (bytes)",
-0xffff);
-
-NumericDefaultValue<uint32_t>       Tcp::defaultTxBuffer
-("TcpDefaultTxBufferSize",
-"Default TCP maximum transmit buffer size (bytes)",
-0xffffffffl);
-
-NumericDefaultValue<uint32_t>       Tcp::defaultRxBuffer
-("TcpDefaultRxBufferSize",
-"Default TCP maximum receive buffer size (bytes)",
-0xffffffffl);
-
-NumericDefaultValue<uint32_t>       Tcp::defaultInitialCWnd
-("TcpDefaultInitialCongestionWindowSize",
-"Default TCP initial congestion window size (segments)",
-1);
-
-NumericDefaultValue<uint32_t>       Tcp::defaultConnTimeout
-("TcpDefaultConnTimeout",
-"Default TCP retransmission timeout when opening connection (seconds)",
-3);
-
-NumericDefaultValue<uint32_t>       Tcp::defaultConnCount
-("TcpDefaultConnCount",
-"Default number of connection attempts (SYN retransmissions) before returning failure",
-6);
-
 NS_OBJECT_ENSURE_REGISTERED (Tcp);
 
 TypeId
 Tcp::GetTypeId (void)
 {
   static TypeId tid = TypeId ("Tcp")
-    .SetParent<SocketFactory> ();
+    .SetParent<SocketFactory> ()
+   .AddAttribute ("TcpDefaultSegmentSize",
+                  "Default TCP maximum segment size in bytes (may be adjusted based on MTU discovery)",
+                  Uinteger (536),
+                  MakeUintegerAccessor (&Tcp::m_defaultSegSize),
+                  MakeUintegerChecker<uint32_t> ())
+    .AddAttribute ("TcpDefaultAdvertisedWindowSize",
+                   "Default TCP advertised window size (bytes)",
+                   Uinteger (0xffff),
+                   MakeUintegerAccessor (&Tcp::m_defaultAdvWin),
+                   MakeUintegerChecker<uint32_t> ())
+    .AddAttribute ("TcpDefaultSlowStartThreshold",
+                   "Default TCP slow start threshold (bytes)",
+                   Uinteger (0xffff),
+                   MakeUintegerAccessor (&Tcp::m_defaultSsThresh),
+                   MakeUintegerChecker<uint32_t> ())
+    .AddAttribute ("TcpDefaultTxBufferSize",
+                   "Default TCP maximum transmit buffer size (bytes)",
+                   Uinteger (0xffffffffl),
+                   MakeUintegerAccessor (&Tcp::m_defaultTxBuffer),
+                   MakeUintegerChecker<uint32_t> ())
+    .AddAttribute ("TcpDefaultRxBufferSize",
+                   "Default TCP maximum receive buffer size (bytes)",
+                   Uinteger (0xffffffffl),
+                   MakeUintegerAccessor (&Tcp::m_defaultRxBuffer),
+                   MakeUintegerChecker<uint32_t> ())
+    .AddAttribute ("TcpDefaultInitialCongestionWindowSize",
+                   "Default TCP initial congestion window size (segments)",
+                   Uinteger (1),
+                   MakeUintegerAccessor (&Tcp::m_defaultInitialCwnd),
+                   MakeUintegerChecker<uint32_t> ())
+    .AddAttribute ("TcpDefaultConnTimeout",
+                   "Default TCP retransmission timeout when opening connection (seconds)",
+                   Uinteger (3),
+                   MakeUintegerAccessor (&Tcp::m_defaultConnTimeout),
+                   MakeUintegerChecker<uint32_t> ())
+    .AddAttribute ("TcpDefaultConnCount",
+                   "Default number of connection attempts (SYN retransmissions) before returning failure",
+                   Uinteger (6),
+                   MakeUintegerAccessor (&Tcp::m_defaultConnCount),
+                   MakeUintegerChecker<uint32_t> ())
+     ;
   return tid;
 }
 
+uint32_t 
+Tcp::GetDefaultSegSize (void) const
+{
+  return m_defaultSegSize;
+}
+uint32_t 
+Tcp::GetDefaultAdvWin (void) const
+{
+  return m_defaultAdvWin;
+}
+uint32_t 
+Tcp::GetDefaultSsThresh (void) const
+{
+  return m_defaultSsThresh;
+}
+uint32_t 
+Tcp::GetDefaultTxBuffer (void) const
+{
+  return m_defaultTxBuffer;
+}
+uint32_t 
+Tcp::GetDefaultRxBuffer (void) const
+{
+  return m_defaultRxBuffer;
+}
+uint32_t 
+Tcp::GetDefaultInitialCwnd (void) const
+{
+  return m_defaultInitialCwnd;
+}
+uint32_t 
+Tcp::GetDefaultConnTimeout (void) const
+{
+  return m_defaultConnTimeout;
+}
+uint32_t 
+Tcp::GetDefaultConnCount (void) const
+{
+  return m_defaultConnCount;
+}
 
 } // namespace ns3
diff --git a/src/node/tcp.h b/src/node/tcp.h
index 189b7fc61..ffb9e22d1 100644
--- a/src/node/tcp.h
+++ b/src/node/tcp.h
@@ -20,7 +20,6 @@
 #ifndef TCP_H
 #define TCP_H
 
-#include "ns3/default-value.h"
 #include "socket-factory.h"
 
 namespace ns3 {
@@ -48,18 +47,26 @@ public:
 
   virtual Ptr<Socket> CreateSocket (void) = 0;
 
-public:
-  static NumericDefaultValue<uint32_t>       defaultSegSize;  
-  static NumericDefaultValue<uint32_t>       defaultAdvWin;   
-  static NumericDefaultValue<uint32_t>       defaultSSThresh; 
-  static NumericDefaultValue<uint32_t>       defaultTxBuffer; 
-  static NumericDefaultValue<uint32_t>       defaultRxBuffer; 
-  static NumericDefaultValue<uint32_t>       defaultInitialCWnd; 
-  static NumericDefaultValue<uint32_t>       defaultConnTimeout;  
-  static NumericDefaultValue<uint32_t>       defaultConnCount;  
+  uint32_t GetDefaultSegSize (void) const;
+  uint32_t GetDefaultAdvWin (void) const;
+  uint32_t GetDefaultSsThresh (void) const;
+  uint32_t GetDefaultTxBuffer (void) const;
+  uint32_t GetDefaultRxBuffer (void) const;
+  uint32_t GetDefaultInitialCwnd (void) const;
+  uint32_t GetDefaultConnTimeout (void) const;
+  uint32_t GetDefaultConnCount (void) const;
+private:
+  uint32_t  m_defaultSegSize;  
+  uint32_t  m_defaultAdvWin;   
+  uint32_t  m_defaultSsThresh; 
+  uint32_t  m_defaultTxBuffer; 
+  uint32_t  m_defaultRxBuffer; 
+  uint32_t  m_defaultInitialCwnd; 
+  uint32_t  m_defaultConnTimeout;  
+  uint32_t  m_defaultConnCount;  
 
 };
 
 } // namespace ns3
 
-#endif /* UDP_H */
+#endif /* TCP_H */