diff --git a/src/common/packet.cc b/src/common/packet.cc
index b2f67c479..82f167d35 100644
--- a/src/common/packet.cc
+++ b/src/common/packet.cc
@@ -308,6 +308,7 @@ Packet::PrintTags (std::ostream &os) const
       Tag *tag = dynamic_cast<Tag *> (constructor ());
       NS_ASSERT (tag != 0);
       os << " ";
+      item.GetTag (*tag);
       tag->Print (os);
       if (i.HasNext ())
         {
diff --git a/src/internet-node/ipv4-l3-protocol.cc b/src/internet-node/ipv4-l3-protocol.cc
index 653068c8c..affe814bb 100644
--- a/src/internet-node/ipv4-l3-protocol.cc
+++ b/src/internet-node/ipv4-l3-protocol.cc
@@ -30,6 +30,7 @@
 #include "ns3/trace-source-accessor.h"
 #include "ns3/object-vector.h"
 #include "ns3/ipv4-header.h"
+#include "ns3/boolean.h"
 #include "arp-l3-protocol.h"
 
 #include "ipv4-l3-protocol.h"
@@ -57,6 +58,11 @@ Ipv4L3Protocol::GetTypeId (void)
                    UintegerValue (64),
                    MakeUintegerAccessor (&Ipv4L3Protocol::m_defaultTtl),
                    MakeUintegerChecker<uint8_t> ())
+    .AddAttribute ("CalcChecksum", "If true, we calculate the checksum of outgoing packets"
+                   " and verify the checksum of incoming packets.",
+                   BooleanValue (false),
+                   MakeBooleanAccessor (&Ipv4L3Protocol::m_calcChecksum),
+                   MakeBooleanChecker ())
     .AddTraceSource ("Tx", "Send ipv4 packet to outgoing interface.",
                    MakeTraceSourceAccessor (&Ipv4L3Protocol::m_txTrace))
     .AddTraceSource ("Rx", "Receive ipv4 packet from incoming interface.",
@@ -464,10 +470,15 @@ Ipv4L3Protocol::Receive( Ptr<NetDevice> device, Ptr<Packet> packet, uint16_t pro
       index++;
     }
   Ipv4Header ipHeader;
+  if (m_calcChecksum)
+    {
+      ipHeader.EnableChecksum ();
+    }
   packet->RemoveHeader (ipHeader);
 
   if (!ipHeader.IsChecksumOk ()) 
     {
+      m_dropTrace (packet);
       return;
     }
 
@@ -490,6 +501,11 @@ Ipv4L3Protocol::Send (Ptr<Packet> packet,
 
   Ipv4Header ipHeader;
 
+  if (m_calcChecksum)
+    {
+      ipHeader.EnableChecksum ();
+    }
+
   ipHeader.SetSource (source);
   ipHeader.SetDestination (destination);
   ipHeader.SetProtocol (protocol);
diff --git a/src/internet-node/ipv4-l3-protocol.h b/src/internet-node/ipv4-l3-protocol.h
index 7b65269d7..40f0be5bd 100644
--- a/src/internet-node/ipv4-l3-protocol.h
+++ b/src/internet-node/ipv4-l3-protocol.h
@@ -191,6 +191,7 @@ private:
   Ipv4InterfaceList m_interfaces;
   uint32_t m_nInterfaces;
   uint8_t m_defaultTtl;
+  bool m_calcChecksum;
   uint16_t m_identification;
   Ptr<Node> m_node;
   TracedCallback<Ptr<const Packet>, uint32_t> m_txTrace;
diff --git a/src/node/ipv4-header.cc b/src/node/ipv4-header.cc
index 3c7fb355f..758358f98 100644
--- a/src/node/ipv4-header.cc
+++ b/src/node/ipv4-header.cc
@@ -29,10 +29,9 @@ namespace ns3 {
 
 NS_OBJECT_ENSURE_REGISTERED (Ipv4Header);
 
-bool Ipv4Header::m_calcChecksum = false;
-
 Ipv4Header::Ipv4Header ()
-  : m_payloadSize (0),
+  : m_calcChecksum (false),
+    m_payloadSize (0),
     m_identification (0),
     m_tos (0),
     m_ttl (0),
@@ -43,7 +42,7 @@ Ipv4Header::Ipv4Header ()
 {}
 
 void 
-Ipv4Header::EnableChecksums (void)
+Ipv4Header::EnableChecksum (void)
 {
   m_calcChecksum = true;
 }
@@ -178,6 +177,22 @@ Ipv4Header::IsChecksumOk (void) const
   return m_goodChecksum;
 }
 
+uint16_t
+Ipv4Header::ChecksumCalculate(Buffer::Iterator &i, uint16_t size)
+{
+  /* see RFC 1071 to understand this code. */
+  uint32_t sum = 0;
+
+  for (int j = 0; j < size/2; j++)
+    sum += i.ReadU16 ();
+
+  if (size & 1)
+     sum += i.ReadU8 ();
+
+  while (sum >> 16)
+    sum = (sum & 0xffff) + (sum >> 16);
+  return ~sum;
+}
 
 TypeId 
 Ipv4Header::GetTypeId (void)
@@ -266,16 +281,12 @@ Ipv4Header::Serialize (Buffer::Iterator start) const
 
   if (m_calcChecksum) 
     {
-#if 0
-      // XXX we need to add Buffer::Iterator::PeekData method
-      uint8_t *data = start.PeekData ();
-      uint16_t checksum = UtilsChecksumCalculate (0, data, GetSize ());
-      checksum = UtilsChecksumComplete (checksum);
+      i = start;
+      uint16_t checksum = ChecksumCalculate(i, 20);
       NS_LOG_LOGIC ("checksum=" <<checksum);
       i = start;
       i.Next (10);
       i.WriteU16 (checksum);
-#endif
     }
 }
 uint32_t
@@ -313,18 +324,11 @@ Ipv4Header::Deserialize (Buffer::Iterator start)
 
   if (m_calcChecksum) 
     {
-#if 0
-      uint8_t *data = start.PeekData ();
-      uint16_t localChecksum = UtilsChecksumCalculate (0, data, headerSize);
-      if (localChecksum == 0xffff) 
-        {
-          m_goodChecksum = true;
-        } 
-      else 
-        {
-          m_goodChecksum = false;
-        }
-#endif
+      i = start;
+      uint16_t checksum = ChecksumCalculate(i, headerSize);
+      NS_LOG_LOGIC ("checksum=" <<checksum);
+
+      m_goodChecksum = (checksum == 0);
     }
   return GetSerializedSize ();
 }
diff --git a/src/node/ipv4-header.h b/src/node/ipv4-header.h
index 29fd7e9c3..59ae97fe4 100644
--- a/src/node/ipv4-header.h
+++ b/src/node/ipv4-header.h
@@ -36,9 +36,9 @@ public:
    */
   Ipv4Header ();
   /**
-   * \brief Enable checksum calculation for IP (XXX currently has no effect)
+   * \brief Enable checksum calculation for this header.
    */
-  static void EnableChecksums (void);
+  void EnableChecksum (void);
   /**
    * \param size the size of the payload in bytes
    */
@@ -131,10 +131,10 @@ public:
   Ipv4Address GetDestination (void) const;
   
   /**
-   * \returns true if the upv4 checksum is correct, false otherwise.
+   * \returns true if the ipv4 checksum is correct, false otherwise.
    *
    * If Ipv4Header::EnableChecksums has not been called prior to
-   * creating this packet, this method will always return true.
+   * deserializing this header, this method will always return true.
    */
   bool IsChecksumOk (void) const;
 
@@ -146,12 +146,13 @@ public:
   virtual uint32_t Deserialize (Buffer::Iterator start);
 private:
 
+  static uint16_t ChecksumCalculate(Buffer::Iterator &i, uint16_t len);
   enum FlagsE {
     DONT_FRAGMENT = (1<<0),
     MORE_FRAGMENTS = (1<<1)
   };
 
-  static bool m_calcChecksum;
+  bool m_calcChecksum;
 
   uint16_t m_payloadSize;
   uint16_t m_identification;
diff --git a/src/routing/olsr/olsr-agent-impl.cc b/src/routing/olsr/olsr-agent-impl.cc
index 2d240e897..b9a9ea7e4 100644
--- a/src/routing/olsr/olsr-agent-impl.cc
+++ b/src/routing/olsr/olsr-agent-impl.cc
@@ -38,6 +38,7 @@
 #include "ns3/inet-socket-address.h"
 #include "ns3/boolean.h"
 #include "ns3/uinteger.h"
+#include "ns3/enum.h"
 #include "ns3/trace-source-accessor.h"
 
 /********** Useful macros **********/
@@ -53,17 +54,6 @@
 
 
 
-/********** Intervals **********/
-
-/// HELLO messages emission interval.
-#define OLSR_HELLO_INTERVAL	Seconds (2)
-
-/// TC messages emission interval.
-#define OLSR_TC_INTERVAL	Seconds (5)
-
-/// MID messages emission interval.
-#define OLSR_MID_INTERVAL	OLSR_TC_INTERVAL
-
 ///
 /// \brief Period at which a node must cite every link and every neighbor.
 ///
@@ -77,11 +67,11 @@
 /// Neighbor holding time.
 #define OLSR_NEIGHB_HOLD_TIME	(Scalar (3) * OLSR_REFRESH_INTERVAL)
 /// Top holding time.
-#define OLSR_TOP_HOLD_TIME	(Scalar (3) * OLSR_TC_INTERVAL)
+#define OLSR_TOP_HOLD_TIME	(Scalar (3) * m_tcInterval)
 /// Dup holding time.
 #define OLSR_DUP_HOLD_TIME	Seconds (30)
 /// MID holding time.
-#define OLSR_MID_HOLD_TIME	(Scalar (3) * OLSR_MID_INTERVAL)
+#define OLSR_MID_HOLD_TIME	(Scalar (3) * m_midInterval)
 
 
 /********** Link types **********/
@@ -122,7 +112,7 @@
 /********** Miscellaneous constants **********/
 
 /// Maximum allowed jitter.
-#define OLSR_MAXJITTER		(OLSR_HELLO_INTERVAL.GetSeconds () / 4)
+#define OLSR_MAXJITTER		(m_helloInterval.GetSeconds () / 4)
 /// Maximum allowed sequence number.
 #define OLSR_MAX_SEQ_NUM	65535
 /// Random number between [0-OLSR_MAXJITTER] used to jitter OLSR packet transmission.
@@ -156,22 +146,26 @@ AgentImpl::GetTypeId (void)
   static TypeId tid = TypeId ("ns3::olsr::AgentImpl")
     .SetParent<Agent> ()
     .AddConstructor<AgentImpl> ()
-    .AddAttribute ("HelloInterval", "XXX",
-                   TimeValue (OLSR_HELLO_INTERVAL),
+    .AddAttribute ("HelloInterval", "HELLO messages emission interval.",
+                   TimeValue (Seconds (2)),
                    MakeTimeAccessor (&AgentImpl::m_helloInterval),
                    MakeTimeChecker ())
-    .AddAttribute ("TcInterval", "XXX",
-                   TimeValue (OLSR_TC_INTERVAL),
+    .AddAttribute ("TcInterval", "TC messages emission interval.",
+                   TimeValue (Seconds (5)),
                    MakeTimeAccessor (&AgentImpl::m_tcInterval),
                    MakeTimeChecker ())
-    .AddAttribute ("MidInterval", "XXX",
-                   TimeValue (OLSR_MID_INTERVAL),
+    .AddAttribute ("MidInterval", "MID messages emission interval.  Normally it is equal to TcInterval.",
+                   TimeValue (Seconds (5)),
                    MakeTimeAccessor (&AgentImpl::m_midInterval),
                    MakeTimeChecker ())
-    .AddAttribute ("Willingness", "XXX",
-                   UintegerValue (OLSR_WILL_DEFAULT),
-                   MakeUintegerAccessor (&AgentImpl::m_willingness),
-                   MakeUintegerChecker<uint8_t> ())
+    .AddAttribute ("Willingness", "Willingness of a node to carry and forward traffic for other nodes.",
+                   EnumValue (OLSR_WILL_DEFAULT),
+                   MakeEnumAccessor (&AgentImpl::m_willingness),
+                   MakeEnumChecker (OLSR_WILL_NEVER, "never",
+                                    OLSR_WILL_LOW, "low",
+                                    OLSR_WILL_DEFAULT, "default",
+                                    OLSR_WILL_HIGH, "high",
+                                    OLSR_WILL_ALWAYS, "always"))
     .AddTraceSource ("Rx", "Receive OLSR packet.",
                      MakeTraceSourceAccessor (&AgentImpl::m_rxPacketTrace))
     .AddTraceSource ("Tx", "Send OLSR packet.",
diff --git a/src/routing/olsr/waf b/src/routing/olsr/waf
new file mode 100755
index 000000000..4283ec141
--- /dev/null
+++ b/src/routing/olsr/waf
@@ -0,0 +1 @@
+exec "`dirname "$0"`"/../../../waf "$@"