--- a/src/internet-node/arp-cache.cc	Thu Jul 26 12:05:31 2007 +0100
+++ b/src/internet-node/arp-cache.cc	Thu Jul 26 12:12:51 2007 +0100
@@ -109,6 +109,8 @@
 ArpCache::Entry *
 ArpCache::Add (Ipv4Address to)
 {
+  NS_ASSERT (m_arpCache.find (to) == m_arpCache.end ());
+
   ArpCache::Entry *entry = new ArpCache::Entry (this);
   m_arpCache[to] = entry;  
   return entry;

--- a/src/internet-node/arp-ipv4-interface.cc	Thu Jul 26 12:05:31 2007 +0100
+++ b/src/internet-node/arp-ipv4-interface.cc	Thu Jul 26 12:12:51 2007 +0100
@@ -21,6 +21,7 @@
  */
 
 #include "ns3/packet.h"
+#include "ns3/debug.h"
 #include "ns3/composite-trace-resolver.h"
 #include "ns3/node.h"
 #include "ns3/net-device.h"
@@ -60,7 +61,19 @@
     {
       Ptr<ArpPrivate> arp = m_node->QueryInterface<ArpPrivate> (ArpPrivate::iid);
       MacAddress hardwareDestination;
-      bool found = arp->Lookup (p, dest, GetDevice (), &hardwareDestination);
+      bool found;
+
+      if (dest.IsBroadcast ())
+        {
+           hardwareDestination = GetDevice ()->GetBroadcast ();
+           found = true;
+        }
+      else
+        {
+          Ptr<ArpPrivate> arp = m_node->QueryInterface<ArpPrivate> (ArpPrivate::iid);
+          found = arp->Lookup (p, dest, GetDevice (), &hardwareDestination);
+        }
+
       if (found)
         {
           GetDevice ()->Send (p, hardwareDestination, Ipv4L3Protocol::PROT_NUMBER);

--- a/src/internet-node/arp-l3-protocol.cc	Thu Jul 26 12:05:31 2007 +0100
+++ b/src/internet-node/arp-l3-protocol.cc	Thu Jul 26 12:12:51 2007 +0100
@@ -87,6 +87,13 @@
   ArpCache *cache = FindCache (device);
   ArpHeader arp;
   packet.RemoveHeader (arp);
+  
+  NS_DEBUG ("ARP: received "<< (arp.IsRequest ()? "request" : "reply") <<
+            " node="<<m_node->GetId ()<<", got request from " <<
+            arp.GetSourceIpv4Address () << " for address " <<
+            arp.GetDestinationIpv4Address () << "; we have address " <<
+            cache->GetInterface ()->GetAddress ());
+
   if (arp.IsRequest () && 
       arp.GetDestinationIpv4Address () == cache->GetInterface ()->GetAddress ()) 
     {
@@ -128,6 +135,12 @@
 	  // XXX report packet as dropped.
         }
     }
+  else
+    {
+      NS_DEBUG ("node="<<m_node->GetId ()<<", got request from " <<
+                arp.GetSourceIpv4Address () << " for unknown address " <<
+                arp.GetDestinationIpv4Address () << " -- drop");
+    }
 }
 bool 
 ArpL3Protocol::Lookup (Packet &packet, Ipv4Address destination, 
@@ -203,6 +216,11 @@
 ArpL3Protocol::SendArpRequest (ArpCache const *cache, Ipv4Address to)
 {
   ArpHeader arp;
+  NS_DEBUG ("ARP: sending request from node "<<m_node->GetId ()<<
+            " || src: " << cache->GetDevice ()->GetAddress () <<
+            " / " << cache->GetInterface ()->GetAddress () <<
+            " || dst: " << cache->GetDevice ()->GetBroadcast () <<
+            " / " << to);
   arp.SetRequest (cache->GetDevice ()->GetAddress (),
 		  cache->GetInterface ()->GetAddress (), 
                   cache->GetDevice ()->GetBroadcast (),
@@ -216,6 +234,10 @@
 ArpL3Protocol::SendArpReply (ArpCache const *cache, Ipv4Address toIp, MacAddress toMac)
 {
   ArpHeader arp;
+  NS_DEBUG ("ARP: sending reply from node "<<m_node->GetId ()<<
+            "|| src: " << cache->GetDevice ()->GetAddress () << 
+            " / " << cache->GetInterface ()->GetAddress () <<
+            " || dst: " << toMac << " / " << toIp);
   arp.SetReply (cache->GetDevice ()->GetAddress (),
                 cache->GetInterface ()->GetAddress (),
                 toMac, toIp);