diff -r 1204fcdb71c2 src/devices/wifi/wifi-test.cc
--- a/src/devices/wifi/wifi-test.cc	Mon Dec 20 22:05:44 2010 -0800
+++ b/src/devices/wifi/wifi-test.cc	Tue Dec 21 19:00:55 2010 +0100
@@ -289,6 +289,123 @@
 
 //-----------------------------------------------------------------------------
 
+/**
+ * Make sure that when two broadcast packets are queued on the same
+ * device in a short succession no virtual collision occurs 
+ * 
+ */
+class Bug555Test : public TestCase
+{
+public:
+  Bug555Test ();
+
+  virtual bool DoRun (void);
+
+  void Receive (Ptr<Packet>, double x, WifiMode mode, enum WifiPreamble preamble);
+
+private:
+  void RunOne (void);
+  void CreateOne (Vector pos, Ptr<YansWifiChannel> channel);
+  void SendOnePacket (Ptr<WifiNetDevice> dev);
+
+  ObjectFactory m_manager;
+  ObjectFactory m_mac; 
+  ObjectFactory m_propDelay;
+
+  unsigned int m_numReceivedPackets;
+};
+
+Bug555Test::Bug555Test ()
+  : TestCase ("Bug555")
+{
+}
+
+void
+Bug555Test::SendOnePacket (Ptr<WifiNetDevice> dev)
+{
+  Ptr<Packet> p = Create<Packet> (1000);
+  dev->Send (p, dev->GetBroadcast (), 1);
+}
+
+bool
+Bug555Test::DoRun (void)
+{
+  m_mac.SetTypeId ("ns3::AdhocWifiMac");
+  m_propDelay.SetTypeId ("ns3::ConstantSpeedPropagationDelayModel");
+  m_manager.SetTypeId ("ns3::ConstantRateWifiManager");
+
+  Ptr<YansWifiChannel> channel = CreateObject<YansWifiChannel> ();
+  Ptr<PropagationDelayModel> propDelay = m_propDelay.Create<PropagationDelayModel> ();
+  Ptr<PropagationLossModel> propLoss = CreateObject<RandomPropagationLossModel> ();
+  channel->SetPropagationDelayModel (propDelay);
+  channel->SetPropagationLossModel (propLoss);
+
+  Ptr<Node> txNode = CreateObject<Node> ();
+  Ptr<WifiNetDevice> txDev = CreateObject<WifiNetDevice> ();
+  Ptr<WifiMac> txMac = m_mac.Create<WifiMac> ();
+  txMac->ConfigureStandard (WIFI_PHY_STANDARD_80211a);
+  Ptr<ConstantPositionMobilityModel> txMobility = CreateObject<ConstantPositionMobilityModel> ();
+  Ptr<YansWifiPhy> txPhy = CreateObject<YansWifiPhy> ();
+  Ptr<ErrorRateModel> txError = CreateObject<YansErrorRateModel> ();
+  txPhy->SetErrorRateModel (txError);
+  txPhy->SetChannel (channel);
+  txPhy->SetDevice (txDev);
+  txPhy->SetMobility (txNode);
+  txPhy->ConfigureStandard (WIFI_PHY_STANDARD_80211a);
+
+  txMobility->SetPosition (Vector (0.0, 0.0, 0.0));
+  txNode->AggregateObject (txMobility);
+  txMac->SetAddress (Mac48Address::Allocate ());
+  txDev->SetMac (txMac);
+  txDev->SetPhy (txPhy);
+  txDev->SetRemoteStationManager (m_manager.Create<WifiRemoteStationManager> ());
+  txNode->AddDevice (txDev);
+
+
+  Ptr<Node> rxNode = CreateObject<Node> ();
+  Ptr<WifiNetDevice> rxDev = CreateObject<WifiNetDevice> ();
+  Ptr<WifiMac> rxMac = m_mac.Create<WifiMac> ();
+  rxMac->ConfigureStandard (WIFI_PHY_STANDARD_80211a);
+  Ptr<ConstantPositionMobilityModel> rxMobility = CreateObject<ConstantPositionMobilityModel> ();
+  Ptr<YansWifiPhy> rxPhy = CreateObject<YansWifiPhy> ();
+  Ptr<ErrorRateModel> rxError = CreateObject<YansErrorRateModel> ();
+  rxPhy->SetErrorRateModel (rxError);
+  rxPhy->SetChannel (channel);
+  rxPhy->SetDevice (rxDev);
+  rxPhy->SetMobility (rxNode);
+  rxPhy->ConfigureStandard (WIFI_PHY_STANDARD_80211a);
+  Ptr<WifiRemoteStationManager> manager = m_manager.Create<WifiRemoteStationManager> ();
+  rxMobility->SetPosition (Vector (0.0, 0.0, 0.0));
+  rxNode->AggregateObject (rxMobility);
+  rxMac->SetAddress (Mac48Address::Allocate ());
+  rxDev->SetMac (rxMac);
+  rxDev->SetPhy (rxPhy);
+  rxDev->SetRemoteStationManager (m_manager.Create<WifiRemoteStationManager> ());
+  rxNode->AddDevice (rxDev);
+
+
+  rxPhy->SetReceiveOkCallback (MakeCallback (&Bug555Test::Receive, this));
+
+  m_numReceivedPackets = 0;
+  Simulator::Schedule (Seconds (1.000000), &Bug555Test::SendOnePacket, this, txDev);
+  Simulator::Schedule (Seconds (1.000040), &Bug555Test::SendOnePacket, this, txDev);
+
+  Simulator::Stop (Seconds (10.0));
+  Simulator::Run ();
+  Simulator::Destroy ();
+
+  return (m_numReceivedPackets != 2);
+}
+
+void 
+Bug555Test:: Receive (Ptr<Packet>, double x, WifiMode mode, enum WifiPreamble preamble)
+{
+  ++m_numReceivedPackets;
+}
+
+
+//-----------------------------------------------------------------------------
+
 class WifiTestSuite : public TestSuite
 {
 public:
@@ -301,6 +418,7 @@
   AddTestCase (new WifiTest);
   AddTestCase (new QosUtilsIsOldPacketTest);
   AddTestCase (new InterferenceHelperSequenceTest); // Bug 991
+  AddTestCase (new Bug555Test); 
 }
 
 WifiTestSuite g_wifiTestSuite;