diff -r 2285ad795bd8 src/devices/wifi/nqsta-wifi-mac.cc
--- a/src/devices/wifi/nqsta-wifi-mac.cc	Thu Oct 30 17:49:29 2008 +0000
+++ b/src/devices/wifi/nqsta-wifi-mac.cc	Thu Oct 30 18:00:39 2008 +0000
@@ -494,6 +495,21 @@
     } 
   else if (hdr->IsData ()) 
     {
+      if (!IsAssociated ())
+        {
+          NS_LOG_LOGIC ("Received data frame while not associated: ignore");
+          return;
+        }
+      if (!(hdr->IsFromDs () && !hdr->IsToDs ()))
+        {
+          NS_LOG_LOGIC ("Received data frame not from the DS: ignore");
+          return;
+        }
+      if (hdr->GetAddr2 () != GetBssid ())
+        {
+          NS_LOG_LOGIC ("Received data frame not from the the BSS we are associated with: ignore");
+          return;
+        }
       NS_LOG_LOGIC ("ForwardUp");
       ForwardUp (packet, hdr->GetAddr2 (), hdr->GetAddr1 ());
     } 
@@ -511,12 +527,16 @@
       if (GetSsid ().IsBroadcast () ||
           beacon.GetSsid ().IsEqual (GetSsid ()))
         {
+          goodBeacon = true;
+        }
+      if (IsAssociated () && hdr->GetAddr3 () != GetBssid ())
+        {
+          goodBeacon = false;
+        }
+      if (goodBeacon)
+        {
           Time delay = MicroSeconds (beacon.GetBeaconIntervalUs () * m_maxMissedBeacons);
           RestartBeaconWatchdog (delay);
-          goodBeacon = true;
-        }
-      if (goodBeacon) 
-        {
           SetBssid (hdr->GetAddr3 ());
         }
       if (goodBeacon && m_state == BEACON_MISSED)