--- a/src/node/simple-net-device.cc	Mon Mar 31 14:36:21 2008 -0700
+++ b/src/node/simple-net-device.cc	Mon Mar 31 14:43:38 2008 -0700
@@ -153,6 +153,14 @@
   m_rxCallback = cb;
 }
 
+void
+SimpleNetDevice::DoDispose (void)
+{
+  m_channel = 0;
+  m_node = 0;
+  NetDevice::DoDispose ();
+}
+
 
 
 } // namespace ns3

--- a/src/node/simple-net-device.h	Mon Mar 31 14:36:21 2008 -0700
+++ b/src/node/simple-net-device.h	Mon Mar 31 14:43:38 2008 -0700
@@ -44,6 +44,8 @@
   virtual bool NeedsArp (void) const;
   virtual void SetReceiveCallback (NetDevice::ReceiveCallback cb);
 
+protected:
+  virtual void DoDispose (void);
 private:
   Ptr<SimpleChannel> m_channel;
   NetDevice::ReceiveCallback m_rxCallback;