get rid of channel during dispose

src/node/simple-net-device.cc

@@ -153,6 +153,14 @@ SimpleNetDevice::SetReceiveCallback (NetDevice::ReceiveCallback cb)
   m_rxCallback = cb;
 }
 
+void
+SimpleNetDevice::DoDispose (void)
+{
+  m_channel = 0;
+  m_node = 0;
+  NetDevice::DoDispose ();
+}
+
 
 
 } // namespace ns3

src/node/simple-net-device.h

@@ -44,6 +44,8 @@ public:
   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;