Fixed missing FCS calculation for ACKs.

src/lr-wpan/examples/lr-wpan-data.cc

@@ -72,6 +72,9 @@ int main (int argc, char *argv[])
       lrWpanHelper.EnableLogComponents ();
     }
 
+  // Enable calculation of FCS in the trailers. Only necessary when interacting with real devices or wireshark.
+  // GlobalValue::Bind ("ChecksumEnabled", BooleanValue (true));
+  
   // Create 2 nodes, and a NetDevice for each one
   Ptr<Node> n0 = CreateObject <Node> ();
   Ptr<Node> n1 = CreateObject <Node> ();

src/lr-wpan/model/lr-wpan-mac.cc

@@ -651,6 +651,12 @@ LrWpanMac::SendAck (uint8_t seqno)
   LrWpanMacTrailer macTrailer;
   Ptr<Packet> ackPacket = Create<Packet> (0);
   ackPacket->AddHeader (macHdr);
+  // Calculate FCS if the global attribute ChecksumEnable is set.
+  if (Node::ChecksumEnabled ())
+    {
+      macTrailer.EnableFcs (true);
+      macTrailer.SetFcs (ackPacket);
+    }
   ackPacket->AddTrailer (macTrailer);
 
   // Enqueue the ACK packet for further processing