--- a/src/virtual-net-device/examples/virtual-net-device.cc	Sat Nov 24 13:56:28 2018 -0800
+++ b/src/virtual-net-device/examples/virtual-net-device.cc	Sat Nov 24 14:59:07 2018 -0800
@@ -14,6 +14,7 @@
  * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
  *
  * Based on simple-global-routing.cc
+ * The Tunnel class adds two tunnels, n0<=>n3 and n1<=>n3
  */
 
 // Network topology
@@ -27,20 +28,15 @@
 //   n1
 //
 // - all links are point-to-point links with indicated one-way BW/delay
-// - CBR/UDP flows from n0 to n3, and from n3 to n1
-// - FTP/TCP flow from n0 to n3, starting at time 1.2 to time 1.35 sec.
-// - UDP packet size of 210 bytes, with per-packet interval 0.00375 sec.
-//   (i.e., DataRate of 448,000 bps)
-// - DropTail queues 
 // - Tracing of queues and packet receptions to file "virtual-net-device.tr"
 
 // Tunneling changes (relative to the simple-global-routing example):
-// n0 will receive an extra virtual interface with address 11.0.0.1
-// n1 will also receive an extra virtual interface with the same address 11.0.0.1
-// n3 will receive an extra virtual interface with address 11.0.0.254
-// The flows will be between 11.0.0.x (tunnel) addresses instead of 10.1.x.y ones
-// n3 will decide, on a per-packet basis, via random number, whether to
-// send the packet to n0 or to n1.
+// - n0 will receive an extra virtual interface with hardcoded inner-tunnel address 11.0.0.1
+// - n1 will also receive an extra virtual interface with the same inner-tunnel address 11.0.0.1
+// - n3 will receive an extra virtual interface with inner-tunnel address 11.0.0.254
+// - The flows will be between 11.0.0.x (inner-tunnel) addresses instead of 10.1.x.y ones
+// - n3 will decide, on a per-packet basis, via random number, whether to
+//   send the packet to n0 or to n1.
 //
 // Note: here we create a tunnel where IP packets are tunneled over
 // UDP/IP, but tunneling directly IP-over-IP would also be possible;
@@ -249,7 +245,7 @@
   // tables in the nodes.
   Ipv4GlobalRoutingHelper::PopulateRoutingTables ();
 
-  // Add the tunnels
+  // Add the tunnels n0<=>n3 and n1<=>n3
   Tunnel tunnel (c.Get (3), c.Get (0), c.Get (1),
                  i3i2.GetAddress (0), i0i2.GetAddress (0), i1i2.GetAddress (0));