diff --git a/examples/tap-dumbbell.cc b/examples/tap-dumbbell.cc
index bbf4e2fce..1f6d846cc 100644
--- a/examples/tap-dumbbell.cc
+++ b/examples/tap-dumbbell.cc
@@ -29,12 +29,13 @@
 //               +--------+     +------------+     +------------+
 //               |  CSMA  |     | CSMA | P2P |-----| P2P | CSMA |
 //               +--------+     +------+-----+     +-----+------+
-//                   |              |                       |         
-//                   |              |                       |         
+//                   |              |           ^           |
+//                   |              |           |           |         
+//                   |              |    P2P Link 10.1.2    |         
 //                   |    n1  n2    |                       |    n5  n6   n7
 //                   |     |   |    |                       |     |   |    |
 //                   ================                       ================
-//                    CSMA LAN 10.1.1                        CSMA LAN 10.1.2
+//                    CSMA LAN 10.1.1                        CSMA LAN 10.1.3
 //
 // The CSMA device on node zero is:  10.1.1.1
 // The CSMA device on node one is:   10.1.1.2