diff --git a/test_hub_discovery/hub-discovery-test.sh b/test_hub_discovery/hub-discovery-test.sh
index 5d50070..861dc8a 100755
--- a/test_hub_discovery/hub-discovery-test.sh
+++ b/test_hub_discovery/hub-discovery-test.sh
@@ -35,21 +35,21 @@
 
 sleep 2
 
-ssh $IP4_B1 "$workdir/test-B-stage1.sh $workdir"
+ssh $CTRL_B "$workdir/test-B-stage1.sh $workdir"
 if [[ $? -ne 0 ]]; then
   echo "Stage 1: multicast discovery failed on node B" >> $testLog
   clean_up
   exit 1
 fi
 
-ssh $IP4_D1 "$workdir/test-D-stage2.sh $workdir"
+ssh $CTRL_D "$workdir/test-D-stage2.sh $workdir"
 if [[ $? -ne 0 ]]; then
   echo "Stage 2: DNS query with default suffix failed on node D" >> $testLog
   clean_up
 exit 1
 fi
 
-ssh $IP4_D1 "$workdir/test-D-stage3.sh $workdir"
+ssh $CTRL_D "$workdir/test-D-stage3.sh $workdir"
 if [[ $? -ne 0 ]]; then
   echo "Stage 3: find home router failed on node D" >> $testLog
   clean_up