Logging improvements.

Change-Id: I79b9ff16a0000e4bd72022f02baef5c779ea1b48
diff --git a/tools/test/bin/onos-config b/tools/test/bin/onos-config
index 35232bd..5c37e39 100755
--- a/tools/test/bin/onos-config
+++ b/tools/test/bin/onos-config
@@ -10,7 +10,8 @@
 
 # Generate a cluster.json from the ON* environment variables
 CDEF_FILE=/tmp/${remote}.cluster.json
-echo "{ \"nodes\":[" > $CDEF_FILE
+echo "{ \"ipPrefix\": \"$ONOS_NIC\"," > $CDEF_FILE
+echo "  \"nodes\":[" >> $CDEF_FILE
 for node in $(env | sort | egrep "OC[2-9]+" | cut -d= -f2); do
     echo "  { \"id\": \"$node\", \"ip\": \"$node\", \"tcpPort\": 9876 }," >> $CDEF_FILE
 done