add using float method

Change-Id: Iea9cacfe589a0a2ab0a2439b6302106d697da9e5
diff --git a/TestON/tests/SDNIPperf/SDNIPperf.py b/TestON/tests/SDNIPperf/SDNIPperf.py
index 238c8f9..cd41ea6 100644
--- a/TestON/tests/SDNIPperf/SDNIPperf.py
+++ b/TestON/tests/SDNIPperf/SDNIPperf.py
@@ -116,7 +116,7 @@
 
         main.step("Sleep 1200 seconds")
         # wait until SDN-IP receives all routes and ONOS installs all intents
-        time.sleep( main.params[ 'timers' ][ 'SystemBoot' ] )
+        time.sleep( float(main.params[ 'timers' ][ 'SystemBoot' ]) )
 
         main.step( "Checking routes installed" )