Inducing small delay to allow ARPs to be seen by controller.

Change-Id: I385c7526c4cada7dc43099dc0621829dd8d63a76
diff --git a/tools/test/topos/onosnet.py b/tools/test/topos/onosnet.py
index f8e4f6a..adb4a10 100644
--- a/tools/test/topos/onosnet.py
+++ b/tools/test/topos/onosnet.py
@@ -49,6 +49,7 @@
         Mininet.start( self )
         if self.gratArp:
             self.waitConnected( timeout=5 )
+            sleep(2)
             info ( '*** Sending a gratuitious ARP from each host\n' )
             self.gratuitousArp()