remove the vbng service's default url
diff --git a/xos/cord/models.py b/xos/cord/models.py
index d55ff2d..26d7d24 100644
--- a/xos/cord/models.py
+++ b/xos/cord/models.py
@@ -689,7 +689,7 @@
 class VBNGService(Service):
     KIND = VBNG_KIND
 
-    simple_attributes = ( ("vbng_url", "http://10.0.3.136:8181/onos/virtualbng/"), )
+    simple_attributes = ( ("vbng_url", ""), )  # "http://10.0.3.136:8181/onos/virtualbng/"
 
     class Meta:
         app_label = "cord"