diff --git a/xos/configurations/cord/README-VTN.md b/xos/configurations/cord/README-VTN.md
index b8a28c1..9827b0e 100644
--- a/xos/configurations/cord/README-VTN.md
+++ b/xos/configurations/cord/README-VTN.md
@@ -72,3 +72,4 @@
 
 Notes:
 * Adding use_vtn=True to the [networking] section in the XOS config file has two effects: 1) it sets the gateway in sync_controller_networks, and 2) it disables automatic creation of nat-net for new slices. This is because VTN will fail if there is no gateway on a network, and because we don't have nat-net under the VTN configuration.
+* When using of-vfctl to look at flow rules, if you get a protocol error, try "ovs-ofctl show -O OpenFlow13 br-int "