diff --git a/neutron/db/l3_dvr_db.py b/neutron/db/l3_dvr_db.py
index 8c1d94f231b..9e94cd23fc5 100644
--- a/neutron/db/l3_dvr_db.py
+++ b/neutron/db/l3_dvr_db.py
@@ -636,11 +636,13 @@ class L3_NAT_with_dvr_db_mixin(l3_db.L3_NAT_db_mixin,
         return port_list
 
     def dvr_vmarp_table_update(self, context, port_dict, action):
-        """Notify the L3 agent of VM ARP table changes.
+        """Notify L3 agents of VM ARP table changes.
 
-        Provide the details of the VM ARP to the L3 agent when
-        a Nova instance gets created or deleted.
+        When a VM goes up or down, look for one DVR router on the port's
+        subnet, and send the VM's ARP details to all L3 agents hosting the
+        router.
         """
+
         # Check this is a valid VM port
         if ("compute:" not in port_dict['device_owner'] or
             not port_dict['fixed_ips']):