int (*get_next_hop)(const struct in_addr *host, struct in_addr *next_hop,
char **netdev_name);
+ /* Looks up the name of the interface out of which traffic will egress if
+ * 'netdev' is a tunnel. If unsuccessful, or 'netdev' is not a tunnel,
+ * will return null. This function does not necessarily return the
+ * physical interface out which traffic will egress. Instead it returns
+ * the interface which is assigned 'netdev's remote_ip. This may be an
+ * internal interface such as a bridge port.
+ *
+ * This function may be set to null if 'netdev' is not a tunnel or it is
+ * not supported. */
+ const char *(*get_tnl_iface)(const struct netdev *netdev);
+
/* Looks up the ARP table entry for 'ip' on 'netdev' and stores the
* corresponding MAC address in 'mac'. A return value of ENXIO, in
* particular, indicates that there is no ARP table entry for 'ip' on