[ -n "$IFACE6RD_DELEGATE" ] && json_add_boolean delegate "$IFACE6RD_DELEGATE"
[ -n "$ZONE6RD" ] || ZONE6RD=$ZONE
[ -n "$ZONE6RD" ] && json_add_string zone "$ZONE6RD"
+ [ -n "$MTU6RD" ] && json_add_string mtu "$MTU6RD"
json_close_object
ubus call network add_dynamic "$(json_dump)"