Logstash and GeoIPASN

Hi all,
i have a question about logstash and GeoIPASN.
I'm using GeoIPASNum.dat and works well: i'm using the snipped code below

        geoip {
            source => "id_orig_h"
            target => "geoIPASN"
            database => "/opt/logstash/vendor/geoip/GeoIPASNum.dat"

I've seen in the database that the starting and ending ip associated to an owner are also present: how can i extract these data?