A method is provided of obtaining information representative of an availability of a communications network, which includes a plurality of equipment exchanging routing data in accordance with a routing protocol. The method includes a stage of storing in chronological order at least some of the routing data exchanged between at least one first equipment and at least one second equipment; a stage of totaling unavailability times as a function of the routing data stored in chronological order for a predetermined time period; a stage of obtaining the information representative of an availability for the time period as a function of the totaled unavailability times.