A technique for collecting information relating to a flow routed in a communication network. This network includes, in a data plane, packet-processing devices that are configured so as to process packets on the basis of flow-processing rules and, in a control plane, at least one control device that is configured so as to control packet-processing devices and to manage the flow-processing rules. An analysis device identifies at least one flow-processing rule configured so as to process a flow including a first characteristic associated with a first endpoint device of a flow to be sought in the communication network and applied by a processing device. Based on the identified processing rule, the control device determines a second characteristic associated with a second endpoint device.