A method and equipment for obtaining routing data for a data transfer packet is presented. The data transfer packet is associated with information indicating a quality-of-service class of the data transfer packet and is related to protocol data associated with a data transfer protocol being used. The method using the protocol data as an input quantity for reading basic data and a reduction rule that are compatible with a routing table and the protocol data, using the information indicating the quality-of-service class as an input quantity of the reduction rule for obtaining auxiliary routing data, and obtaining the routing data on the basis of the basic data and the auxiliary routing data. The reduction rule connects auxiliary data to each quality-of-service class in such a way that each auxiliary data is associated with at least two different quality-of-service classes in order to reduce the amount of required storage capacity.