A method, by a target node classification entity, to control an application of a service providing module to a data packet flow, wherein the data packet flow is transmitted to a target node (310, 320) through a service network, and wherein the service providing module applies a service to the data packet flow, the method comprising the steps of: - receiving, from a flow classification entity, flow classification data about the data packet flow, the flow classification data including at least a flow classifier classifying the data packet flow, a flow identifier uniquely identifying the data packet flow, and a target node address to which the data packet flow is addressed; - classifying the target node (310, 320) based on the flow classifier contained in the received flow classification data, wherein a first service classifier is generated for the target node (310, 320) based on the flow classifier; - checking whether a classification database has to be updated based on the first service classifier of the target node (310, 320), wherein the classification database storing, for different target nodes, which at least one service has to be applied to data packet flows to the corresponding target nodes; - updating the classification database, wherein the updating comprises storing the target node (310, 320) in the classification database in connection with the first service classifier, as a second service classifier, when the classification database does not contain information about the target node (310, 320), wherein the target node (310, 320) with the second service classifier is only stored in the classification database when the second service classifier of the target node (310, 320) indicates that the data packet flows, through the service network to the target node (310, 320), do not follow a default service path through the service network, and wherein if the information in the classification database has to be updated: - generating a flow command for a central flow controller which controls the data packet flows through the service network, wherein the generated flow command contains the information that successive data packet flows in the service network transmitted to the target node address should be passed through the service network in accordance with the generated first service classifier of the target node (310, 320); and - transmitting the generated flow command to the central flow controller. - receiving, from a flow classification entity, flow classification data about the data packet flow, the flow classification data including at least a flow classifier classifying the data packet flow, a flow identifier uniquely identifying the data packet flow, and a target node address to which the data packet flow is addressed; - classifying the target node (310, 320) based on the flow classifier contained in the received flow classification data, wherein a first service classifier is generated for the target node (310, 320) based on the flow classifier; - checking whether a classification database has to be updated based on the first service classifier of the target node (310, 320), wherein the classification database storing, for different target nodes, which at least one service has to be applied to data packet flows to the corresponding target nodes; - updating the classification database, wherein the updating comprises storing the target node (310, 320) in the classification database in connection with the first service classifier, as a second service classifier, when the classification database does not contain information about the target node (310, 320), wherein the target node (310, 320) with the second service classifier is only stored in the classification database when the second service classifier of the target node (310, 320) indicates that the data packet flows, through the service network to the target node (310, 320), do not follow a default service path through the service network, and wherein if the information in the classification database has to be updated: - generating a flow command for a central flow controller which controls the data packet flows through the service network, wherein the generated flow command contains the information that successive data packet flows in the service network transmitted to the target node address should be passed through the service network in accordance with the generated first service classifier of the target node (310, 320); and - transmitting the generated flow command to the central flow controller. - generating a flow command for a central flow controller which controls the data packet flows through the service network, wherein the generated flow command contains the information that successive data packet flows in the service network transmitted to the target node address should be passed through the service network in accordance with the generated first service classifier of the target node (310, 320); and - transmitting the generated flow command to the central flow controller.