A method includes receiving, by a network node, a first data packet from a client, wherein the first data packet includes an identifier of a service. The method further includes obtaining, by the network node, flow affinity attribute information of the service based on the identifier of the service, wherein the flow affinity attribute information of the service includes a flow affinity type of the service and a flow affinity timeout time of the service. The method further includes establishing, by the network node, a flow entry based on the flow affinity attribute information of the service in response to the first data packet being a 1st data packet in a data flow, wherein the flow entry is useable to forward a subsequent data packet in the data flow.