a method and a control node for establishing network functions for processing data packets of a data flow from a delivering node to a receiving node over a communication network . the control node identifies flow characteristics relating to the data flow and determines a succession of network functions in the network for processing the data packets , based on the identified flow characteristics . the network functions are then instructed to forward the data packets in the data flow according to the determined succession . the sequence of network functions specifies a service chain . the controller uses openflow . network functions are dynamically relocated based on network conditions .