In modern telecommunication networks, the trend toward “softwarization” is shifting the execution of switching and protocol functionalities from specialized devices to general purpose hardware located in datacenters or at the network edge. Incoming flows generated by User Equipment are processed by different functional modules executed in Virtual Machines (VMs) or containers. The paper considers a modeling and control architecture in this environment, for the assignment of flows to the first functional blocks in a chain of Virtual Network Functions (VNFs) and the balancing of the load among the VMs where they are executed.