A method of forwarding packet flows in a network includes originating the packet flows from a plurality of end hosts in the network; and transmitting the packet flows from a respective end host of the plurality of end hosts to a sink node via a predefined routing path that includes one or more SDN switches that are under control of an SDN controller. The one or more SDN switches include an edge switch having at least one port connected to the end host. Forwarding of a packet flow from the respective end host by the edge switch is enabled by a dedicated door-opener packet that, when being processed at the one or more SDN switches, effectuates activation or installation of a forwarding rule within the one or more SDN switches for forwarding the packet flow to a next switch along the predefined routing path.