Avoiding Inconsistency in OpenFlow Stateful Applications Caused by Multiple Flow Requests

When developing a stateful application (e.g. a load balancer) for an OpenFlow network, it is mandatory that the applications receive a consistent view of the network state from the controller. However, when a burst of packets arrive in an OpenFlow switch and the default action is to send those packets to the controller (via Packet-In), a stateful application can be taken to an inconsistent state if the controller passes all those packets to the application. Previous works proposed the modification of the OpenFlow specification or in the switches in order to alter this default behavior. The main idea of this paper is to make some modifications in the controller software and to tune the parameters of the OpenFlow protocol to avoid inconsistency in OpenFlow applications state that required an appropriate treatment of multiple Packet-In events. The results indicate that the proposed scheme indeed delivers a consistent view of the network state for stateful OpenFlow applications.