Towards transiently secure updates in asynchronous SDNs

Software-Defined Networks (SDNs) promise to overcome the often complex and error-prone operation of traditional computer networks, by enabling programmability, automation and verifiability. Yet, SDNs also introduce new challenges, for example due to the asynchronous communication channel between the logically centralized control platform and the switches in the data plane. In particular, the asynchronous communication of network update commands (e.g., OpenFlow FlowMod messages) may lead to transient inconsistencies, such as loops or bypassed waypoints (e.g., firewalls). One approach to ensure transient consistency even in asynchronous environments is to employ smart scheduling algorithms: algorithms which update subsets of switches in each communication round only, where each subset in itself guarantees consistency. In this demo, we show how to change routing policies in a transiently consistent manner. We demonstrate two algorithms, namely, Wayup [5] and Peacock [4], which partition the network updates sent from SDN controller towards OpenFlow software switches into multiple rounds as per respective algorithms. Later, the barrier messages are utilized to ensure reliable network updates.