Transactional Network Updates in SDN

In current software-defined networks, network updates are neither atomic nor isolated. As such, when performed concurrently, they can lead to inconsistencies such as two conflicting policies installed in different parts of the network. This paper proposes transactional (i.e. atomic and isolated) network updates, embodied in a simple and clean architecture that parallels that of database management systems and involves a transaction manager (TM) running on the controller and a resource manager (RM) that runs on the switch. We implement these as extensions to a state of the art controller (Floodlight) and SDN switch (OVS). The implementation not only demonstrates the feasibility of the design but also shows the ease of its realization. We also evaluate our design by measuring how much time it takes to push transactional updates and at what throughput under various update arrival rates, for various update types and underlying topologies. We find out that, for example, with small path redundancy, we can setup almost all flows that arrive at a rate as high as 1000s(-1), while providing to each a delay within only few milliseconds.