ESPRES: Easy Scheduling and Prioritization for SDN

Network state is always in flux. Due to traffic engineering, topology changes, policy updates, VM migrations, etc., today’s networks undergo a variety of large updates that concurrently affect many switches. Transitioning between network states can be a source of instability, leading to outages, disruptions and security vulnerabilities. Consistent network updates introduces a mechanism that guarantees to preserve well defined behaviors when transitioning between states. However, a major problem for this technique is the update performance, that is, the time it takes to install a network state update onto the data-plane—the current generation of OpenFlow switches can install flows with rate as low as 40 rules/second. Even moderate-sized updates can take several seconds, during which operators are in the dark about how badly links could be congested. Therefore it is desirable to complete updates quickly. However, we note that the lowest bound of the total time to complete the update is determined by the switch that is last to complete.