Delay updating in Software-Defined Datacenter networks

Software-Define Datacenter networks (SDDCs) are constantly changing due to various network update events. A set of involved flows of each update event should be migrated to the feasible paths without congestion. To tackle a single update event, prior methods find and execute a migration sequence so as to transform the initial traffic distribution to the final traffic distribution. However, when handling a queue of multiple update events, the head-of-line blocking problem always appears and considerably lower the efficiency of network update. To tackle this problem, we employ the idea of delay updating which schedules other queued events instead of the blocked head-event, aiming to break the blocking state and provide updating opportunities for other events. We formulate this problem as an optimization problem and propose partial delay updating (PDU) strategy. PDU tackles the queued update events based on their arrival order to preserve the fairness. Moreover, it prefers to just delay those blocked flows, lacking enough bandwidth resources, instead of all flows in the head-event. The evaluation results show that our delay updating strategy achieves 60%–80% reduction in average completion time of update events, compared to FIFO scheduling strategy, in four types of flow size.