Adaptive Quorum-inspired SLA-Aware Consistency for Distributed SDN Controllers

This paper addresses the knowledge dissemination problem in distributed SDN control by proposing an adaptive and continuous consistency model for the distributed SDN controllers in large-scale deployments. We put forward a scalable and intelligent replication strategy following Quorum-replicated consistency: It uses the read and write Quorum parameters as adjustable control knobs for a fine-grained consistency level tuning. The main purpose is to find, at runtime, appropriate partial Quorum configurations that achieve, under changing network and workload conditions, balanced trade-offs between the application's continuous performance and consistency requirements. Our approach was implemented for a CDN-like application that we designed on top of the ONOS controllers. When compared to ONOS's static consistency model, our model proved efficient in minimizing the application's inter-controller overhead while satisfying the SLA-style application requirements.