Adaptive and Continuous Consistency for Distributed SDN Controllers
Fetia Bannour, Sami Souihi, Abdelhamid Mellouk · 2022
In this chapter, the authors conduct a background review of eventual consistency models in modern distributed data store systems. They present their adaptive and continuous Quorum-based consistency model for the distributed ONOS controllers in large-scale deployments. Modern distributed database systems supporting standard eventual consistency models suffer from the inevitable trade-offs between consistency, availability and request latency. The authors describe their methodology for implementing the proposed consistency strategy on a CDN-like application that they designed on top of the ONOS controllers. The applications on top of the ONOS controllers can benefit from the continuous consistency model introduced with TACT by continuously and dynamically specifying their consistency requirements using three application-independent metrics to capture the consistency spectrum and bound consistency: numerical error, order error and staleness. The authors show the considered continuous and SLA-style performance and consistency metrics.