More Is Not Always Better: An Analytical Study of Controller Synchronizations in Distributed SDN

Abstract Distributed software-defined networks (SDN), consisting of multiple inter-connected network domains, each managed by one SDN controller, is an emerging networking architecture that offers balanced centralized control and distributed operations. In such net- working paradigm, most existing works focus on designing sophisticated controller-synchronization strategies to improve joint controller-decision- making for inter-domain routing. However, there is still a lack of fundamental understanding of how the performance of distributed SDN is related to network attributes, thus impossible to justify the necessity of complicated strategies. In this regard, we analyze and quantify how the performance enhancement of distributed SDN architectures is influenced by inter-domain synchronization levels and network structural properties. Based on a generic network model incorporating link preference for path constructions, we establish analytical lower bounds for quantifying the routing performance under any arbitrarily given network synchro- nization status. Such performance bounds are proved to be tight; their accuracies are also confirmed by extensive experiments using both real and synthetic networks. The significance of these performance bounds is that they can be used to quantify the contribution of controller synchronization levels in improving the network performance under different network parameters, which therefore serves as a fundamental guidance for future SDN performance analysis and protocol designs.
  • Ziyao Zhang (Imperial)
  • Liang Ma (IBM US)
  • Kin Leung (Imperial)
  • Franck Le (IBM US)
Date Sep-2019
Venue Annual Fall Meeting of the DAIS ITA, 2019