Traffic engineering in hierarchical SDN control plane

Decoupling of control and data plane in Software Define Networks (SDN) creates significant flexibility in network management. As networks are evolving into a complex multi-domain multi-layer architecture, traffic engineering across multiple domains and layers entails challenges for the control plane, especially when each separate administrative domain does not disclose their network topology and resource information. In this paper, we present a hierarchical controller design over multidomain and multi-layer networks, by adopting a root controller at the top layer. We allow to aggregate network topology and QoS information into a hierarchical Network Information Base (NIB) for the confidentiality concern. Then, we devise a communication protocol, which enables controllers at different layers and domains to work collaboratively on bandwidth allocation by reading to the hierarchical NIB. We also present an improved traffic engineering algorithm by considering bandwidth and delay simultaneously, to maximize the network utilization while respecting max-min fairness. Experiments on a 717-switches 5-domain network topology demonstrate that our proposal could drive the link utilization ratio to more than 85%.