Controller Placement in Software-defined Satellite Networks

Software-defined satellite networks (SDSN) move the control logic off the forwarding devices and into the external controller, which achieves network flexibility, programmability, evolvability, and visibility. The controller placement in SDSN, as the foundation of SDSN implementation, has been seldom studied. In this paper, we proposed a three-layer hierarchical controller architecture for software-defined geostationary earth orbit/low earth orbit (GEO/LEO) satellite networks. Specifically, network operations control center (NOCC) is deployed as super controller, GEO satellites are domain controllers, and a part of LEO satellites are slave controllers. Based on this architecture, we further proposed a slave controller selection strategy to facilitate cost reduction and stability enhancement. The feasibility of this controller architecture is validated in terms of the maximum switch to controller and controller to controller delays. Besides, the influences of service request distribution on these two control delays are analyzed.