Virtualized Controller Placement for Multidomain Optical Transport Networks Optical multidomain transport networks are often controlled by a hierarchical distributed architecture of controllers. Optimal placement of these controllers is very important for their efficient management and control. Traditional SDN controller placement methods focus mostly on controller placement in datacenter networks. But the problem of virtualized controller placement for multidomain transport networks needs to be solved in the context of geographicallydistributed heterogeneous multidomain networks. In this context, Edge Datacenters have enabled network operators to place virtualized controller instances closer to users, besides providing more candidate locations for controller placement. In this study, we propose a dynamic controller placement method for optical transport networks that considers the heterogeneity of optical controllers, resource limitations at edge hosting locations, latency requirements, and costs. Simulation studies considering practical scenarios show significant cost savings and delay reductions compared to standard placement approaches.

Minimizing MultiController Deployment Cost in SoftwareDefined Networking Aiming at various issues, such as performance, loadbalance and robustness, of SoftwareDefined Networking (SDN) controller cluster, several deployment strategies have been proposed. As a supplement, our work delivers a costeffective multicontroller deployment strategy in terms of economic benefits. In this paper, we formalize a Costoptimized MultiController Deployment (COMCD) problem by concerning the controllerxe2x80x99s deployment cost and the network servicexe2x80x99s delay cost. Meanwhile, we characterize the communication between the controller and the switch using a queuing system, and design an algorithm to determine the optimal deployment in the specified environment. Simulation results validate that the proposed algorithm can always obtain a deployment solution which minimizes the economic cost of the entire SDN network. This work aims at being a useful primer to provide insights regarding the economic impact of multiple controllers in the realistic SDN deployment, so that network owners plan their investments more rationally.