Introduction of Security in the Controller Placement Problem

Software-Defined Networking (SDN) is a networking paradigm that decouples the forwarding plane from the control plane. The orchestration of the control plane is a critical challenge in SDN deployment, addressed by the Controller Placement Problem (CPP). At the same time, securing the control plane is another major concern, as controllers are primary targets for attacks. To address this, mechanisms such as consensus protocols are implemented. However, these mechanisms introduce additional costs, such as increased controller response time, which can render them unsuitable for delay-sensitive applications. This work introduces the concept of integrating security constraints into the CPP to analyze the impact of such mechanisms on network performance, particularly in terms of response time. As a case study, a consensus mechanism is examined, and an efficient algorithm is proposed to optimize the problem. The proposed algorithm is compared against a solver-generated solution on the real network topology GEANT. Results demonstrate that the proposed algorithm is time-efficient and with a gap of at most 10% compared to the optimal one. It permits to analyze the trade-off and show that it is possible to implement security mechanisms, such as consensus, at the control plane level and still meet performance constraints for delay-sensitive applications, provided that a certain level of security is accepted.