Software-Defined Networking (SDN) is becoming prevalently in recent years. Practical SDN (e.g., production Software-defined Wide Area Network) deployments leverage multiple commercial controllers, which partitions the network into multiple domains, and each domain uses a dedicated controller. Commercial controllers are usually used for reliability and fully post-sales supports. However, using a single type of SDN controllers can compromise the whole network if the attacker can exploit its vulnerabilities. In this paper, we consider this security issue and present the Secure and Cost-effective Controller Deployment (SCCD) problem. The SCCD problem aims to replace a few controllers with different types of commercial SDN controllers, which satisfies the security requirement at a minimal cost. The complexity of the SCCD problem comes from common vulnerabilities shared among different types of SDN controllers and attack propagations among network domains. We prove the non-deterministic polynomial-time hardness (NP-hardness) of the problem and propose the Baguette algorithm to efficiently solve the problem. Baguette judiciously chooses and replaces controllers for critical domains with selected types of commercial SDN controllers. Simulation results show that Baguette can achieve comparable performance to the Optimal solution and can stably achieve up to 12.6x security enhancement compared with the single controller type deployment and reduce to 11.1% cost of the securest deployment.

近年来，软件定义网络（SDN）越来越流行。实际的SDN（例如，生产软件定义的广域网）部署利用多个商业控制器，这些控制器将网络划分为多个域，并且每个域都使用一个专用控制器。商用控制器通常用于可靠性和全面的售后支持。但是，如果攻击者可以利用它的漏洞，则使用单一类型的SDN控制器可能会危害整个网络。在本文中，我们考虑了此安全问题，并提出了安全且具有成本效益的控制器部署（SCCD）问题。SCCD问题旨在用不同类型的商用SDN控制器替换一些控制器，从而以最小的成本满足安全性要求。SCCD问题的复杂性来自不同类型的SDN控制器之间共享的常见漏洞以及网络域之间的攻击传播。我们证明了问题的非确定性多项式时间硬度（NP-hardness），并提出了Baguette算法来有效解决问题。Baguette会明智地为关键域选择控制器，并将其替换为选定类型的商业SDN控制器。仿真结果表明，法式长棍面包 与单控制器类型的部署相比，可以达到与Optimal解决方案相当的性能，并且可以稳定地实现高达12.6倍的安全性增强，并可以将最安全的部署的成本降低到11.1％。