In Software-Defined Networking (SDN), the control and data planes are decoupled, leading to a more programmable and efficient network management. In this paper, the controller placement problem in SDN is addressed, jointly with the problem of exploring a high-availability tree subgraph, in order to support delay and availability requirements between the switches and the controllers. We consider that each switch connects to a primary and to a backup controller. We formulate the joint optimization model as an integer linear programming model (ILP), and propose a heuristic method when the exact model becomes impractical. Furthermore, we compare two ILP formulations, and we also compare the controller redundancy solutions with those considering path redundancy alone.

在软件定义网络 (SDN) 中，控制平面和数据平面分离，从而实现更可编程和更高效的网络管理。在本文中，解决了 SDN 中的控制器放置问题，以及探索高可用性树子图的问题，以支持交换机和控制器之间的延迟和可用性要求。我们认为每个交换机都连接到一个主控制器和一个备用控制器。我们将联合优化模型制定为整数线性规划模型 (ILP)，并在精确模型变得不切实际时提出一种启发式方法。此外，我们比较了两种 ILP 公式，我们还将控制器冗余解决方案与单独考虑路径冗余的解决方案进行了比较。