Software-Defined Network Design driven by Availability Requirements

In Software Defined Networking (SDN), the controller locations are mainly constrained by delays between switches and controllers, and between the controllers themselves. In addition to the delay requirements, the availability of the connections between switches and controllers is also a key issue for control plane performance. Here, we explore the idea of having a spanning tree substructure called the spine, whose links can be upgraded to have high availability in order to support availability requirements for the control paths (routing paths between switches and controllers). We formulate an optimization model of the joint controller placement and spine design problem for SDN networks, under delay, availability and path redundancy requirements. Numerical results are presented showing the trade-offs between the number of controllers, delay requirements and upgrade cost.