Salience-Based Distributed Controllers Placement in Software Defined Networks

Software defined networking (SDN) and network function virtualization (NFV) technologies enable us to create, manage and operate network services more flexibly. Distributed placement of controllers reduces the response time of control operations and distributes load of controllers. Many prior studies have investigated several algorithms of controller placement in networks. However, those algorithms take longer computation time and require a lot of information. Thus, they are difficult to use, especially in large networks. To simplify the controller placement problem, we propose a salience-based approach, where the salience value of a link is defined as the number of shortest path trees that traverse the link. We found that by placing controller functions on the nodes having many high-salient links, the controller placement approach shortens the length of control paths and keeps controllers' load low even in large networks.