AAMcon: an adaptively distributed SDN controller in data center networks

摘要

When evaluating the performance of distributed software-defined network (SDN) controller architecture in data center networks, the required number of controllers for a given network topology and their location are major issues of interest. To address these issues, this study proposes the adaptively adjusting and mapping controllers (AAMcon) to design a stateful data plane. We use the complex network community theory to select a key switch to place the controller which is closer to switches it controls in a subnet. A physically distributed but logically centralized controller pool is built based on the network function virtualization (NFV). And then we propose a fast start/overload avoid algorithm to adaptively adjust the number of controllers according to the demand. We performed an analysis for AAMcon to find the optimal distance between the switch and controller. Finally, experiments show the following results. (1) For the number of controllers, AAMcon can greatly follow the demand; for the placement location of controller, controller can respond to the request of switch with the least distance to minimize the delay between the switch and it. (2) For failure tolerance, AAMcon shows good robustness. (3) AAMcon requires less delay to the network with more significant community structure. In fact, there is an inverse relationship between the community modularity and average distance between the switch and controller, i.e., the average delay decreases when the community modularity increases.(4) AAMcon can achieve the load balance between the controllers. (5) Compared to DCP-GK and k-critical, AAMcon shows good performance.