Minimizing flow statistics collection cost of SDN using wildcard requests

In a software defined network (SDN), the control plane needs to frequently collect flow statistics measured at the data plane switches for different applications, such as traffic engineering, flow re-routing, and attack detection. However, existing solutions for flow statistics collection may result in large bandwidth cost in the control channel and long processing delay on switches, which significantly interfere with the basic functions such as packet forwarding and route update. To address this challenge, we propose a Cost-Optimized Flow Statistics Collection (CO-FSC) scheme using wildcard-based requests. We prove that the CO-FSC problem is NP-Hard and present a rounding-based algorithm with an approximation factor f, where f is the maximum number of switches visited by each flow. Moreover, our CO-FSC problem is extended to the general case, in which only a part of flows in a network need to be collected. The extensive simulation results show that the proposed algorithms can reduce the bandwidth overhead by over 41% and switch processing delay by over 45% compared with the existing solutions.