A Novel and Efficient Link Discovery Mechanism in SDN

Software Defined Networking (SDN) is one of the hottest technology in the network field today. SDN divides the network into the data plane and control plane. The control plane needs to monitor the underlying network and provides an up-to-date global network view for the applications running on it by topology discovery. The most important one in topology discovery is link discovery. Based on the characteristics of SDN, most implementations use OpenFlow Discovery Protocol (OFDP), which is simple but wastes a lot of bandwidth resources on the control plane. In this paper, we divide link discovery into two stages and propose some modifications and extensions based on OFDP for the second stage. Our approach divides the initial network view into multiple paths, and each path contains multiple links. At the cost of sacrificing a small amount of flow table resources, our approach enables one probe packet to be responsible for the detection of a path, thereby significantly reducing the number of sent and received probe packets, and reducing the consumption of control plane's bandwidth resources.