  Topology discovery is one of the most critical tasks of Software-Defined
Network (SDN) controllers. Current SDN controllers use the OpenFlow Discovery
Protocol (OFDP) as the de-facto protocol for discovering the underlying network
topology. In a previous work, we have shown the functional, performance and
security limitations of OFDP. In this paper, we introduce and detail a novel
protocol called secure and efficient OpenFlow Discovery Protocol sOTDP. sOFTDP
requires minimal changes to OpenFlow switch design, eliminates major
vulnerabilities in the topology discovery process and improves its performance.
We have implemented sOFTDP as a topology discovery module in Floodlight for
evaluation. The results show that our implementation is more secure than OFDP
and previous security workarounds. Also, sOFTDP reduces the topology discovery
time several orders of magnitude compared to the original OFDP and existing
OFDP improvements.
