Incremental SDN-enabled switch deployment for hybrid software-defined networks

Software-defined networking (SDN) is a promising technique that has reshaped the landscape of network management. By providing simplified, cost-effective management, SDN has been envisioned as the next-generation network paradigm. However, due to economic, organizational, and technical challenges, replacing all conventional switches in current operational networks by SDN-enabled switches is impractical in the short term. It thus is desirable to deploy SDN-enabled switches into existing networks incrementally, and such a network consisting of SDN-enabled switches and conventional switches is referred to as a hybrid SDN network. The incremental deployment of SDN-enabled switches is challenging because the number of conventional switches that can be replaced is typically limited, due to budget constraints or operational network stability concerns, yet the impact of the deployment should be maximized. In this paper, we deal with the SDN-enabled switch placement problem with the aim to maximize system performance, given K switches to be replaced, for which we first propose heuristics by replacing conventional switches one by one iteratively. We then devise scalable algorithms that replace multiple switches, instead of a single switch, in each iteration. We finally evaluate the performance of the proposed algorithms based on real and synthetic network topologies. Experimental results demonstrate that the proposed algorithms are promising and exhibiting high scalability.