SDN candidate and protection path selection for link failure protection in hybrid SDNs

Software -Defined Networks (SDNs) have emerged as significant frameworks for enhancing the network flexibility. Currently, the migration from legacy IP networks to pure SDNs promotes the development of hybrid SDNs. However, the inevitable link failures will damage the network reliability. Therefore, this paper focuses on upgrading the legacy routers to SDN switches with minimal deployment overhead for protecting against all link failures, and selecting appropriate protection paths with the routing flexibility of these switches, thus improving the network performance and resilience. Firstly, we propose the heuristic SCS_LN algorithm for SDN Candidate Selection (SCS) that narrows the selection range of SDN candidate nodes through the link protection difficulty and selects the upgraded nodes based on the node protection capability. Secondly, we develop PPS_PM algorithm with the weight -based selection rule for adaptive Protection Path Selection (PPS), which takes interactive path parameters into account, such as Protection Path Length (PPL) and Maximum Link Utilization (MLU). Finally, extensive simulation experiments on diverse network topologies with various parameters are conducted to demonstrate that our proposed algorithms save up to 12.58% of the SDN switch deployment, and gain up to 12.15% and 7.34% improvement of the average PPL and MLU over existing algorithms, respectively.