Comparison of Routing Algorithms with Static and Dynamic Link Cost in Software Defined Networking (SDN)

In this paper, we compared the existing routing algorithms in the context of Software Defined Networking (SDN), where a logically centralized controller acquires the global view of the network, selects the paths using a routing algorithm, and installs the determined routing rules to the switches. We divided existing routing algorithms (RA) into three categories: RA with static link cost (RA-SLC), RA with dynamic link cost (RA-DLC), and RA with dynamic link cost and minimum interference (RA-DLCMI). We then implemented various routing algorithms from each category using RYU SDN controller and compared their performances on Mininet emulator. For the network state information (NSI) needed for the routing algorithms, we first consider the idealistic case where the accurate NSI is available, as assumed in the literature. However, since this is not possible in practice, we also considered the practical case where the controller periodically collects the NSI with some inaccuracy. In our experiments, we observed that while RA-DLC and RA-DLCMI give similar performance, RA-SLC falls behind of RA-DLC and RA-DLCMI in the number of accepted flows and total throughput. We also showed that the performance of every algorithm is adversely affected from the inaccuracy of NSI, calling for further research on developing effective NSI collection methods.