Achieving efficient routing in constrained networks with unidirectional links through Software Defined Networking

Routing protocols targeting low power wireless networks commonly assume they operate over bidirectional links, ignoring the possibility of routing over unidirectional links. However, experiments show this is not always the case since device heterogeneity and environmental factors can lead to asymmetric links. Our main contribution consists on the design of algorithms that are capable of using unidirectional links to route packets. We took on a Software Defined Networking approach, as its centralized feature allows for a generic and efficient solution to the challenge of routing over unidirectional links. We conducted experiments to investigate the trade-offs between fully using all available links in the network and the additional overhead required in maintaining unidirectional routes. The gist of our findings is that unidirectional links must be considered during protocol design, while actually leveraging such links for routing tends to improve network metrics, especially if the links are long-reaching.