Proactive versus reactive revisited: IPv6 routing for Low Power Lossy Networks

In this paper, we revisit the reactive versus proactive debate, however in the context of Low Power Lossy Networks (LLNs). We investigate the suitability of two protocols: RPL (proactive), standardized by the IETF for use in LLNs, and LOAD-ng (reactive) recently being discussed in the IETF MANET working group as a promising reactive candidate protocol with deployment in LLNs. We provide a detailed and impartial simulation study that is based on two real deployment topologies and realistic traffic profiles provided by the industry. We investigate typical routing requirements, and delve into metrics of interest, such as overhead for multicast traffic, path quality, end-to-end delay for alert traffic, and memory requirements. The results of this study suggest that a proactive protocol, such as RPL, is the best candidate for most deployment scenarios. Our analysis also helped identify areas of concern and provide suggestions for further improvements.