Multipoint-to-point and broadcast in RPL

Recent trends in Wireless Sensor Networks (WSNs) have suggested converging to such being IPv6-based. To this effect, the Internet Engineering Task Force has chartered a Working Group to develop a routing protocol specification, enabling IPv6-based multi-hop Wireless Sensor Networks. This routing protocol, denoted RPL, has been under development for approximately a year, and this paper takes a critical look at the state of advancement hereof: it provides a brief algorithmic description of the protocol, and discusses areas where - in the authors view - further efforts are required in order for the protocol to become a viable candidate for general use in WSNs. Among these areas is the lack of a proper broadcast mechanism. This paper suggests two such broadcast mechanisms, both aiming at (i) exploiting the existing routing state of RPL, while (ii) requiring no additional state maintenance, and studies the performance of RPL and of these suggested mechanisms.