Performance evaluation and optimization of neighbor discovery implementation over Contiki OS

IPv6 Neighbor Discovery (ND) based on RFC 4861 is not designed for non-transitive wireless links. Its heavy use of multicast transmission makes it inefficient and sometimes impractical for IPv6 over Low power Wireless Personal Area Networks (6LoWPAN). Recently, further optimizations have been proposed by Internet Engineering Task Force (IETF) to make ND more suitable for 6LoWPAN. In this paper, we provide an implementation of the most prominent features of the new optimized ND protocol based on RFC 6775 over the Contiki operating system (OS). First, we evaluate the performance of the basic non-optimized IPv6 ND protocol, and analyze its originally implemented functions to set up a good foundation for our implementation and to maintain compatibility. Then, we implement the new optimized Router Solicitation (RS) and Router Advertisement (RA) messaging scheme that reduces the effect of multicasting and unfavorable periodic RA messages. Our results show that the optimized RFC 6775 ND protocol reduces the number of the exchange radio messages in the network by 60-80%. Such optimization alleviates network congestion and saves more power.