Optimized neighbor discovery for 6LoWPANs: Implementation and performance evaluation

Abstract

In this paper, we provide an implementation and thorough performance evaluation of the RFC 6775 optimized Neighbor Discovery (ND) protocol. RFC 6775 was developed by the Internet Engineering Task Force (IETF) to standardize IPv6 neighbor discovery over Low power Wireless Personal Area Networks (6LoWPAN). First, we investigate and analyze the basic RFC 4861 ND, developed for general networks running IPv6. We explain why such a basic ND protocol is inefficient and sometimes impractical for 6LoWPANs. This is because of (i) its heavy use of multicast transmission, and (ii) being originally not designed for IEEE 802.15.4 non-transitive wireless environments in which all nodes are not necessarily within range of each other. Second, we overview and explain the optimized RFC 6775 ND. Third, we implement such an optimized ND on the widely used Contiki OS. Finally, we evaluate the performance of our implementation of the optimized ND protocol and compare it with the current RFC 4861-based ND implementation. Our results show that the implementation of the optimized ND protocol reduces the number of the exchanged control messages in the network by up to 70% compared to RFC 4861-based ND. Moreover, multicast ND control messages are reduced by 30% to 70%. We show that the RFC 6775 optimizations alleviate network congestion, enhance the delivery ratio of ND packets to almost 100% and save more power. Even in the case of variable node reachability, the optimized ND protocol shows a better performance compared to the RFC 4861 basic ND.