Rescue‐Sink: Dynamic sink augmentation for RPL in the Internet of Things

Abstract

AbstractThe Internet of Things (IoT) is largely built on the interconnection of low‐power networked devices, generally referred to as low‐power and lossy networks (LLNs). The prime routing protocol designed over IPv6, named routing protocol for LLNs (RPL), presents the main effort to standardize an IPv6‐based routing protocol for all LLNs. Routing protocol for LLNs has gained significant prominence in IoT research due to its flexibility in adapting to different topologies and could run in agnostic replicas over the same network to serve different applications. However, as RPL is based on virtualizing a tree topology, many challenges ensue in scaling with network traffic and diverse traffic patterns in the IoT. The current RPL standard focus on operation under a single sink, toward which all traffic flows, and thereby its survivability determines the lifetime of the IoT network. However, it mentions briefly in its RFC6550, the using of multiple roots. However, it does not study when, where, and how deploying multiple roots. In this paper, we propose a dynamic Rescue Sink protocol, which actively monitors the performance of IoT nodes in a given RPL network and introduces a dynamic mechanism for mitigating RPL performance by introducing new sinks when needed. We define a suffering index computed over intervals by RPL nodes in a decentralized approach, which monitors their tendency to yield high traffic load without inducing control overhead. Furthermore, our Rescue Sink protocol is designed in line with the RPL standard, and we elaborate on all the components to integrate with the standard. We present a thorough evaluation of our Sink Rescue protocol, using the Cooja simulator over the Contiki OS, most prevalently used in IoT devices. We demonstrate the performance improvements in terms of energy consumption and data delivery.