Analysis of RPL Objective Functions with Security Perspective

Abstract

The IPv6 Routing Protocol for Low Power Lossy Networks (RPL) is one of the standardized routing protocols for lossy networks consisting of resource-constrained Internet of Things (IoT) devices. RPL allows to use different objective functions based on different routing metrics such as expected transmission count (ETX), hop count, and energy to determine effective routes. In the literature, the performance of two objective functions namely Objective Function Zero (OF0), Minimum Rank with Hysteresis Objective Function (MRHOF) are evaluated thoroughly, since they are accepted as standard objective functions in RPL. However their performance under attack has not been evaluated comprehensively yet. Although RPL has defined some specifications for its security, it is still vulnerable to insider attacks, which could dramatically affect the network performance. Therefore, this study investigates how the performance of objective functions are affected by RPL specific attacks. Version number, DIS flooding, and worst parent attacks are analyzed by using the following performance metrics: packet delivery ratio, overhead, latency, and power consumption. Moreover, how they are affected by the number of attackers in the network are analyzed. To the best of the authors' knowledge, this is the first study that comprehensively explores RPL objective functions on networks under attacks.