Integrating Mobility in RPL

Abstract

In the last years the Low Power and Lossy Networks (LLNs), have become more and more popular. LLNs are inherently dynamic - nodes move, associate, disassociate or experience link perturbations. In order to meet the specific requirements for LLNs, the IETF has developed a new routing protocol - IPv6 Routing Protocol for Low-Power and Lossy Networks (RPL) that routes packets inside LLNs. RPL has to work in such dynamic environment and mechanisms that can mitigate such conditions are suggested in the standard such as Neighbor Unreachability Detection or Bidirectional Forwarding Detection. In this article, we show that such mechanisms fail to prevent serious node disconnection, which significantly increases the packet loss and leads to severe underachievements. To provide RPL the ability to mitigate network dynamics generated by node disconnection, we therefore propose a new cross-layer protocol operating at layers 2 and 3 known as Mobility-Triggered RPL (MT-RPL). MT-RPL benefits from the X-Machiavel MAC protocol that favors medium access to mobile devices. X-Machiavel has been extended to trigger RPL operations in order to maintain efficient connectivity with the network. MT-RPL is evaluated together with Neighbor Unreachability Detection and Bidirectional Forwarding Detection through an extensive simulation campaign. Results show that MT-RPL significantly reduces the disconnection time, which increases the packet delivery ratio and reduces energy consumption per data packet.