The P2P-RPL routing protocol for IPv6 sensor networks: Testbed experiments

An important part of the foreseen Internet of Things consists in wireless sensor networks running adapted IPv6 protocols. Since the way sensors are scattered is generally unplanned and may evolve with time, a routing protocol is needed in order to provide paths across such networks. Efforts towards standardizing RPL, a routing protocol targeting sensor networks, have thus recently taken place. This paper analyzes some fundamental tradeoffs inherent to RPL, which enables the protocol to require smaller routing state than most other routing protocols. However, these tradeoffs are on the other hand an issue in several Home and Building Automation use-cases, which require sensor to sensor communication - aside of communication from sensor to sink. RPL basically requires that all communication paths go through a central router (the sink), which provides severely suboptimal paths in these use-cases. In order to alleviate this, an extension of the protocol is proposed based on a reactive scheme that can provide shorter paths on-demand, without necessarily going through the sink. This paper then evaluates this extension via experiments on a sensor network testbed running RPL and its extension over IEEE 802.15.4 radio. These experiments confirm that the extension provides substantially shorter paths.