Master thesis : SNAC Compliance and Augmentation of the OpenThread Border Router

Abstract

The fast expansion of the Internet of Things industry has created the need for a low-power, IPv6-based networking technology specifically designed for battery-powered devices, a solution provided by the Thread protocol. This thesis focuses on OpenThread, the open source implementation of this protocol developed by Google, and more particularly on the analysis and enhancement of the OpenThread Border Router (OTBR), the gateway responsible for connecting the Thread network to other IP networks. This project is divided into four main parts. A dedicated laboratory test environment is deployed for the successful realization of the tasks described below. One of the primary goals of this thesis is to analyze and study the conformity of the implementation of the OTBR with the SNAC draft specification, defined by the IETF which describes how to link a stub network such as a Thread network to a standard Wi-Fi network. As a result, this work confirms the OTBR’s compliance as it successfully supports all core services required by SNAC. Secondly, the project focuses on the development of an IPFIX functionality for the OTBR as an internal additional service. This involves the definition of observation points within the observation domain and the creation of a metering process responsible for measuring flow statistics in the OpenThread core. Simultaneously, an exporting process service is implemented in the OTBR source code to transmit these records to the IPFIX collector as IPFIX messages. As a continuation of the previous objective, this thesis also involves the deployment and configuration of a IPFIX collector tailored specifically for the IPFIX messages send by the OTBR IPFIX exporter module which includes some Thread network specific statistics. The solution relies on pmacct combined with Telegraf for collecting and aggregating the IPFIX messages and ingesting the flow data into a PostgreSQL database configured with the TimescaleDB extension. Furthermore, Grafana is used to visualize and monitor the collected flow information stored in the database. As a result, a complete IPFIX solution is obtained for the OTBR, which allows to perform network troubleshooting, unusual device behavior detection and performance analysis of the Thread network. Finally, the thesis also focuses on the development of an Time Exceeded Detector functionality for the OTBR as an internal additional service. This development work involves the implementation of a simulation mechanism which predicts the path taken by every packet coming from the infrastructure network using topology information obtained in the OTBR via OpenThread mesh diagnostics messages and the Dijkstra’s algorithm. If the hop limit of such a packet is detected to expire before reaching the destination, an ICMPv6 time exceeded message is sent back to the sender of the original packet. As a result, this prevents injecting useless packets into the Thread network and also enables the traceroute functionality in Thread.