doiSerbia

Correctness of the Chord protocol

Marinković Bojan (Mathematical Institute of the Serbian Academy of Sciences and Arts, Beograd, Serbia)
Ognjanović Zoran (Mathematical Institute of the Serbian Academy of Sciences and Arts, Beograd, Serbia)
Glavan Paola (Faculty of Mechanical Engineering and Naval Architecture, University of Zagreb, Zagreb, Croatia)
Kos Anton (Faculty of Electrical Engineering, University of Ljubljana, Ljubljana, Slovenia)
Umek Anton (Faculty of Electrical Engineering, University of Ljubljana, Ljubljana, Slovenia)

Internet of Things (IoT) can be seen as a cooperation of various devices with limited performances that participate in the same system. IoT devices compose a distributed architecture system. The core of every IoT system is its discovery and control services. To realize such services, some authors used the developed solutions from the different domains. One such solution is the Chord protocol, one of the first, the simplest and the most popular distributed protocols. Unfortunately, the application of the Chord protocol was realized using the correctness of the Chord protocol for granted, or by the very hard assumptions. In this paper we prove the correctness of the Chord protocol using the logic of time and knowledge with the respect to the set of possible executions, called regular runs. We provide the deterministic description of the correctness of the Chord protocol and consider Chord actions that maintain ring topology while the nodes can freely join or leave.

Keywords: IoT, DHT, Chord, correctness, temporal logic, epistemic logic

Projects of the Serbian Ministry of Education, Science and Technological Development, Grant no. ON174026 and Grant no. III44006