Section: New Results

Parametric verification of time synchronization protocols

Participants : Ocan Sankur, Jean-Pierre Talpin.

In the context of the associate-team COMPOSITE, we addressed the verification one of the apparently simplest services in any loosely-coupled distributed system : the time service. In many instances of such systems, traffic and power grids, banking and transaction networks, the accuracy and reliability of this service are critical.

In the instance of sensor networks, it is of particular interest to verify the robustness of such protocols to variations caused by the environment. Lake of power, varying temperatures, imperfect hardware, are sources of local drifts and jitters in time measurement that require self-calibration and fault-tolerance to reach distributed consensus. FTSP, the flooding time synchronization protocol, provides fault-tolerance and enables time synchronization.

In [16], we introduce an environment abstraction technique and an incremental model checking technique to prove that FTSP eventually elects a leader for any network topology and configuration (anonymized identifiers), up to a diameter N=7 (with synchronous communications) and N=5 (desynchronized communications), resulting in significant improvements over previous results.